Publications by authors named "Shi-Yu Liang"

25 Publications

  • Page 1 of 1

Overexpression of UHRF1 promoted the proliferation of vascular smooth cells via the regulation of Geminin protein levels.

Biosci Rep 2019 02 26;39(2). Epub 2019 Feb 26.

Department of Cardiology, Southwest Hospital, Third Military Medical University (Army Medical University), China

Geminin is an inhibitor of DNA replication licensing and cell cycle. Our previous study demonstrates that Geminin plays an important role in regulating phenotypic diversity and growth of vascular smooth cells (VSMCs). Ubiquitin-like with PHD and RING Finger domains 1 (UHRF1) is an epigenetic coordinator, whose RING domain confers intrinsic E3 ligase activity, mediating the ubiquitination of several proteins and the protein-protein interaction. Aberrant expression of UHRF1 was related to aggressiveness of multiple human malignancies, where knockdown of UHRF1 led to decreased proliferation of cancer cells. However, it is unclear whether proper UHRF1 function is involved in aberrant proliferation and phenotypic switching of VSMCs via altering Geminin protein levels. In present study, in UHRF1-overexpressing A10 cells, 3H-thymidine and 5-ethynyl-20-deoxyuridine (EdU) and CCK8 were used to examine the proliferation of VSMCs. RT-PCR and Western blot analyses were performed to investigate whether UHRF1-mediated effects were achieved by altering Geminin expression in VSMCs. RNA-seq analysis was performed to dissect related mechanisms or signaling pathways of these effects. The results of experiments suggested that UHRF1 prompted proliferation and cell cycle of VSMCs via the down-regulation of Geminin protein levels with no change in Geminin mRNA expression. Besides, PI3K-Akt signaling pathway was increased upon UHRF1 up-regulation. Our study demonstrated that overexpressing UHRF1 was involved in VSMCs proliferation through reducing inhibitory Geminin protein levels to promote cell cycle as well as activating PI3K-Akt signaling. This may provide key knowledge for the development of better strategies to prevent diseases related to VSMCs abnormal proliferation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1042/BSR20181341DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6390124PMC
February 2019

Cold exposure promotes obesity and impairs glucose homeostasis in mice subjected to a high‑fat diet.

Mol Med Rep 2018 Oct 10;18(4):3923-3931. Epub 2018 Aug 10.

Department of Cardiology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing 400038, P.R. China.

Cold exposure is considered to be a form of stress and has various adverse effects on the body. The present study aimed to investigate the effects of chronic daily cold exposure on food intake, body weight, serum glucose levels and the central energy balance regulatory pathway in mice fed with a high‑fat diet (HFD). C57BL/6 mice were divided into two groups, which were fed with a standard chow or with a HFD. Half of the mice in each group were exposed to ice‑cold water for 1 h/day for 7 weeks, while the controls were exposed to room temperature. Chronic daily cold exposure significantly increased energy intake, body weight and serum glucose levels in HFD‑fed mice compared with the control group. In addition, 1 h after the final cold exposure, c‑fos immunoreactivity was significantly increased in the central amygdala of HFD‑fed mice compared with HFD‑fed mice without cold exposure, indicating neuronal activation in this brain region. Notably, 61% of these c‑fos neurons co‑expressed the neuropeptide Y (NPY), and the orexigenic peptide levels were significantly increased in the central amygdala of cold‑exposed mice compared with control mice. Notably, cold exposure significantly decreased the anorexigenic brain‑derived neurotropic factor (BDNF) messenger RNA (mRNA) levels in the ventromedial hypothalamic nucleus and increased growth hormone releasing hormone (GHRH) mRNA in the paraventricular nucleus. NPY‑ergic neurons in the central amygdala were activated by chronic cold exposure in mice on HFD via neuronal pathways to decrease BDNF and increase GHRH mRNA expression, possibly contributing to the development of obesity and impairment of glucose homeostasis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3892/mmr.2018.9382DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6131648PMC
October 2018

[Effects of sodium nitroprusside on growth and physiological characteristics of tomato seedlings under iron deficiency and NO stress].

Ying Yong Sheng Tai Xue Bao 2017 Apr;28(4):1246-1254

College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an 271018, Shandong, China.

