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Barloese M, Chitgar M, Hannibal J, Møller S. Pituitary adenylate cyclase-activating peptide: Potential roles in the pathophysiology and complications of cirrhosis. Liver Int 2020; 40:2578-2589. [PMID: 32654367 DOI: 10.1111/liv.14602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 06/29/2020] [Accepted: 07/05/2020] [Indexed: 12/20/2022]
Abstract
Pituitary adenylate cyclase-activating peptide (PACAP) is a ubiquitous neuropeptide with diverse functions throughout the organism. Most abundantly investigated for its role in several neurological disorders as well as in circadian rhythms, other fields of medicine, including cardiology, have recently shown interest in the role of PACAP and its potential as a biomarker. Timely diagnosis and treatment of cirrhosis and its complications is a considerable challenge for health services world-wide and development of new areas of research is warranted. Direct and indirect evidence exists of PACAP involvement in the cascade of pathological events and processes ultimately leading to cirrhosis and its complications, but its exact role remains to be determined. Studies have documented PACAP involvement in immune function, metabolism, local vasoconstriction and dilatation and systemic vascular decompensation and there is ongoing research of a possible role in liver reperfusion injury. Considering these reports, PACAP could theoretically exude influence on the disease course of cirrhosis through the hypothalamus-pituitary-adrenal axis, chronic inflammation, fibrogenesis, vasodilation and reduced vascular resistance. The paucity of literature on the specific topic of PACAP and cirrhosis reflects complex mechanisms and difficulty in accurate measurements and sample taking. This does not detract from the need to further characterize and elucidate the role PACAP plays in the underdiagnosed and undertreated condition of cirrhosis.
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Affiliation(s)
- Mads Barloese
- Department of Clinical Physiology and Nuclear Medicine, Center for Functional and Diagnostic Imaging and Research, Faculty of Health Sciences Hvidovre Hospital, University of Copenhagen, Hvidovre, Denmark
| | - Mohammadnavid Chitgar
- Department of Clinical Physiology and Nuclear Medicine, Center for Functional and Diagnostic Imaging and Research, Faculty of Health Sciences Hvidovre Hospital, University of Copenhagen, Hvidovre, Denmark
| | - Jens Hannibal
- Department of Clinical Biochemistry, Bispebjerg Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Søren Møller
- Department of Clinical Physiology and Nuclear Medicine, Center for Functional and Diagnostic Imaging and Research, Faculty of Health Sciences Hvidovre Hospital, University of Copenhagen, Hvidovre, Denmark
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Role of PACAP and Its PACAP Type I Receptor in the Central Control of Reproductive Hormones. ACTA ACUST UNITED AC 2016. [DOI: 10.1007/978-3-319-35135-3_22] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
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3
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Interactions between Two Different G Protein-Coupled Receptors in Reproductive Hormone-Producing Cells: The Role of PACAP and Its Receptor PAC1R. Int J Mol Sci 2016; 17:ijms17101635. [PMID: 27681724 PMCID: PMC5085668 DOI: 10.3390/ijms17101635] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 09/10/2016] [Accepted: 09/19/2016] [Indexed: 12/22/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) and gonadotropins are indispensable hormones for maintaining female reproductive functions. In a similar manner to other endocrine hormones, GnRH and gonadotropins are controlled by their principle regulators. Although it has been previously established that GnRH regulates the synthesis and secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH)—both gonadotropins—from pituitary gonadotrophs, it has recently become clear that hypothalamic GnRH is under the control of hypothalamic kisspeptin. Prolactin, which is also known as luteotropic hormone and is released from pituitary lactotrophs, stimulates milk production in mammals. Prolactin is also regulated by hypothalamic factors, and it is thought that prolactin synthesis and release are principally under inhibitory control by dopamine through the dopamine D2 receptor. In addition, although it remains unknown whether it is a physiological regulator, thyrotropin-releasing hormone (TRH) is a strong secretagogue for prolactin. Thus, GnRH, LH and FSH, and prolactin are mainly regulated by hypothalamic kisspeptin, GnRH, and TRH, respectively. However, the synthesis and release of these hormones is also modulated by other neuropeptides in the hypothalamus. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a hypothalamic peptide that was first isolated from sheep hypothalamic extracts based on its ability to stimulate cAMP production in anterior pituitary cells. PACAP acts on GnRH neurons and pituitary gonadotrophs and lactotrophs, resulting in the modulation of their hormone producing/secreting functions. Furthermore, the presence of the PACAP type 1 receptor (PAC1R) has been demonstrated in these cells. We have examined how PACAP and PAC1R affect GnRH- and pituitary hormone-secreting cells and interact with their principle regulators. In this review, we describe our understanding of the role of PACAP and PAC1R in the regulation of GnRH neurons, gonadotrophs, and lactotrophs, which are regulated mainly by kisspeptin, GnRH, and TRH, respectively.
