Publications by authors named "Kirsten Raun"

42 Publications

Evaluation of VGF peptides as potential anti-obesity candidates in pre-clinical animal models.

Peptides 2021 Feb 24;136:170444. Epub 2020 Nov 24.

Novo Nordisk Research Center Seattle Inc., 530 Fairview Ave N, Seattle, WA, 98109, USA. Electronic address:

VGF is a peptide precursor expressed in neuroendocrine cells that is suggested to play a role in the regulation of energy homeostasis. VGF is proteolytically cleaved to yield multiple bioactive peptides. However, the specific actions of VGF-derived peptides on energy homeostasis remain unclear. The aim of the present work was to investigate the role of VGF-derived peptides in energy homeostasis and explore the pharmacological actions of VGF-derived peptides on body weight in preclinical animal models. VGF-derived peptides (NERP-1, NERP-2, PGH-NH, PGH-OH, NERP-4, TLQP-21, TLQP-30, TLQP-62, HHPD-41, AQEE-30, and LQEQ-19) were synthesized and screened for their ability to affect neuronal activity in vitro on hypothalamic brain slices and modulate food intake and energy expenditure after acute central administration in vivo. In addition, the effects of NERP-1, NERP-2, PGH-NH, TLQP-21, TLQP-62, and HHPD-41 on energy homeostasis were studied after chronic central infusion. NERP-1, PGH-NH, HHPD-41, and TLQP-62 increased the functional activity of hypothalamic neuronal networks. However, none of the peptides altered energy homeostasis after either acute or chronic ICV administration. The present data do not support the potential use of the tested VGF-derived peptides as novel anti-obesity drug candidates.
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http://dx.doi.org/10.1016/j.peptides.2020.170444DOI Listing
February 2021

FGF21 regulates hepatic metabolic pathways to improve steatosis and inflammation.

Endocr Connect 2020 Aug;9(8):755-768

Global Obesity and Liver Disease Research, Novo Nordisk A/S, Måløv, Denmark.

The prevalence of non-alcoholic fatty liver disease (NAFLD) has increased dramatically worldwide and, subsequently, also the risk of developing non-alcoholic steatohepatitis (NASH), hepatic fibrosis, cirrhosis and cancer. Today, weight loss is the only available treatment, but administration of fibroblast growth factor 21 (FGF21) analogues have, in addition to weight loss, shown improvements on liver metabolic health but the mechanisms behind are not entirely clear. The aim of this study was to investigate the hepatic metabolic profile in response to FGF21 treatment. Diet-induced obese (DIO) mice were treated with s.c. administration of FGF21 or subjected to caloric restriction by switching from high fat diet (HFD) to chow to induce 20% weight loss and changes were compared to vehicle dosed DIO mice. Cumulative caloric intake was reduced by chow, while no differences were observed between FGF21 and vehicle dosed mice. The body weight loss in both treatment groups was associated with reduced body fat mass and hepatic triglycerides (TG), while hepatic cholesterol was slightly decreased by chow. Liver glycogen was decreased by FGF21 and increased by chow. The hepatic gene expression profiles suggest that FGF21 increased uptake of fatty acids and lipoproteins, channeled TGs toward the production of cholesterol and bile acid, reduced lipogenesis and increased hepatic glucose output. Furthermore, FGF21 appeared to reduce inflammation and regulate hepatic leptin receptor-a expression. In conclusion, FGF21 affected several metabolic pathways to reduce hepatic steatosis and improve hepatic health and markedly more genes than diet restriction (61 vs 16 out of 89 investigated genes).
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http://dx.doi.org/10.1530/EC-20-0152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7424338PMC
August 2020

Effects of a selective long-acting amylin receptor agonist on alcohol consumption, food intake and body weight in male and female rats.

Addict Biol 2021 03 8;26(2):e12910. Epub 2020 May 8.

Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.

Alcohol use disorder is a complex neuropsychiatric disorder affecting both males and females worldwide; however, the efficacy of current pharmacotherapies varies. Recent advances show that gut-brain peptides, like amylin, regulate alcohol behavioural responses by acting on brain areas involved in alcohol reward processes. Thus, the activation of amylin receptors (AMYRs) by salmon calcitonin (sCT) decreases alcohol behaviours in male rodents. Given that sCT also activates the sole calcitonin receptor (CTR), studies of more selective AMYR agonists in both male and female rodents are needed to explore amylinergic modulation of alcohol behaviours. Therefore, we investigated the effects of repeated administration of a selective long-acting AMYR agonist, NNC0174-1213 (AM1213), on alcohol, water and food intake, as well as body weight in male and female rats chronically exposed to alcohol. We confirm our previous studies with sCT in male rats, as repeated AM1213 administration for 2 weeks initially decreased alcohol intake in both male and female rats. However, this reduction ceases in both sexes on later sessions, accompanied by an increase in males. AM1213 reduced food intake and body weight in both male and female rats, with sustained body weight loss in males after discontinuation of the treatment. Moreover, AM1213 administration for 3 or 7 days, differentially altered dopamine, serotonin and their metabolites in the reward-related areas in males and females, providing tentative, but different, downstream mechanism through which selective activation of AMYR may alter alcohol intake. Our data provide clarified insight into the importance of AMYRs for alcohol intake regulation in both sexes.
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http://dx.doi.org/10.1111/adb.12910DOI Listing
March 2021

Semaglutide lowers body weight in rodents via distributed neural pathways.

JCI Insight 2020 03 26;5(6). Epub 2020 Mar 26.

Institute of Experimental Medicine Hungarian Academy of Sciences, Budapest, Hungary.

Semaglutide, a glucagon-like peptide 1 (GLP-1) analog, induces weight loss, lowers glucose levels, and reduces cardiovascular risk in patients with diabetes. Mechanistic preclinical studies suggest weight loss is mediated through GLP-1 receptors (GLP-1Rs) in the brain. The findings presented here show that semaglutide modulated food preference, reduced food intake, and caused weight loss without decreasing energy expenditure. Semaglutide directly accessed the brainstem, septal nucleus, and hypothalamus but did not cross the blood-brain barrier; it interacted with the brain through the circumventricular organs and several select sites adjacent to the ventricles. Semaglutide induced central c-Fos activation in 10 brain areas, including hindbrain areas directly targeted by semaglutide, and secondary areas without direct GLP-1R interaction, such as the lateral parabrachial nucleus. Automated analysis of semaglutide access, c-Fos activity, GLP-1R distribution, and brain connectivity revealed that activation may involve meal termination controlled by neurons in the lateral parabrachial nucleus. Transcriptomic analysis of microdissected brain areas from semaglutide-treated rats showed upregulation of prolactin-releasing hormone and tyrosine hydroxylase in the area postrema. We suggest semaglutide lowers body weight by direct interaction with diverse GLP-1R populations and by directly and indirectly affecting the activity of neural pathways involved in food intake, reward, and energy expenditure.
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http://dx.doi.org/10.1172/jci.insight.133429DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7213778PMC
March 2020

Salmon calcitonin distributes into the arcuate nucleus to a subset of NPY neurons in mice.

