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Vastagh C, Farkas I, Csillag V, Watanabe M, Kalló I, Liposits Z. Cholinergic Control of GnRH Neuron Physiology and Luteinizing Hormone Secretion in Male Mice: Involvement of ACh/GABA Cotransmission. J Neurosci 2024; 44:e1780232024. [PMID: 38320853 PMCID: PMC10957212 DOI: 10.1523/jneurosci.1780-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 01/12/2024] [Accepted: 01/22/2024] [Indexed: 03/22/2024] Open
Abstract
Gonadotropin-releasing hormone (GnRH)-synthesizing neurons orchestrate reproduction centrally. Early studies have proposed the contribution of acetylcholine (ACh) to hypothalamic control of reproduction, although the causal mechanisms have not been clarified. Here, we report that in vivo pharmacogenetic activation of the cholinergic system increased the secretion of luteinizing hormone (LH) in orchidectomized mice. 3DISCO immunocytochemistry and electron microscopy revealed the innervation of GnRH neurons by cholinergic axons. Retrograde viral labeling initiated from GnRH-Cre neurons identified the medial septum and the diagonal band of Broca as exclusive sites of origin for cholinergic afferents of GnRH neurons. In acute brain slices, ACh and carbachol evoked a biphasic effect on the firing rate in GnRH neurons, first increasing and then diminishing it. In the presence of tetrodotoxin, carbachol induced an inward current, followed by a decline in the frequency of miniature postsynaptic currents (mPSCs), indicating a direct influence on GnRH cells. RT-PCR and whole-cell patch-clamp studies revealed that GnRH neurons expressed both nicotinic (α4β2, α3β4, and α7) and muscarinic (M1-M5) AChRs. The nicotinic AChRs contributed to the nicotine-elicited inward current and the rise in firing rate. Muscarine via M1 and M3 receptors increased, while via M2 and M4 reduced the frequency of both mPSCs and firing. Optogenetic activation of channelrhodopsin-2-tagged cholinergic axons modified GnRH neuronal activity and evoked cotransmission of ACh and GABA from a subpopulation of boutons. These findings confirm that the central cholinergic system regulates GnRH neurons and activates the pituitary-gonadal axis via ACh and ACh/GABA neurotransmissions in male mice.
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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, HUN-REN Institute of Experimental Medicine, Budapest H-1083, Hungary
| | - Imre Farkas
- Laboratory of Endocrine Neurobiology, HUN-REN Institute of Experimental Medicine, Budapest H-1083, Hungary
| | - Veronika Csillag
- Laboratory of Endocrine Neurobiology, HUN-REN Institute of Experimental Medicine, Budapest H-1083, Hungary
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
| | - Imre Kalló
- Laboratory of Endocrine Neurobiology, HUN-REN Institute of Experimental Medicine, Budapest H-1083, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, HUN-REN Institute of Experimental Medicine, Budapest H-1083, Hungary
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Shostak DM, Constantin S, Flannery J, Wray S. Acetylcholine regulation of GnRH neuronal activity: A circuit in the medial septum. Front Endocrinol (Lausanne) 2023; 14:1147554. [PMID: 36950690 PMCID: PMC10025473 DOI: 10.3389/fendo.2023.1147554] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 02/22/2023] [Indexed: 03/08/2023] Open
Abstract
In vertebrates, gonadotropin-releasing hormone (GnRH)-secreting neurons control fertility by regulating gonadotrophs in the anterior pituitary. While it is known that acetylcholine (ACh) influences GnRH secretion, whether the effect is direct or indirect, and the specific ACh receptor (AChR) subtype(s) involved remain unclear. Here, we determined 1) whether ACh can modulate GnRH cellular activity and 2) a source of ACh afferents contacting GnRH neurons. Calcium imaging was used to assay GnRH neuronal activity. With GABAergic and glutamatergic transmission blocked, subtype-specific AChR agonists and antagonists were applied to identify direct regulation of GnRH neurons. ACh and nicotine caused a rise in calcium that declined gradually back to baseline after 5-6 min. This response was mimicked by an alpha3-specific agonist. In contrast, muscarine inhibited GnRH calcium oscillations, and blocking M2 and M4 together prevented this inhibition. Labeling for choline acetyltransferase (ChAT) and GnRH revealed ChAT fibers contacting GnRH neurons, primarily in the medial septum (MS), and in greater number in females than males. ChAT positive cells in the MS are known to express p75NGFRs. Labeling for p75NGFR, ChAT and GnRH indicated that ChAT fibers contacting GnRH cells originate from cholinergic cells within these same rostral areas. Together, these results indicate that cholinergic cells in septal areas can directly regulate GnRH neurons.