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Condro MC, Matynia A, Foster NN, Ago Y, Rajbhandari AK, Van C, Jayaram B, Parikh S, Diep AL, Nguyen E, May V, Dong HW, Waschek JA. High-resolution characterization of a PACAP-EGFP transgenic mouse model for mapping PACAP-expressing neurons. J Comp Neurol 2016; 524:3827-3848. [PMID: 27197019 DOI: 10.1002/cne.24035] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 02/10/2016] [Accepted: 05/12/2016] [Indexed: 12/23/2022]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP, gene name Adcyap1) regulates a wide variety of neurological and physiological functions, including metabolism and cognition, and plays roles in of multiple forms of stress. Because of its preferential expression in nerve fibers, it has often been difficult to trace and identify the endogenous sources of the peptide in specific populations of neurons. Here, we introduce a transgenic mouse line that harbors in its genome a bacterial artificial chromosome containing an enhanced green fluorescent protein (EGFP) expression cassette inserted upstream of the PACAP ATG translation initiation codon. Analysis of expression in brain sections of these mice using a GFP antibody reveals EGFP expression in distinct neuronal perikarya and dendritic arbors in several major brain regions previously reported to express PACAP from using a variety of approaches, including radioimmunoassay, in situ hybridization, and immunohistochemistry with and without colchicine. EGFP expression in neuronal perikarya was modulated in a manner similar to PACAP gene expression in motor neurons after peripheral axotomy in the ipsilateral facial motor nucleus in the brainstem, providing an example in which the transgene undergoes proper regulation in vivo. These mice and the high-resolution map obtained are expected to be useful in understanding the anatomical patterns of PACAP expression and its plasticity in the mouse. J. Comp. Neurol. 524:3827-3848, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Michael C Condro
- Department of Psychiatry, University of California, Los Angeles, USA 90095
| | - Anna Matynia
- Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, USA 90095.,Brain Research Institute, University of California, Los Angeles, USA 90095
| | - Nicholas N Foster
- Institute of Neuro Imaging and Informatics, Keck School of Medicine, University of Southern California, Los Angeles, CA USA 90089
| | - Yukio Ago
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan 565-0871
| | - Abha K Rajbhandari
- Department of Psychiatry, University of California, Los Angeles, USA 90095.,Department of Psychology, University of California, Los Angeles, USA 90095
| | - Christina Van
- Department of Psychiatry, University of California, Los Angeles, USA 90095
| | - Bhavaani Jayaram
- Department of Psychiatry, University of California, Los Angeles, USA 90095
| | - Sachin Parikh
- Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, USA 90095.,Brain Research Institute, University of California, Los Angeles, USA 90095
| | - Anna L Diep
- Department of Psychiatry, University of California, Los Angeles, USA 90095
| | - Eileen Nguyen
- Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, USA 90095.,Brain Research Institute, University of California, Los Angeles, USA 90095
| | - Victor May
- Department of Neurological Sciences, University of Vermont, USA 05405
| | - Hong-Wei Dong
- Institute of Neuro Imaging and Informatics, Keck School of Medicine, University of Southern California, Los Angeles, CA USA 90089
| | - James A Waschek
- Department of Psychiatry, University of California, Los Angeles, USA 90095
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5
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Halvorson LM. PACAP modulates GnRH signaling in gonadotropes. Mol Cell Endocrinol 2014; 385:45-55. [PMID: 24095645 DOI: 10.1016/j.mce.2013.09.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/23/2013] [Accepted: 09/24/2013] [Indexed: 12/18/2022]
Abstract
Hypothalamic gonadotropin-releasing hormone is known to be critical for normal gonadotropin biosynthesis and secretion by the gonadotrope cells of the anterior pituitary gland. Additional regulation is provided by gonadal steroid feedback as well as by intrapituitary factors, such as activin and follistatin. Less well-appreciated is the role of pituitary adenylate-cyclase activating polypeptide (PACAP) as both a hypothalamic-pituitary releasing factor as well as an autocrine-paracrine factor within the pituitary. PACAP regulates gonadotropin expression alone and through modulation of GnRH responsiveness achieved by increases in GnRH receptor expression and interactions at the level of intracellular signaling pathways. In addition to direct effects on the gonadotrope, PACAP stimulates follistatin secretion by the folliculostellate cells and thereby contributes to differential expression of the gonadotropin subunits. Conversely, GnRH augments the ability of PACAP to regulate gonadotrope function by increasing pituitary PACAP and PACAP receptor expression. This review will summarize the current understanding of the mechanisms by which PACAP modulates gonadotrope function, with a focus on interactions with GnRH.
