Growing up on the Richelieu River in Quebec I developed a keen interest for aquatic life from a young age. I pursued this interest through an undergraduate degree in marine biology at McGill and then as a graduate student at UBC and at the University of Ottawa. While my graduate work focused on understanding the physiological and endocrine mechanisms that help fish cope with hypoxia and hypotension, my post-doctoral research at the University of Alberta dealt with the neuroendocrine pathways that regulate both appetite and the stress response. Now as a faculty member in the Department of Integrative Biology, I am studying the neuroendocrine pathways in fish by which stressors are perceived, processed, and transduced to further our understanding of how environmental stressors affect food intake, growth, and embryonic development.
- B.Sc. - McGill 1986
- M.Sc. - British Columbia 1994
- Ph.D. - Ottawa 1998
Research in my laboratory is focused on identifying and understanding the pathways by which environmental, social and physical stressors are perceived, processed, and transduced into a neuroendocrine response. Several projects are aimed at elucidating the basic neural circuits that mediate stress in fish and focused specifically on the physiological functions of the corticotropin-releasing factor (CRF) system. Another major focus is to investigate the interactions between the stress response and the regulation of appetite and growth in fish. Overall, we use a variety of molecular, endocrine and physiological tools to study the pathways that mediate these interactions. The long-term goal of our research is to provide the basis for the original development of a model on the neuroendocrine pathways that mediate the physiological effects of stress.
Stress and the Neuroendocrine Regulation of Appetite
The regulation of food intake in vertebrates is achieved via a complex brain neuronal circuitry that integrates several stimulatory and inhibitory signals of central and peripheral origin. Members of the corticotropin-releasing factor (CRF) family of neuropeptides, on the other hand, are generally recognized as critical brain mediators of the stress response. Although our studies show that CRF and the related peptide urotensin I (UI) have potent appetite-suppressing effects in fish, we do not know the nature of the interactions between the neuronal pathways involved in mediating the stress response and those involved in the control of appetite. Therefore, a major thrust of our research is to determine to what extent the CRF- and UI-synthesizing neurons of the brain mediate the appetite-suppressing effects of known environmental stressors such as hypoxia, ammonia toxicity, and the transition from fresh to saltwater. Using a combination of molecular, pharmacological, and microscopy techniques, we are also investigating the neuroanatomical targets of the CRF- and UI-synthesizing neurons within the hypothalamic feeding center.
The Caudal Neurosecretory System as a Mediator of the Stress Response
In fish, in addition to the potential role of brain CRF-related peptides in mediating the appetite-suppressing effects of stress, peripheral CRF and UI may also be involved in the regulation of food intake and growth. The caudal neurosecretory system (CNSS), a unique neuroendocrine structure found in the tail of fish, has high levels of CRF and UI gene expression. Therefore, we are currently undertaking a series of experiments to determine whether peripheral CRF and UI are mediators of the stress response and to assess the potential roles of circulating CRF-related peptides in gastrointestinal physiology.
- Bernier, N.J. and P.M. Craig 2005. CRF-related peptides contribute to the stress response and the regulation of appetite in hypoxic rainbow trout. Am. J. Physiol. Regul. Integr. Comp. Physiol. 289: R982-R990.
- Craig, P.M., H. Al-Timimi, and N.J. Bernier 2005. Differential increase in forebrain and caudal neurosecretory system CRF and urotensin I gene expression associated with seawater transfer in rainbow trout. Endocrinology. 146: 3851-3860.
- Essex-Fraser, P.A., S.L. Steele , N.J. Bernier, B.W. Murray, E.D. Stevens, P.A. Wright 2005. Expression of four glutamine synthetase genes in early stages of development of rainbow trout (Oncorhynchus mykiss) in relationship to nitrogen excretion. J. Biol. Chem. 280: 20268-20273.
- Volkoff, H., L.F. Canosa, S. Unniappan, J.M. Cerda-Reverter, N.J. Bernier, S.P. Kelly and R.E. Peter 2005. Neuropeptides and the control of food intake in fish. Gen. Comp. Endocrinol., 142: 3-19.
- Ortega, V.A., K.J. Renner and N.J. Bernier 2005. Appetite-suppressing effects of ammonia exposure in rainbow trout associated with regional and temporal activation of brain monoaminergic and CRF systems. J. Exp. Biol., 208: 1855-1866.
- Bernier, N.J., N. Bedard and R.E. Peter. 2004. Effects of cortisol on food intake, growth, and forebrain neuropeptide Y and corticotropin-releasing factor gene expression in goldfish. Gen. Comp. Endocrinol., 135: 230-240.
- Chin, A., F.C. Guo, N.J. Bernier and P.T.K. Woo. 2004. Effect of Cryptobia salmositica-induced anorexia on feeding behavior and immune response in juvenile rainbow trout Oncorhynchus mykiss. Dis. Aquat. Org. 58: 17-26.
- Bernier, N.J. and R.E. Peter. 2001. Appetite-suppressing effects of urotensin I and corticotropin-releasing hormone in goldfish (Carassius auratus). Neuroendocrinology 73: 248-260.
- Bernier, N.J. and R.E. Peter. 2001. The hypothalamic-pituitary-interrenal axis and the control of food intake in teleost fish. Comparative Biochemistry and Physiology 129B: 639-644.
- Lin, X., H. Volkoff, Y. Narnaware, N.J. Bernier, P. Peyon and R.E. Peter. 2000. Brain regulation of feeding behavior and food intake in fish. Comparative Biochemistry and Physiology 126A: 415-434.
- ZOO*2100 Development Biology
- ZOO*3200 Comparative Animal Physiology I
- ZOO*3210 Comparative Animal Physiology II
- ZOO*4170 Experimental Comparative Animal Physiology
- ZOO*6010 Advances in Physiology
- ZOO*6550 Aquaculture
- Mark Bernards (MSc)
- Kelly Levesque (MSc) *Co-advised by Pat Wright
- Trevor Partch (MSc) *Co-advised by Glen Van Der Kraak
- Tegan Williams (PhD)