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Dobolyi A, Oláh S, Keller D, Kumari R, Fazekas EA, Csikós V, Renner É, Cservenák M. Secretion and Function of Pituitary Prolactin in Evolutionary Perspective. Front Neurosci 2020; 14:621. [PMID: 32612510 PMCID: PMC7308720 DOI: 10.3389/fnins.2020.00621] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 05/19/2020] [Indexed: 12/16/2022] Open
Abstract
The hypothalamo-pituitary system developed in early vertebrates. Prolactin is an ancient vertebrate hormone released from the pituitary that exerts particularly diverse functions. The purpose of the review is to take a comparative approach in the description of prolactin, its secretion from pituitary lactotrophs, and hormonal functions. Since the reproductive and osmoregulatory roles of prolactin are best established in a variety of species, these functions are the primary subjects of discussion. Different types of prolactin and prolactin receptors developed during vertebrate evolution, which will be described in this review. The signal transduction of prolactin receptors is well conserved among vertebrates enabling us to describe the whole subphylum. Then, the review focuses on the regulation of prolactin release in mammals as we have the most knowledge on this class of vertebrates. Prolactin secretion in response to different reproductive stimuli, such as estrogen-induced release, mating, pregnancy and suckling is detailed. Reproduction in birds is different from that in mammals in several aspects. Prolactin is released during incubation in avian species whose regulation and functional significance are discussed. Little information is available on prolactin in reptiles and amphibians; therefore, they are mentioned only in specific cases to explain certain evolutionary aspects. In turn, the osmoregulatory function of prolactin is well established in fish. The different types of pituitary prolactin in fish play particularly important roles in the adaptation of eutherian species to fresh water environments. To achieve this function, prolactin is released from lactotrophs in hyposmolarity, as they are directly osmosensitive in fish. In turn, the released prolactin acts on branchial epithelia, especially ionocytes of the gill to retain salt and excrete water. This review will highlight the points where comparative data give new ideas or suggest new approaches for investigation in other taxa.
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Affiliation(s)
- Arpád Dobolyi
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Szilvia Oláh
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Dávid Keller
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Rashmi Kumari
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Emese A. Fazekas
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Vivien Csikós
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Éva Renner
- Human Brain Tissue Bank and Microdissection Laboratory, Semmelweis University, Budapest, Hungary
| | - Melinda Cservenák
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
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Huang YL, Peng M, Zhu G. Topiramate in the treatment of antipsychotic-induced hyperprolactinemia. Med Hypotheses 2020; 138:109607. [DOI: 10.1016/j.mehy.2020.109607] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 01/29/2020] [Indexed: 02/06/2023]
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Kovács Z, Lakatos RK, Barna J, Dobolyi Á. Absence epileptic activity in Wistar Albino Glaxo Rijswijk rat mothers. Brain Res 2017; 1657:368-376. [PMID: 28065565 DOI: 10.1016/j.brainres.2017.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/16/2016] [Accepted: 01/02/2017] [Indexed: 11/27/2022]
Abstract
Absence epileptic activity was analyzed during pregnancy, the postpartum period and after weaning to establish alterations of seizures throughout the reproductive cycle. Wistar Albino Glaxo Rijswijk (WAG/Rij) rats were used in the study as a model of absence epilepsy and because their seizures do not interfere with rearing offspring. The number of spike-wave discharges (SWDs) was gradually elevated from the 19th pregnancy day to delivery. Meanwhile, the characteristics of individual SWDs did not change suggesting that SWD generation remained the same. In the postpartum and postweaning periods, the number of SWDs was not increased in the absence of pups. However, returning the pups to mothers resulted in a markedly elevated number of SWDs for 1h. If pups were taken away after 30min, the number of SWDs dropped immediately suggesting that the presence of pups increased the SWD number. The time mothers spent with the litter and in kyphosis suckling posture were in correlation with their SWD number further suggesting the importance of interaction with pups in SWD induction. Suckling elevates prolactin levels but surprisingly, its intracerebroventricular injection markedly reduced SWD number in suckled WAG/Rij mothers suggesting that the SWD-inducing effect of suckling is not mediated by prolactin. Rather, the elevated prolactin level may provide some protection against pro-epileptic effects of suckling. In conclusion, we first identified periods within the reproductive cycle with increased absence epileptic activity, implying that more attention should be devoted to epileptic activity changes in mothers.