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Affiliation(s)
- Lisa M Halvorson
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9032, United States.
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6
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Thomas RL, Crawford NM, Grafer CM, Halvorson LM. Pituitary Adenylate Cyclase–Activating Polypeptide (PACAP) in the Hypothalamic–Pituitary–Gonadal Axis. Reprod Sci 2012; 20:857-71. [DOI: 10.1177/1933719112466310] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Robin L. Thomas
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, USA
| | - Natalie M. Crawford
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, USA
| | - Constance M. Grafer
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, USA
| | - Lisa M. Halvorson
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, USA
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Vaudry D, Falluel-Morel A, Bourgault S, Basille M, Burel D, Wurtz O, Fournier A, Chow BKC, Hashimoto H, Galas L, Vaudry H. Pituitary Adenylate Cyclase-Activating Polypeptide and Its Receptors: 20 Years after the Discovery. Pharmacol Rev 2009; 61:283-357. [DOI: 10.1124/pr.109.001370] [Citation(s) in RCA: 829] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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Jamen F, Alonso G, Shibuya I, Widmer H, Vacher CM, Calas A, Bockaert J, Brabet P, Dayanithi G. Impaired somatodendritic responses to pituitary adenylate cyclase-activating polypeptide (PACAP) of supraoptic neurones in PACAP type I -receptor deficient mice. J Neuroendocrinol 2003; 15:871-81. [PMID: 12899682 DOI: 10.1046/j.1365-2826.2003.01075.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The role of pituitary adenylate cyclase-activating polypeptide (PACAP) type I receptor (PAC1 receptor) in regulating hypothalamic supraoptic neurones was investigated using PAC1 receptor-deficient male mice (PAC1-/-). The effects of PACAP on [Ca2+]i were investigated in freshly dissociated supraoptic neurones and on the somatodendritic release of vasopressin and oxytocin, examined on intact supraoptic nuclei. In supraoptic neurones from wild-type mice (PAC1+/+), 100 nm PACAP induced an increase in [Ca2+]i and release of vasopressin and oxytocin, whereas in heterozygous (PAC1+/-) and null-mutant mice (PAC1-/-), PACAP was much less effective. PACAP had no effect on these two parameters when applied to isolated neurohypophysial nerve terminals of PAC1+/+ and PAC1-/- mice, and rats. In conclusion, the PAC1 receptor is solely responsible for the PACAP-induced [Ca2+]i signalling and secretion of vasopressin and oxytocin in the somatodendritic region of supraoptic neurones.
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Affiliation(s)
- F Jamen
- UPR 9023-CNRS and UMR 5101-CNRS, CCIPE, Montpellier, France
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9
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Yon L, Alexandre D, Montéro M, Chartrel N, Jeandel L, Vallarino M, Conlon JM, Kikuyama S, Fournier A, Gracia-Navarro F, Roubos E, Chow B, Arimura A, Anouar Y, Vaudry H. Pituitary adenylate cyclase-activating polypeptide and its receptors in amphibians. Microsc Res Tech 2001; 54:137-57. [PMID: 11458398 DOI: 10.1002/jemt.1129] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP), a novel peptide of the secretin/glucagon/vasoactive intestinal polypeptide superfamily, has been initially characterized in mammals in 1989 and, only 2 years later, its counterpart has been isolated in amphibians. A number of studies conducted in the frog Rana ridibunda have demonstrated that PACAP is widely distributed in the central nervous system (particularly in the hypothalamus and the median eminence) and in peripheral organs including the adrenal gland. The cDNAs encoding the PACAP precursor and 3 types of PACAP receptors have been cloned in amphibians and their distribution has been determined by in situ hybridization histochemistry. Ontogenetic studies have revealed that PACAP is expressed early in the brain of tadpoles, soon after hatching. In the frog Rana ridibunda, PACAP exerts a large array of biological effects in the brain, pituitary, adrenal gland, and ovary, suggesting that, in amphibians as in mammals, PACAP may act as neurotrophic factor, a neurotransmitter and a neurohormone.