Neuropharmacology 2020 05 5;167:107987. Epub 2020 Feb 5.

Institute of Veterinary Physiology, University of Zurich, CH-8057, Zurich, Switzerland. Electronic address:

The amylin receptor (AMY) and calcitonin receptor (CTR) agonists induce acute suppression of food intake in rodents by binding to receptors in the area postrema (AP) and potentially by targeting arcuate (ARC) neurons directly. Salmon calcitonin (sCT) induces more potent, longer lasting anorectic effects compared to amylin. We thus aimed to investigate whether AMY/CTR agonists target key neuronal populations in the ARC, and whether differing brain distribution patterns could mediate the observed differences in efficacy with sCT and amylin treatment. Brains were examined by whole brain 3D imaging and confocal microscopy following subcutaneous administration of fluorescently labelled peptides to mice. We found that sCT, but not amylin, internalizes into a subset of ARC NPY neurons, along with an unknown subset of ARC, AP and dorsal vagal motor nucleus cells. ARC POMC neurons were not targeted. Furthermore, amylin and sCT displayed similar distribution patterns binding to receptors in the AP, the organum vasculosum of the lamina terminalis (OVLT) and the ARC. Amylin distributed within the median eminence with only specs of sCT being present in this region, however amylin was only detectable 10 minutes after injection while sCT displayed a residence time of up to 2 hours post injection. We conclude that AMY/CTR agonists bind to receptors in a subset of ARC NPY neurons and in circumventricular organs. Furthermore, the more sustained and greater anorectic efficacy of sCT compared to rat amylin is not attributable to differences in brain distribution patterns but may more likely be explained by greater potency at both the CTR and AMY.
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http://dx.doi.org/10.1016/j.neuropharm.2020.107987DOI Listing
May 2020

Synthesis and evaluation of zirconium-89 labelled and long-lived GLP-1 receptor agonists for PET imaging.

Nucl Med Biol 2020 Mar - Apr;82-83:49-56. Epub 2019 Dec 4.

Global Research Technologies, Novo Nordisk A/S, Denmark. Electronic address:

Introduction: Lately, zirconium-89 has shown great promise as a radionuclide for PET applications of long circulating biomolecules. Here, the design and synthesis of protracted and long-lived GLP-1 receptor agonists conjugated to desferrioxamine and labelled with zirconium-89 is presented with the purpose of studying their in vivo distribution by PET imaging. The labelled conjugates were evaluated and compared to a non-labelled GLP-1 receptor agonist in both in vitro and in vivo assays to certify that the modification did not significantly alter the peptides' structure or function. Finally, the zirconium-89 labelled peptides were employed in PET imaging, providing visual verification of their in vivo biodistribution.

Methods: The evaluation of the radiolabelled peptides and comparison to their non-labelled parent peptide was performed by in vitro assays measuring binding and agonistic potency to the GLP-1 receptor, physicochemical studies aiming at elucidating change in peptide structure upon bioconjugation and labelling as well as an in vivo food in-take study illustrating the compounds' pharmacodynamic properties. The biodistribution of the labelled GLP-1 analogues was determined by ex vivo biodistribution and in vivo PET imaging.

Results: The results indicate that it is surprisingly feasible to design and synthesize a protracted, zirconium-89 labelled GLP-1 receptor agonist without losing in vitro potency or affinity as compared to a non-labelled parent peptide. Physicochemical properties as well as pharmacodynamic properties are also maintained. The biodistribution in rats shows high accumulation of radiolabelled peptide in well-perfused organs such as the liver, kidney, heart and lungs. The PET imaging study confirmed the findings from the biodistribution study with a significant high uptake in kidneys and presence of activity in liver, heart and larger blood vessels.

Conclusions And Advances In Knowledge: This initial study indicates the potential to monitor the in vivo distribution of long-circulating incretin hormones using zirconium-89 based PET.
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http://dx.doi.org/10.1016/j.nucmedbio.2019.11.006DOI Listing
December 2019

UCP1-independent glucose-lowering effect of leptin in type 1 diabetes: only in conditions of hypoleptinemia.

Am J Physiol Endocrinol Metab 2020 01 19;318(1):E72-E86. Epub 2019 Nov 19.

Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.

The possibility to use leptin therapeutically for lowering glucose levels in patients with type 1 diabetes has attracted interest. However, earlier animal models of type 1 diabetes are severely catabolic with very low endogenous leptin levels, unlike most patients with diabetes. Here, we aim to test glucose-lowering effects of leptin in novel, more human-like murine models. We examined the glucose-lowering potential of leptin in diabetic models of two types: streptozotocin-treated mice and mice treated with the insulin receptor antagonist S961. To prevent hypoleptinemia, we used combinations of thermoneutral temperature and high-fat feeding. Leptin fully normalized hyperglycemia in standard chow-fed streptozotocin-treated diabetic mice. However, more humanized physiological conditions (high-fat diets or thermoneutral temperatures) that increased adiposity - and thus also leptin levels - in the diabetic mice abrogated the effects of leptin, i.e., the mice developed leptin resistance also in this respect. The glucose-lowering effect of leptin was not dependent on the presence of the uncoupling protein-1 and was not associated with alterations in plasma insulin, insulin-like growth factor 1, food intake or corticosterone but fully correlated with decreased plasma glucagon levels and gluconeogenesis. An important implication of these observations is that the therapeutic potential of leptin as an additional treatment in patients with type 1 diabetes is probably limited. This is because such patients are treated with insulin and do not display low leptin levels. Thus, the potential for a glucose-lowering effect of leptin would already have been attained with standard insulin therapy, and further effects on blood glucose level through additional leptin cannot be anticipated.
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http://dx.doi.org/10.1152/ajpendo.00253.2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6985793PMC
January 2020

PYY(3-36) and exendin-4 reduce food intake and activate neuronal circuits in a synergistic manner in mice.

Neuropeptides 2019 Feb 19;73:89-95. Epub 2018 Nov 19.

Obesity Research, Novo Nordisk A/S, 2760 Måløv, Denmark.

