Publications by authors named "Csaba Vastagh"

21 Publications

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The cryptic gonadotropin-releasing hormone neuronal system of human basal ganglia.

Elife 2021 Jun 15;10. Epub 2021 Jun 15.

Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary.

Human reproduction is controlled by ~2000 hypothalamic gonadotropin-releasing hormone (GnRH) neurons. Here, we report the discovery and characterization of additional ~150,000-200,000 GnRH-synthesizing cells in the human basal ganglia and basal forebrain. Nearly all extrahypothalamic GnRH neurons expressed the cholinergic marker enzyme choline acetyltransferase. Similarly, hypothalamic GnRH neurons were also cholinergic both in embryonic and adult human brains. Whole-transcriptome analysis of cholinergic interneurons and medium spiny projection neurons laser-microdissected from the human putamen showed selective expression of and autoreceptors in the cholinergic cell population and uncovered the detailed transcriptome profile and molecular connectome of these two cell types. Higher-order non-reproductive functions regulated by GnRH under physiological conditions in the human basal ganglia and basal forebrain require clarification. The role and changes of GnRH/GnRHR1 signaling in neurodegenerative disorders affecting cholinergic neurocircuitries, including Parkinson's and Alzheimer's diseases, need to be explored.
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http://dx.doi.org/10.7554/eLife.67714DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8245125PMC
June 2021

Gonadal Cycle-Dependent Expression of Genes Encoding Peptide-, Growth Factor-, and Orphan G-Protein-Coupled Receptors in Gonadotropin- Releasing Hormone Neurons of Mice.

Front Mol Neurosci 2020 18;13:594119. Epub 2021 Jan 18.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Budapest, Hungary.

Rising serum estradiol triggers the surge release of gonadotropin-releasing hormone (GnRH) at late proestrus leading to ovulation. We hypothesized that proestrus evokes alterations in peptidergic signaling onto GnRH neurons inducing a differential expression of neuropeptide-, growth factor-, and orphan G-protein-coupled receptor (GPCR) genes. Thus, we analyzed the transcriptome of GnRH neurons collected from intact, proestrous and metestrous GnRH-green fluorescent protein (GnRH-GFP) transgenic mice using Affymetrix microarray technique. Proestrus resulted in a differential expression of genes coding for peptide/neuropeptide receptors including , and . In this gene cluster, mRNA expression was upregulated and the others were downregulated. Expression of growth factor receptors and their related proteins was also altered showing upregulation of , and and downregulation of and genes. , an orphan GPCR, was upregulated during proestrus, while others were significantly downregulated (, and ). Further affected receptors included vomeronasal receptors (, and ) and platelet-activating factor receptor (), all with marked downregulation. Patch-clamp recordings from mouse GnRH-GFP neurons carried out at metestrus confirmed that the differentially expressed IGF-1, secretin, and GPR107 receptors were operational, as their activation by specific ligands evoked an increase in the frequency of miniature postsynaptic currents (mPSCs). These findings show the contribution of certain novel peptides, growth factors, and ligands of orphan GPCRs to regulation of GnRH neurons and their preparation for the surge release.
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http://dx.doi.org/10.3389/fnmol.2020.594119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7863983PMC
January 2021

Insulin-like growth factor 1 (IGF-1) increases GABAergic neurotransmission to GnRH neurons via suppressing the retrograde tonic endocannabinoid signaling pathway in mice.

Neuroendocrinology 2020 Dec 24. Epub 2020 Dec 24.

Introduction: Hypophysiotropic gonadotropin releasing-hormone (GnRH) neurons orchestrate various physiological events that control the onset of puberty. Previous studies showed that insulin-like growth factor 1 (IGF-1) induces the secretion of GnRH and accelerates the onset of puberty, suggesting a regulatory role of this hormone upon GnRH neurons.

Methods: To reveal responsiveness of GnRH neurons to IGF-1 and elucidate molecular pathways acting downstream to the IGF-1 receptor (IGF-1R), in vitro electrophysiological experiments were carried out on GnRH-GFP neurons in acute brain slices from prepubertal (23-29 days) and pubertal (50-day) male mice.

Results: Administration of IGF-1 (13 nM) significantly increased the firing rate and frequency of spontaneous postsynaptic currents (sPSCs), and that of excitatory GABAergic miniature postsynaptic currents (mPSCs). No GABAergic mPSCs were induced by IGF-1 in the presence of GABAA-R blocker picrotoxin. The increase in the mPSC frequency was prevented by the use of IGF-1R antagonist, JB1 (1 µM) or the intracellularly applied PI3K blocker (LY294002, 50 µM) showing involvement of IGF-1R and PI3K in the mechanism. Blockade of the transient receptor potential vanilloid 1 (TRPV1), an element of the tonic retrograde endocannabinoid machinery by AMG9810 (10 µM) or antagonizing cannabinoid receptor type-1 (CB1) by AM251 (1 µM) abolished the effect.

Discussion/conclusion: These findings indicate that IGF-1 arrests the tonic retrograde endocannabinoid pathway in GnRH neurons and this disinhibition increases the release of GABA from presynaptic terminals that, in turn, activates GnRH neurons leading to the fine-tuning of the hypothalamo-pituitary-gonadal axis.
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http://dx.doi.org/10.1159/000514043DOI Listing
December 2020

Networking of glucagon-like peptide-1 axons with GnRH neurons in the basal forebrain of male mice revealed by 3DISCO-based immunocytochemistry and optogenetics.