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Affiliation(s)
- L Yon
- European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U-413, UA CNRS, University of Rouen, 76821 Mont-Saint-Aignan, France
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10
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Sherwood NM, Krueckl SL, McRory JE. The origin and function of the pituitary adenylate cyclase-activating polypeptide (PACAP)/glucagon superfamily. Endocr Rev 2000; 21:619-70. [PMID: 11133067 DOI: 10.1210/edrv.21.6.0414] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The pituitary adenylate cyclase-activating polypeptide (PACAP)/ glucagon superfamily includes nine hormones in humans that are related by structure, distribution (especially the brain and gut), function (often by activation of cAMP), and receptors (a subset of seven-transmembrane receptors). The nine hormones include glucagon, glucagon-like peptide-1 (GLP-1), GLP-2, glucose-dependent insulinotropic polypeptide (GIP), GH-releasing hormone (GRF), peptide histidine-methionine (PHM), PACAP, secretin, and vasoactive intestinal polypeptide (VIP). The origin of the ancestral superfamily members is at least as old as the invertebrates; the most ancient and tightly conserved members are PACAP and glucagon. Evidence to date suggests the superfamily began with a gene or exon duplication and then continued to diverge with some gene duplications in vertebrates. The function of PACAP is considered in detail because it is newly (1989) discovered; it is tightly conserved (96% over 700 million years); and it is probably the ancestral molecule. The diverse functions of PACAP include regulation of proliferation, differentiation, and apoptosis in some cell populations. In addition, PACAP regulates metabolism and the cardiovascular, endocrine, and immune systems, although the physiological event(s) that coordinates PACAP responses remains to be identified.
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Affiliation(s)
- N M Sherwood
- Department of Biology, University of Victoria, British Columbia, Canada.
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11
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Chakfe Y, Bourque CW. Excitatory peptides and osmotic pressure modulate mechanosensitive cation channels in concert. Nat Neurosci 2000; 3:572-9. [PMID: 10816313 DOI: 10.1038/75744] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Behavioral and neuroendocrine responses underlying systemic osmoregulation are synergistically controlled by osmoreceptors and neuropeptides released within the hypothalamus. Although mechanisms underlying osmoreception are understood, the cellular basis for the integration of osmotic and peptidergic signals remains unknown. Here we show that the excitatory effects of angiotensin II, cholecystokinin and neurotensin on supraoptic neurosecretory neurons are due to the stimulation of the stretch-inactivated cation channels responsible for osmoreception. This molecular convergence underlies the facilitatory effects of neuropeptides on responses to osmotic stimulation and provides a basis for the gating effects of plasma osmolality on the responsiveness of osmoregulatory neurons to peptidergic stimulation.
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Affiliation(s)
- Y Chakfe
- Centre for Research In Neuroscience, Montreal General Hospital and McGill University, 1650 Cedar Avenue, Montreal, Quebec H3G 1A4, Canada
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12
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Giustina A, Veldhuis JD. Pathophysiology of the neuroregulation of growth hormone secretion in experimental animals and the human. Endocr Rev 1998; 19:717-97. [PMID: 9861545 DOI: 10.1210/edrv.19.6.0353] [Citation(s) in RCA: 211] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
During the last decade, the GH axis has become the compelling focus of remarkably active and broad-ranging basic and clinical research. Molecular and genetic models, the discovery of human GHRH and its receptor, the cloning of the GHRP receptor, and the clinical availability of recombinant GH and IGF-I have allowed surprisingly rapid advances in our knowledge of the neuroregulation of the GH-IGF-I axis in many pathophysiological contexts. The complexity of the GHRH/somatostatin-GH-IGF-I axis thus commends itself to more formalized modeling (154, 155), since the multivalent feedback-control activities are difficult to assimilate fully on an intuitive scale. Understanding the dynamic neuroendocrine mechanisms that direct the pulsatile secretion of this fundamental growth-promoting and metabolic hormone remains a critical goal, the realization of which is challenged by the exponentially accumulating matrix of experimental and clinical data in this arena. To the above end, we review here the pathophysiology of the GHRH somatostatin-GH-IGF-I feedback axis consisting of corresponding key neurotransmitters, neuromodulators, and metabolic effectors, and their cloned receptors and signaling pathways. We propose that this system is best viewed as a multivalent feedback network that is exquisitely sensitive to an array of neuroregulators and environmental stressors and genetic restraints. Feedback and feedforward mechanisms acting within the intact somatotropic axis mediate homeostatic control throughout the human lifetime and are disrupted in disease. Novel effectors of the GH axis, such as GHRPs, also offer promise as investigative probes and possible therapeutic agents. Further understanding of the mechanisms of GH neuroregulation will likely allow development of progressively more specific molecular and clinical tools for the diagnosis and treatment of various conditions in which GH secretion is regulated abnormally. Thus, we predict that unexpected and enriching insights in the domain of the neuroendocrine pathophysiology of the GH axis are likely be achieved in the succeeding decades of basic and clinical research.
