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Jiang Z, Chen C, Weiss GL, Fu X, Stelly CE, Sweeten BLW, Tirrell PS, Pursell I, Stevens CR, Fisher MO, Begley JC, Harrison LM, Tasker JG. Stress-induced glucocorticoid desensitizes adrenoreceptors to gate the neuroendocrine response to somatic stress in male mice. Cell Rep 2022; 41:111509. [PMID: 36261014 PMCID: PMC9635929 DOI: 10.1016/j.celrep.2022.111509] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 08/05/2022] [Accepted: 09/23/2022] [Indexed: 11/29/2022] Open
Abstract
Noradrenergic afferents to hypothalamic corticotropin releasing hormone (CRH) neurons provide a major excitatory drive to the hypothalamic-pituitary-adrenal (HPA) axis via α1 adrenoreceptor activation. Noradrenergic afferents are recruited preferentially by somatic, rather than psychological, stress stimuli. Stress-induced glucocorticoids feed back onto the hypothalamus to negatively regulate the HPA axis, providing a critical autoregulatory constraint that prevents glucocorticoid overexposure and neuropathology. Whether negative feedback mechanisms target stress modality-specific HPA activation is not known. Here, we describe a desensitization of the α1 adrenoreceptor activation of the HPA axis following acute stress in male mice that is mediated by rapid glucocorticoid regulation of adrenoreceptor trafficking in CRH neurons. Glucocorticoid-induced α1 receptor trafficking desensitizes the HPA axis to a somatic but not a psychological stressor. Our findings demonstrate a rapid glucocorticoid suppression of adrenergic signaling in CRH neurons that is specific to somatic stress activation, and they reveal a rapid, stress modality-selective glucocorticoid negative feedback mechanism. Physical and psychological stressors activate neuroendocrine secretion of corticosteroid. Noradrenaline circuits are critical to the neuroendocrine response to physical but not psychological stress. Jiang et al. show that stress-induced corticosteroids decrease noradrenaline sensitivity in the brain, which suppresses the response to subsequent physical stressors but leaves the psychological stress response intact.
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Affiliation(s)
- Zhiying Jiang
- Cell and Molecular Biology Department, Tulane University, New Orleans, LA 70118, USA
| | - Chun Chen
- Cell and Molecular Biology Department, Tulane University, New Orleans, LA 70118, USA
| | - Grant L Weiss
- Cell and Molecular Biology Department, Tulane University, New Orleans, LA 70118, USA
| | - Xin Fu
- Neuroscience Program, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
| | - Claire E Stelly
- Cell and Molecular Biology Department, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
| | - Brook L W Sweeten
- Cell and Molecular Biology Department, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
| | - Parker S Tirrell
- Neuroscience Program, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
| | - India Pursell
- Neuroscience Program, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
| | - Carly R Stevens
- Cell and Molecular Biology Department, Tulane University, New Orleans, LA 70118, USA
| | - Marc O Fisher
- Neuroscience Program, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
| | - John C Begley
- Neuroscience Program, Tulane University, New Orleans, LA 70118, USA
| | - Laura M Harrison
- Cell and Molecular Biology Department, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
| | - Jeffrey G Tasker
- Cell and Molecular Biology Department, Tulane University, New Orleans, LA 70118, USA; Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA.
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Kim LU, D'Orsogna MR, Chou T. Onset, timing, and exposure therapy of stress disorders: mechanistic insight from a mathematical model of oscillating neuroendocrine dynamics. Biol Direct 2016; 11:13. [PMID: 27013324 PMCID: PMC4807591 DOI: 10.1186/s13062-016-0117-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 03/17/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The hypothalamic-pituitary-adrenal (HPA) axis is a neuroendocrine system that regulates numerous physiological processes. Disruptions in the activity of the HPA axis are correlated with stress-related diseases such as post-traumatic stress disorder (PTSD) and major depressive disorder. In this paper, we characterize "normal" and "diseased" states of the HPA axis as basins of attraction of a dynamical system describing the inhibition of peptide hormones such as corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH) by circulating glucocorticoids such as cortisol (CORT). RESULTS In addition to including key physiological features such as ultradian oscillations in cortisol levels and self-upregulation of CRH neuron activity, our model distinguishes the relatively slow process of cortisol-mediated CRH biosynthesis from rapid trans-synaptic effects that regulate the CRH secretion process. We show that the slow component of the negative feedback allows external stress-induced reversible transitions between "normal" and "diseased" states in novel intensity-, duration-, and timing-dependent ways. CONCLUSION Our two-step negative feedback model suggests a mechanism whereby exposure therapy of stress disorders such as PTSD may act to normalize downstream dysregulation of the HPA axis. Our analysis provides a causative rationale for improving treatments and guiding the design of new protocols.