Peptide YY(3-36) ((PYY(3-36)) and glucagon like peptide 1 (GLP-1) in combination reduce food intake and body weight in an additive or synergistic manner in animal models and in humans. Nevertheless, the mechanisms behind are not completely understood. The present study aims to investigate the effect of combining PYY(3-36) and the GLP-1 receptor agonist exendin-4 (Ex4) by examining acute food intake and global neuronal activation as measured by c-fos in C57BL/6 J mice. An additive reduction in food intake was found 1.5 h after s.c dosing with the combination of PYY(3-36) (200 μg/kg) and Ex4 (2.5 μg/kg). This was associated with a synergistic enhancement of c-fos reactivity in central amygdalar nucleus (CeA), rostral part of the mediobasal arcuate nucleus (ARH), supratrigeminal nucleus (SUT), lateral parabrachial nucleus (PB), area postrema (AP) and nucleus tractus solitarius (NTS) compared to vehicle, PYY(3-36) and Ex4 individually dosed mice. The regions activated by Ex4 individually and PYY(3-36) and Ex4 in combination resembled each other, but the combination group had a significantly stronger c-fos response. Twenty-five brain areas were activated by PYY(3-36) and Ex4 in combination compared to vehicle versus nine brain areas by Ex4 individually. No significant increase in c-fos reactivity was found by PYY(3-36) compared to vehicle dosed mice. The neuronal activation of ARH and the AP/NTS to PB to CeA pathway is important for appetite regulation while SUT has not previously been reported in the regulation of energy balance. As PYY(3-36) and Ex4 act on different neurons leading to recruitment of different signalling pathways within and to the brain, an interaction of these pathways may contribute to their additive/synergistic action. Thus, PYY(3-36) boosts the effect of Ex4 possibly by inducing less inhibition of neuronal activity leading to an enhanced neuronal activity induced by Ex4.
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http://dx.doi.org/10.1016/j.npep.2018.11.004DOI Listing
February 2019

FGF21 decreases food intake and body weight in obese Göttingen minipigs.

Diabetes Obes Metab 2019 03 20;21(3):592-600. Epub 2018 Nov 20.

Global Research, Måløv, Denmark.

Aims: The aim of this study was to assess the effect of FGF21 on food intake, body weight, body composition, glucose homeostasis, bone mineral density (BMD), cortisol and growth hormone (GH) in obese minipigs. The pig is a unique model for studying FGF21 pharmacology as it does not express UCP1, unlike mice and humans.

Methods: Twelve obese Göttingen minipigs with a mean body weight of 91.6 ± 6.7 kg (mean ± SD) received subcutaneously either vehicle (n = 6) or recombinant human FGF21 (n = 6) once daily for 14 weeks (0.1 mg/kg for 9.5 weeks and 0.3 mg/kg for 4.5 weeks).

Results: Treatment of obese minipigs with FGF21 led to a 50% reduction in food intake and a body weight loss of, on average, 18 kg compared to the vehicle group after 14 weeks of dosing. Glucose tolerance and insulin sensitivity, evaluated by intravenous glucose tolerance test, were significantly improved in the FGF21 group compared to the vehicle group at the end of the study. The plasma cortisol profile was unaffected by FGF21, whereas a small decrease in peak GH values was observed in the FGF21-treated animals after 7 to 9.5 weeks of treatment compared to the vehicle group. Whole-body BMD was not affected by 13 weeks of FGF21 dosing.

Conclusion: Despite a lack of UCP-1 in obese minipigs, FGF21 treatment induced a significant weight loss, primarily a result of reduction in food intake, with no adverse effect on BMD or plasma cortisol.
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http://dx.doi.org/10.1111/dom.13560DOI Listing
March 2019

Differential receptor selectivity of the FGF15/FGF19 orthologues determines distinct metabolic activities in mice.

Biochem J 2018 09 25;475(18):2985-2996. Epub 2018 Sep 25.

Global Drug Discovery, Novo Nordisk A/S, Måløv, Denmark

Fibroblast growth factors (FGF) 19, 21 and 23 are characterized by being endocrinely secreted and require co-receptor α-klotho or β-klotho (BKL) for binding and activation of the FGF receptors (FGFR). FGF15 is the rodent orthologue of human FGF19, but the two proteins share only 52% amino acid identity. Despite the physiological role of FGF21 and FGF19 being quite different, both lower blood glucose (BG) when administered to diabetic mice. The present study was designed to clarify why two human proteins with distinct physiological functions both lower BG in mice and if the mouse orthologue FGF15 has similar effect to FGF19 and FGF21. Recombinant human FGF19, -21 and a mouse FGF15 variant (C110S) were expressed and purified from While rhFGF19 (recombinant human fibroblast growth factor 19) and rhFGF21 (recombinant human fibroblast growth factor) bound FGFRs in complex with both human and mouse BKL, rmFGF15CS (recombinant mouse fibroblast growth factor 15 C110S) only bound the FGFRs when combined with mouse BKL. Recombinant hFGF21 and rhFGF19, but not rmFGF15CS, increased glucose uptake in mouse adipocytes, while rhFGF19 and rmFGF15CS potently decreased expression in rat hepatocytes. The lack of effect of rmFGF15CS on glucose uptake in adipocytes was associated with rmFGF15CS's inability to signal through the FGFR1c/mouse BKL complex. In mice, only rhFGF19 and rhFGF21 decreased BG while rmFGF15CS and rhFGF19, but not rhFGF21, increased total cholesterol. These data demonstrate receptor- and species-specific differential activity of FGF15 and FGF19 which should be taken into consideration when FGF19 is used as a substitute for FGF15.
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http://dx.doi.org/10.1042/BCJ20180555DOI Listing
September 2018

Hypothalamic oxidative stress and inflammation, and peripheral glucose homeostasis in Sprague-Dawley rat offspring exposed to maternal and postnatal chocolate and soft drink.

Nutr Diabetes 2018 07 19;8(1):44. Epub 2018 Jul 19.

Diabetes and Obesity Research, Novo Nordisk A/S, Måløv, 2760, Denmark.

Background: Predisposition to obesity and type 2 diabetes can arise during foetal development and in early postnatal life caused by imbalances in maternal nutritional overload. We aimed to investigate the effects of maternal and postnatal intake of chocolate and soft drink on hypothalamic anti-oxidative stress markers, inflammation and peripheral glucose homeostasis.