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Affiliation(s)
- A Giustina
- Department of Internal Medicine, University of Brescia, Italy
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13
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Abstract
In addition to the release of neurotransmitters from their axon terminals, several neuronal populations are able to release their products from their dendrites. The cell bodies and dendrites of vasopressin- and oxytocin-producing neurones are mainly located within the hypothalamic supraoptic and paraventricular nuclei and neuropeptide release within the magnocellular nuclei has been shown in vitro and in vivo. Local release is induced by a range of physiological and pharmacological stimuli, and is regulated by a number of brain areas; locally released peptides are mainly involved in pre- and postsynaptic modulation of the electrical activity of magnocellular neurones. Spatial and temporal differences between peptide release within the nuclei and that from the distant axonal varicosities indicate that the release mechanisms are at least partially independent, supporting the hypothesis of locally regulated dendritic release of vasopressin and oxytocin. In this respect, magnocellular neurones show similarities to other neuronal populations and thus autoregulation of neuronal activity by dendritic neuromodulator release may be a general phenomenon within the brain.
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Affiliation(s)
- M Ludwig
- Department of Physiology, University of Edinburgh Medical School, UK.
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Nussdorfer GG, Malendowicz LK. Role of VIP, PACAP, and related peptides in the regulation of the hypothalamo-pituitary-adrenal axis. Peptides 1998; 19:1443-67. [PMID: 9809661 DOI: 10.1016/s0196-9781(98)00102-8] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are members of a family of regulatory peptides that are widely distributed in the body and share numerous biologic actions. The two peptides display a remarkable amino acid-sequence homology, and bind to a class of G protein-coupled receptors, named PACAP/VIP receptors (PVRs), whose signaling mechanism mainly involves the activation of adenylate-cyclase and phospholipase-C cascades. A large body of evidence suggests that VIP and PACAP play a role in the control of the hypothalamo--pituitary-adrenal (HPA) axis, almost exclusively acting in a paracrine manner, since their blood concentration is very low. VIP and PACAP are contained in both nerve fibers and neurons of the hypothalamus, and VIP, but not PACAP, is also synthesized in the pituitary gland. Both peptides are expressed in the adrenal gland, and especially in medullary chromaffin cells. All the components of the HPA axis are provided with PVRs. VIP and PACAP enhance pituitary ACTH secretion, VIP by eliciting the hypothalamic release of CRH and potentiating its secretagogue action, and PACAP by directly stimulating pituitary corticotropes. Through this central mechanism, VIP and PACAP may increase mineralo- and glucocorticoid secretion of the adrenal cortex. VIP but not PACAP also exerts a weak direct secretagogue action on adrenocortical cells by activating both PVRs and probably a subtype of ACTH receptors. VIP and PACAP raise aldosterone production via a paracrine indirect mechanism involving the stimulation of medullary chromaffin cells to release catecholamines, which in turn enhance the secretion of zona glomerulosa cells via a beta-adrenoceptor-mediated mechanism. PACAP appears to be able to evoke a glucocorticoid response through the activation, at least in the rat, of the intramedullary CRH/ACTH system. The relevance of these effects of VIP and PACAP under basal conditions is questionable, although there are indications that endogenous VIP is involved in the maintenance of the normal growth and steroidogenic capacity of rat adrenal cortex. However, indirect evidence suggests that these peptides might play a relevant role under paraphysiological conditions (e.g., in the mediation of HPA axis responses to cold and inflammatory stresses) or may be somehow involved in the pathogenesis of Cushing disease or some case of hyperaldosteronism associated with secreting pheochromocytomas.
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Köves K, Kántor O, Scammell JG, Arimura A. PACAP colocalizes with luteinizing and follicle-stimulating hormone immunoreactivities in the anterior lobe of the pituitary gland. Peptides 1998; 19:1069-72. [PMID: 9700757 DOI: 10.1016/s0196-9781(98)00049-7] [Citation(s) in RCA: 46] [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: 11/20/2022]
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) and its close relative vasoactive intestinal polypeptide (VIP) were demonstrated in the anterior pituitary gland. The cells which exhibited PACAP immunoreactivity were oval or round shaped. Their distribution was similar to that of gonadotropes but the number of PACAP immunoreactive cells was less. Double labeling revealed that PACAP immunoreactivity partially colocalized with luteinizing and follicle-stimulating hormone; however, colocalization with other pituitary hormone immunoreactivities was not demonstrated. Our results suggest an autocrine or paracrine role of PACAP in the regulation of pituitary functions.
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Affiliation(s)
- K Köves
- Department of Human Morphology and Developmental Biology, Semmelweis University Medical School, Budapest, Hungary.