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Affiliation(s)
- Zsolt Kovács
- Department of Zoology, University of West Hungary, Savaria Campus, Szombathely, Károlyi Gáspár tér 4., 9700, Hungary.
| | - Renáta Krisztina Lakatos
- Department of Zoology, University of West Hungary, Savaria Campus, Szombathely, Károlyi Gáspár tér 4., 9700, Hungary; Institute of Biology, University of Pécs, Pécs, Ifjúság útja 6., 7624, Hungary
| | - János Barna
- Laboratory of Neuromorphology and Human Brain Tissue Bank, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Tűzoltó u. 58., 1094, Hungary
| | - Árpád Dobolyi
- Laboratory of Neuromorphology and Human Brain Tissue Bank, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Tűzoltó u. 58., 1094, Hungary; MTA-ELTE NAP B Laboratory of Molecular and Systems Neurobiology, Institute of Biology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest, Pázmány Péter sétány 1C, 1117, Hungary.
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Abstract
Prolactin (PRL) released from lactotrophs of the anterior pituitary gland in response to the suckling by the offspring is the major hormonal signal responsible for stimulation of milk synthesis in the mammary glands. PRL secretion is under chronic inhibition exerted by dopamine (DA), which is released from neurons of the arcuate nucleus of the hypothalamus into the hypophyseal portal vasculature. Suckling by the young activates ascending systems that decrease the release of DA from this system, resulting in enhanced responsiveness to one or more PRL-releasing hormones, such as thyrotropin-releasing hormone. The neuropeptide oxytocin (OT), synthesized in magnocellular neurons of the hypothalamic supraoptic, paraventricular, and several accessory nuclei, is responsible for contracting the myoepithelial cells of the mammary gland to produce milk ejection. Electrophysiological recordings demonstrate that shortly before each milk ejection, the entire neurosecretory OT population fires a synchronized burst of action potentials (the milk ejection burst), resulting in release of OT from nerve terminals in the neurohypophysis. Both of these neuroendocrine systems undergo alterations in late gestation that prepare them for the secretory demands of lactation, and that reduce their responsiveness to stimuli other than suckling, especially physical stressors. The demands of milk synthesis and release produce a condition of negative energy balance in the suckled mother, and, in laboratory rodents, are accompanied by a dramatic hyperphagia. The reduction in secretion of the adipocyte hormone, leptin, a hallmark of negative energy balance, may be an important endocrine signal to hypothalamic systems that integrate lactation-associated food intake with neuroendocrine systems.
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Affiliation(s)
- William R Crowley
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah Health Sciences Center, Salt Lake City, Utah
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Ptak GE, Modlinski JA, Loi P. Embryonic diapause in humans: time to consider? Reprod Biol Endocrinol 2013; 11:92. [PMID: 24044744 PMCID: PMC3848826 DOI: 10.1186/1477-7827-11-92] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 09/11/2013] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND When a competent blastocyst stage embryo finds itself in an unreceptive uterus, it delays development. In around one hundred species representing various orders, this delay is known to be reversible, but this phenomenon - termed embryonic diapause (ED) - is not considered a general characteristic of all mammals. PRESENTATION OF THE HYPOTHESIS Recently, however, we demonstrated that a non-diapausing species, the sheep, is capable of ED, suggesting the hypothesis that this is in fact an ancestral trait common to all mammals, including humans. TESTING THE HYPOTHESIS In spite of the obvious difficulties in testing this idea, we propose a combination of indirect observations on human fertility patients, and direct study of the embryos of non-human primates. IMPLICATIONS OF THE HYPOTHESIS Support for our hypothesis would require revision of obstetric interventions routinely performed when a human pregnancy extends beyond the due date.
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Affiliation(s)
- Grazyna E Ptak
- Department of Comparative Biomedical Sciences, University of Teramo, Piazza A. Moro, Teramo 64100, Italy
- Department of Experimental Embryology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzebiec, Poland
| | - Jacek A Modlinski
- Department of Experimental Embryology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzebiec, Poland
| | - Pasqualino Loi
- Department of Comparative Biomedical Sciences, University of Teramo, Piazza A. Moro, Teramo 64100, Italy
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Abstract
Newborn mammals are totally dependent on maternal milk and care for survival. The mother's brain undergoes different behavioural, physiological and emotional adaptations that make the mother more likely to satisfy the demands of the offspring. Recent reports from our group show that, compared to nulliparous rats, lactation diminishes cell damage induced by excitotoxicity in the dorsal hippocampus of the dam after systemic or i.c. administration of kainic acid (KA) and the resulting motor seizures. Elevated levels of prolactin (PRL), oxytocin, progesterone and glucocorticoids are characteristics of lactation, and the pronounced fluctuation of these hormones occurring in this phase may play a role protecting the hippocampus. Indeed, PRL administration to ovariectomised rats significantly diminishes the deleterious effects of KA in the dorsal hippocampus and reduces the progression of KA-induced seizures. Thus, lactation is a natural model for neuroprotection because it effectively prevents acute and chronic cell damage of the hippocampus induced by excitotoxicity.