Methods: Pregnant Sprague-Dawley rats were fed ad libitum chow diet only (C) or with chocolate and high sucrose soft drink supplements (S). At birth, litter size was adjusted into 10 male offspring per dam. After weaning at 3 weeks of age, offspring from both dietary groups were assigned to either S or C diet, giving four groups until the end of the experiment at 26 weeks of age.

Results: Offspring exposed to maternal S had up-regulated hypothalamic anti-oxidative markers such as SOD2 and catalase at 3 weeks of age as an indication of oxidative stress. However, at 12 weeks of age these anti-oxidative markers tended to decrease while pro-inflammatory markers such as TNF and IL-1β became up-regulated of all offspring exposed to S diet during some point of their life. Thus, despite an increase in anti-oxidative stress response, offspring exposed to maternal S had a reduced ability to counteract hypothalamic inflammation. At the same time point, postnatal S resulted in increased adiposity, reduced glucose tolerance and insulin sensitivity with no effect on body weight. However, at 25 weeks of age, the impaired glucose tolerance was reversible to the response of the control regardless of increased adiposity and body weight pointing towards a compensatory response of the insulin sensitivity or insulin secretion.

Conclusion: Indications of hypothalamic oxidative stress was observed prior to the inflammatory response in offspring exposed to maternal S. Both maternal and postnatal S induced hypothalamic inflammation prior to increased weight gain and thus contributing to obese phenotype.
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http://dx.doi.org/10.1038/s41387-018-0051-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6053394PMC
July 2018

FGF21 decreases body weight without reducing food intake or bone mineral density in high-fat fed obese rhesus macaque monkeys.

Int J Obes (Lond) 2018 06 11;42(6):1151-1160. Epub 2018 Jun 11.

Division of Diabetes, Obesity & Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, 97006, USA.

Objective: Administration of FGF21 and FGF21 analogues reduce body weight; improve insulin sensitivity and dyslipidemia in animal models of obesity and in short term clinical trials. However potential adverse effects identified in mice have raised concerns for the development of FGF21 therapeutics. Therefore, this study was designed to address the actions of FGF21 on body weight, glucose and lipid metabolism and importantly its effects on bone mineral density (BMD), bone markers, and plasma cortisol in high-fat fed obese rhesus macaque monkeys.

Methods: Obese non-diabetic rhesus macaque monkeys (five males and five ovariectomized (OVX) females) were maintained on a high-fat diet and treated for 12 weeks with escalating doses of FGF21. Food intake was assessed daily and body weight weekly. Bone mineral content (BMC) and BMD were measured by DEXA scanning prior to the study and on several occasions throughout the treatment period as well as during washout. Plasma glucose, glucose tolerance, insulin, lipids, cortisol, and bone markers were likewise measured throughout the study.

Results: On average, FGF21 decreased body weight by 17.6 ± 1.6% after 12 weeks of treatment. No significant effect on food intake was observed. No change in BMC or BMD was observed, while a 2-fold increase in CTX-1, a marker of bone resorption, was seen. Overall glucose tolerance was improved with a small but significant decrease in HbA. Furthermore, FGF21 reduced concentrations of plasma triglycerides and very low density lipoprotein cholesterol. No adverse changes in clinical chemistry markers were demonstrated, and no alterations in plasma cortisol were observed during the study.

Conclusion: In conclusion, FGF21 reduced body weight in obese rhesus macaque monkeys without reducing food intake. Furthermore, FGF21 had beneficial effects on body composition, insulin sensitivity, and plasma triglycerides. No adverse effects on bone density or plasma cortisol were observed after 12 weeks of treatment.
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http://dx.doi.org/10.1038/s41366-018-0080-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6733401PMC
June 2018

Brief Communication: Plasma lipid oxidation predicts atherosclerotic status better than cholesterol in diabetic apolipoprotein E deficient mice.

Exp Biol Med (Maywood) 2017 Jan 24;242(1):88-91. Epub 2016 Jul 24.

3 Department of Diabetes Pharmacology, Novo Nordisk A/S, DK-2760 Maaloev, Denmark.

Increased levels of oxidative stress have been suggested to play a detrimental role in the development of diabetes-related vascular complications. Here, we investigated whether the concentration of malondialdehyde, a marker of lipid oxidation correlated to the degree of aortic plaque lesions in a proatherogenic diabetic mouse model. Three groups of apolipoprotein E knockout mice were studied for 20 weeks, a control, a streptozotocin-induced diabetic, and a diabetic enalapril-treated group. Enalapril was hypothesized to lower oxidative stress level and thus the plaque burden. Both diabetic groups were significantly different from the control group as they had higher blood glucose, HbA, total cholesterol, low-density lipoprotein, very low-density lipoprotein, together with a lower high-density lipoprotein concentration and body weight. Animals in the diabetic group had significantly higher plaque area and plasma malondialdehyde than controls. The two diabetic groups did not differ significantly in any measured characteristic. In summary, there was a positive correlation between plasma malondialdehyde concentration and aorta plaque area in apolipoprotein E knockout. Even though further investigation of the role of lipid oxidation in the development of atherosclerosis is warranted, these results suggest that biomarkers of lipid oxidation may be of value in the evaluation of cardiovascular risk.
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http://dx.doi.org/10.1177/1535370216650520DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5206975PMC
January 2017

α-MSH Stimulates Glucose Uptake in Mouse Muscle and Phosphorylates Rab-GTPase-Activating Protein TBC1D1 Independently of AMPK.

PLoS One 2016 28;11(7):e0157027. Epub 2016 Jul 28.

Monash Obesity & Diabetes Institute, Metabolic Neurophysiology Laboratory, Monash University, 3168 Clayton, Australia.

The melanocortin system includes five G-protein coupled receptors (family A) defined as MC1R-MC5R, which are stimulated by endogenous agonists derived from proopiomelanocortin (POMC). The melanocortin system has been intensely studied for its central actions in body weight and energy expenditure regulation, which are mainly mediated by MC4R. The pituitary gland is the source of various POMC-derived hormones released to the circulation, which raises the possibility that there may be actions of the melanocortins on peripheral energy homeostasis. In this study, we examined the molecular signaling pathway involved in α-MSH-stimulated glucose uptake in differentiated L6 myotubes and mouse muscle explants. In order to examine the involvement of AMPK, we investigate -MSH stimulation in both wild type and AMPK deficient mice. We found that -MSH significantly induces phosphorylation of TBC1 domain (TBC1D) family member 1 (S237 and T596), which is independent of upstream PKA and AMPK. We find no evidence to support that -MSH-stimulated glucose uptake involves TBC1D4 phosphorylation (T642 and S704) or GLUT4 translocation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0157027PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4965092PMC
July 2017

Analytic framework for peptidomics applied to large-scale neuropeptide identification.