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Shibuya I, Noguchi J, Tanaka K, Harayama N, Inoue U, Kabashima N, Ueta Y, Hattori Y, Yamashita H. PACAP increases the cytosolic Ca2+ concentration and stimulates somatodendritic vasopressin release in rat supraoptic neurons. J Neuroendocrinol 1998; 10:31-42. [PMID: 9510056 DOI: 10.1046/j.1365-2826.1998.00168.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP)-like immunoreactivity and its receptor mRNA have been reported in the supraoptic and the paraventricular nucleus (SON and PVN, respectively) and PACAP has been implicated in the regulation of magnocellular neurosecretory cell function. To examine the site and the mechanism of the action of PACAP in the neurosecretory cells, we measured AVP release from SON slice preparations and the cytosolic Ca2+ concentration ([Ca2+]i) from single dissociated SON neurons. PACAP at concentrations from 10(-12) to 10(-7) M increased [Ca2+]i in dissociated SON neurons in a dose-dependent manner. The patterns of the PACAP-induced [Ca2+]i increase were either sustained increase or cytosolic Ca2+ oscillations. PACAP (10[-7] M) increased [Ca2+]i in 27 of 27 neurons and glutamate (10[-4] M) increased [Ca2+]i in 19 of 19 SON neurons examined, whereas angiotensin II (10[-7] M) increased [Ca2+]i in only 15 of 60 SON neurons examined. PACAP at lower concentrations (10[-10] to 10[-8] M) increased [Ca2+]i in 70-80% of neurons examined. Although the onset and recovery of the PACAP-induced [Ca2+]i increase were slower than those observed with glutamate, the spatial distribution of the [Ca2+]i increases in response to the two ligands were similar: [Ca2+]i increase at the proximal dendrites was larger and faster and that at the center of the soma was smaller and slower. The PACAP-induced [Ca2+]i responses were abolished by extracellular Ca2+ removal, the L-type Ca2+-channel blocker, nicardipine, or by replacement of extracellular Na+ with N-methyl D-glucamine, and were partially inhibited by the Na+-channel blocker, tetrodotoxin. The N-type Ca2+-channel blocker, omega-conotoxin GVIA did not significantly inhibit the PACAP-induced [Ca2+]i responses. Furthermore, PACAP (10[-7] M) as well as glutamate (10[-4] M) increased AVP release from SON slice preparations, and extracellular Ca2+ removal or nicardipine inhibited the AVP release in response to PACAP. These results indicate that PACAP enhances Ca2+ entry via voltage-gated Ca2+ channels and increases [Ca2+]i, which, in turn, stimulates somatodendritic vasopressin release by directly activating PACAP receptors on SON neurons. The results also suggest that PACAP in the SON may play a pivotal role in the control of the neurohypophyseal function at the level of the soma or the dendrites.
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Affiliation(s)
- I Shibuya
- Department of Physiology, University of Occupational and Environmental Health, School of Medicine, Kitakyusyu, Japan
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17
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Tanaka K, Shibuya I, Harayama N, Nomura M, Kabashima N, Ueta Y, Yamashita H. Pituitary adenylate cyclase-activating polypeptide potentiation of Ca2+ entry via protein kinase C and A pathways in melanotrophs of the pituitary pars intermedia of rats. Endocrinology 1997; 138:4086-95. [PMID: 9322916 DOI: 10.1210/endo.138.10.5442] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) has been reported to stimulate melanotroph secretion, and PACAP-like immunoreactivity and expression of PACAP type I receptor messenger RNA have been identified in the pituitary pars intermedia (PI). The present study showed that PACAP messenger RNA is also expressed in the PI. To examine the mechanism of PACAP action in the PI, cytosolic Ca2+ concentrations ([Ca2+]i) and ionic currents were measured in acutely dissociated rat melanotrophs. In about 40% of the melanotrophs studied, PACAP induced an increase in [Ca2+]i, which was suppressed by extracellular Ca2+ removal; extracellular Na+ replacement; the blocker of L-type Ca2+ channels, nicardipine; or the secreto-inhibitory neurotransmitter, dopamine. The PACAP-induced [Ca2+]i increase was mimicked by activators of protein kinase A (PKA) and protein kinase C (PKC), Sp-diastereomer of cAMP and 1-oleoyl-2-acetyl-sn-glycerol, and was reduced by inhibitors of PKA and PKC, Rp-diastereomer of cAMP and staurosporine. Patch-clamp analysis revealed that PACAP caused inward currents with a reversal potential of -0.8 mV and facilitated voltage-dependent Ba2+ currents. It further revealed that PACAP-induced inward currents were mimicked by 1-oleoyl-2-acetyl-sn-glycerol and inhibited by staurosporine, and that Sp-diastereomer of cAMP facilitated Ba2+ currents. These results suggest that PACAP potentiates Ca2+ entry mechanisms of rat melanotrophs by activation of nonselective cation channels via PKC and facilitation of voltage-dependent Ca2+ channels via PKA.