The solution culture method was used to study the effects of sodium nitroprusside (SNP) on plant growth, nutrient uptake and antioxidant enzyme activities of tomato seedlings under iron deficiency and NO stress. The results indicated that after 7 d of treatment, iron deficiency inhibited the tomato seedling growth, decreased chlorophyll (a and b) and carotenoid contents, and led to obvious chlorosis; iron deficiency also reduced the activity of SOD, POD and CAT, resulting in significant accumulation of MDA contents and higher electrolytic leakage; proline and soluble sugar contents were not significantly changed; contents of N, P, K, Ca, Mg and Fe in both leaves and roots of tomato seedlings were decreased under iron deficiency in varying degrees. The combined stress of NO stress and iron deficiency promoted the inhibition of plant growth, decreased chlorophyll (a and b), carotenoid contents and the activities of SOD, POD and CAT; electrolytic leakage MDA, proline and soluble sugar contents of N, P, Mg, Fe in both leaves and roots of tomato seedlings were much lower, but the contents of K and Ca were significantly increased. Compared to the treatment without SNP, adding 0.1 mmol·L SNP could alleviate the growth inhibition of stressed tomato seedlings. Adding 0.1 mmol·L SF (sodium ferrocyanide) also showed alleviating or promoting effect on some above indexes including the activity of SOD, POD and CAT to some degree, but the other physiological indexes were not significantly changed because iron was contained in SF.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.13287/j.1001-9332.201704.015DOI Listing
April 2017

Current views on neuropeptide Y and diabetes-related atherosclerosis.

Diab Vasc Dis Res 2017 07 20;14(4):277-284. Epub 2017 Apr 20.

1 Department of Cardiology, Southwest Hospital, Third Military Medical University, Chongqing, China.

Diabetes-induced atherosclerotic cardiovascular disease is the leading cause of death of diabetic patients. Neuronal regulation plays a critical role in glucose metabolism and cardiovascular function under physiological and pathological conditions, among which, neurotransmitter neuropeptide Y has been shown to be closely involved in these two processes. Elevated central neuropeptide Y level promotes food intake and reduces energy expenditure, thereby increasing adiposity. Neuropeptide Y is co-localized with noradrenaline in central and sympathetic nervous systems. As a major peripheral vascular contractive neurotransmitter, through interactions with its receptors, neuropeptide Y has been implicated in the pathology and progression of diabetes, by promoting the proliferation of endothelial cells and vascular fibrosis, which may contribute to diabetes-induced cardiovascular disease. Neuropeptide Y also participates in the pathogenesis of atherosclerosis, the major form of cardiovascular disease, via aggravating endothelial dysfunction, growth of vascular smooth muscle cells, formation of foam cells and platelets aggregation. This review highlights the causal role of neuropeptide Y and its receptor system in the development of diabetes mellitus and one of its complications: atherosclerotic cardiovascular disease. The information from this review provides both critical insights onto the mechanisms underlying the pathogenesis of atherosclerosis and evidence for the development of therapeutic strategies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1479164117704380DOI Listing
July 2017

Different effects of neuropeptide Y on proliferation of vascular smooth muscle cells via regulation of Geminin.

Mol Cell Biochem 2017 Sep 6;433(1-2):205-211. Epub 2017 Apr 6.

Department of Cardiology, Southwest Hospital, Third Military Medical University, No. 30 Gaotanyan, Shapingba, Chongqing, 400038, China.

The proliferation-promoting effect of neuropeptide Y (NPY) always functions in low-serum-cultured vascular smooth muscle cells (VSMCs), and the phenotypic switch of VSMCs is regulated by concentrations of serum. Whether the property of the NPY proliferative effect in VSMCs relies on phenotype of VSMCs is unclear. We aimed to explore the role of NPY on proliferation of different VSMC phenotypes in the pathogenesis of atherosclerosis. By stimulating A10 cells with 200 nM NPY in 0.5 or 10% serum, 3H-thymidine and 5-ethynyl-2'-deoxyuridine (EdU) and CCK8 measurements were used to detect VSMC proliferation. RT-PCR and Flow cytometry were performed to detect the factors involved in different properties of the NPY proliferative effect in VSMCs. Instead of facilitating proliferation, NPY had no significant effect on the growth of VSMCs when cultured in 10% serum (VSMCs stayed at synthetic states). The underlying mechanism may be involved in down-regulation of Y1 receptor (P < 0.05 vs. Vehicle) and up-regulation of Geminin (P < 0.05 vs. Vehicle) in 10% serum-cultured VSMCs co-incubated with 200 nM NPY. Besides, modulation of Geminin was effectively blocked by the Y1 receptor antagonist. The stimulation of NPY on proliferation of VSMCs could be a double-edged sword in the development of atherosclerosis and thus provides new knowledge for therapy of atherosclerosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11010-017-3028-7DOI Listing
September 2017

Biological effects of toosendanin, a triterpenoid extracted from Chinese traditional medicine.

Prog Neurobiol 2007 May 15;82(1):1-10. Epub 2007 Feb 15.

Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, PR China.

Toosendanin (TSN) is a triterpenoid extracted from Melia toosendan Sieb et Zucc, which was used as a digestive tract-parasiticide and agricultural insecticide in ancient China. TSN was demonstrated to be a selective presynaptic blocker and an effective antibotulismic agent. By interfering with neurotransmitter release through an initial facilitation followed by a subsequent depression, TSN eventually blocks synaptic transmission at both the neuro-muscular junction and central synapses. Despite sharing some similar actions with botulinum neurotoxin (BoNT), TSN has a marked antibotulismic effect in vivo and in vitro. Studies suggest that the antibotulismic effect of TSN is achieved by preventing BoNT from approaching its enzymatic substrate, the SNARE protein. It is also found that TSN can induce differentiation and apoptosis in several cell lines, and suppress proliferation of various human cancer cells. TSN inhibits various K(+)-channels, selectively facilitates Ca(2+)-influx via L-type Ca(2+) channels and increases intracellular Ca(2+) concentration ([Ca(2+)](i)). The TSN-induced [Ca(2+)](i) increase and overload could be responsible for the TSN-induced biphasic effect on transmitter release, cell differentiation, apoptosis as well as the cytoxicity of TSN.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.pneurobio.2007.02.002DOI Listing
May 2007

[Biological effects of toosendanin, an active ingredient of herbal vermifuge in Chinese traditional medicine].

Sheng Li Xue Bao 2006 Oct;58(5):397-406

Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.

The fact that the fruit and bark of plant belonging to family Melia could be used as digestive tract-parasiticide and agricultural insecticide was recorded about two thousand years ago in ancient China. Toosendanin (TSN, C30H38O11, FW=574), a triterpenoid derivative, was extracted from the bark of Melia toosendan Sieb. et Zucc. by Chinese scientists in 1950os and used as an ascarifuge in China instead of imported sendanin. Studies have demonstrated that TSN possesses special biological actions as well as considerable various values in scientific research, clinic medicine and agriculture. The first is that by interfering with neurotransmitter release by causing an initial facilitation, TSN eventually blocks synaptic transmission at both the neuromuscular junction and central synapses. The action might result from TSN-induced Ca(2+)-sensitivity change and final elimination of transmitter release machinery. The second is that despite sharing many similar actions with botulinum neurotoxin (BoNT) on blocking neuromuscular transmission, TSN has a markedly antibotulismic action in vivo and in vitro: TSN-treatment saves the botulism mice or monkeys from death; TSN-incubation in vitro or TSN-injection in vivo endows neuromuscular junction with a high tolerance to BoNT. Studies suggest that the antibotulismic action is achieved by preventing BoNT from approaching its enzymatic substrate, SNARE protein. The third, in recent years, it is also observed that TSN can induce differentiation and apoptosis in several cell lines, and suppress proliferation of various human cancer cells. The TSN-induced differentiation is Ca(2+)-dependent and the mitochondria-dependent apoptosis pathway is involved in the TSN-induced apoptosis. The fourth is that TSN inhibits various K(+) channels and selectively facilitates Ca(2+) current through L-type Ca(2+) channels and hence elevates [Ca(2+)](i). The TSN-induced [Ca(2+)](i) increase and overload could be responsible for the TSN-induced biphasic effect on neurotransmitter release, cell differentiation, apoptosis as well as the cytotoxicity of TSN.
View Article and Find Full Text PDF

Download full-text PDF

Source
October 2006

Toosendanin interferes with pore formation of botulinum toxin type A in PC12 cell membrane.

Acta Pharmacol Sin 2006 Jan;27(1):66-70

Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai.

Aim: Botulinum neurotoxins (BoNT) abort the process of neurotransmitter release at presynaptic motor nerve terminals, causing muscle paralysis. The ability of botulinum toxin to produce its effect is dependent on the ability of the light chain to cleave the SNARE proteins associated with transmitter release. Translocation of the light chain protease through the heavy chain-formed channel is a pivotal step in the intoxication process. Toosendanin (TSN), a triterpenoid derivative extracted from a Chinese traditional medicine, has been demonstrated to be an effective cure for experimental botulism. This study was designed to explore the antibotulismic mechanisms of toosendanin.

Methods: The inside-out single-channel recording patch-clamp technique was used to record the BoNT/A-induced currents in the presence and absence of TSN.

Results: Channel formation was delayed and the sizes of the channels were reduced in the TSN-treated PC12 cell membrane.

Conclusion: The antibotulismic effect of TSN might occur via interference with toxin translocation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1745-7254.2006.00236.xDOI Listing
January 2006

Growth inhibition and apoptosis-induced effect on human cancer cells of toosendanin, a triterpenoid derivative from chinese traditional medicine.