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Vieyra-Valdez E, Linares-Culebro R, Rosas-Gavilán G, Ramírez-Hernández D, Domínguez-Casalá R, Morales-Ledesma L. Roles of the cholinergic system and vagal innervation in the regulation of GnRH secretion and ovulation: Experimental evidence. Brain Res Bull 2020; 165:129-138. [PMID: 32966849 DOI: 10.1016/j.brainresbull.2020.09.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 09/04/2020] [Accepted: 09/14/2020] [Indexed: 12/20/2022]
Abstract
Reproduction is the biological process that sustains life. It is regulated by a neuro-hormonal mechanism that is synchronized by the interaction among the hypothalamus, hypophysis, and ovaries. Ovulation is regulated by the secretion of the gonadotropin-releasing hormone (GnRH), which stimulates the release of the luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In addition to these neuroendocrine signals, other signals originating from the central nervous system, hypophysis, thyroid, adrenal glands, and the ovary itself are also involved. One of the neurotransmission systems involved in the regulation of ovulation is the cholinergic system, which not only participates in the regulation of reproductive functions but also modulates motor coordination, thermoregulation, and cognitive function. In mammals, the vagus nerve is one of the pathways through which acetylcholine reaches the ovary, and this pathway also participates in the regulation of ovulation. However, this regulation depends on the age of the animal (prepubertal or adult) and its endocrine status. The present review analyzes evidence of the roles of the central and peripheral cholinergic system and vagal innervation in the regulation of GnRH secretion and ovulation as well as their roles in the development and persistence of polycystic ovary syndrome (PCOS).
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Affiliation(s)
- Elizabeth Vieyra-Valdez
- Biology of Reproduction Research Unit, Physiology of Reproduction Laboratory, Facultad de Estudios Superiores Zaragoza, UNAM, AP 9-020, CP 15000, México City, Mexico; Biology of Reproduction Research Unit, Laboratorio de Investigación en Cronobiología y Reproducción, Facultad de Estudios Superiores Zaragoza, UNAM, AP 9-020, CP 15000, México City, Mexico.
| | - Rosa Linares-Culebro
- Biology of Reproduction Research Unit, Physiology of Reproduction Laboratory, Facultad de Estudios Superiores Zaragoza, UNAM, AP 9-020, CP 15000, México City, Mexico.
| | - Gabriela Rosas-Gavilán
- Biology of Reproduction Research Unit, Physiology of Reproduction Laboratory, Facultad de Estudios Superiores Zaragoza, UNAM, AP 9-020, CP 15000, México City, Mexico.
| | - Deyra Ramírez-Hernández
- Facultad de Estudios Superiores Zaragoza Campus III, UNAM, CP90640, San Miguel Contla, Tlaxcala, Mexico.
| | - Roberto Domínguez-Casalá
- Biology of Reproduction Research Unit, Laboratorio de Investigación en Cronobiología y Reproducción, Facultad de Estudios Superiores Zaragoza, UNAM, AP 9-020, CP 15000, México City, Mexico.
| | - Leticia Morales-Ledesma
- Biology of Reproduction Research Unit, Physiology of Reproduction Laboratory, Facultad de Estudios Superiores Zaragoza, UNAM, AP 9-020, CP 15000, México City, Mexico.
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Herman AP, Skipor J, Krawczyńska A, Bochenek J, Wojtulewicz K, Pawlina B, Antushevich H, Herman A, Tomaszewska-Zaremba D. Effect of Central Injection of Neostigmine on the Bacterial Endotoxin Induced Suppression of GnRH/LH Secretion in Ewes during the Follicular Phase of the Estrous Cycle. Int J Mol Sci 2019; 20:ijms20184598. [PMID: 31533319 PMCID: PMC6769544 DOI: 10.3390/ijms20184598] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 09/10/2019] [Accepted: 09/16/2019] [Indexed: 12/29/2022] Open
Abstract
Induced by a bacterial infection, an immune/inflammatory challenge is a potent negative regulator of the reproduction process in females. The reduction of the synthesis of pro-inflammatory cytokine is considered as an effective strategy in the treatment of inflammatory induced neuroendocrine disorders. Therefore, the effect of direct administration of acetylcholinesterase inhibitor—neostigmine—into the third ventricle of the brain on the gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) secretions under basal and immune stress conditions was evaluated in this study. In the study, 24 adult, 2-years-old Blackhead ewes during the follicular phase of their estrous cycle were used. Immune stress was induced by the intravenous injection of LPS Escherichia coli in a dose of 400 ng/kg. Animals received an intracerebroventricular injection of neostigmine (1 mg/animal) 0.5 h before LPS/saline treatment. It was shown that central administration of neostigmine might prevent the inflammatory-dependent decrease of GnRH/LH secretion in ewes and it had a stimulatory effect on LH release. This central action of neostigmine is connected with its inhibitory action on local pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)α synthesis in the hypothalamus, which indicates the importance of this mediator in the inhibition of GnRH secretion during acute inflammation.
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Affiliation(s)
- Andrzej Przemysław Herman
- The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-100 Jabłonna, Poland; (A.K.); (J.B.); (K.W.); (B.P.); (H.A.); (D.T.-Z.)