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Affiliation(s)
- T Morales
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, México.
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Ulrich-Lai YM, Jones KR, Ziegler DR, Cullinan WE, Herman JP. Forebrain origins of glutamatergic innervation to the rat paraventricular nucleus of the hypothalamus: differential inputs to the anterior versus posterior subregions. J Comp Neurol 2011; 519:1301-19. [PMID: 21452198 PMCID: PMC3893028 DOI: 10.1002/cne.22571] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The hypothalamic paraventricular nucleus (PVN) regulates numerous homeostatic systems and functions largely under the influence of forebrain inputs. Glutamate is a major neurotransmitter in forebrain, and glutamate neurosignaling in the PVN is known to mediate many of its functions. Previous work showed that vesicular glutamate transporters (VGluTs; specific markers for glutamatergic neurons) are expressed in forebrain sites that project to the PVN; however, the extent of this presumed glutamatergic innervation to the PVN is not clear. In the present study retrograde FluoroGold (FG) labeling of PVN-projecting neurons was combined with in situ hybridization for VGluT1 and VGluT2 mRNAs to identify forebrain regions that provide glutamatergic innervation to the PVN and its immediate surround in rats, with special consideration for the sources to the anterior versus posterior PVN. VGluT1 mRNA colocalization with retrogradely labeled FG neurons was sparse. VGluT2 mRNA colocalization with FG neurons was most abundant in the ventromedial hypothalamus after anterior PVN FG injections, and in the lateral, posterior, dorsomedial, and ventromedial hypothalamic nuclei after posterior PVN injections. Anterograde tract tracing combined with VGluT2 immunolabeling showed that 1) ventromedial nucleus-derived glutamatergic inputs occur in both the anterior and posterior PVN; 2) posterior nucleus-derived glutamatergic inputs occur predominantly in the posterior PVN; and 3) medial preoptic nucleus-derived inputs to the PVN are not glutamatergic, thereby corroborating the innervation pattern seen with retrograde tracing. The results suggest that PVN subregions are influenced by varying amounts and sources of forebrain glutamatergic regulation, consistent with functional differentiation of glutamate projections.
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Affiliation(s)
- Yvonne M Ulrich-Lai
- Department of Psychiatry, University of Cincinnati, Cincinnati, Ohio 45267, USA.
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Dimitrov E, Usdin TB. Tuberoinfundibular peptide of 39 residues modulates the mouse hypothalamic-pituitary-adrenal axis via paraventricular glutamatergic neurons. J Comp Neurol 2010; 518:4375-94. [PMID: 20853513 PMCID: PMC3004125 DOI: 10.1002/cne.22462] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Neurons in the subparafascicular area at the caudal border of the thalamus that contain the neuropeptide tuberoinfundibular peptide of 39 residues (TIP39) densely innervate several hypothalamic areas, including the paraventricular nucleus (PVN). These areas contain a matching distribution of TIP39's receptor, the parathyroid hormone receptor 2 (PTH2R). Frequent PTH2R coexpression with a vesicular glutamate transporter (VGlut2) suggests that TIP39 could presynaptically regulate glutamate release. By using immunohistochemistry we found CRH-ir neurons surrounded by PTH2R-ir fibers and TIP39-ir axonal projections in the PVN area of the mouse brain. Labeling hypothalamic neuroendocrine neurons by peripheral injection of fluorogold in PTH2R-lacZ knock-in mice showed that most PTH2Rs are on PVN and peri-PVN interneurons and not on neuroendocrine cells. Double fluorescent in situ hybridization revealed a high level of coexpression between PTH2R and VGlut2 mRNA by cells located in the PVN and nearby brain areas. Local TIP39 infusion (100 pmol) robustly increased pCREB-ir in the PVN and adjacent perinuclear zone. It also increased plasma corticosterone and decreased plasma prolactin. These effects of TIP39 on pCREB-ir, corticosterone, and prolactin were abolished by coinfusion of the ionotropic glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and DL-2-amino-5-phosphonopentanoic acid (AP-5; 30 pmol each) and were absent in PTH2R knockout mice. Basal plasma corticosterone was slightly decreased in TIP39 knockout mice just before onset of their active phase. The present data indicate that the TIP39 ligand/PTH2 receptor system provides facilitatory regulation of the hypothalamic-pituitary-adrenal axis via hypothalamic glutamatergic neurons and that it may regulate other neuroendocrine systems by a similar mechanism.