Brain Struct Funct 2021 Jan 9;226(1):105-120. Epub 2020 Nov 9.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Szigony u. 43, 1083, Budapest, Hungary.

Glucagon-like peptide-1 (GLP-1) regulates reproduction centrally, although, the neuroanatomical basis of the process is unknown. Therefore, the putative networking of the central GLP-1 and gonadotropin-releasing hormone (GnRH) systems was addressed in male mice using whole mount immunocytochemistry and optogenetics. Enhanced antibody penetration and optical clearing procedures applied to 500-1000 µm thick basal forebrain slices allowed the simultaneous visualization of the two distinct systems in the basal forebrain. Beaded GLP-1-IR axons innervated about a quarter of GnRH neurons (23.2 ± 1.4%) forming either single or multiple contacts. GnRH dendrites received a more intense GLP-1 innervation (64.6 ± 0.03%) than perikarya (35.4 ± 0.03%). The physiological significance of the innervation was examined by optogenetic activation of channelrhodopsin-2 (ChR2)-expressing axons of preproglucagon (GCG) neurons upon the firing of GnRH neurons by patch clamp electrophysiology in acute brain slices of triple transgenic mice (Gcg-cre/ChR2/GFP-GnRH). High-frequency laser beam stimulation (20 Hz, 10 ms pulse width, 3 mW laser power) of ChR2-expressing GCG axons in the mPOA increased the firing rate of GnRH neurons (by 75 ± 17.3%, p = 0.0007). Application of the GLP-1 receptor antagonist, Exendin-3-(9-39) (1 μM), prior to the photo-stimulation, abolished the facilitatory effect. In contrast, low-frequency trains of laser pulses (0.2 Hz, 60 pulses) had no effect on the spontaneous postsynaptic currents of GnRH neurons. The findings indicate a direct wiring of GLP-1 neurons with GnRH cells which route is excitatory for the GnRH system. The pathway may relay metabolic signals to GnRH neurons and synchronize metabolism with reproduction.
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http://dx.doi.org/10.1007/s00429-020-02167-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817561PMC
January 2021

Secretin Regulates Excitatory GABAergic Neurotransmission to GnRH Neurons via Retrograde NO Signaling Pathway in Mice.

Front Cell Neurosci 2019 23;13:371. Epub 2019 Aug 23.

Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.

In mammals, reproduction is regulated by a wide range of metabolic hormones that maintain the proper energy balance. In addition to regulating feeding and energy expenditure, these metabolic messengers also modulate the functional performance of the hypothalamic-pituitary-gonadal (HPG) axis. Secretin, a member of the secretin-glucagon-vasoactive intestinal peptide hormone family, has been shown to alter reproduction centrally, although the underlying mechanisms have not been explored yet. In order to elucidate its central action in the neuroendocrine regulation of reproduction, electrophysiological slice experiments were carried out on GnRH-GFP neurons in male mice. Bath application of secretin (100 nM) significantly increased the frequency of the spontaneous postsynaptic currents (sPSCs) to 118.0 ± 2.64% compared to the control, and that of the GABAergic miniature postsynaptic currents (mPSCs) to 147.6 ± 19.19%. Resting membrane potential became depolarized by 12.74 ± 4.539 mV after secretin treatment. Frequency of evoked action potentials (APs) also increased to 144.3 ± 10.8%. The secretin-triggered elevation of the frequency of mPSCs was prevented by using either a secretin receptor antagonist (3 μM) or intracellularly applied G-protein-coupled receptor blocker (GDP-β-S; 2 mM) supporting the involvement of secretin receptor in the process. Regarding the actions downstream to secretin receptor, intracellular blockade of protein kinase A (PKA) with KT-5720 (2 μM) or intracellular inhibition of the neuronal nitric oxide synthase (nNOS) by NPLA (1 μM) abolished the stimulatory effect of secretin on mPSCs. These data suggest that secretin acts on GnRH neurons via secretin receptors whose activation triggers the cAMP/PKA/nNOS signaling pathway resulting in nitric oxide release and in the presynaptic terminals this retrograde NO machinery regulates the GABAergic input to GnRH neurons.
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http://dx.doi.org/10.3389/fncel.2019.00371DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6716020PMC
August 2019

Proestrus Differentially Regulates Expression of Ion Channel and Calcium Homeostasis Genes in GnRH Neurons of Mice.

Front Mol Neurosci 2019 31;12:137. Epub 2019 May 31.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.