Invest New Drugs 2005 Dec;23(6):547-53

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai, 200031 P. R. China.

Toosendanin, a triterpenoid derivative isolated from the barks of Melia toosendan Sieb et Zucc, has been used as an anthelmintic vermifuge against ascaris for more than fifty years in China. In the present study, we investigated the growth inhibition and apoptosis-induced effect of toosendanin on human cancer cells. The result showed that toosendanin significantly suppressed the proliferation of tested human cancer cell lines. The IC(50) values were less than 1.7 x 10(-7) M and U937 was the most sensitive cell line with a IC(50) of 5.4 x 10(-9) M. Flow cytometric analysis revealed that treatment of U937 cells with toosendanin resulted in a dose- and time-dependent accumulation of cells in the S phase with a concomitant decrease in cells processing to G(0)/G(1) phase. The growth inhibition of U937 cells after exposure to toosendanin was subsequently associated with the induction of apoptosis, as evidence by the typical condensed and fragmented nuclei, DNA fragmentation, and exposure of phosphatidylserine on the outer leaflet of plasma membrane. All these results indicated that toosendanin could serve as a potential candidate for anticancer drug.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10637-005-0909-5DOI Listing
December 2005

The long-term effect of toosendanin on current through nifedipine-sensitive Ca2+ channels in NG108-15 cells.

Toxicon 2005 Jan;45(1):53-60

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, People's Republic of China.

Toosendanin is a triterpenoid derivative extracted from Melia toosendan Sieb et Zucc. Previous studies demonstrated that toosendanin could block neurotransmission and stimulate PC12 cell into differentiation and apoptosis. These actions of toosendanin were suggested to result from a continuous increase in Ca2+ influx, which led to intracellular Ca2+ overload. Here, we observed the long-term effect of toosendanin on Ca2+ channels in NG108-15 cells by whole-cell patch-clamp recording. Obtained data showed that a prolonged exposure to toosendanin induced a continuous increase in the Ca2+ influx in a concentration and time-dependent manner while a brief treatment induced an irreversible increase in Ca2+ influx in differentiated NG108-15 cells. The nifedipine-sensitive L-type currents were significantly increased after exposure to TSN while the nifedipine-resistant or omega-conotoxin MVIIC-sensitive currents were not affected.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.toxicon.2004.09.010DOI Listing
January 2005

Toosendanin, a triterpenoid derivative, acts as a novel agonist of L-type Ca2+ channels in neonatal rat ventricular cells.

Eur J Pharmacol 2004 Oct;501(1-3):71-8

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, P.R. China.

Toosendanin, a triterpenoid derivative extracted from Melia toosendan Sieb et Zucc, was demonstrated to be potentially useful in medical and scientific researches. Here, we investigated the effects of toosendanin on L-type voltage-dependent Ca(2+) channels in cultured neonatal rat ventricular cells, using whole-cell patch-clamp method. Toosendanin irreversibly increased L-type Ca(2+) current (I(Ca(L))) in a concentration-dependent manner and shifted the maximum of the current/voltage relationship from 8.3+/-3.7 to 1.7+/-3.7 mV, without modifying the threshold potential of the current. Toosendanin shifted the steady-state activation and inactivation curves to the left. The deactivation kinetics of the I(Ca(L)) was significantly slowed by toosendanin while the activation kinetics was not affected. The cells pretreated with 100 nM 1,4-dihydro-2,6-dimethyl-5-nitro-4-[2-(trifluoromethyl)phenyl]-3-pyridinecarboxylic acid methyl ester (S(-)-BayK8644) still respond to further addition of 87 microM toosendanin, and vice versa. These results prove toosendanin to be a novel L-type Ca(2+) channel agonist, which possesses a distinct binding site from BayK8644.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejphar.2004.08.027DOI Listing
October 2004

Involvement of cytochrome c release and caspase activation in toosendanin-induced PC12 cell apoptosis.

Toxicology 2004 Sep;201(1-3):31-8

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China.

Our previous study showed that toosendanin, a triterpenoid derivative isolated from a Chinese traditional medicine, could induce apoptosis in PC12 cells. In this study we confirmed the apoptosis-inducing effect of toosendanin in PC12 cells with new evidences in morphology and biochemistry: the shrinkage of cytosol, the condensation and fragmentation of nuclei and the formation of DNA ladder. It was also demonstrated that toosendanin decreased the PC12 cell viability in a time- and concentration-dependent manner. To elucidate the pathway linked with the toosendanin-induced apoptosis, the cytochrome c in the cytosol and the cleavage of poly(ADP-ribose) polymerase (PARP) were examined. The obtained results showed that toosendanin caused the release of cytochrome c from mitochondria into the cytosol and then led to the activation of caspase, indicating that the cytochrome c release and caspase activation were involved in the toosendanin-induced apoptosis process. These results suggested the possibility that toosendanin could serve as a candidate for anti-cancer drug.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.tox.2004.03.023DOI Listing
September 2004

Cure of experimental botulism and antibotulismic effect of toosendanin.