- Correspondence: ; Tel.: +48-22-765-33-02; Fax: +48-22-765-33-03
| | - Janina Skipor
- Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, 10-748 Olsztyn, Poland;
| | - Agata Krawczyńska
- The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-100 Jabłonna, Poland; (A.K.); (J.B.); (K.W.); (B.P.); (H.A.); (D.T.-Z.)
| | - Joanna Bochenek
- The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-100 Jabłonna, Poland; (A.K.); (J.B.); (K.W.); (B.P.); (H.A.); (D.T.-Z.)
| | - Karolina Wojtulewicz
- The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-100 Jabłonna, Poland; (A.K.); (J.B.); (K.W.); (B.P.); (H.A.); (D.T.-Z.)
| | - Bartosz Pawlina
- The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-100 Jabłonna, Poland; (A.K.); (J.B.); (K.W.); (B.P.); (H.A.); (D.T.-Z.)
| | - Hanna Antushevich
- The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-100 Jabłonna, Poland; (A.K.); (J.B.); (K.W.); (B.P.); (H.A.); (D.T.-Z.)
| | - Anna Herman
- Faculty of Health Sciences, Warsaw School of Engineering and Health, 02-366 Warsaw, Poland;
| | - Dorota Tomaszewska-Zaremba
- The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-100 Jabłonna, Poland; (A.K.); (J.B.); (K.W.); (B.P.); (H.A.); (D.T.-Z.)
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Messi E, Pimpinelli F, Andrè V, Rigobello C, Gotti C, Maggi R. The alpha-7 nicotinic acetylcholine receptor is involved in a direct inhibitory effect of nicotine on GnRH release: In vitro studies. Mol Cell Endocrinol 2018; 460:209-218. [PMID: 28754351 DOI: 10.1016/j.mce.2017.07.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 07/04/2017] [Accepted: 07/24/2017] [Indexed: 12/28/2022]
Abstract
The activation of nicotinic cholinergic receptors (nAChR) inhibits the reproductive axis; however, it is not clear whether nicotine may directly modulate the release of hypothalamic gonadotropin-releasing hormone (GnRH). Experiments carried out in GT1-1 immortalized GnRH neurons reveal the presence of a single class of high affinity α4β2 and α7 nAchR subtypes. The exposure of GT1-1 cells to nicotine does not modify the basal accumulation of GnRH. However, nicotine was found to modify GnRH pulsatility in perifusion experiments and inhibits, the release of GnRH induced by prostaglandin E1 or by K+-induced cell depolarization; these effects were reversed by D-tubocurarine and α-bungarotoxin. In conclusion, the results reported here indicate that: functional nAChRs are present on GT1-1 cells, the activation of the α-bungarotoxin-sensitive subclass (α7) produces an inhibitory effect on the release of GnRH and that the direct action of nicotine on GnRH neurons may be involved in reducing fertility of smokers.
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Affiliation(s)
- Elio Messi
- Dept. of Pharmacological and Biomedical Sciences, Università Degli Studi di Milano, Milan, Italy
| | - Federica Pimpinelli
- Dept. of Pharmacological and Biomedical Sciences, Università Degli Studi di Milano, Milan, Italy
| | - Valentina Andrè
- Dept. of Pharmacological and Biomedical Sciences, Università Degli Studi di Milano, Milan, Italy
| | - Chiara Rigobello
- Dept. of Pharmacological and Biomedical Sciences, Università Degli Studi di Milano, Milan, Italy
| | - Cecilia Gotti
- CNR, Neuroscience Institute-Milano, Biometra University of Milan, Milan, Italy
| | - Roberto Maggi
- Dept. of Pharmacological and Biomedical Sciences, Università Degli Studi di Milano, Milan, Italy.
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Peripheral Inhibitor of AChE, Neostigmine, Prevents the Inflammatory Dependent Suppression of GnRH/LH Secretion during the Follicular Phase of the Estrous Cycle. BIOMED RESEARCH INTERNATIONAL 2017; 2017:6823209. [PMID: 28894751 PMCID: PMC5574266 DOI: 10.1155/2017/6823209] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 07/06/2017] [Accepted: 07/16/2017] [Indexed: 11/17/2022]
Abstract
The study was designed to test the hypothesis that the inhibition of acetylcholinesterase (AChE) activity at the periphery by Neostigmine (0.5 mg/animal) will be sufficient to prevent inflammatory dependent suppression of the gonadotropin-releasing hormone (GnRH)/luteinising hormone (LH) secretion in ewes in the follicular phase of the estrous cycle, and this effect will be comparable with the systemic AChE inhibitor, Donepezil (2.5 mg/animal). An immune/inflammatory challenge was induced by peripheral administration of lipopolysaccharide (LPS; 400 ng/kg). Peripheral treatment with Donepezil and Neostigmine prevented the LPS-induced decrease (P < 0.05) in LHβ gene expression in the anterior pituitary gland (AP) and in LH release. Moreover, Donepezil completely abolished (P < 0.05) the suppressory effect of inflammation on GnRH synthesis in the preoptic area, when pretreatment with Neostigmine reduced (P < 0.05) the decrease in GnRH content in this hypothalamic structure. Moreover, administration of both AChE inhibitors diminished (P < 0.05) the inhibitory effect of LPS treatment on the expression of GnRH receptor in the AP. Our study shows that inflammatory dependent changes in the GnRH/LH secretion may be eliminated or reduced by AChE inhibitors suppressing inflammatory reaction only at the periphery such as Neostigmine, without the need for interfering in the central nervous system.