In proestrus, the changing gonadal hormone milieu alters the physiological properties of GnRH neurons and contributes to the development of the GnRH surge. We hypothesized that proestrus also influences the expression of different ion channel genes in mouse GnRH neurons. Therefore, we performed gene expression profiling of GnRH neurons collected from intact, proestrous and metestrous GnRH-GFP transgenic mice, respectively. Proestrus changed the expression of 37 ion channel and 8 calcium homeostasis-regulating genes. Voltage-gated sodium channels responded with upregulation of three alpha subunits (, , and ). Within the voltage-gated potassium channel class, , , , and were upregulated, while others (, , , and ) underwent downregulation. Proestrus also had impact on inwardly rectifying potassium channel subunits manifested in enhanced expression of and genes, whereas , , and subunit genes were downregulated. The two-pore domain potassium channels also showed differential expression with upregulation of and reduced expression of three subunit genes (, , and ). Changes in expression of chloride channels involved both the voltage-gated ( and ) and the intracellular () subtypes. Regarding the pore-forming alpha-1 subunits of voltage-gated calcium channels, two ( and ) were upregulated, while showed downregulation. The ancillary subunits were also differentially regulated (, , , , , , , and ). In addition, ryanodine receptor 1 () gene was downregulated, while a transient receptor potential cation channel () gene showed enhanced expression. Genes encoding proteins regulating the intracellular calcium homeostasis were also influenced (, , , , , , and ). The differential expression of genes coding for ion channel proteins in GnRH neurons at late proestrus indicates that the altering hormone milieu contributes to remodeling of different kinds of ion channels of GnRH neurons, which might be a prerequisite of enhanced cellular activity of GnRH neurons and the subsequent surge release of the neurohormone.
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http://dx.doi.org/10.3389/fnmol.2019.00137DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6554425PMC
May 2019

Estradiol Increases Glutamate and GABA Neurotransmission into GnRH Neurons via Retrograde NO-Signaling in Proestrous Mice during the Positive Estradiol Feedback Period.

eNeuro 2018 Jul-Aug;5(4). Epub 2018 Aug 3.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest H-1083, Hungary.

Surge release of gonadotropin-releasing hormone (GnRH) is essential in the activation of pituitary gonadal unit at proestrus afternoon preceded by the rise of serum 17β-estradiol (E2) level during positive feedback period. Here, we describe a mechanism of positive estradiol feedback regulation acting directly on GnRH-green fluorescent protein (GFP) neurons of mice. Whole-cell clamp and loose patch recordings revealed that a high physiological dose of estradiol (200 pM), significantly increased firing rate at proestrus afternoon. The mPSC frequency at proestrus afternoon also increased, whereas it decreased at metestrus afternoon and had no effect at proestrus morning. Inhibition of the estrogen receptor β (ERβ), intracellular blockade of the Src kinase and phosphatidylinositol 3 kinase (PI3K) and scavenge of nitric oxide (NO) inside GnRH neurons prevented the facilitatory estradiol effect indicating involvement of the ERβ/Src/PI3K/Akt/nNOS pathway in this fast, direct stimulatory effect. Immunohistochemistry localized soluble guanylate cyclase, the main NO receptor, in both glutamatergic and GABAergic terminals innervating GnRH neurons. Accordingly, estradiol facilitated neurotransmissions to GnRH neurons via both GABA-R and glutamate/AMPA/kainate-R. These results indicate that estradiol acts directly on GnRH neurons via the ERβ/Akt/nNOS pathway at proestrus afternoon generating NO that retrogradely accelerates GABA and glutamate release from the presynaptic terminals contacting GnRH neurons. The newly explored mechanism might contribute to the regulation of the GnRH surge, a fundamental prerequisite of the ovulation.
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http://dx.doi.org/10.1523/ENEURO.0057-18.2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6073979PMC
February 2019

Chronic Amyloid β Oligomer Infusion Evokes Sustained Inflammation and Microglial Changes in the Rat Hippocampus via NLRP3.

Neuroscience 2019 05 6;405:35-46. Epub 2018 Mar 6.

Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary. Electronic address:

Microglia are instrumental for recognition and elimination of amyloid β oligomers (AβOs), but the long-term consequences of AβO-induced inflammatory changes in the brain are unclear. Here, we explored microglial responses and transciptome-level inflammatory signatures in the rat hippocampus after chronic AβO challenge. Middle-aged Long Evans rats received intracerebroventricular infusion of AβO or vehicle for 4 weeks, followed by treatment with artificial CSF or MCC950 for the subsequent 4 weeks. AβO infusion evoked a sustained inflammatory response including activation of NF-κB, triggered microglia activation and increased the expression of pattern recognition and phagocytic receptors. Aβ plaques were not detectable likely due to microglial elimination of infused oligomers. In addition, we found upregulation of neuronal inhibitory ligands and their cognate microglial receptors, while downregulation of Esr1 and Scn1a, encoding estrogen receptor alpha and voltage-gated sodium-channel Na(v)1.1, respectively, was observed. These changes were associated with impaired hippocampus-dependent spatial memory and resembled early neurological changes seen in Alzheimer's disease. To investigate the role of inflammatory actions in memory deterioration, we performed MCC950 infusion, which specifically blocks the NLRP3 inflammasome. MCC950 attenuated AβO-evoked microglia reactivity, restored expression of neuronal inhibitory ligands, reversed downregulation of ERα, and abolished memory impairments. Furthermore, MCC950 abrogated AβO-invoked reduction of serum IL-10. These findings provide evidence that in response to AβO infusion microglia change their phenotype, but the resulting inflammatory changes are sustained for at least one month after the end of AβO challenge. Lasting NLRP3-driven inflammatory alterations and altered hippocampal gene expression contribute to spatial memory decline.
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http://dx.doi.org/10.1016/j.neuroscience.2018.02.046DOI Listing
May 2019

Impact of Proestrus on Gene Expression in the Medial Preoptic Area of Mice.

Front Cell Neurosci 2017 4;11:183. Epub 2017 Jul 4.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary.