Acta Pharmacol Sin 2004 Jun;25(6):839-48

Key laboratory of Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, Shanghai 200031, China.

Botulinum neurotoxins (BoNTs), a group of bacterial proteins that comprise a light chain disulfide linked a heavy chain, are the most lethal biotoxins known to mankind. By inhibiting neurotransmitter release, BoNTs cause severe neuroparalytic disease, botulism. A series of important findings in the past 10 years which displayed the molecular targets of BoNTs and hence proposed a four-step action mechanism to explain BoNT intoxication greatly advanced the study of antibotulismic drug. In this article, we reviewed these progresses and anti-botulismic compounds found in recent years. These compounds function due to their facilitation on neurotransmitter release or to their interference on the binding, internalization, translocation, and endopeptidase activity of the toxins. Toosendanin is a triterpenoid derivative extracted from a digestive tract-parasiticide in Chinese traditional medicine. Chinese scientists have found that the compound is a selective prejunctional blocker. In spite of sharing some similar action with BoNT, toosendanin can protect botulism animals that have been administrated with lethal doses of BoNT/A or BoNT/B for several hours from death and make them restore normal activity. The neuromuscular junction preparations isolated from the rats that have been injected with toosendanin tolerate BoNT/A challenge. Toosendanin seems to have no effect on endopeptidase activity of BoNT, but blocks the toxin approach to its enzymatic substrate.
View Article and Find Full Text PDF

Download full-text PDF

Source
June 2004

Toosendanin, a triterpenoid derivative, increases Ca2+ current in NG108-15 cells via L-type channels.

Neurosci Res 2004 Jun;49(2):197-203

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, PR China.

Toosendanin, a triterpenoid derivative extracted from Melia toosendan Sieb et Zucc, was demonstrated to be a selective presynaptic blocker and an effective antibotulismic agent in previous studies. Here, we observed its effects on Ca(2+) channels in NG108-15 cells by whole-cell patch-clamp recording. Obtained data showed that toosendanin concentration dependently increased the high-voltage-activated (HVA) Ca(2+) current with an EC(50) of 5.13 microM in differentiated NG108-15 cells. The enhancement effect was still observed when the cells were pretreated with 5 microM omega-conotoxin MVIIC. However, when the cells were preincubated with 5 microM nifedipine or 10 microM verapamil-containing solution, the effect was absent. In undifferentiated NG108-15 cells, which only express T-type Ca(2+) channels, toosendanin did not affect Ca(2+) currents. These results show that toosendanin increases Ca(2+) influx in NG108-15 cells via L-type Ca(2+) channels.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neures.2004.02.012DOI Listing
June 2004

Toosendanin increases free-Ca(2+) concentration in NG108-15 cells via L-type Ca(2+) channels.

Acta Pharmacol Sin 2004 May;25(5):597-601

Key Laboratory of Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.

Aim: To examine if toosendanin (TSN) affects intracellular free-Ca(2+) concentration ([Ca(2+)](i)) in neuroblastoma pluglioma hybrid cells (NG108-15 cells).

Methods: The [Ca(2+)](i) was determined by laser-scanning confocal microscopic imaging technique in which Fluo-3 was used as Ca(2+) indicator.

Results: TSN induced an increase in resting [Ca(2+)](i) and in high K(+)-evoked Ca(2+) transient in differentiated NG108-15 cells. The TSN-induced increase in [Ca(2+)](i) was dose-dependent and disappeared in CdCl(2-), nifedipine-containing or Ca(2+)-free solution, and appeared after washing out the Ca(2+) channel blockers or adding Ca(2+).

Conclusion: TSN increased [Ca(2+)](i) in differentiated NG108-15 cells. The [Ca(2+)](i) enhancement was due to the influx of extracellular Ca(2+) and related to L-type Ca(2+) channels.
View Article and Find Full Text PDF

Download full-text PDF

Source
May 2004

Opioid receptor antagonists increase [Ca2+]i in rat arterial smooth muscle cells in hemorrhagic shock.

Acta Pharmacol Sin 2004 Mar;25(3):395-400

Institute of Surgery, Department of Pharmacology, Third Military Medical University, Chongqing 400042, China.

