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BSc (Concordia University)
MSc (McGill University)
PhD (McGill University)
Office: 604-822-3899, Lab: 604-822-9736
Email: viau@interchange.ubc.ca |
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The hypothalamic-pituitary-adrenal (HPA) axis is an important hormonal system in man and rodents, which ultimately controls secretion of glucocorticoids from the adrenal gland: cortisol in humans, and corticosterone in rats. Stress-induced activation of the HPA axis resulting in acute elevations in circulating glucocorticoids levels protect the organism from physiological insult by regulating a variety of physiological processes. For example, they provide adequate substrate for increased metabolic need and help to sustain blood pressure and depress immune function. On the other hand, chronic elevations in glucocorticoids produced by repeated stress exposure have been implicated in the pathogenesis of several forms of systemic, neurodegenerative, and affective disorders.
We have evidence showing that testosterone acts centrally to inhibit stress-induced HPA activity and corticosterone release in the rat. Using a functional neuroanatomical approach assisted by tract-tracing, in-situ histochemical, and early-gene techniques, our goal is to reveal the routes, neurotransmitters, and cellular mechanisms by which testosterone alters circuits in the brain conveying stress-related information. Because gonadal steroid release in both males and females varies as a function of reproductive and social status, this research will lay the groundwork for future studies aimed at understanding the central bases of social- and gender-based differences in stress reactivity. |
Williamson M, Viau V (2008) Selective contributions of the medial preoptic nucleus to testosterone dependant inhibition of the PVN and HPA axis. American Journal of Physiology Regulatory, Integrated and Comparative Physiology 295: R1020-1030. [PubMed]
Bingham B, Viau V (2008) Neonatal gonadectomy and adult testosterone replacement suggest an involvement of limbic arginine vasopressin and androgen receptors in the organization of the HPA axis. Endocrinology 149: 3581-3591. [PubMed]
Williamson M, Viau V (2007) Androgen receptor expressing neurons that project to the paraventricular nucleus of the hypothalamus in the male rat. Journal of Comparative Neurology 503: 717-740. [PubMed]
Bingham B, Williamson M, Viau V (2006) Androgen and estrogen receptor-ß distribution within spinal projecting and neurosecretory neurons in the paraventricular nucleus of the male rat. Journal of Comparative Neurology 499: 911-923. [PubMed]
Williamson M, Bingham B, Viau V (2005) Central organization of androgen-sensitive pathways to the hypothalamic-pituitary-adrenal axis: implications for individual differences in responses to homeostatic threat and predisposition to disease. Progress in Neuro-Psychopharmacology & Biological Psychiatry 29: 1239-1248. [PubMed]
Viau V, Bingham B, Davis J, Lee P, Wong M (2005) Gender and puberty interact on the stress-induced activation of parvocellular neurosecretory neurons and corticotropin-releasing hormone messenger ribonucleic acid expression in the rat. Endocrinology 146: 137-146. [PubMed]
Viau V, Meaney MJ (2004) Alpha1 adrenoreceptors mediate the stimulatory effects of oestrogen on stress-related hypothalamic-pituitary-adrenal activity in the female rat. Journal of Neuroendocrinology 16: 72-78. [PubMed]
Viau V, Meaney MJ (2004) Testosterone-dependent variations in plasma and intrapituitary corticosteroid binding globulin and stress HPA activity in the male rat. Journal of Endocrinology 181: 223-231. [PubMed]
Viau V, Lee P, Sampson J, Wu J (2003) A testicular influence on restraint-induced activation of medial parvocellular neurons in the paraventricular nucleus in the male rat. Endocrinology 144: 3067-3075. [PubMed]
Viau V (2002) Functional cross-talk between the hypothalamic-pituitary-gonadal and -adrenal axes. Journal of Neuroendocrinology 14: 506-513. [PubMed]