The antero-ventral periventricular zone (AVPV) and medial preoptic area (MPOA) have been recognized as gonadal hormone receptive regions of the rodent brain that-via wiring to gonadotropin-releasing hormone (GnRH) neurons-contribute to orchestration of the preovulatory GnRH surge. We hypothesized that neural genes regulating the induction of GnRH surge show altered expression in proestrus. Therefore, we compared the expression of 48 genes obtained from intact proestrous and metestrous mice, respectively, by quantitative real-time PCR (qPCR) method. Differential expression of 24 genes reached significance ( < 0.05). Genes upregulated in proestrus encoded neuropeptides (kisspeptin (KP), galanin (GAL), neurotensin (NT), cholecystokinin (CCK)), hormone receptors (growth hormone secretagogue receptor, μ-opioid receptor), gonadal steroid receptors (estrogen receptor alpha (ERα), progesterone receptor (PR), androgen receptor (AR)), solute carrier family proteins (vesicular glutamate transporter 2, vesicular monoamine transporter 2), proteins of transmitter synthesis (tyrosine hydroxylase (TH)) and transmitter receptor subunit (AMPA4), and other proteins (uncoupling protein 2, nuclear receptor related 1 protein). Proestrus evoked a marked downregulation of genes coding for adenosine A2a receptor, vesicular gamma-aminobutyric acid (GABA) transporter, 4-aminobutyrate aminotransferase, tachykinin precursor 1, NT receptor 3, arginine vasopressin receptor 1A, cannabinoid receptor 1, ephrin receptor A3 and aldehyde dehydrogenase 1 family, member L1. Immunocytochemistry was used to visualize the proteins encoded by and genes in neuronal subsets of the AVPV/MPOA of the proestrous mice. The results indicate that gene expression of the AVPV/MPOA is significantly modified at late proestrus including genes that code for neuropeptides, gonadal steroid hormone receptors and synaptic vesicle transporters. These events support cellular and neuronal network requirements of the positive estradiol feedback action and contribute to preparation of the GnRH neuron system for the pre-ovulatory surge release.
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http://dx.doi.org/10.3389/fncel.2017.00183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5495965PMC
July 2017

Altered Expression of Genes Encoding Neurotransmitter Receptors in GnRH Neurons of Proestrous Mice.

Front Cell Neurosci 2016 7;10:230. Epub 2016 Oct 7.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary; Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic UniversityBudapest, Hungary.

Gonadotropin-releasing hormone (GnRH) neurons play a key role in the central regulation of reproduction. In proestrous female mice, estradiol triggers the pre-ovulatory GnRH surge, however, its impact on the expression of neurotransmitter receptor genes in GnRH neurons has not been explored yet. We hypothesized that proestrus is accompanied by substantial changes in the expression profile of genes coding for neurotransmitter receptors in GnRH neurons. We compared the transcriptome of GnRH neurons obtained from intact, proestrous, and metestrous female GnRH-GFP transgenic mice, respectively. About 1500 individual GnRH neurons were sampled from both groups and their transcriptome was analyzed using microarray hybridization and real-time PCR. In this study, changes in mRNA expression of genes involved in neurotransmitter signaling were investigated. Differential gene expression was most apparent in GABA-ergic (), glutamatergic (), cholinergic () and dopaminergic (), adrenergic (), adenosinergic (), glycinergic (), purinergic (), and serotonergic () receptors. In concert with these events, expression of genes in the signaling pathways downstream to the receptors, i.e., G-proteins (), adenylate-cyclases (), protein kinase A () protein kinase C () and certain transporters () were also changed. The marked differences found in the expression of genes involved in neurotransmitter signaling of GnRH neurons at pro- and metestrous stages of the ovarian cycle indicate the differential contribution of these neurotransmitter systems to the induction of the pre-ovulatory GnRH surge, the known prerequisite of the subsequent hormonal cascade inducing ovulation.
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http://dx.doi.org/10.3389/fncel.2016.00230DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5054603PMC
October 2016

Glucagon-Like Peptide-1 Excites Firing and Increases GABAergic Miniature Postsynaptic Currents (mPSCs) in Gonadotropin-Releasing Hormone (GnRH) Neurons of the Male Mice via Activation of Nitric Oxide (NO) and Suppression of Endocannabinoid Signaling Pathways.

Front Cell Neurosci 2016 12;10:214. Epub 2016 Sep 12.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary; Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic UniversityBudapest, Hungary.