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Arai Y, Ishii H, Kobayashi M, Ozawa H. Subunit profiling and functional characteristics of acetylcholine receptors in GT1-7 cells. J Physiol Sci 2017; 67:313-323. [PMID: 27343174 PMCID: PMC10717232 DOI: 10.1007/s12576-016-0464-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 06/09/2016] [Indexed: 12/21/2022]
Abstract
GnRH neurons form a final common pathway for the central regulation of reproduction. Although the involvement of acetylcholine in GnRH secretion has been reported, direct effects of acetylcholine and expression profiles of acetylcholine receptors (AChRs) still remain to be studied. Using immortalized GnRH neurons (GT1-7 cells), we analyzed molecular expression and functionality of AChRs. Expression of the mRNAs were identified in the order α7 > β2 = β1 ≧ α4 ≧ α5 = β4 = δ > α3 for nicotinic acetylcholine receptor (nAChR) subunits and m4 > m2 for muscarinic acetylcholine receptor (mAChR) subtypes. Furthermore, this study revealed that α7 nAChRs contributed to Ca2+ influx and GnRH release and that m2 and m4 mAChRs inhibited forskolin-induced cAMP production and isobutylmethylxanthine-induced GnRH secretion. These findings demonstrate the molecular profiles of AChRs, which directly contribute to GnRH secretion in GT1-7 cells, and provide one possible regulatory action of acetylcholine in GnRH neurons.
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Affiliation(s)
- Yuki Arai
- Department of Anatomy and Neurobiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8602, Japan
- Department of Life Science, International Christian University, 3-10-2, Osawa, Mitaka-shi, Tokyo, 181-8585, Japan
| | - Hirotaka Ishii
- Department of Anatomy and Neurobiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8602, Japan.
| | - Makito Kobayashi
- Department of Life Science, International Christian University, 3-10-2, Osawa, Mitaka-shi, Tokyo, 181-8585, Japan
| | - Hitoshi Ozawa
- Department of Anatomy and Neurobiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8602, Japan
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Vastagh C, Rodolosse A, Solymosi N, Liposits Z. Altered Expression of Genes Encoding Neurotransmitter Receptors in GnRH Neurons of Proestrous Mice. Front Cell Neurosci 2016; 10:230. [PMID: 27774052 PMCID: PMC5054603 DOI: 10.3389/fncel.2016.00230] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/22/2016] [Indexed: 11/13/2022] Open
Abstract
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 (Gabbr1, Gabra3, Gabrb3, Gabrb2, Gabrg2), glutamatergic (Gria1, Gria2, Grin1, Grin3a, Grm1, Slc17a6), cholinergic (Chrnb2, Chrm4) and dopaminergic (Drd3, Drd4), adrenergic (Adra1b, Adra2a, Adra2c), adenosinergic (Adora2a, Adora2b), glycinergic (Glra), purinergic (P2rx7), and serotonergic (Htr1b) receptors. In concert with these events, expression of genes in the signaling pathways downstream to the receptors, i.e., G-proteins (Gnai1, Gnai2, Gnas), adenylate-cyclases (Adcy3, Adcy5), protein kinase A (Prkaca, Prkacb) protein kinase C (Prkca) and certain transporters (Slc1a4, Slc17a6, Slc6a17) 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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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary
| | - Annie Rodolosse
- Functional Genomics Core, Institute for Research in Biomedicine (IRB Barcelona)Barcelona, Spain
| | - Norbert Solymosi
- Department of Animal Hygiene, Herd-Health and Veterinary Ethology, University of Veterinary MedicineBudapest, Hungary
| | - Zsolt Liposits
- 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
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Herman A, Krawczyńska A, Bochenek J, Haziak K, Romanowicz K, Misztal T, Antushevich H, Herman A, Tomaszewska-Zaremba D. The effect of rivastigmine on the LPS-induced suppression of GnRH/LH secretion during the follicular phase of the estrous cycle in ewes. Anim Reprod Sci 2013; 138:203-12. [DOI: 10.1016/j.anireprosci.2013.03.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 03/02/2013] [Accepted: 03/05/2013] [Indexed: 11/24/2022]
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Zemkova H, Kucka M, Bjelobaba I, Tomic M, Stojilkovic SS. Multiple cholinergic signaling pathways in pituitary gonadotrophs. Endocrinology 2013; 154:421-33. [PMID: 23161872 PMCID: PMC3529387 DOI: 10.1210/en.2012-1554] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Acetylcholine (ACh) has been established as a paracrine factor in the anterior pituitary gland, but the receptors mediating ACh action and the cell types bearing these receptors have not been identified. Our results showed that the expression of the nicotinic subunits mRNAs followed the order β2 > β1 = α9 > α4 in cultured rat pituitary cells. The expression of the subunits in immortalized LβT2 mouse gonadotrophs followed the order β2 > α4 = α1. M4 > M3 muscarinic receptor mRNA were also identified in pituitary and LβT2 cells. The treatment of cultured pituitary cells with GnRH down-regulated the expression of α9 and α4 mRNAs, without affecting the expression of M3 and M4 receptor mRNAs, and ACh did not alter the expression of GnRH receptor mRNA. We also performed double immunostaining to show the expression of β2-subunit and M4 receptor proteins in gonadotrophs. Functional nicotinic channels capable of generating an inward current, facilitation of electrical activity, and Ca(2+) influx were identified in single gonadotrophs and LβT2 cells. In both cell types, the M3 receptor-mediated, phospholipase C-dependent Ca(2+) mobilization activated an outward apamin-sensitive K(+) current and caused hyperpolarization. The activation of M4 receptors by ACh inhibited cAMP production and GnRH-induced LH release in a pertussis toxin-sensitive manner. We concluded that multiple cholinergic receptors are expressed in gonadotrophs and that the main secretory action of ACh is inhibitory through M4 receptor-mediated down-regulation of cAMP production. The expression of nicotinic receptors in vitro compensates for the lack of regular GnRH stimulation of gonadotrophs.