Viau V, Sawchenko PE (2002) Hypophysiotropic neurons of the paraventricular nucleus respond in spatially, temporally, and phenotypically differentiated manners to acute vs repeated restraint stress. Journal of Comparative Neurology 445: 293-307. [PubMed]
Viau V, Soriano L, Dallman MF (2001) Androgens alter corticotropin-releasing hormone and arginine vasopressin mRNA within forebrain sites known to regulate activity in the hypothalamic-pituitary-adrenal axis. Journal of Neuroendocrinology 13: 442-452. [PubMed]
Viau V, Chu A, Soriano L, Dallman MF (1999) Independent and overlapping effects of testosterone and corticosterone on basal CRH and AVP mRNA expression in the paraventricular nucleus of the hypothalamus and stress-induced ACTH release. Journal of Neuroscience 19: 6684-6693. [PubMed]
Viau V, Meaney MJ (1996) The inhibitory effect of testosterone on hypothalamic-pituitary-adrenal responses to stress is mediated by the medial preoptic area. Journal of Neuroscience 16: 1866-1876. [PubMed]
Viau V, Sharma S, Meaney MJ (1996) Changes in plasma adrenocorticotropin, corticosterone, corticosteroid-binding globulin, and hippocampal receptor occupancy and translocation in rat pups in response to stress. Journal of Neuroendocrinology 8: 1-8. [PubMed]
Viau V, Sharma S, Plotsky PM, Meaney MJ (1993) The hypothalamic-pituitary-adrenal response to stress in handled and non-handled rats: Differences in stress-induced plasma ACTH secretion are not dependent upon increased corticosterone levels. Journal of Neuroscience 13: 1097-1105. [PubMed]
Viau V, Montagne MN, Sarrieau A, Meaney MJ, Rostene WH (1992) Changes in vasoactive intestinal peptide binding site densities in the female rat central nervous system and pituitary during lactation. Journal of Neuroendocrinology 4: 759-764. [Abstract]
Viau V, Meaney MJ (1991) Variations in the hypothalamic-pituitary adrenal response to stress over the estrous cycle in the rat. Endocrinology 129: 2503-2511. [PubMed] |
| I am very grateful to several, whose guidance and training have helped me develop a unique approach to the study of stress, including Dr. Mary Dallman, Liza Soriano, Alan Chu (University of California San Francisco); Dr. Paul Sawchenko, Carlos Arias, Kris Trulock, Casey Peto (Salk Institute), Dr. Micheal Meaney, Shakti Sharma, David Aitken (Douglas Hospital Research Centre, McGill University). I am also grateful for the generous support of the Department of Anatomy and the Canadian Institutes of Health Research. |
Photomicrographs illustrating some of the techniques used in my laboratory, and the connective and phenotypic features of the paraventricular nucleus of the hypothalamus (PVH), the neuroendocrine interface through which the brain regulates pituitary and adrenal output during stress. The PVH houses at least three major effector neuron classes, including magnocellular neurosecretory neurons that regulate posterior pituitary function, pre-autonomic neurons that give rise to preganglionic projections regulating both the parasympathetic and sympathetic divisions of the autonomic nervous system, and parvocellular neurosecretory neurons that express CRH among other several adrenocorticotropic (ACTH) co-secretagogues. While the PVH is arranged in a complex mosaic manner, different effector neurons can be separated based on cytoarchitectonic (Nissl), histochemical (e.g. CRH expression), and connectional (spinal- vs pituitary-projecting) criteria. Posterior Magnocellular, pm; medial parvocellular dorsal, mpd; medial parvocellular ventral, mpv; dorsal parvocellular, dp. See Swanson and Sawchenko, Ann Rev Neurosci, 1983, and Sawchenko et al., Prog Brain Res, 1996.
Dark-field photomicrographs of CRH and AVP mRNA expression in the PVH showing how gonadal and adrenal steroids interact on HPA function. In this case, removal of glucocorticoid negative feedback by adrenalectomy (ADX) stimulates both CRH and AVP mRNA levels within mpd neurons of the PVH. Note, however, that gonadectomy attenuates the stimulatory effects of ADX on AVP, but not CRH mRNA expression (GDX+ADX). See Viau et al., J Neuroscience, 1999.
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