Glucagon-like peptide-1 (GLP-1), a metabolic signal molecule, regulates reproduction, although, the involved molecular mechanisms have not been elucidated, yet. Therefore, responsiveness of gonadotropin-releasing hormone (GnRH) neurons to the GLP-1 analog Exendin-4 and elucidation of molecular pathways acting downstream to the GLP-1 receptor (GLP-1R) have been challenged. Loose patch-clamp recordings revealed that Exendin-4 (100 nM-5 μM) elevated firing rate in hypothalamic GnRH-GFP neurons of male mice via activation of GLP-1R. Whole-cell patch-clamp measurements demonstrated increased excitatory GABAergic miniature postsynaptic currents (mPSCs) frequency after Exendin-4 administration, which was eliminated by the GLP-1R antagonist Exendin-3(9-39) (1 μM). Intracellular application of the G-protein inhibitor GDP-β-S (2 mM) impeded action of Exendin-4 on mPSCs, suggesting direct excitatory action of GLP-1 on GnRH neurons. Blockade of nitric-oxide (NO) synthesis by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME; 100 μM) or N(5)-[Imino(propylamino)methyl]-L-ornithine hydrochloride (NPLA; 1 μM) or intracellular scavenging of NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO; 1 mM) partially attenuated the excitatory effect of Exendin-4. Similar partial inhibition was achieved by hindering endocannabinoid pathway using cannabinoid receptor type-1 (CB1) inverse-agonist 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-(1-piperidyl) pyrazole-3-carboxamide (AM251; 1 μM). Simultaneous blockade of NO and endocannabinoid signaling mechanisms eliminated action of Exendin-4 suggesting involvement of both retrograde machineries. Intracellular application of the transient receptor potential vanilloid 1 (TRPV1)-antagonist 2E-N-(2, 3-Dihydro-1,4-benzodioxin-6-yl)-3-[4-(1, 1-dimethylethyl)phenyl]-2-Propenamide (AMG9810; 10 μM) or the fatty acid amide hydrolase (FAAH)-inhibitor PF3845 (5 μM) impeded the GLP-1-triggered endocannabinoid pathway indicating an anandamide-TRPV1-sensitive control of 2-arachidonoylglycerol (2-AG) production. Furthermore, GLP-1 immunoreactive (IR) axons innervated GnRH neurons in the hypothalamus suggesting that GLP-1 of both peripheral and neuronal sources can modulate GnRH neurons. RT-qPCR study confirmed the expression of GLP-1R and neuronal NO synthase (nNOS) mRNAs in GnRH-GFP neurons. Immuno-electron microscopic analysis revealed the presence of nNOS protein in GnRH neurons. These results indicate that GLP-1 exerts direct facilitatory actions via GLP-1R on GnRH neurons and modulates NO and 2-AG retrograde signaling mechanisms that control the presynaptic excitatory GABAergic inputs to GnRH neurons.
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http://dx.doi.org/10.3389/fncel.2016.00214DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5018486PMC
September 2016

Altered Gene Expression Profiles of the Hypothalamic Arcuate Nucleus of Male Mice Suggest Profound Developmental Changes in Peptidergic Signaling.

Neuroendocrinology 2016 25;103(3-4):369-82. Epub 2015 Aug 25.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.

Neuropeptides of the hypothalamic arcuate nucleus (ARC) regulate important homeostatic and endocrine functions and also play critical roles in pubertal development. The altered peptidergic and aminoacidergic neurotransmission accompanying pubertal maturation of the ARC is not fully understood. Here we studied the developmental shift in the gene expression profile of the ARC of male mice. RNA samples for quantitative RT-PCR studies were isolated from the ARC of 14-day-old infantile and 60-day-old adult male mice with laser capture microdissection. The expression of 18 neuropeptide, 15 neuropeptide receptor, 4 sex steroid receptor and 6 classic neurotransmitter marker mRNAs was compared between the two time points. The adult animals showed increased mRNA levels encoding cocaine- and amphetamine-regulated transcripts, galanin-like peptide, dynorphin, kisspeptin, proopiomelanocortin, proenkephalin and galanin and a reduced expression of mRNAs for pituitary adenylate cyclase-activating peptide, calcitonin gene-related peptide, neuropeptide Y, substance P, agouti-related protein, neurotensin and growth hormone-releasing hormone. From the neuropeptide receptors tested, melanocortin receptor-4 showed the most striking increase (5-fold). Melanocortin receptor-3 and the Y1 and Y5 neuropeptide Y receptors increased 1.5- to 1.8-fold, whereas δ-opioid receptor and neurotensin receptor-1 transcripts were reduced by 27 and 21%, respectively. Androgen receptor, progesterone receptor and α-estrogen receptor transcripts increased by 54-72%. The mRNAs of glutamic acid decarboxylases-65 and -67, vesicular GABA transporter and choline acetyltransferase remained unchanged. Tyrosine hydroxylase mRNA increased by 44%, whereas type-2 vesicular glutamate transporter mRNA decreased by 43% by adulthood. Many of the developmental changes we revealed in this study suggest a reduced inhibitory and/or enhanced excitatory neuropeptidergic drive on fertility in adult animals.
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http://dx.doi.org/10.1159/000439430DOI Listing
May 2017

Differential Gene Expression in Gonadotropin-Releasing Hormone Neurons of Male and Metestrous Female Mice.

Neuroendocrinology 2015 29;102(1-2):44-59. Epub 2015 Apr 29.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.

Background: Gonadotropin-releasing hormone (GnRH) neurons play a pivotal role in the regulation of the hypothalamic-pituitary gonadal axis in a sex-specific manner. We hypothesized that the differences seen in reproductive functions of males and females are associated with a sexually dimorphic gene expression profile of GnRH neurons.