Aim: To examine the effects of opioid receptor antagonists and norepinephrine on intracellular free Ca2+ concentration ([Ca2+]i) in mesenteric arterial (MA) smooth muscle cells (SMC) isolated from normal and hemorrhagic shocked rats in the vascular hyporesponse stage.

Methods: The rat model of hemorrhagic shock was made by withdrawing blood to decrease the artery mean blood pressure to 3.73-4.26 kPa and keeping at the level for 3 h. [Ca2+]i of vascular smooth muscle cells (VSMC) were detected by the laser scan confocal microscopy.

Results: In the hyporesponse VMSC of rats in hemorrhagic shock, selective delta-, kappa-, and mu-opioid receptor antagonists (naltrindole, nor-binaltorphimine, and beta-funaltrexamine, 100 nmol/L) as well as norepinephrine 5 micromol/L significantly increased [Ca2+]i by 47 %+/-13 %, 37 %+/-14 %, 33 %+/-10 %, and 54 %+/-17 %, respectively, although their effects were lower than those in the normal rat cells (the increased values were 148 %+/-54 %, 130 %+/-44 %, 63 %+/-17 % and 110 %+/-38 %, respectively); and the norepinephrine-induced increase in [Ca2+]i was further augmented by three delta-, kappa-, and mu-opioid receptor antagonists (50 nmol/L, respectively) application (from 52 %+/-16 % to 99 %+/-29 %, 146 %+/-54 % and 137 %+/-47 %, respectively).

Conclusion: The disorder of [Ca2+]i regulation induced by hemorrhagic shock was mediated by opioid receptor and alpha-adrenoceptor, which may be partly responsible for the vascular hyporesponse, and the opioid receptor antagonists improved the response of resistance arteries to vascular stimulants in decompensatory stage of hemorrhagic shock.
View Article and Find Full Text PDF

Download full-text PDF

Source
March 2004

Antagonism of botulinum toxin type A-induced cleavage of SNAP-25 in rat cerebral synaptosome by toosendanin.

FEBS Lett 2003 Dec;555(2):375-9

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, PR China.

Toosendanin (TSN), a triterpenoid derivative extracted from Chinese traditional medicine, has been demonstrated to be an effective cure for experimental botulism. This study is designed to explore its antibotulismic mechanism by Western blotting. The results showed that TSN incubation did not change the electrophoresis pattern and the amounts of synaptosomal-associated protein of 25 kDa (SNAP-25), syntaxin and synaptobrevin/vesicle-associated membrane protein in rat cerebral synaptosomes, but made the synaptosomes completely resistant to botulinum neurotoxin A (BoNT/A)-mediated cleavage of SNAP-25. After binding of BoNT/A to synaptosomes, TSN still partially antagonized the toxin-mediated cleavage of SNAP-25. However, TSN-incubated synaptosomal membrane fraction did not resist the cleavage of SNAP-25 by the light chain of BoNT/A. It is suggested that the antibotulismic effect of TSN results from blocking the toxin's approach to its enzymatic substrate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/s0014-5793(03)01291-2DOI Listing
December 2003

Effects of demethylzeylasteral and celastrol on spermatogenic cell Ca2+ channels and progesterone-induced sperm acrosome reaction.

Eur J Pharmacol 2003 Mar;464(1):9-15

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, 200031, Shanghai, PR China.

The male antifertility effect of a water-chloroform extract of Tripterygium wilfordii Hook. f. (GTW) and several monomers isolated from GTW has attracted worldwide interest. In the present study, the effects of two isolated monomers from GTW, demethylzeylasteral and celastrol, on the Ca(2+) channels in mouse spermatogenic cells and on the sperm acrosome reaction were investigated by whole-cell patch-clamp recording and chlortetracycline staining methods, respectively. The results showed that demethylzeylasteral concentration-dependently and in a partially reversible manner inhibited the Ca(2+) current in spermatogenic cells with an IC(50) of 8.8 microg/ml. Celastrol decreased the Ca(2+) current in the cells time-dependently and irreversibly. The changes in the activation and inactivation time constants of Ca(2+) currents after application of these two compounds were also examined. Demethylzeylasteral increased both activation and inactivation time constants of Ca(2+) currents, and celastrol had no significant effect on them. The two compounds also inhibited significantly the sperm acrosome reaction initiated by progesterone. These data suggest that inhibition of Ca(2+) currents could be responsible for the antifertility activity of these compounds.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/s0014-2999(03)01351-7DOI Listing
March 2003

Toosendanin induces outgrowth of neuronal processes and apoptosis in PC12 cells.