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Affiliation(s)
- K Tanaka
- Department of Physiology, University of Occupational and Environmental Health, School of Medicine, Kitakyusyu, Japan
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18
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Shioda S, Shuto Y, Somogyvari-Vigh A, Legradi G, Onda H, Coy DH, Nakajo S, Arimura A. Localization and gene expression of the receptor for pituitary adenylate cyclase-activating polypeptide in the rat brain. Neurosci Res 1997; 28:345-54. [PMID: 9274830 DOI: 10.1016/s0168-0102(97)00065-5] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) is a recently identified member of the secretin/vasoactive intestinal polypeptide (VIP) family. There are at least two types of receptor for PACAP: type I (PACAPR), which specifically binds PACAP; and type II (VIP/PACAPR), which binds both PACAP and VIP. The localization of PACAPR in the rat brain was determined by in situ hybridization and immunocytochemistry. We raised antisera against a synthetic peptide that corresponds to the carboxy-terminal cytoplasmic domain which is found in all subtypes of PACAPR in order to localize PACAPR-like immunoreactivity (PACAPR-LI) in the rat brain. In general, the distribution of PACAPR-LI correlated well with the distribution of PACAPR transcripts. Particularly strong PACAPR mRNA expression was detected in the olfactory bulb, hippocampus, cerebellum and hypothalamus and moderate labeling was detected in other scattered regions. At the cellular level, PACAPR-LI appeared to be concentrated predominantly in neuronal perikarya and dendrites. At the ultrastructural level, strong immunostaining for the PACAPR was found in plasma membranes, rough endoplasmic reticulum, cytoplasmic matrix, and at synapses. This study provides the basis for a better understanding of the functions of PACAP in the rat brain.
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Affiliation(s)
- S Shioda
- US-Japan Biomedical Research Laboratories, Tulane University Hebert Center, Belle Chasse, LA 70037, USA.
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19
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Haraguchi H, Watanabe YG. The Localization of Vasoactive Intestinal Peptide (VIP)-Like Immunoreactivity in Gonadotropes of the Rat Anterior Pituitary. Zoolog Sci 1997. [DOI: 10.2108/zsj.14.483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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20
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Gonzalez BJ, Basille M, Vaudry D, Fournier A, Vaudry H. Pituitary adenylate cyclase-activating polypeptide promotes cell survival and neurite outgrowth in rat cerebellar neuroblasts. Neuroscience 1997; 78:419-30. [PMID: 9145799 DOI: 10.1016/s0306-4522(96)00617-3] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
High concentrations of pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptors have been detected in the rat cerebellum during ontogenesis. In particular, PACAP receptors are actively expressed in immature granule cells, suggesting that PACAP may act as a neurotrophic factor in the developing rat cerebellum. In the present study, we have investigated the effect of PACAP on cell survival and neurite outgrowth in cultured immature cerebellar granule cells. In control conditions, cultured granule cells undergo programmed cell death. Exposure of cultured cells to PACAP for 24 and 48 h provoked a significant increase in the number of living cells. The effect of PACAP on cell survival was inhibited by the PACAP antagonist PACAP(6-38). Vasoactive intestinal polypeptide was approximately 1000 times less potent than PACAP in promoting cell survival. PACAP also induced a significant increase in the number of processes and in the cumulated length of neurites borne by cultured neuroblasts. The present results demonstrate that PACAP promotes cell survival and neurite outgrowth in cultured immature granule cells. Since PACAP and its receptors are expressed in situ in the rat cerebellar cortex, these data strongly suggest that PACAP plays a physiological role in the survival and differentiation of cerebellar granule cells.
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Affiliation(s)
- B J Gonzalez
- European Institute for Peptide Research (IFRMP no. 23), INSERM U413, UA CNRS, University of Rouen, Mont-Saint-Aignan, France
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21
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Palkovits M, Somogyvári-Vigh A, Arimura A. Concentrations of pituitary adenylate cyclase activating polypeptide (PACAP) in human brain nuclei. Brain Res 1995; 699:116-20. [PMID: 8616598 DOI: 10.1016/0006-8993(95)00869-r] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Concentrations of pituitary adenylate cyclase activating polypeptide (PACAP) in 79 microdissected human brain regions from adult 40- to 80-year-old adult males were measured by radioimmunoassay. Although PACAP was detectable in all of the brain nuclei investigated, the distribution of the peptide was regionally very heterogeneous. The ratio of the highest to the lowest concentrations measured in brain regions exceeded 160:1. The highest concentrations were found in the dorsal vagal complex, the bed nucleus of the stria terminalis, the median eminence-pituitary stalk, and in the periventricular and paraventricular hypothalamic nuclei. They were followed by some hypothalamic (supraoptic and ventromedial), preoptic and brainstem nuclei. High concentrations were also measured in the septum pellucidum, periaqueductal and spinal gray matters, the motor facial, and in the spinal nucleus of the trigeminal nerve. The distribution pattern of PACAP in the human brain was unique; it did not show any similarities to the distributions of other neuropeptides in the central nervous system.