Methods And Results: We compared the transcriptome of GnRH neurons obtained from intact metestrous female and male GnRH-green fluorescent protein transgenic mice. About 1,500 individual GnRH neurons from each sex were sampled with laser capture microdissection followed by whole-transcriptome amplification for gene expression profiling. Under stringent selection criteria (fold change >1.6, adjusted p value 0.01), Affymetrix Mouse Genome 430 PM array analysis identified 543 differentially expressed genes. Sexual dimorphism was most apparent in gene clusters associated with synaptic communication, signal transduction, cell adhesion, vesicular transport and cell metabolism. To validate microarray results, 57 genes were selected, and 91% of their differential expression was confirmed by real-time PCR. Similarly, 88% of microarray results were confirmed with PCR from independent samples obtained by patch pipette harvesting and pooling of 30 GnRH neurons from each sex. We found significant differences in the expression of genes involved in vesicle priming and docking (Syt1, Cplx1), GABAergic (Gabra3, Gabrb3, Gabrg2) and glutamatergic (Gria1, Grin1, Slc17a6) neurotransmission, peptide signaling (Sstr3, Npr2, Cxcr4) and the regulation of intracellular ion homeostasis (Cacna1, Cacnb1, Cacng5, Kcnq2, Kcnc1).

Conclusion: The striking sexual dimorphism of the GnRH neuron transcriptome we report here contributes to a better understanding of the differences in cellular mechanisms of GnRH neurons in the two sexes.
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http://dx.doi.org/10.1159/000430818DOI Listing
June 2016

Hippocampal Gene Expression Is Highly Responsive to Estradiol Replacement in Middle-Aged Female Rats.

Endocrinology 2015 Jul 29;156(7):2632-45. Epub 2015 Apr 29.

Laboratory of Endocrine Neurobiology (M.S., I.K., E.H., C.V., Z.L.), Institute of Experimental Medicine, Hungarian Academy of Sciences, 1083 Budapest, Hungary; Faculty of Information Technology and Bionics (I.K., Z.L.), Pázmány Péter Catholic University, 1083 Budapest, Hungary; Faculty of Veterinary Science (N.S.), Szent István University, 1078 Budapest, Hungary; Functional Genomics Core (A.R.), Institute for Research in Biomedicine, 08028 Barcelona, Spain; and Functional Genomics Consulting (H.A.), 08780 Palleja, Spain.

In the hippocampus, estrogens are powerful modulators of neurotransmission, synaptic plasticity and neurogenesis. In women, menopause is associated with increased risk of memory disturbances, which can be attenuated by timely estrogen therapy. In animal models of menopause, 17β-estradiol (E2) replacement improves hippocampus-dependent spatial memory. Here, we explored the effect of E2 replacement on hippocampal gene expression in a rat menopause model. Middle-aged ovariectomized female rats were treated continuously for 29 days with E2, and then, the hippocampal transcriptome was investigated with Affymetrix expression arrays. Microarray data were analyzed by Bioconductor packages and web-based softwares, and verified with quantitative PCR. At standard fold change selection criterion, 156 genes responded to E2. All alterations but 4 were transcriptional activation. Robust activation (fold change > 10) occurred in the case of transthyretin, klotho, claudin 2, prolactin receptor, ectodin, coagulation factor V, Igf2, Igfbp2, and sodium/sulfate symporter. Classification of the 156 genes revealed major groups, including signaling (35 genes), metabolism (31 genes), extracellular matrix (17 genes), and transcription (16 genes). We selected 33 genes for further studies, and all changes were confirmed by real-time PCR. The results suggest that E2 promotes retinoid, growth factor, homeoprotein, neurohormone, and neurotransmitter signaling, changes metabolism, extracellular matrix composition, and transcription, and induces protective mechanisms via genomic effects. We propose that these mechanisms contribute to effects of E2 on neurogenesis, neural plasticity, and memory functions. Our findings provide further support for the rationale to develop safe estrogen receptor ligands for the maintenance of cognitive performance in postmenopausal women.
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http://dx.doi.org/10.1210/en.2015-1109DOI Listing
July 2015

The spatiotemporal segregation of GAD forms defines distinct GABA signaling functions in the developing mouse olfactory system and provides novel insights into the origin and migration of GnRH neurons.

Dev Neurobiol 2015 Mar 14;75(3):249-70. Epub 2014 Aug 14.

Division of Medical Gene Technology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary; Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.

Gamma-aminobutyric acid (GABA) has a dual role as an inhibitory neurotransmitter in the adult central nervous system (CNS) and as a signaling molecule exerting largely excitatory actions during development. The rate-limiting step of GABA synthesis is catalyzed by two glutamic acid decarboxylase isoforms GAD65 and GAD67 coexpressed in the GABAergic neurons of the CNS. Here we report that the two GADs show virtually nonoverlapping expression patterns consistent with distinct roles in the developing peripheral olfactory system. GAD65 is expressed exclusively in undifferentiated neuronal progenitors confined to the proliferative zones of the sensory vomeronasal and olfactory epithelia In contrast GAD67 is expressed in a subregion of the nonsensory epithelium/vomeronasal organ epithelium containing the putative Gonadotropin-releasing hormone (GnRH) progenitors and GnRH neurons migrating from this region through the frontonasal mesenchyme into the basal forebrain. Only GAD67+, but not GAD65+ cells accumulate detectable GABA. We further demonstrate that GAD67 and its embryonic splice variant embryonic GAD (EGAD) concomitant with GnRH are dynamically regulated during GnRH neuronal migration in vivo and in two immortalized cell lines representing migratory (GN11) and postmigratory (GT1-7) stage GnRH neurons, respectively. Analysis of GAD65/67 single and double knock-out embryos revealed that the two GADs play complementary (inhibitory) roles in GnRH migration ultimately modulating the speed and/or direction of GnRH migration. Our results also suggest that GAD65 and GAD67/EGAD characterized by distinct subcellular localization and kinetics have disparate functions during olfactory system development mediating proliferative and migratory responses putatively through specific subcellular GABA pools.
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http://dx.doi.org/10.1002/dneu.22222DOI Listing
March 2015

Estradiol and isotype-selective estrogen receptor agonists modulate the mesocortical dopaminergic system in gonadectomized female rats.