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Affiliation(s)
- Lae U Kim
- Department of Biomathematics, Univ of California, Los Angeles, 5109 Life Sciences 621 Charles E. Young Dr. South, Los Angeles, USA
| | - Maria R D'Orsogna
- Department of Mathematics, CalState-Northridge, 18111 Nordhoff St., Los Angeles, USA
| | - Tom Chou
- Department of Biomathematics and Department of Mathematics, University of California, Los Angeles, 5209 Life Sciences 621 Charles E. Young Dr. South, Los Angeles, USA.
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Wamsteeker Cusulin JI, Bains JS. Embedded synaptic feedback in the neuroendocrine stress axis. J Neuroendocrinol 2015; 27:481-6. [PMID: 25612538 DOI: 10.1111/jne.12260] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 01/07/2015] [Accepted: 01/15/2015] [Indexed: 11/28/2022]
Abstract
Neural regulation of blood glucocorticoid levels is critical for defence of homeostasis during physiological or psychoemotional challenges. In mammals, this function is carried out by the neuroendocrine stress axis, coordinated by parvocellular neuroendocrine cells (PNCs) of the paraventricular hypothalamic nucleus. Feedback regulation of PNCs by glucocorticoids provides complex experience-dependent shaping of neuroendocrine responses. We review recent evidence for metaplastic actions of glucocorticoids as 'circuit breakers' at synapses directly regulating PNC excitability and explore how such mechanisms may serve as substrates for stress adaptation.
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Affiliation(s)
- J I Wamsteeker Cusulin
- Hotchkiss Brain Institute and the Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - J S Bains
- Hotchkiss Brain Institute and the Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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Wamsteeker JI, Bains JS. A synaptocentric view of the neuroendocrine response to stress. Eur J Neurosci 2010; 32:2011-21. [DOI: 10.1111/j.1460-9568.2010.07513.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Riedemann T, Patchev AV, Cho K, Almeida OFX. Corticosteroids: way upstream. Mol Brain 2010; 3:2. [PMID: 20180948 PMCID: PMC2841592 DOI: 10.1186/1756-6606-3-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 01/11/2010] [Indexed: 01/20/2023] Open
Abstract
Studies into the mechanisms of corticosteroid action continue to be a rich bed of research, spanning the fields of neuroscience and endocrinology through to immunology and metabolism. However, the vast literature generated, in particular with respect to corticosteroid actions in the brain, tends to be contentious, with some aspects suffering from loose definitions, poorly-defined models, and appropriate dissection kits. Here, rather than presenting a comprehensive review of the subject, we aim to present a critique of key concepts that have emerged over the years so as to stimulate new thoughts in the field by identifying apparent shortcomings. This article will draw on experience and knowledge derived from studies of the neural actions of other steroid hormones, in particular estrogens, not only because there are many parallels but also because 'learning from differences' can be a fruitful approach. The core purpose of this review is to consider the mechanisms through which corticosteroids might act rapidly to alter neural signaling.