Nat Commun 2016 May 4;7:11436. Epub 2016 May 4.

Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark.

Large-scale mass spectrometry-based peptidomics for drug discovery is relatively unexplored because of challenges in peptide degradation and identification following tissue extraction. Here we present a streamlined analytical pipeline for large-scale peptidomics. We developed an optimized sample preparation protocol to achieve fast, reproducible and effective extraction of endogenous peptides from sub-dissected organs such as the brain, while diminishing unspecific protease activity. Each peptidome sample was analysed by high-resolution tandem mass spectrometry and the resulting data set was integrated with publically available databases. We developed and applied an algorithm that reduces the peptide complexity for identification of biologically relevant peptides. The developed pipeline was applied to rat hypothalamus and identifies thousands of neuropeptides and their post-translational modifications, which is combined in a resource format for visualization, qualitative and quantitative analyses.
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http://dx.doi.org/10.1038/ncomms11436DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4857386PMC
May 2016

Long acting analogue of the calcitonin gene-related peptide induces positive metabolic effects and secretion of the glucagon-like peptide-1.

Eur J Pharmacol 2016 Feb 22;773:24-31. Epub 2016 Jan 22.

Diabetes Biology Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Måløv, Denmark.

The pharmacological potential of Calcitonin gene-related peptide (CGRP) beyond vasodilation is not completely understood and studies are limited by the potent vasodilatory effect and the short half-life of CGRP. In particular, the effects of CGRP on metabolic diseases are not clarified. A peptide analogue of the α form of CGRP (αAnalogue) with prolonged half-life (10.2 ± 0.9h) in rodents was synthesised and used to determine specific metabolic effects in 3 rodent models; normal rats, diet-induced obese rats and the Leptin deficient mouse model (ob/ob mice). The αAnalogue (100 nmol/kg) induced elevated energy expenditure and reduced food intake after single dosing in normal rats. In addition, the αAnalogue increased levels of circulating Glucagon-Like Peptide-1 (GLP-1) by >60% and a specific concentration dependent CGRP-induced GLP-1 secretion was verified in a murine L-cell line. Two weeks treatment of the type 2 diabetic ob/ob mice with the αAnalogue caused reduction in fasting insulin levels (199 ± 36 pM vs 332 ± 68 pM) and a tendency to reduce fasting blood glucose (11.2 ± 1.1mM vs 9.5 ± 0.5mM) and % glycosylated haemoglobin (HbA1c) (5.88 ± 0.17 vs 5.12 ± 0.24), demonstrating a potential anti-diabetic effect. Furthermore, two weeks treatment of diet-induced obese rats with the αAnalogue caused reduction in food intake and a significant decline in body weight (3.6 ± 1.9 gvs. -36 ± 1.1g). We have demonstrated that long-acting CGRP analogues may have a therapeutic potential for the treatment of type 2 diabetes through positive metabolic effects and effect on GLP-1 secretion.
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http://dx.doi.org/10.1016/j.ejphar.2016.01.003DOI Listing
February 2016

Pulsatile Hyperglycaemia Induces Vascular Oxidative Stress and GLUT 1 Expression More Potently than Sustained Hyperglycaemia in Rats on High Fat Diet.

PLoS One 2016 20;11(1):e0147412. Epub 2016 Jan 20.

Department of Diabetes Pharmacology, Global Research, Novo Nordisk A/S, Måløv, Denmark.

Introduction: Pulsatile hyperglycaemia resulting in oxidative stress may play an important role in the development of macrovascular complications. We investigated the effects of sustained vs. pulsatile hyperglycaemia in insulin resistant rats on markers of oxidative stress, enzyme expression and glucose metabolism in liver and aorta. We hypothesized that liver's ability to regulate the glucose homeostasis under varying states of hyperglycaemia may indirectly affect oxidative stress status in aorta despite the amount of glucose challenged with.

Methods: Animals were infused with sustained high (SHG), low (SLG), pulsatile (PLG) glucose or saline (VEH) for 96 h. Oxidative stress status and key regulators of glucose metabolism in liver and aorta were investigated.

Results: Similar response in plasma lipid oxidation was observed in PLG as in SHG. Likewise, in aorta, PLG and SHG displayed increased expression of glucose transporter 1 (GLUT1), gp-91PHOX and super oxide dismutase (SOD), while only the PLG group showed increased accumulation of oxidative stress and oxidised low density lipoprotein (oxLDL) in aorta.

Conclusion: Pulsatile hyperglycaemia induced relatively higher levels of oxidative stress systemically and in aorta in particular than overt sustained hyperglycaemia thus supporting the clinical observations that pulsatile hyperglycaemia is an independent risk factor for diabetes related macrovascular complications.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147412PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4720376PMC
August 2016

Melanocortin agonists stimulate lipolysis in human adipose tissue explants but not in adipocytes.

BMC Res Notes 2015 Oct 12;8:559. Epub 2015 Oct 12.

Diabetes and Obesity Biology, Novo Nordisk A/S, 2760, Maaloev, Denmark.

Background: The central melanocortin system is broadly involved in the regulation of mammalian nutrient utilization. However, the function of melanocortin receptors (MCRs) expressed directly in peripheral metabolic tissues is still unclear. The objective of this study was to investigate the lipolytic capacity of MC1-5R in differentiated adipocytes versus intact white adipose tissue.

Results: Non-selective MCR agonist α-MSH, MC5R-selective agonist PG-901 and MC4R-selective agonist LY2112688 significantly stimulated lipolysis in intact white adipose tissue, whereas stimulation of MCRs in differentiated adipocytes failed to do so. The lipolytic response of MC5R was decreased in intact human white adipose tissue when co-treating with β-adrenergic antagonist propranolol, suggesting that the effect may be dependent on neuronal innervation via noradrenalin release.

Conclusion: When developing an anti-obesity therapeutic drug with selective MC4R/MC5R properties, effects on lipolysis in white adipose tissue may be physiologically relevant.
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http://dx.doi.org/10.1186/s13104-015-1539-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4604100PMC
October 2015

Does Glucagon-like Peptide-1 Ameliorate Oxidative Stress in Diabetes? Evidence Based on Experimental and Clinical Studies.

Curr Diabetes Rev 2016 ;12(4):331-358

Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870, Frederiksberg C, Denmark.