Brain Res 2014 Oct 26;1583:1-11. Epub 2014 Jun 26.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony utca 43, 1083 Budapest, Hungary; Faculty of Information Technology, Pázmány Péter Catholic University, Práter utca 50/A, 1083 Budapest, Hungary.

The mesocortical dopaminergic pathway projecting from the ventral tegmental area (VTA) to the prefrontal cortex (PFC) contributes to the processing of reward signals. This pathway is regulated by gonadal steroids including estradiol. To address the putative role of estradiol and isotype-selective estrogen receptor (ER) agonists in the regulation of the rodent mesocortical system, we combined fMRI, HPLC-MS and qRT-PCR techniques. In fMRI experiments adult, chronically ovariectomized rats, treated with either vehicle, estradiol, ERα agonist 16α-lactone-estradiol (LE2) or ERβ agonist diarylpropionitrile (DPN), received a single dose of d-amphetamine-sulphate (10mg/kg, i.p.) and BOLD responses were monitored in the VTA and the PFC. Ovariectomized rats showed no significant response to amphetamine. In contrast, the VTA of ER agonist-substituted ovariectomized rats showed robust amphetamine-evoked BOLD increases. The PFC of estradiol-replaced animals was also responsive to amphetamine. Mass spectroscopic analysis of dopamine and its metabolites revealed a two-fold increase in both dopamine and 3,4-dihydroxyphenylacetic acid content of the PFC in estradiol-replaced animals compared to ovariectomized controls. qRT-PCR studies revealed upregulation of dopamine transporter and dopamine receptor in the VTA and PFC, respectively, of ER agonist-treated ovariectomized animals. Collectively, the results indicate that E2 and isotype-selective ER agonists can powerfully modulate the responsiveness of the mesocortical dopaminergic system, increase the expression of key genes related to dopaminergic neurotransmission and augment the dopamine content of the PFC. In a broader sense, the findings support the concept that the manifestation of reward signals in the PFC is dependent on the actual estrogen milieu of the brain.
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http://dx.doi.org/10.1016/j.brainres.2014.06.020DOI Listing
October 2014

Ghrelin decreases firing activity of gonadotropin-releasing hormone (GnRH) neurons in an estrous cycle and endocannabinoid signaling dependent manner.

PLoS One 2013 4;8(10):e78178. Epub 2013 Oct 4.

Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.

The orexigenic peptide, ghrelin is known to influence function of GnRH neurons, however, the direct effects of the hormone upon these neurons have not been explored, yet. The present study was undertaken to reveal expression of growth hormone secretagogue receptor (GHS-R) in GnRH neurons and elucidate the mechanisms of ghrelin actions upon them. Ca(2+)-imaging revealed a ghrelin-triggered increase of the Ca(2+)-content in GT1-7 neurons kept in a steroid-free medium, which was abolished by GHS-R-antagonist JMV2959 (10 µM) suggesting direct action of ghrelin. Estradiol (1nM) eliminated the ghrelin-evoked rise of Ca(2+)-content, indicating the estradiol dependency of the process. Expression of GHS-R mRNA was then confirmed in GnRH-GFP neurons of transgenic mice by single cell RT-PCR. Firing rate and burst frequency of GnRH-GFP neurons were lower in metestrous than proestrous mice. Ghrelin (40 nM-4 μM) administration resulted in a decreased firing rate and burst frequency of GnRH neurons in metestrous, but not in proestrous mice. Ghrelin also decreased the firing rate of GnRH neurons in males. The ghrelin-evoked alterations of the firing parameters were prevented by JMV2959, supporting the receptor-specific actions of ghrelin on GnRH neurons. In metestrous mice, ghrelin decreased the frequency of GABAergic mPSCs in GnRH neurons. Effects of ghrelin were abolished by the cannabinoid receptor type-1 (CB1) antagonist AM251 (1µM) and the intracellularly applied DAG-lipase inhibitor THL (10 µM), indicating the involvement of retrograde endocannabinoid signaling. These findings demonstrate that ghrelin exerts direct regulatory effects on GnRH neurons via GHS-R, and modulates the firing of GnRH neurons in an ovarian-cycle and endocannabinoid dependent manner.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0078178PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3790731PMC
May 2014

N-methyl-D-aspartate (NMDA) receptor composition modulates dendritic spine morphology in striatal medium spiny neurons.

J Biol Chem 2012 May 9;287(22):18103-14. Epub 2012 Apr 9.

Department of Pharmacological Sciences, University of Milano, Milano, Italy.