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Affiliation(s)
- Hana Zemkova
- Institute of Physiology, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague 4, Czech Republic.
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Rucinski M, Ziolkowska A, Szyszka M, Hochol A, Malendowicz LK. Evidence suggesting that ghrelin O-acyl transferase inhibitor acts at the hypothalamus to inhibit hypothalamo-pituitary-adrenocortical axis function in the rat. Peptides 2012; 35:149-59. [PMID: 22543218 DOI: 10.1016/j.peptides.2012.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 04/10/2012] [Accepted: 04/10/2012] [Indexed: 10/28/2022]
Abstract
Production of n-octanoyl-modified ghrelin (GHREL), an active form of the peptide requires prohormone processing protease and GHREL O-acyltransferase (GOAT), as well as n-octanoic acid. Recently a selective GOAT antagonist (GO-CoA-Tat) was invented and this tool was used to study the possible role of endogenous GHREL in regulating HPA axis function in the rat. Administration of GOAT inhibitor (GOATi) resulted in a notable decrease in plasma ACTH, aldosterone and corticosterone concentrations at min 60 of experiment. Octanoic acid (OA) administration had no effect on levels of studied hormones. Plasma levels of unacylated and acylated GHREL remained unchanged for 60min after either GOATi or OA administration. Under experimental conditions applied, no significant changes were observed in the levels of GOAT mRNA in hypothalamus, pituitary, adrenal and stomach fundus. After GOATi injection hypothalamic CRH mRNA levels were elevated at 30 min and pituitary POMC mRNA levels at 60 min. Both GOATi and OA lowered basal, but not K(+)-stimulated CRH release by hypothalamic explants and had no effect on basal or CRH-stimulated ACTH release by pituitary slices. Neither GOATi nor OA affected corticosterone secretion by freshly isolated or cultured rat adrenocortical cells. Thus, results of our study suggest that in the rat endogenous GHREL exerts tonic stimulating effect on hypothalamic CRH release. This effect could be demonstrated by administering rats with selected inhibitor of ghrelin O-acyltransferase, the enzyme responsible for GHREL acylation, a process which is absolutely required for both GHSR-1a binding and its central endocrine activities.