Glucagon-like peptide-1 (GLP-1) has shown to influence the oxidative stress status in a number of in vitro, in vivo and clinical studies. Well-known effects of GLP-1 including better glycemic control, decreased food intake, increased insulin release and increased insulin sensitivity may indirectly contribute to this phenomenon, but glucose-independent effects on ROS level, production and antioxidant capacity have been suggested to also play a role. The potential 'antioxidant' activity of GLP-1 along with other proposed glucose-independent modes of action related to ameliorating redox imbalance remains a controversial topic but could hold a therapeutic potential against micro- and macrovascular diabetic complications. This review discusses the presently available knowledge from experimental and clinical studies on the effects of GLP-1 on oxidative stress in diabetes and diabetes-related complications.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5101636PMC
http://dx.doi.org/10.2174/1573399812666150918150608DOI Listing
March 2017

Fibroblast growth factor 21 prevents glycemic deterioration in insulin deficient mouse models of diabetes.

Eur J Pharmacol 2015 Oct 2;764:189-194. Epub 2015 Jul 2.

Department of Clinical Sciences, Lund University, Lund, Sweden.

In type 1 diabetes, there is a rapid loss of glycemic control immediately after onset of the disease. We aimed to determine if the deterioration of glycemic control that occurs early after the onset of insulin-deficient diabetes could be blunted by treatment with recombinant fibroblast growth factor 21 (FGF21). Normal C57BL/6J mice made diabetic by a single high dose injection of streptozotocin (STZ) were randomized to receive twice daily subcutaneous injection of vehicle or recombinant human FGF21 at doses of 0.3 and 1.0 mg/kg for 10 days. Body weight was recorded daily and 5 h fasted glucose, insulin, glucagon, free fatty acids and ketones were determined at 6 and 10 days post-randomization. The increase in fasting plasma glucose induced by STZ in untreated mice was prevented with FGF21 at 0.3 mg/kg BID. In contrast, at 1.0 mg/kg BID, FGF21 did not prevent the rise in plasma glucose after STZ. At the end of the study, plasma glucagon was significantly higher in the diabetic group treated with FGF21 1.0 mg/kg BID than in the untreated group. This was not seen for the group treated with FGF21 0.3 mg/kg BID. There were significant dose dependent reductions in plasma free fatty acids with FGF21 treatment but no significant change in plasma ketones (β-hydroxybutyrate). FGF21 treatment did not have significant effects on body weight in lean insulin deficient mice. In conclusion, FGF21 prevents increases in glycaemia and has lipid lowering properties in mouse models of insulin deficient diabetes, although by increasing the dose increased glucagon levels are seen and hyperglycemia persists.
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http://dx.doi.org/10.1016/j.ejphar.2015.07.003DOI Listing
October 2015

Impaired oxidative capacity due to decreased CPT1b levels as a contributing factor to fat accumulation in obesity.

Am J Physiol Regul Integr Comp Physiol 2015 Jun 8;308(11):R973-82. Epub 2015 Apr 8.

Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Section for Metabolic Receptology and Enteroendocrinology, The Novo Nordisk Foundation Center for basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark;

To characterize mechanisms responsible for fat accumulation we used a selectively bred obesity-prone (OP) and obesity-resistant (OR) rat model where the rats were fed a Western diet for 76 days. Body composition was assessed by magnetic resonance imaging scans, and as expected, the OP rats developed a higher degree of fat accumulation compared with OR rats. Indirect calorimetry showed that the OP rats had higher respiratory exchange ratio (RER) compared with OR rats, indicating an impaired ability to oxidize fat. The OP rats had lower expression of carnitine palmitoyltransferase 1b in intra-abdominal fat, and higher expression of stearoyl-CoA desaturase 1 in subcutaneous fat compared with OR rats, which could explain the higher fat accumulation and RER values. Basal metabolic parameters were also examined in juvenile OP and OR rats before and during the introduction of the Western diet. Juvenile OP rats likewise had higher RER values, indicating that this trait may be a primary and contributing factor to their obese phenotype. When the adult obese rats were exposed to the orexigenic and adipogenic hormone ghrelin, we observed increased RER values in both OP and OR rats, while OR rats were more sensitive to the orexigenic effects of ghrelin as well as ghrelin-induced attenuation of activity and energy expenditure. Thus increased fat accumulation characterizing obesity may be caused by impaired oxidative capacity due to decreased carnitine palmitoyltransferase 1b levels in the white adipose tissue, whereas ghrelin sensitivity did not seem to be a contributing factor.
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http://dx.doi.org/10.1152/ajpregu.00219.2014DOI Listing
June 2015

The arcuate nucleus mediates GLP-1 receptor agonist liraglutide-dependent weight loss.

J Clin Invest 2014 Oct 9;124(10):4473-88. Epub 2014 Sep 9.

Liraglutide is a glucagon-like peptide-1 (GLP-1) analog marketed for the treatment of type 2 diabetes. Besides lowering blood glucose, liraglutide also reduces body weight. It is not fully understood how liraglutide induces weight loss or to what degree liraglutide acts directly in the brain. Here, we determined that liraglutide does not activate GLP-1-producing neurons in the hindbrain, and liraglutide-dependent body weight reduction in rats was independent of GLP-1 receptors (GLP-1Rs) in the vagus nerve, area postrema, and paraventricular nucleus. Peripheral injection of fluorescently labeled liraglutide in mice revealed the presence of the drug in the circumventricular organs. Moreover, labeled liraglutide bound neurons within the arcuate nucleus (ARC) and other discrete sites in the hypothalamus. GLP-1R was necessary for liraglutide uptake in the brain, as liraglutide binding was not seen in Glp1r(-/-) mice. In the ARC, liraglutide was internalized in neurons expressing proopiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART). Electrophysiological measurements of murine brain slices revealed that GLP-1 directly stimulates POMC/CART neurons and indirectly inhibits neurotransmission in neurons expressing neuropeptide Y (NPY) and agouti-related peptide (AgRP) via GABA-dependent signaling. Collectively, our findings indicate that the GLP-1R on POMC/CART-expressing ARC neurons likely mediates liraglutide-induced weight loss.
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http://dx.doi.org/10.1172/JCI75276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4215190PMC
October 2014

Novel α-MSH analog causes weight loss in obese rats and minipigs and improves insulin sensitivity.

J Endocrinol 2014 Feb 8;220(2):97-107. Epub 2014 Jan 8.

Novo Nordisk Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Maaloev, Denmark.