Neurosci Res 2003 Feb;45(2):225-31

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, PR China.

In the present study, the effects of toosendanin on cell differentiation and apoptosis were investigated in PC12 cells. The results showed that after 24-48 h of culture in a medium containing toosendanin (approximately 1-10x10(-7) M), cell differentiation and outgrowth of neuronal processes were promoted. Combined treatment with toosendanin and a calcium channel blocker, nifedipine or omega-conotoxin GVIA, resulted in a significant inhibition of the toosendanin-induced effects. Pretreatment of PC12 cells with BAPTA-AM also inhibited the toosendanin-induced effects; however, these effects were not inhibited by pertussis toxin and H-7 in the medium. Toosendanin also induced cell apoptosis. Based on the DNA content determined by flow cytometric analysis, the number of apoptotic cells significantly increased when the incubation time in the toosendanin-containing medium was lasted up to 72 h. Toosendanin at a higher concentration (> or =1 x 10(-6) M) caused cell death while it had no effect on cell division at concentrations lower than 1 x 10(-7) M.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/s0168-0102(02)00225-0DOI Listing
February 2003

Effects of myasthenia gravis patients' sera with different autoantibodies on slow K+ current at mouse motor nerve terminals.

Neurol Res 2003 Jan;25(1):58-62

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, P.R. China.

The antibodies against pre-synaptic membrane receptor (PsmR) and acetylcholine receptor (AChR) in serum samples of myasthenia gravis (MG) patients and healthy donors were tested by enzyme-linked immunosorbent assays (ELISA). The serum samples of eight MG patients with different autoantibodies and those of six healthy donors without these two kinds of autoantibodies were collected to investigate their effects on the peri-neurially recorded membrane currents at mouse motor nerve terminals. After inhibition of both fast and Ca(2+)-dependent K+ currents by tetra-ethylammonium (TEA), a positive wave was revealed, which was a balance of the slow K+(Ik,s) and Ca2+ currents (ICa). Application of anti-PsmR antibody negative MG sera and healthy donor sera, whether anti-AChR antibody positive or negative, did not affect the positive wave. However, the positive wave shifted to prolonged Ca(2+)-plateau when adding two of four anti-PsmR antibody positive serum samples from MG patients, indicating an inhibition of Ik,s by anti-PsmR antibody positive sera. Meanwhile, all serum samples derived from either patients or healthy donors did not affect INa.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1179/016164103101200932DOI Listing
January 2003

Opioid receptor antagonists modulate Ca2+-activated K+ channels in mesenteric arterial smooth muscle cells of rats in hemorrhagic shock.

Shock 2003 Jan;19(1):85-90

Institute of Surgery, Daping Hospital, Department of Pharmacology, Third Military Medical University, Chongqing, 400042, People's Republic of China.

Previous study has indicated a significant enhancement of activity of large-conductance Ca2+-activated K+ channel (BKCa) in mesenteric arterial vascular smooth muscle cells isolated from rats in vascular hyporesponsive stage of hemorrhagic shock. In the present study, the effect of opioid receptor antagonism on BKCa activity in the vascular smooth muscle cells of rats in the hyporesponse stage of hemorrhagic shock was investigated by using inside-out configuration of the patch-clamp technique. The results showed that naloxone (10 microM) down-regulated the activity of BKCa by reducing open probability (Po) and open frequency of the channels. The reduction of Po resulted from a decrease of mean open time and an increase of the slow closed time constant. Naltrindole and nor-binaltorphimine (100 nM) had the similar effects to that of naloxone, but no significant effect of beta-funaltrexamine (100 nM) on the activity of the channels could be found. These results suggest that delta- and kappa-opioid receptors, but not mu-receptors, may be involved in the regulation of BKCa in vascular hyporesponse stage, and that inhibition of BKCa may be one of the mechanisms of the opioid receptor antagonists improving the response of resistance arteries to vasoactive stimulants during the decompensatory stage of hemorrhagic shock.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/00024382-200301000-00016DOI Listing
January 2003

Ion-channels in human sperm membrane and contraceptive mechanisms of male antifertility compounds derived from Chinese traditional medicine.

Acta Pharmacol Sin 2003 Jan;24(1):22-30

Key Laboratory of Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.