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Affiliation(s)
- Marcin Rucinski
- Department of Histology and Embryology, Medical University, Poznan, Poland
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12
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Turi GF, Liposits Z, Hrabovszky E. Cholinergic afferents to gonadotropin-releasing hormone neurons of the rat. Neurochem Int 2008; 52:723-8. [DOI: 10.1016/j.neuint.2007.09.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 08/31/2007] [Accepted: 09/03/2007] [Indexed: 11/29/2022]
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13
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Karanth S, Yu WH, Mastronardi CA, McCann SM. Inhibition of melatonin-induced ascorbic acid and LHRH release by a nitric oxide synthase and cyclic GMP inhibitor. Exp Biol Med (Maywood) 2004; 229:650-6. [PMID: 15229359 DOI: 10.1177/153537020422900709] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Melatonin (MEL), the principle secretory product of the pineal gland, has been shown to function as an antioxidant and free-radical scavenger. We previously showed that the release of ascorbic acid (AA) and luteinizing hormone releasing hormone (LHRH) from medial basal hypothalamus (MBH) was mediated by nitric oxide (NO) that released cyclic guanosine 3'5'-mono-phosphate (cGMP). Therefore, it was of interest to evaluate the effect of MEL on AA and LHRH release and study the effect of a nitric oxide synthase (NOS) inhibitor, 6-anilino-5,8-quinoline-dione (LY 83583), and a guanylyl cyclase (GC) inhibitor, 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (O.D.Q.), on the release process. Because NO has been shown to activate soluble guanylyl cyclase that elicited an elevation of cGMP in target cells, in the current investigation LY 83583, O.D.Q., or N(G)-monomethyl-l-arginine (NMMA), a competitive inhibitor of NOS, were used to evaluate their effects on MEL-induced AA and LHRH release. Medial basal hypothalami were incubated in 0.5 ml of Krebs-Ringer bicarbonate (KRB) buffer for 1 hr. Subsequently, the tissues were incubated with graded concentrations of MEL (10(-8) to 10(-4) M), MEL + NMMA (3 x 10(-4) M), MEL + LY 83583 (10(-6) M), or MEL + O.D.Q. (10(-5) M) for 1 hr. Ascorbic acid and LHRH released into the medium were measured by high-performance liquid chromatography (HPLC) and radio-immunoassay (RIA), respectively. Melatonin (10(-6) and 10(-5) M) significantly stimulated both AA and LHRH release, but the lower and the highest concentrations were ineffective. A combination of MEL + NMMA completely blocked both AA and LHRH release, supporting a role for NO in the releasing action. Both LY 83583 and O.D.Q. significantly suppressed MEL-induced AA and LHRH release, emphasizing the role of NOS, GC, and cGMP in mediating the action of MEL. The data of these in vitro experiments support a role for MEL in the hypothalamic control of AA and LHRH release.
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Affiliation(s)
- Sharada Karanth
- Pennington Biomedical Research Center, Louisiana State University, 6400 Perkins Road, Baton Rouge, LA 70808-4124, USA.
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Kimura F, Shinohara K, Funabashi T, Daikoku S, Suyama K, Mitsushima D, Sano A. Nicotine inhibition of pulsatile GnRH secretion is mediated by GABAA receptor system in the cultured rat embryonic olfactory placode. Psychoneuroendocrinology 2004; 29:749-56. [PMID: 15110924 DOI: 10.1016/s0306-4530(03)00119-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2003] [Revised: 04/04/2003] [Accepted: 04/07/2003] [Indexed: 11/30/2022]
Abstract
In past work, we suggested that nicotine inhibition of in vivo pulsatile LH release is not mediated by opiate receptors known to be involved in the inhibition of LH release. In the present study, we examined whether nicotine inhibits the pulsatile gonadotropin-releasing hormone (GnRH) release, and whether this inhibition of GnRH release by nicotine is mediated by the GABA receptor system, by checking in vitro pulsatile GnRH release from cultured GnRH neurons obtained from olfactory placodes of rat embryos at E13.5. The mean interpulse interval of pulsatile GnRH release into the medium was 34.2+/-2.0 min in the control period and increased to 95.3+/-19.0 min (n=6) in the period of nicotine treatment at a concentration of 500 nM, showing an inhibitory effect of nicotine on pulsatile GnRH release. The GABA(A) receptor antagonist bicuculline used alone at a concentration of 20 microM caused no significant changes in the pulsatile GnRH release, but when used in combination with 500 nM of nicotine, bicuculline blocked the nicotine inhibition of GnRH release. In a separate experiment, nicotine treatment at a concentration of 500 nM significantly increased GABA release. These results suggest that, in the cultured embryonic olfactory placode, nicotine stimulates GABA release, which then inhibits GnRH release through GABA(A) receptor system.
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Affiliation(s)
- Fukuko Kimura
- Department of Neuroendocrinology, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan.
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15
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Abstract
Exposure to environmental toxicants can have profound effects on normal growth and development. However, the mechanisms by which these toxicants exert these effects are not well understood. Many environmental toxicants alter reproductive function and have effects on the central nervous system and behavior, yet the link between these reproductive and neurologic phenomena has not been systematically investigated. The neuroendocrine (hypothalamic-pituitary-gonadal) axis, which integrates inputs to and outputs from the nervous and reproductive systems, is functionally and anatomically situated to mediate effects of environmental toxicants, particularly those that are endocrine-disrupting chemicals (EDCs), on developmental processes. This article reviews the current literature on EDC effects on the neuroendocrine system, particularly at the level of hypothalamic gonadotropin-releasing hormone (GnRH) neurons, the key cells involved in the regulation of reproductive function. The focus of this article is on two polychlorinated biphenyl mixtures (Aroclor 1221, Aroclor 1254) and two organochlorine pesticides (methoxychlor and chlorpyrifos). Some experimental data are presented for each of the four urban environmental toxicants on GnRH cells in vitro and in vivo. The results of in vitro experiments indicate that all four of the toxicants profoundly affect hypothalamic GnRH gene expression, cell survival, and neurite outgrowth, demonstrating direct effects of EDCs on a GnRH cell line. In in vivo experiments, three of the toxicants (Aroclor 1221, methoxychlor, and chlorpyrifos) caused significant alterations in GnRH mRNA levels in female rats. Both the in vitro and in vivo findings support the novel concept of chlorpyrifos as an EDC. The results, taken together with the literature, support the hypothesis that the neuroendocrine axis, and specifically GnRH neurons, are sensitive to urban environmental toxicants, and that reproductive and neurologic effects of EDCs may be mediated at this level of the hypothalamic-pituitary-gonadal axis.