Obesity is a major burden to people and to health care systems around the world. The aim of the study was to characterize the effect of a novel selective α-MSH analog on obesity and insulin sensitivity. The subchronic effects of the selective MC4-R peptide agonist MC4-NN1-0182 were investigated in diet-induced obese (DIO) rats and DIO minipigs by assessing the effects on food intake, energy consumption, and body weight. The acute effect of MC4-NN1-0182 on insulin sensitivity was assessed by a euglycemic-hyperinsulinemic clamp study in normal rats. Three weeks of treatment of DIO rats with MC4-NN1-0182 caused a decrease in food intake and a significant decrease in body weight 7±1%, P<0.05 compared with 3±1% increase with the vehicle control. In DIO minipigs, 8 weeks of treatment with MC4-NN1-0182 resulted in a body weight loss of 13.3±2.5 kg (13±3%), whereas the vehicle control group had gained 3.7±1.4 kg (4±1%). Finally, clamp studies in normal rats showed that acute treatment with MC4-NN1-0182 caused a significant increase in glucose disposal (Rd) compared with vehicle control (Rd, mg/kg per min, 17.0±0.7 vs 13.9±0.6, P<0.01). We demonstrate that treatment of DIO rats or minipigs with a selective MC4-R peptide agonist causes weight loss. Moreover, we have demonstrated weight-independent effects on insulin sensitivity. Our observations identify MC4 agonism as a viable target for the treatment of obesity and insulin resistance.
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http://dx.doi.org/10.1530/JOE-13-0284DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3888513PMC
February 2014

Laparoscopic Roux-en-Y gastric bypass in super obese Göttingen minipigs.

Am J Transl Res 2013 25;5(6):643-53. Epub 2013 Sep 25.

Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Denmark.

Background: The specific mechanisms behind weight loss and comorbidity improvements in obese patients after Roux-en-Y gastric bypass (RYGBP) are still poorly understood. The aim of this study was to establish and evaluate the feasibility of a long-term survival RYGBP model in super obese Göttingen minipigs in order to improve the translational potential relative to current animal models.

Methods: Eleven Göttingen minipigs with diet-induced obesity underwent laparoscopic RYGBP and were followed up to 9 months after surgery. Intra- and post-operative complications, body weight (BW), food intake and necropsy data were recorded.

Results: Five minipigs survived without complications to the end of the study. Four minipigs developed surgical related complications and were euthanized while two minipigs died due to central venous catheter related complications. BW and food intake is reported for the six minipigs surviving longer than 4.5 months post-surgery. Weight loss and reduced food intake was seen in all minipigs. After 2-3 months of weight loss, weight regain was evident in all but two minipigs which seemed to continue losing weight. Necropsy revealed some variation in the length of the alimentary, biliary and common limb between minipigs.

Conclusion: The use of obese Göttingen minipigs as a translational RYGBP model is feasible and has potential for the study of RYGBP-related changes in gut function, type-2 diabetes and appetite regulation. Still, the surgical procedure is technically highly demanding in obese Göttingen minipigs and the peri-operative animal care and follow up requires close monitoring.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3786271PMC
October 2013

Fibroblast growth factor 21 (FGF21) and glucagon-like peptide 1 contribute to diabetes resistance in glucagon receptor-deficient mice.

Diabetes 2014 Jan 23;63(1):101-10. Epub 2013 Sep 23.

Department of Clinical Sciences, Lund University, Lund, Sweden.

Mice genetically deficient in the glucagon receptor (Gcgr(-/-)) show improved glucose tolerance, insulin sensitivity, and α-cell hyperplasia. In addition, Gcgr(-/-) mice do not develop diabetes after chemical destruction of β-cells. Since fibroblast growth factor 21 (FGF21) has insulin-independent glucose-lowering properties, we investigated whether FGF21 was contributing to diabetes resistance in insulin-deficient Gcgr(-/-) mice. Plasma FGF21 was 25-fold higher in Gcgr(-/-) mice than in wild-type mice. FGF21 was found to be expressed in pancreatic β- and α-cells, with high expression in the hyperplastic α-cells of Gcgr(-/-) mice. FGF21 expression was also significantly increased in liver and adipose tissue of Gcgr(-/-) mice. To investigate the potential antidiabetic actions of FGF21 in insulin-deficient Gcgr(-/-) mice, an FGF21-neutralizing antibody was administered prior to oral glucose tolerance tests (OGTTs). FGF21 neutralization caused a decline in glucose tolerance in insulin-deficient Gcgr(-/-) mice during the OGTT. Despite this decline, insulin-deficient Gcgr(-/-) mice did not develop hyperglycemia. Glucagon-like peptide 1 (GLP-1) also has insulin-independent glucose-lowering properties, and an elevated circulating level of GLP-1 is a known characteristic of Gcgr(-/-) mice. Neutralization of FGF21, while concurrently blocking the GLP-1 receptor with the antagonist Exendin 9-39 (Ex9-39), resulted in significant hyperglycemia in insulin-deficient Gcgr(-/-) mice, while blocking with Ex9-39 alone did not. In conclusion, FGF21 acts additively with GLP-1 to prevent insulinopenic diabetes in mice lacking glucagon action.
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http://dx.doi.org/10.2337/db13-0710DOI Listing
January 2014

The young Göttingen minipig as a model of childhood and adolescent obesity: influence of diet and gender.

Obesity (Silver Spring) 2013 Jan;21(1):149-58

Diabetes Research Unit, Novo Nordisk A/S, Måløv, Denmark.

Objective: Gender and sex hormones influence the development of obesity and metabolic syndrome in humans and Göttingen minipigs. The aim of this study was to investigate possible gender differences in the metabolic response to a high energy diet in young Göttingen minipigs as a model of childhood/adolescent obesity.

Design And Methods: Nine-week-old male and female Göttingen minipigs were fed restrictedly on either a low energy diet (LED) or a high energy diet (HED) for 4 months (n = 5-7). Parameters of interest were fat percentage, visceral fat mass, plasma lipids and glucose tolerance, insulin resistance, and β-cell function measured by oral and intravenous glucose tolerance tests.

Results: At 11 to 12 weeks of age, after 2 weeks diet feeding, both genders on HED had increased fat percentage, glucose intolerance, decreased insulin sensitivity, and increased plasma levels of cholesterol and triglycerides (TGs). There was no gender difference in body weight (BW) or fat percentage, but males had lower glucose tolerance than females. After 3.5 to 4 months on the diets, the pigs on HED had increased BW, fat percentage, and visceral fat mass and were more glucose intolerant and insulin resistant than pigs on LED. Also increases in plasma cholesterol and TG levels were observed in the pigs on HED. Females had higher fat percentage and more visceral fat, were more insulin resistant, and had a more unfavorable lipid profile compared with males independent of diet.