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Affiliation(s)
- Eugene Dimitrov
- Section on Fundamental Neuroscience, National Institute of Mental Health, Bethesda, Maryland 20892
| | - Ted Björn Usdin
- Section on Fundamental Neuroscience, National Institute of Mental Health, Bethesda, Maryland 20892
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Tejadilla D, Cerbón M, Morales T. Prolactin reduces the damaging effects of excitotoxicity in the dorsal hippocampus of the female rat independently of ovarian hormones. Neuroscience 2010; 169:1178-85. [PMID: 20570717 DOI: 10.1016/j.neuroscience.2010.05.074] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 05/27/2010] [Accepted: 05/28/2010] [Indexed: 12/29/2022]
Abstract
We reported previously that lactation prevents the cell damage induced by kainic acid (KA) excitotoxicity in the CA1, CA3, and CA4 areas of the dorsal hippocampus compared to rats in diestrus phase, and hypothesize that pronounced fluctuations of hormones, such as ovarian steroids and prolactin (PRL), have a role in the neuroprotection of the dorsal hippocampus during lactation. PRL is thought to be involved in modulating neural excitability and seizure activity. To investigate actions of prolactin that minimize KA-induced cell damage in the hippocampus, female intact and ovariectomized (OVX) rats were treated for 4 days with a daily dose of 100 microg of prolactin or vehicle. On the third day of prolactin treatment, rats received a systemic dose of 7.5 mg/kg of KA and were sacrificed 48 h later. Immunostaining for Neu-N revealed a significant decrease in cell number in the CA1, CA3 and CA4 areas of intact or OVX, vehicle-treated rats after KA, whereas prolactin treatment prevented cell loss in the CA3 area of intact, and in the CA1, CA3, and CA4 of OVX rats. Fluoro-Jade C staining confirmed these observations. Kainate-induced seizure behavior progressed further in OVX rats, but was attenuated in prolactin-treated rats, both intact and OVX, compared to vehicle-treated rats. These data indicate that prolactin diminishes the damaging actions of excitotoxicity in the kainate model of epilepsy.
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Affiliation(s)
- D Tejadilla
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Qro 76230, México
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Bodnár I, Bánky Z, Zelena D, Halász B. Glutamate receptor antagonist infused into the hypothalamic suprachiasmatic nuclei interferes with the diurnal fluctuations in plasma prolactin and corticosterone levels and injected into the mesencephalic dorsal raphe nucleus attenuates the suckling stimulus-induced release of prolactin of the rat. Brain Res Bull 2009; 80:9-16. [DOI: 10.1016/j.brainresbull.2009.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 06/05/2009] [Accepted: 06/05/2009] [Indexed: 11/25/2022]
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Prolactin and the Skin: A Dermatological Perspective on an Ancient Pleiotropic Peptide Hormone. J Invest Dermatol 2009; 129:1071-87. [DOI: 10.1038/jid.2008.348] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Durand D, Pampillo M, Caruso C, Lasaga M. Role of metabotropic glutamate receptors in the control of neuroendocrine function. Neuropharmacology 2008; 55:577-83. [PMID: 18616955 DOI: 10.1016/j.neuropharm.2008.06.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 05/23/2008] [Accepted: 06/12/2008] [Indexed: 11/25/2022]
Abstract
Glutamate exerts its effects through binding and activation of two classes of specific receptors: ionotropic (iGluRs) and metabotropic (mGluRs). Group I mGluR includes mGluR1 and mGluR5 subtypes, group II includes mGluR2 and mGluR3 subtypes and group III includes the subtypes mGluR 4, 6, 7 and 8. Glutamate and its receptors are found in all key hypothalamic areas critically involved in reproduction and neuroendocrine function. To date, considerable data support an important role for iGluRs in the control of neuroendocrine function; however, the role of mGluRs as regulators of hypothalamic-pituitary function has not been clearly elucidated. mGluRs could be exerting a fine tune on the release of hypothalamic factors that regulate hormone release such as Substance P, GABA, alpha-MSH and CRH. Group II mGluR exert a direct inhibitory effect on anterior pituitary prolactin and GH secretion. Moreover, some group II mGluR agonists, like LY 354,740 and LY 379,268, can modulate PRL secretion from the anterior pituitary through their actions as dopamine receptor agonists. Evidence suggests a role for group III mGluR subtypes in stress-related behavioral disorders. Several reports indicate that selective ligands for mGluR subtypes have potential for the treatment of a wide variety of neurological and psychiatric disorders, including depression, anxiety disorders, schizophrenia, epilepsy and Alzheimer's disease among others. Since converging lines of evidence suggest a role for mGluRs subtypes in neuroendocrine regulation of hormone secretion, mGluRs neuroendocrine actions must be taken in consideration to insure proper treatment of these diseases. Moreover, discovery of selective agonists provides an opportunity to investigate the physiological role of mGluR subtypes and to directly test the neuroendocrine actions of mGluRs. Finally, mGluRs selective agonists may have an impact in the treatment of conditions involving chronic stress, such as depression and anxiety disorders, since they regulate neuroendocrine stress circuits involving the HPA axis and stress-sensitive hormones such as oxytocin and prolactin. This review aims to provide a survey of our current understanding of the effects of mGluR activation on neuroendocrine function.