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Affiliation(s)
- A C Gore
- Fishberg Research Center for Neurobiology, and Schwartz Department of Geriatrics and Adult Development, Mount Sinai School of Medicine, New York, NY 10029, USA.
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Maitra SK, Dey M, Dutta S, Bhattacharya S, Dey R, Sengupta A. Influences of graded dose of melatonin on the levels of blood glucose and adrenal catecholamines in male roseringed parakeets (Psittacula krameri ) under different photoperiods. Arch Physiol Biochem 2000; 108:444-50. [PMID: 11262603 DOI: 10.1076/apab.108.5.444.4297] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Effects of daily evening (just before the onset of darkness in a 24 h light dark cycle) administration of graded doses (25, 50, or 100 microg/100 g body wt./day for 30 days) of melatonin on the concentrations of blood glucose and adrenal catecholamines were studied in sexually active male roseringed parakeets under natural (NP; approximately 12L: 12D) and artificial long (LP; 16L: 8D) and short (SP; 8L: 16D) photoperiods. Blood samples and adrenal glands were collected from each bird during the mid-day on the following day of the last treatment. The concentrations of glucose in blood and epinephrine (E) and norepinephrine (NE) in the adrenals were measured. The results of the study indicated that exogenous melatonin induces hypo- or hyperglycemia depending on the dose of hormone administered as well as to the length of photoperiod to which birds were exposed. The levels of E and NE in the adrenals were shown also to vary in relation to photoperiod and the dose of melatonin administered. But the nature of the influence of melatonin becomes different under altered photoperiodic conditions. It appears that short photoperiods are more effective than long photoperiods as a modulator of glycemic and adrenal catecholaminergic responses to exogenous melatonin. A statistically significant correlation between the levels of blood glucose and that of E and NE in the adrenals was found in the control birds, but not in the melatonin treated birds. The results suggested that the responses of blood glucose and adrenal catecholamines to the treatment with melatonin in the roseringed parakeets may not be dependent on each other.
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Affiliation(s)
- S K Maitra
- Department of Zoology, University of Burdwan, Burdwan, India.
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Messager S, Caillol M, Martinet L. Long-term exposure of hypothalamic explants to melatonin alters the release of gonadotrophin releasing hormone and the density of melatonin binding sites in the pars tuberalis of the male mink (Mustela vison). J Pineal Res 1999; 26:17-27. [PMID: 10102756 DOI: 10.1111/j.1600-079x.1999.tb00562.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To investigate the action of melatonin on the reproductive system, the effect of prolonged versus short-term exposure to melatonin on the release of gonadotrophin releasing hormone (GnRH) was examined in hypothalamic explants of male mink sacrificed in July, September or November. Mediobasal hypothalamic (MBH) explants including the pars tuberalis (PT) were incubated for 1 night with or without melatonin (10(-8) M) for 8 hr or 16 hr and the release of GnRH was then measured. The next day, the explants were incubated further but in a melatonin free buffer, and the release of GnRH was measured with increasing time. Half of the July and September explants had melatonin binding sites quantified by autoradiography. In November, a 16-hr exposure to melatonin induced a significant increase in the release of GnRH during the night, compared with control or 8-hr melatonin exposure. This increase persisted for at least 45 min after the withdrawal of melatonin, suggesting a stimulatory effect of melatonin on the synthesis of GnRH; this effect was apparent in July, September and November. In September, the density of melatonin binding in the PT was significantly lower in the explants incubated for 16 hr with melatonin, compared with those incubated for 8 hr. Thus, in vitro, a long exposure to melatonin, mimicking a single long night, stimulates the release and synthesis of GnRH in parallel with a decrease in the density of melatonin binding in the PT. These effects seem to depend heavily on the duration of exposure to melatonin.
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Affiliation(s)
- S Messager
- Laboratoire de Physiologie Sensorielle, Institut National de la Recherche Agronomique, Jouy-en-Josas, France
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18
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Cagnacci A, Soldani R, Yen SS. Exogenous melatonin enhances luteinizing hormone levels of women in the follicular but not in the luteal menstrual phase. Fertil Steril 1995; 63:996-9. [PMID: 7720945 DOI: 10.1016/s0015-0282(16)57536-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE To investigate the effect of exogenous melatonin on LH pulsatility in women during the follicular and luteal menstrual phases. DESIGN Randomized, double-blind placebo-controlled study. PATIENTS Normal cycling young women (25 to 35 years old). INTERVENTIONS Each subject was admitted at the Clinical Research Center for 2 consecutive days on both the follicular and the luteal menstrual phases. On each day, at 7:00 A.M. an indwelling catether was placed in an antecubital vein for a 10 minutes blood sampling from 9:00 A.M. to 5:00 P.M. On the 2 consecutive days of both the follicular and the luteal menstrual phases, each subject randomly received either placebo or melatonin pills (1 mg at 8:00 and 0.75 mg at 10:00 and 12:00 A.M.). MAIN OUTCOME MEASURE Luteinizing hormone pulsatility. RESULTS The amplitude of LH pulses and mean LH levels were increased by melatonin in the follicular but not in the luteal menstrual phase. CONCLUSIONS The stimulatory effect of exogenous melatonin on LH is modulated by the endocrine environment and selectively exerted in the follicular phase of the menstrual cycle.