Dendritic spines of medium spiny neurons represent an essential site of information processing between NMDA and dopamine receptors in striatum. Even if activation of NMDA receptors in the striatum has important implications for synaptic plasticity and disease states, the contribution of specific NMDA receptor subunits still remains to be elucidated. Here, we show that treatment of corticostriatal slices with NR2A antagonist NVP-AAM077 or with NR2A blocking peptide induces a significant increase of spine head width. Sustained treatment with D1 receptor agonist (SKF38393) leads to a significant decrease of NR2A-containing NMDA receptors and to a concomitant increase of spine head width. Interestingly, co-treatment of corticostriatal slices with NR2A antagonist (NVP-AAM077) and D1 receptor agonist augmented the increase of dendritic spine head width as obtained with SKF38393. Conversely, NR2B antagonist (ifenprodil) blocked any morphological effect induced by D1 activation. These results indicate that alteration of NMDA receptor composition at the corticostriatal synapse contributes not only to the clinical features of disease states such as experimental parkinsonism but leads also to a functional and morphological outcome in dendritic spines of medium spiny neurons.
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http://dx.doi.org/10.1074/jbc.M112.347427DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3365766PMC
May 2012

Blocking ADAM10 synaptic trafficking generates a model of sporadic Alzheimer's disease.

Brain 2010 Nov 30;133(11):3323-35. Epub 2010 Aug 30.

Department of Pharmacological Sciences and Centre of Excellence on Neurodegenerative Diseases, Università degli Studi di Milano, 20133 Milan, Italy.

We describe here an innovative, non-transgenic animal model of Alzheimer's disease. This model mimics early stages of sporadic disease, which represents the vast majority of cases. The model was obtained by interfering with the complex between a disintegrin and metalloproteinase domain containing protein 10 (ADAM10), the main α-secretase candidate, and its partner, synapse-associated protein 97, a protein of the postsynaptic density-membrane associated guanylate kinase family. Association of ADAM10 with synapse-associated protein 97 governs enzyme trafficking and activity at synapses. Interfering with the ADAM10/synapse-associated protein 97 complex for 2 weeks by means of a cell-permeable peptide strategy is sufficient to shift the metabolism of the amyloid precursor protein towards amyloidogenesis and allows the reproduction of initial phases of sporadic Alzheimer's disease. After 2 weeks of treatment, we detected progressive Alzheimer's disease-like neuropathology, with an increase of β-amyloid aggregate production and of tau hyperphosphorylation, and a selective alteration of N-methyl-d-aspartic acid receptor subunit composition in the postsynaptic compartment of mouse brain. Behavioural and electrophysiological deficits were also induced by peptide treatment.
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http://dx.doi.org/10.1093/brain/awq217DOI Listing
November 2010

Postnatal expression pattern of doublecortin (DCX) in some areas of the developing brain of mouse.

Ideggyogy Sz 2007 Mar;60(3-4):144-7

Infobionic and Neurobiological Plasticity Research Group, Hungarian Academy of Sciences - Peter Pazmany Catholic University - Semmelweis University, Budapest.

We have investigated the spatio-temporal expression pattern of doublecortin (DCX) protein from postnatal day (P) 2 to postnatal day (P) 22 in the brain of developing mouse. We compared the expression of DCX in the rostral migratory stream (RMS) and dentate gyrus of the hippocampus (DG). Weak expression of DCX was detected in the RMS at P5, it became gradually stronger during the second postnatal week and reached its strongest expression by P18-P22. Moderate DCX immunostaining was present in the DG at P11, its marked expression--characteristic of newly generated neurons in the adult DG -appeared only after P22. Morphological and functional maturation was different in the RMS and DG, continuous neurogenesis appeared earlier in the RMS than in the DG.
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March 2007

Distribution of mGluR1alpha and SMI 311 immunoreactive Lugaro cells in the kitten cerebellum.

J Neurocytol 2003 Mar;32(3):217-27

Neurobiology Research Group, United Research Organization of the Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary.

The Lugaro cell is a feedback interneuron of the cerebellar cortex, recognizable by its characteristic morphology. Postnatal neuronal migration to the cortex has been described for several cerebellar interneurons. Since in our previous studies we observed Lugaro-like cells (LCs) in the white matter (WM) and internal granular layer (IGL) of the cerebellum of young cats, we assumed that a proportion of these cells migrate also postnatally to their destination. In the present study using and immunostaining for the metabotropic glutamate receptor mGluR1alpha and neurofilament protein SMI 311 the number and spatial distribution of LCs at different postnatal days were investigated. We found that the number and distribution of both mGluR1a-immunoreactive (ir) and of SMI 311-ir LCs changed with age in the developing cerebellar cortex of kittens: developing LCs express mGluR1alpha already in the newborn, while expression of SMI 311-ir in LCs appears only about a week later. At postnatal day 1 (P1) relatively few mGluR1-ir LCs were detected in the WM and at the border of WM and IGL. Later, their number increased sharply until P15 (6-7 fold) and decreased continuously between P15 and P135. SMI 311-ir LCs were not present at P1 and even at P8 only a few were observed in the WM or in infraganglionic positions. Their number increased gradually (12-14 fold) until adulthood when their number was stabilized at 8.000-10.000/cerebellum. At the same time the number of probably ectopic SMI 311-ir LCs decreased with age: at P22 about one third of them was found in "ectopic" position, whereas in the adult cat only about 10-12% of LCs's was either in the WM or scattered in the whole depth of the granular layer. These results suggest that: (1) most LCs appear in the cerebellar cortex postnatally; and (2) postnatal migration and incorporation of LCs to the cortex is a much longer process than previously expected, occurring even after the cytoarchitectonic built-up (about P65-P70 in cat) of the cerebellum.
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http://dx.doi.org/10.1023/B:NEUR.0000010081.54613.94DOI Listing
March 2003