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Affiliation(s)
- Daniela Durand
- Research Center in Reproduction, School of Medicine, University of Buenos Aires, Paraguay 2155, Piso 10, 1121 Buenos Aires, Argentina
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Abstract
L-glutamate, the main excitatory neurotransmitter, influences virtually all neurones of the neuroendocrine hypothalamus via synaptic mechanisms. Vesicular glutamate transporters (VGLUT1-3), which selectively accumulate L-glutamate into synaptic vesicles, provide markers with which to visualise glutamatergic neurones in histological preparations; excitatory neurones in the endocrine hypothalamus synthesise the VGLUT2 isoform. Results of recent dual-label in situ hybridisation studies indicate that glutamatergic neurones in the preoptic area and the hypothalamic paraventricular, supraoptic and periventricular nuclei include parvocellular and magnocellular neurosecretory neurones which secrete peptide neurohormones into the bloodstream to regulate endocrine functions. Neurosecretory terminals of GnRH, TRH, CRF-, somatostatin-, oxytocin- and vasopressin-secreting neurones contain VGLUT2 immunoreactivity, suggesting the co-release of glutamate with hypophysiotrophic peptides. The presence of VGLUT2 also indicates glutamate secretion from non-neuronal endocrine cells, including gonadotrophs and thyrotrophs of the anterior pituitary. Results of in vitro studies show that ionotropic glutamate receptor analogues can elicit hormone secretion at neuroendocrine/endocrine release sites. Structural constituents of the median eminence, adenohypophysis and neurohypophysis contain elements of glutamatergic transmission, including glutamate receptors and enzymes of the glutamate/glutamine cycle. The synthesis of VGLUT2 exhibits robust up-regulation in response to certain endocrine challenges, indicating that altered glutamatergic signalling may represent an important adaptive mechanism. This review article discusses the newly emerged non-synaptic role of glutamate in neuroendocrine and endocrine communication.
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Affiliation(s)
- E Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
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Debeljuk L, Lasaga M. Tachykinins and the control of prolactin secretion. Peptides 2006; 27:3007-19. [PMID: 16930771 DOI: 10.1016/j.peptides.2006.07.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Revised: 07/14/2006] [Accepted: 07/17/2006] [Indexed: 11/28/2022]
Abstract
Tachykinins are present in the pituitary gland and in brain areas involved in the control of the secretion of pituitary hormones. Tachykinins have been demonstrated to stimulate prolactin release acting directly on the anterior pituitary gland. These peptides have also been revealed to be able to act at the hypothalamic level, interacting with neurotransmitters and neuropeptides that have the potential to affect prolactin secretion. Tachykinins seem to act by stimulating or inhibiting the release of the factors that affect prolactin secretion. Among them, tachykinins have been demonstrated to stimulate oxytocin and vasopressin release, which in turn results in prolactin release. Tachykinins also potentiated the response to vasoactive intestinal peptide (VIP) and reinforced the action of glutamate, which in turn result in prolactin release. They have also been shown to interact with serotonin, a neurotransmitter involved in the control of prolactin secretion. In addition, tachykinins have been shown to inhibit GABA release, a neurotransmitter with prolactin-release inhibiting effect. This inhibition may result in an increased prolactin secretion by removal of the GABA inhibition. On the other hand, tachykinins have also been shown to stimulate dopamine release by the hypothalamus, an action that results in an inhibition of prolactin release. Dopamine is a well known inhibitor of prolactin secretion. In conclusion, although tachykinins have been shown to have a predominantly stimulatory effect on prolactin secretion, especially at the pituitary level, under some circumstances they may also exert an inhibitory influence on prolactin release, by stimulating dopamine release at the hypothalamic level.
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Affiliation(s)
- Luciano Debeljuk
- School of Allied Health (Anatomy and Physiology), College of Applied Sciences and Arts, Southern Illinois University, Carbondale, IL 62901, USA.
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