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Affiliation(s)
- A Cagnacci
- Department of Reproductive Medicine, University of California San Diego, School of Medicine, La Jolla, USA
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Olcese J. The mammalian pineal gland and reproduction. Controversies and strategies for future research. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1995; 377:1-14. [PMID: 7484417 DOI: 10.1007/978-1-4899-0952-7_1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Evidence for a role of the pineal gland and its major hormonal product, melatonin, in mammalian reproduction has accumulated for over three decades. In sorting through the masses of data pertaining to this issue, certain facts are becoming established. For example, the pineal gland is clearly involved in seasonal reproductive cycles via transduction of daylength (more properly nightlength) information in the form of plasma melatonin rhythms. Specific melatonin receptors are found in the hypothalamus and pituitary pars tuberalis of most of the mammalian species examined thus far. Melatonin's mode of action on the reproductive axis is quite variable but may, in many cases, involve modulation of gonadotropin-releasing hormone secretion from the median eminence. Clinical evidence continues to support the idea that melatonin may play a role in the timing of puberty.
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Affiliation(s)
- J Olcese
- Institute for Hormone and Fertility Research, University of Hamburg, Germany
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Rasmussen DD. Diurnal modulation of rat hypothalamic gonadotropin-releasing hormone release by melatonin in vitro. J Endocrinol Invest 1993; 16:1-7. [PMID: 8445151 DOI: 10.1007/bf03345819] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The mechanism(s) by which melatonin (MEL) can regulate gonadotropin secretion remains unresolved. Accordingly, we used acute in vitro incubations of male rat hypothalamic tissues to investigate effects of MEL on hypothalamic gonadotropin-releasing hormone (GnRH) secretion. At 10:00 h (3.5 after lights on), addition of 1 nM MEL to the medium inhibited (p = 0.028) GnRH release from the median eminence (ME) by 24%, 100 nM MEL had no significant effect on GnRH release, and 10 microM MEL tended to inhibit (p = 0.056, 21%) GnRH release. At 15:00 h, none of these MEL dosages significantly altered GnRH release from the ME. When the effect of a lower range of MEL dosages was evaluated, 1 nM MEL again inhibited (24%, p = 0.032) GnRH release from the ME at 10:00 h, and a linear dose-response relationship between initially increasing dosages (0, 0.01, 0.1, 1 nM) of MEL treatment and decreasing GnRH release was evident (r = 0.88), although a further 10 fold increase in MEL dosage (10 nM) resulted in a loss of suppression by MEL. Treatment with these dosages of MEL did not significantly alter ME GnRH release at 15:00 h. In contrast to the results with the ME alone, treatment with 0.1 microM MEL increased (p = 0.018) GnRH release from the arcuate-median eminence region (ARC-ME) by 60.2% at 10:00 h, whereas treatment with either 0.001 or 10 microM MEL did not significantly affect GnRH release. Treatment with these dosages of MEL did not significantly alter ARC-ME GnRH release at 15:00 h.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D D Rasmussen
- Department of Reproductive Medicine, University of California, San Diego, La Jolla 92093-0802
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Alonso-Bedate M, Delgado MJ, Carballada R. In vivo effect of melatonin and gonadotropin-releasing hormone on testicular function in Rana temporaria. J Pineal Res 1988; 5:323-32. [PMID: 3062162 DOI: 10.1111/j.1600-079x.1988.tb00881.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Studies concerning pineal-gonadal interactions and investigations about the effect of the putative pineal hormone melatonin in male amphibians are very scarce. In this work we investigate the effects of melatonin, synthetic gonadotropin-releasing hormone (GnRH), or both when injected in Rana temporaria males. We conclude that melatonin inhibits spermiation and spermatogonial multiplication when injected alone or with GnRH. We have been unable to find any significant differences in plasma testosterone levels when melatonin or GnRH are injected alone, but when melatonin is injected with GnRH the levels of testosterone are significantly increased. These results seem to demonstrate that melatonin could play a role in the regulation of the gonadal function in the male Rana temporaria.
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Affiliation(s)
- M Alonso-Bedate
- Departmento de Fisiologia Animal, Facultad de Biologia, Universidad Complutense de Madrid, Spain
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Dilman VM, Revskoy SY, Golubev AG. Neuroendocrine-ontogenetic mechanism of aging: toward an integrated theory of aging. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1986; 28:89-156. [PMID: 3542876 DOI: 10.1016/s0074-7742(08)60107-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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