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Affiliation(s)
- M Palkovits
- Laboratory of Neuromorphology, Semmelweis University Medical School, Budapest, Hungary
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22
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Lania A, Gil-del-Alamo P, Saccomanno K, Persani L, Faglia G, Spada A. Mechanism of action of pituitary adenylate cyclase-activating polypeptide (PACAP) in human nonfunctioning pituitary tumors. J Neuroendocrinol 1995; 7:695-702. [PMID: 8547947 DOI: 10.1111/j.1365-2826.1995.tb00811.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Several evidence suggest that pituitary adenylate cyclase activating polypeptides (PACAP-38 and -27) could function as hypophysiotropic factors. Both peptides interact with either the type I receptor, which preferentially binds the two PACAPs and has a much lower affinity for vasoactive intestinal polypeptide (VIP) or the type II receptor, which binds the two PACAPs and VIP with a nearly equal affinity. In addition to the stimulation of adenylyl cyclase (AC) activity, in different cell types PACAP causes an increase of cytosolic calcium levels ([Ca2+]i), consequent to phospholipase-C activation. In the present study, we investigated the effect of PACAP on cAMP formation and [Ca2+]i levels in 16 human nonfunctioning pituitary adenomas (NFPA). PACAP-38 increased cAMP formation in all tumors; the peptide stimulated either AC activity in membrane preparations from 26 +/- 10 to 214 +/- 179 pmol/mg prot/min (P < 0.01) or cAMP efflux from 12 +/- 5.4 to 73.2 +/- 32 pmol/well (P < 0.01) in cultured cells. The effect, detectable at concentrations higher than 1-10 pM, was maximal at 0.1-10 nM. While PACAP-38 and PACAP-27 were nearly equally effective and potent, 100-fold higher concentrations of VIP were required to obtain similar AC activation. GHRH and CRH were ineffective in any NFPA. The PACAP effect was not antagonized by a VIP antagonist, while PACAP fragment 6-27 amide partially reduced the stimulatory effects of both PACAP-27 and VIP in 2 out of 3 tumors tested. PACAP-38 caused a [Ca2+]i rise in cells obtained from 7 NFPA (from 110 +/- 34 to 151 +/- 40 nM [Ca2+]i, P < 0.05) while in the remaining 7 the peptide was ineffective at any concentrations tested (from 1 nM to 10 microM). In the responsive tumors, PACAP-38 effect was not consequence of phospholipase-C activation since removal of extracellular Ca2+ as well as blockade of L-type Ca2+ channels by dihydropyridine antagonists abolished [Ca2+]i increase triggered by the peptide. These data indicate that PACAP is by far the most potent activator of cAMP formation in NFPA and suggest a possible modulatory action of this peptide on cell growth.
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Affiliation(s)
- A Lania
- Institute of Endocrine Sciences, Ospedale Maggiore IRCCS, University of Milan, Italy
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Shiotani Y, Kimura S, Ohshige Y, Yanaihara C, Yanaihara N. Immunohistochemical localization of pituitary adenylate cyclase-activating polypeptide (PACAP) in the adrenal medulla of the rat. Peptides 1995; 16:1045-50. [PMID: 8532586 DOI: 10.1016/0196-9781(95)00076-v] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Localization of PACAP in rat adrenal glands was examined by light and electron microscopic immunohistochemistry using a specific antiserum to PACAP 38, R0831. In the light microscopic study, PACAP immunoreactivity was observed in some cell groups in the medulla, but not in the cortex. In comparison with adjacent sections stained with antisera to catecholamine synthesizing enzymes, PACAP-positive cells were immunoreactive to tyrosine hydroxylase and dopamine beta-hydroxylase, but not to phenylethanolamine-N-methyltransferase, suggesting that they were coincident with noradrenaline secreting cells. In the electron microscopic study using the ABC method, DAB reaction products were diffusely distributed in the cytoplasmic matrix of PACAP-positive cells, without intense accumulation on the secretory granules. The splanchnic nerve terminals were PACAP negative. In postembedding immunohistochemistry, gold particles were localized diffusely in the cytoplasma, but not aggregated on the secretory granules. It was suggested that PACAP would localize in the cytoplasmic matrix of noradrenaline cells and stimulate the catecholamine synthesis and release in the adrenal medulla.
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Affiliation(s)
- Y Shiotani
- Department of Neuroanatomy, Osaka University Medical School, Japan
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