Ion channel plays a key role in maturation, capacitation and acrosome reaction of sperm. However, as it is difficult to record channel currents from a mature mammal sperm directly by patch-clamp technique, there were no basic data on the types and properties of the channels in human sperm until the method reconstituting the channels into bilayer was used. By reconstituting the channel proteins isolated from sperm membrane into phospholipid-forming bilayer, we have characterized several kinds of Ca2+-, Na+-, K+-, and Cl--permeable channels with different conductance and properties in human sperm membrane. To study the channels in spermatogenic cells is another approach to understand the ion-channels in mature sperm. The cell is used as a model to analyze the effects of male antifertility agents on Ca2+-channel. To date, several male contraceptives derived from Chinese traditional medicine have been attached worldwide interest, a lot of compounds have been purified from them, and the antifertility effects of some compounds were demonstrated. We studied the effects of gossypol and several compounds isolated from Tripterygium wilffordii on Ca2+ channel in mouse spermatogenic cells and found that each of them inhibited the channel and sperm acrosome reaction at a proximate concentration, suggesting that the inhibition of Ca2+ channels may be one mechanism of the antifertility effects of these contraceptives.
View Article and Find Full Text PDF

Download full-text PDF

Source
January 2003

Modulation of Ca2+ channels by opioid receptor antagonists in mesenteric arterial smooth muscle cells of rats in hemorrhagic shock.

J Cardiovasc Pharmacol 2002 Oct;40(4):618-24

Institute of Surgery, Daping Hospital, Department of Pharmacology, Third Millitary Medical University, Chongqing, China.

The effects of hemorrhagic shock on Ba currents ( ) via Ca channels and the regulation of the channels in the vascular hyporesponse stage of hemorrhagic shock by opioid receptor antagonists were examined by using the whole-cell recording of patch-clamp technique in mesenteric arterial smooth muscle cells of rats. The results showed that hemorrhagic shock induced an inhibition of Ca channels in the cells; 10 micro M of naloxone and 100 n of naltrindole, nor-binaltorphimine, and beta-funaltrexamine increased the in the cells of rats in shock. After inhibition of protein kinase C by using 1-(5-isoquindinesulfonyl)-2-methylpiperazine via electrodes, the enhancement of by the antagonists was not observed. These results suggested that the inhibition of Ca channel induced by hemorrhagic shock was mediated by delta-, kappa-, and mu -opioid receptors in the cells and may be partly responsible for vascular hyporesponse. The enhancement of was mediated by activation of protein kinase C and may be responsible for the antagonist-caused improvement in the response of resistance arteries to vasoactive stimulants at the decompensatory stage of hemorrhagic shock.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/00005344-200210000-00016DOI Listing
October 2002

Inhibition of Ca(2+) channels in mouse spermatogenic cells by male antifertility compounds from Tripterygium wilfordii Hook. f.

Contraception 2002 Jun;65(6):441-5

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.

The male antifertility effect of a water-chloroform extract (GTW) from the root xylem of Tripterygium wilfordii has attracted worldwide interest. In the present study, by using whole-cell recording, the effects of GTW and two isolated monomers from GTW, demethylzeylasteral and L-epicatechin, on the T-type Ca(2+) channels in mouse spermatogenic cells were investigated. The results showed that each of them concentration-dependently and partially reversibly inhibited T-type Ca(2+) current in the cells. The IC(50) of GTW and demethylzeylasteral were approximate, while L-epicatechin inhibited the channels at a much higher concentration. The voltage dependence of the inhibitory effect and the changes in activation and inactivation time constants after application of these compounds were also examined. These data suggest that the inhibition of T-type Ca(2+) currents could be responsible for the antifertility activity of these compounds.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/s0010-7824(02)00312-8DOI Listing
June 2002

Beta-agkistrodotoxin inhibits large-conductance calcium-activated potassium channels in rat hippocampal CA1 pyramidal neurons.

Brain Res 2002 Jun;940(1-2):21-6

Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, 200031, Shanghai, China.

Effect of beta-agkistrodotoxin (beta-AgTx), a presynaptic neurotoxin purified from snake venom, on large-conductance calcium-activated potassium channels (BK(Ca)) was studied in rat hippocampal CA1 pyramidal neurons using inside-out configuration of patch-clamp technique. The results showed that in equimolar K+ (150 mM) and 1 microM intracellular Ca2+ conditions, internal application of beta-AgTx inhibited the activity of BK(Ca) by reducing open probability (P(o)) of the channels in a concentration-dependent manner. High concentration (74 nM) of beta-AgTx completely eliminated opening of the channels. However, 37 nM beta-AgTx (at -40 mV) decreased P(o) from 0.49+/-0.07 to 0.03+/-0.03, switched two open time constants (0.51+/-0.32 and 8.77+/-1.63 ms) to be a single time constant of 0.46+/-0.40 ms. The results indicate that inhibition of BK(Ca) by beta-AgTx may account for the facilitatory phase of the toxin on acetylcholine release from nerve terminals.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/s0006-8993(02)02560-xDOI Listing
June 2002
-->