Conclusion: In conclusion, the young Göttingen minipig, and especially the female gender, seems to be a potential model for diet induced childhood/adolescent obesity and metabolic syndrome.
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http://dx.doi.org/10.1002/oby.20249DOI Listing
January 2013

Early onset inflammation in pre-insulin-resistant diet-induced obese rats does not affect the vasoreactivity of isolated small mesenteric arteries.

Pharmacology 2012 24;90(3-4):125-32. Epub 2012 Jul 24.

Hagedorn Research Institute, Novo Nordisk, Gentofte, Denmark.

Background: Obesity is an increasing burden affecting developed and emerging societies since it is associated with an increased risk of diabetes and consequent cardiovascular complications. Increasing evidence points towards a pivotal role of inflammation in the etiology of vascular dysfunction. Our study aimed to investigate signs of inflammation and their relation to vascular dysfunction in rats receiving a high fat diet.

Methods: Diet-induced obese (DIO) rats were used as a model since these rats exhibit a human pre-diabetic pathology. Oral glucose and insulin tolerance tests were conducted on DIO rats and their controls prior to the development of insulin resistance. Furthermore, the plasma contents of selected cytokines [macrophage chemoattractant protein (MCP-1), interleukin-6 (IL-6), and interleukin-1 (IL-1)] and the concentration of adiponectin were measured. Using wire myography, we tested the vascular function of isolated small mesenteric arteries.

Results: DIO animals had significantly (p < 0.05) increased body weight (721.2 ± 6.3 g) compared to age- and sex-matched controls (643.4 ± 14.6 g), as well as a significant increase (p < 0.01) in body fat percentage (29.7 ± 1.7% and 22.7 ± 0.97%, respectively). No significant difference in fasting plasma insulin levels could be detected between the two groups (chow-fed group 141.5 ± 15.1 pmol/l; high fat-fed group 125.9 ± 18.8 pmol/l). However, the levels of MCP-1 (89.7 ± 4.2 pg/ml vs. 60.8 ± 7.7 pg/ml) and IL-6 (61.6 ± 3.1 pg/ml vs. 41.6 ± 7.4 pg/ml) were significantly elevated in DIO animals (p < 0.05) as compared to controls. Adiponectin levels were also significantly increased (p < 0.01) in DIO rats (10.8 ± 0.7 ng/ml) versus controls (6.9 ± 0.5 ng/ml). No difference in vascular or endothelial function was evident as determined by responses to acetylcholine, sodium nitroprusside, endothelin-1, and calcitonin gene-related peptide.

Conclusion: In DIO rats, which have not yet developed hyperinsulinaemia or glucose intolerance, the levels of inflammatory mediators MCP-1 and Il-6 are significantly increased without concomitant vascular dysfunction. The results show that inflammation and obesity are tightly associated, and that inflammation is manifested prior to significant insulin resistance and vascular dysfunction.
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http://dx.doi.org/10.1159/000340054DOI Listing
April 2013

Identification and in vivo and in vitro characterization of long acting and melanocortin 4 receptor (MC4-R) selective α-melanocyte-stimulating hormone (α-MSH) analogues.

J Med Chem 2012 Mar 24;55(5):1969-77. Epub 2012 Feb 24.

Protein & Peptide Chemistry, Novo Nordisk, Novo Nordisk Park, 2760 Måløv, Denmark.

We report in vitro and in vivo data of new α-melanocyte-stimulating hormone (α-MSH) analogues which are N-terminal modified with a long chain fatty acid derivative. While keeping the pharmacophoric motif (d-Phe-Arg-Trp) fixed, we tried to improve selectivity and physicochemical parameters like solubility and stability of these analogues by replacing amino acids further away from the motif. Receptor specific changes in binding affinity to the melanocortin receptors were observed between the acetyl derivatives and the fatty acid analogues. Furthermore, amino acids at the N-terminal of α-MSH (Ser-Tyr-Ser) not considered to be part of the pharmacophore were found to have an influence on the MC4/MC1 receptor selectivity. While the acetyl analogues have an in vivo effect for around 7 h, the long chain fatty acid analogues have an effect up to 48 h in an acute feeding study in male Sprague-Dawley rats after a single subcutaneous administration.
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http://dx.doi.org/10.1021/jm201489aDOI Listing
March 2012

Laboratory animals as surrogate models of human obesity.

Acta Pharmacol Sin 2012 Feb;33(2):173-81

Diabetes Research Unit, Novo Nordisk A/S, Beijing Novo Nordisk Pharmaceuticals Sci & Tech Co Ltd., Beijing, China.

Obesity and obesity-related metabolic diseases represent a growing socioeconomic problem throughout the world. Great emphasis has been put on establishing treatments for this condition, including pharmacological intervention. However, there are many obstacles and pitfalls in the development process from pre-clinical research to the pharmacy counter, and there is no certainty that what has been observed pre-clinically will translate into an improvement in human health. Hence, it is important to test potential new drugs in a valid translational model early in their development. In the current mini-review, a number of monogenetic and polygenic models of obesity will be discussed in view of their translational character.
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http://dx.doi.org/10.1038/aps.2011.203DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4010334PMC
February 2012

Fluctuating hyperglycaemia increases oxidative stress response in lean rats compared to sustained hyperglycaemia despite lower glycaemic exposure.

Diab Vasc Dis Res 2011 Oct;8(4):295-8

Section of Biomedicine, Department of Veterinary Disease Biology, University of Copenhagen, Denmark.

Objective: To compare the effect of fluctuating glucose with sustained hyperglycaemia on systemic oxidative stress during 72 h of glucose infusion.

Methods: Catheterised male Sprague-Dawley rats were given either a continuous high (CHG), low (CLG) or pulsatile (FLU) infusion of glucose or saline (VEH) for 72 h. Plasma ascorbate oxidation ratio (AOR) and malondialdehyde (MDA) were used as biomarkers of oxidative stress and damage.

Results: The FLU group showed significant increases in both plasma AOR and MDA at 48 and 72 h (p < 0.05 all cases), whereas the CHG group, despite being infused with three times the amount of glucose, only showed increased MDA levels at 72 h time point (p < 0.05).

Conclusion: Our data suggests that fluctuating glucose levels lead to oxidative stress similar to that of sustained hyperglycaemia despite a much lower total glycaemic exposure. Thus, our data supports the notion that fluctuating glucose may be relatively more deleterious than sustained hyperglycaemia.
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http://dx.doi.org/10.1177/1479164111421033DOI Listing
October 2011