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Affiliation(s)
- Therese Riedemann
- Max-Planck-Institute of Psychiatry, Kraepelin Str. 2-10, 80804 Munich, Germany
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Faculty of Medicine and Dentistry, University of Bristol, Bristol, UK
| | - Alexandre V Patchev
- Max-Planck-Institute of Psychiatry, Kraepelin Str. 2-10, 80804 Munich, Germany
| | - Kwangwook Cho
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Faculty of Medicine and Dentistry, University of Bristol, Bristol, UK
| | - Osborne FX Almeida
- Max-Planck-Institute of Psychiatry, Kraepelin Str. 2-10, 80804 Munich, Germany
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6
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Abstract
Glucocorticoids are secreted into the systemic circulation from the adrenal cortex and initiate a broad range of actions throughout the organism that regulate the function of multiple organ systems, including the liver, muscle, the immune system, the pancreas, fat tissue, and the brain. Delayed glucocorticoid effects are mediated by classical steroid mechanisms involving transcriptional regulation. Relatively rapid effects of glucocorticoids also occur that are incompatible with genomic regulation and invoke a noncanonical mode of steroid action. Studies conducted in several labs and on different species suggest that the rapid effects of glucocorticoids are mediated by the activation of one or more membrane-associated receptors. Here, we provide a brief review focused on multiple lines of evidence suggesting that rapid glucocorticoid actions are triggered by, or at least dependent on, membrane-associated G protein-coupled receptors and activation of downstream signaling cascades. We also discuss the possibility that membrane-initiated actions of glucocorticoids may provide an additional mechanism for the regulation of gene transcription.
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Affiliation(s)
- Jeffrey G Tasker
- Department of Cell and Molecular Biology, Tulane University, 6400 Freret Street, New Orleans, Louisiana 70118, USA.
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Zaki A, Barrett-Jolley R. Rapid neuromodulation by cortisol in the rat paraventricular nucleus: an in vitro study. Br J Pharmacol 2002; 137:87-97. [PMID: 12183334 PMCID: PMC1573460 DOI: 10.1038/sj.bjp.0704832] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. We have used a range of in vitro electrophysiological techniques to investigate the mechanism of rapid cortisol neuromodulation of parvocellular neurones in the rat paraventricular nucleus. 2. In our study, we found that cortisol (10 microM) increased spontaneous action-current firing frequency to 193%. This effect was insensitive to the glucocorticoid intracellular-receptor antagonist mifepristone. 3. Cortisol (0.1-10 microM) had no detectable effects on whole-cell GABA current amplitudes, or GABA(A) single-channel kinetics. 4. Cortisol (10 microM) inhibited whole-cell potassium currents in parvocellular neurones by shifting the steady-state activation curve by 14 mV to the right. 5. Additionally, in a cell line expressing both the glucocorticoid intracellular receptor and recombinant, fast inactivating potassium channels (hKv1.3), cortisol (1 and 10 microM) inhibited potassium currents by shifting their steady-state activation curves to the right by 12 mV (10 microM cortisol). This effect was also insensitive to the cortisol antagonist, mifepristone. 6. These data suggest that inhibition of voltage-gated potassium channels may contribute to the rapid neuromodulatory effects of cortisol, possibly by direct interaction with the ion channel itself.
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Affiliation(s)
- Abu Zaki
- Department of Physiology, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT
| | - R Barrett-Jolley
- Department of Physiology, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT
- Author for correspondence:
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8
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Abstract
Steroid, amine and peptide hormones affect the peripheral vestibular system. Vasopressin hypersensitivity of the endolymphatic sac may be implicated in the pathogenesis of Meniere's disease. Specific vasopressin antagonists will help define the role of vasopressin in Meniere's disease. The modulation of central vestibular pathways by neuroactive steroids may involve effects on gamma-aminobutyric acid-ergic and glutaminergic pathways. The vestibular nuclei also express enzymes that are important in the synthesis of steroids and the modulation of their activity. Steroids mediate both facilitatory and deleterious effects of stress on vestibular compensation. The quality and quantity of stressor that determines the pattern of hormonal output, may be important. Clinical observation suggests that episodic ataxia type 2, a P/Q calcium channelopathy, may be phenotypically modulated by endocrine fluctuations. Steroid hormones may affect the episodic ataxia type 2 phenotype by modulation of voltage-gated calcium channel activity via second messenger systems and ion channel subunit expression. Despite evidence to support the link, the role of the endocrine system in vestibular function and disease is as yet virtually unexplored.
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Affiliation(s)
- B M Seemungal
- Medical Research Council Human Movement and Balance Unit, National Hospital for Neurology and Neurosurgery, London, UK.
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Shimogori H, Yamashita H, Watanabe T, Nakamura S. A role of glucocorticoid receptors in the guinea pig vestibular system. Brain Res 1999; 851:258-60. [PMID: 10642853 DOI: 10.1016/s0006-8993(99)02141-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To investigate glucocorticoid receptor (GR) function in the vestibular periphery, GR antagonist RU38486 was administered to the guinea pig inner ear by osmotic pump, and we observed post-rotatory nystagmus (PRN) changes as a marker of vestibular function. Ten days after treatment, RU38486 (1 mM) resulted in ipsilateral vestibule hyperexcitability in response to rotation stimulation. This effect was dose-dependent. These data indicate that steroid hormones may play an important role in maintaining vestibular function.
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Affiliation(s)
- H Shimogori
- Department of Otolaryngology, Yamaguchi University School of Medicine, Japan.
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Yamanaka T, Amano T, Sasa M, Matsunaga T. Prednisolone excitation of medial vestibular nucleus neurons in cats. Eur Arch Otorhinolaryngol 1995; 252:112-8. [PMID: 7598871 DOI: 10.1007/bf00168032] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
An electrophysiological study was performed to determine whether prednisolone hydrochloride directly influenced neuronal activities of the medial vestibular nucleus (MVN) in alpha-chloralose-anesthetized cats. Single neuronal activities of MVN were recorded extracellularly with a glass-insulated silver wire microelectrode attached along a seven-barreled micropipette. Each barrel was filled with prednisolone, glutamate, glutamic acid diethylester (GDEE) or CoCl2. Except for prednisolone, which was administered both intravenously and microiontophoretically, other chemicals were applied microiontophoretically to the immediate vicinity of the target neurons. These MVN neurons were classified as type I and II neurons according to their responses to horizontal and sinusoidal rotations. Intravenous prednisolone (up to 5 mg/kg) enhanced spontaneous and rotation-induced neuronal firings of both type I and II neurons in a dose-dependent manner. In a similar tendency, microiontophoretically applied prednisolone (50-200 nA) dose-dependently increased spontaneous and rotation-induced firings of both type I and II neurons. Microiontophoretic GDEE, a non-selective glutamate receptor antagonist, inhibited glutamate- and rotation-induced neuronal discharges without affecting prednisolone-induced increases in neuronal responses of MVN. In addition, iontophoretically applied CoCl2, a Ca2+ channel blocker, did not affect prednisolone-, glutamate- and rotation-induced neuronal findings of MVN. These results suggest that prednisolone induces excitation of type I and II neurons, probably by acting directly on the membrane of MVN neurons. Thus, glucocorticoids such as prednisolone may be effective for the treatment of vertigo resulting from hypofunction of vestibular nucleus neurons.
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Affiliation(s)
- T Yamanaka
- Department of Oto-Rhino-Laryngology, Nara Medical University, Japan
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11
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Chen HL, Romsos DR. Type II glucocorticoid receptors in the CNS regulate metabolism in ob/ob mice independent of protein synthesis. THE AMERICAN JOURNAL OF PHYSIOLOGY 1994; 266:E427-32. [PMID: 8166263 DOI: 10.1152/ajpendo.1994.266.3.e427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A single intracerebroventricular injection of dexamethasone rapidly (within 30 min) decreases brown adipose tissue thermogenesis by 25% as assessed by GDP binding and increases plasma insulin twofold in adrenalectomized ob/ob mice. The present study investigated the type of corticoid receptor(s) that mediate these effects and determined whether protein synthesis was necessary for expression of these glucocorticoid actions in ob/ob mice. Intracerebroventricular injection of aldosterone (a type I-corticoid receptor agonist) was ineffective in altering peripheral metabolism in adrenalectomized ob/ob mice, whereas RU-486 (a type II-corticoid receptor antagonist) abolished the effects of dexamethasone. Thus type II-like corticoid receptors, not type I receptors, mediated the rapid effects of dexamethasone in adrenalectomized ob/ob mice. Anisomycin (0.5 mg) administered subcutaneously almost completely suppressed (-92%) cerebral protein synthesis, but anisomycin did not abolish the rapid effects of dexamethasone in adrenalectomized ob/ob mice. Thus protein synthesis is not a prerequisite for rapid effects of dexamethasone in adrenalectomized ob/ob mice.
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Affiliation(s)
- H L Chen
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing 48824-1224
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12
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Whitnall MH. Regulation of the hypothalamic corticotropin-releasing hormone neurosecretory system. Prog Neurobiol 1993; 40:573-629. [PMID: 8484004 DOI: 10.1016/0301-0082(93)90035-q] [Citation(s) in RCA: 452] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- M H Whitnall
- Department of Physiology, Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5145
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13
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Saphier D, Feldman S. Iontophoresis of cortisol inhibits responses of identified paraventricular nucleus neurones to sciatic nerve stimulation. Brain Res 1990; 535:159-62. [PMID: 2292021 DOI: 10.1016/0006-8993(90)91836-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Responses of paraventricular nucleus (PVN) neurones were examined following stimulation of the sciatic nerve, and concomitant with iontophoretic application of cortisol. Sciatic nerve stimulation excited the majority of cells (22/24, 92%) and iontophoretic application of cortisol reduced the spontaneous activity of 16 of the cells tested (67%). Cortisol prevented neuronal responses to sciatic nerve stimulation in 11 cases (50%) but some of the cells inhibited by the steroid still responded to the stimulation, whilst some cells unaffected by cortisol alone were found not to respond during exposure to the stimulus. These results indicate an inhibitory role for glucocorticoids in the regulation of PVN neuronal activity and responses to afferent neural stimuli.
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Affiliation(s)
- D Saphier
- Department of Pharmacology and Therapeutics, Louisiana State University Medical School, Shreveport 71130-3932
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Stanley BG, Lanthier D, Chin AS, Leibowitz SF. Suppression of neuropeptide Y-elicited eating by adrenalectomy or hypophysectomy: reversal with corticosterone. Brain Res 1989; 501:32-6. [PMID: 2804697 DOI: 10.1016/0006-8993(89)91023-8] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Neuropeptide Y (NPY) injected into the paraventricular hypothalamus (PVN) stimulates a robust eating response in the satiated rat. To examine whether the NPY-feeding system interacts with the pituitary-adrenal axis, the eating response to PVN injections of NPY (78 pmol) was tested in adult male rats before and after sham surgery, adrenalectomy (ADX), hypophysectomy (HYPX), and/or corticosterone (CORT) replacement therapy. In unoperated or sham groups, NPY elicited 5.7-8.8 g of food intake in 1 h as compared to 0.4-1.1 g for vehicle-injected animals. In ADX groups, the NPY-elicited response was reduced by 60-71%, to between 2.4 and 2.8 g. Likewise, the average response of the HYPX group was reduced by 69%, to 1.7 g. Corticosterone replacement, via subcutaneous implant of a 100 mg CORT pellet, normalized the NPY-induced feeding response in both the ADX and HYPX groups. These findings suggest that the hypothalamic NPY-feeding system is largely dependent upon circulating CORT and that no other adrenal or pituitary hormone is essential.
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Lightman SL, Young WS. Influence of steroids on the hypothalamic corticotropin-releasing factor and preproenkephalin mRNA responses to stress. Proc Natl Acad Sci U S A 1989; 86:4306-10. [PMID: 2786213 PMCID: PMC287441 DOI: 10.1073/pnas.86.11.4306] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We have used in situ hybridization histochemistry to investigate the influence of both circulating corticosteroids and the stress paradigm of i.p. hypertonic saline on the levels of mRNAs encoding corticotropin-releasing factor (CRF) and preproenkephalin in parvocellular neurons of the rat hypothalamus. Stress increased both CRF and preproenkephalin mRNAs, whereas adrenalectomy increased only CRF mRNA. After adrenalectomy, even when CRF mRNA had reached peak levels, stress still further increased CRF mRNA and caused an exaggerated rise in preproenkephalin mRNA. Dexamethasone administration in the fast or intermediate-feedback time domains had no effect on CRF or preproenkephalin mRNA responses to stress; however, when administered over a longer period of time in the slow-feedback time domain dexamethasone reduced basal CRF mRNA levels and the stress-stimulated levels of CRF and preproenkephalin mRNA. These results show that different stimuli to the parvocellular paraventricular hypothalamus differentially regulate CRF transcript levels. Furthermore, in spite of the lack of any detectable effect of changes in circulating glucocorticoid levels on basal levels of preproenkephalin mRNA, glucocorticoids markedly alter the preproenkephalin mRNA response to stress.
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Affiliation(s)
- S L Lightman
- Laboratory of Cell Biology, National Institute of Mental Health, Bethesda, MD 20892
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