Gregory E. Demas
B.A., Millersville University, 1991
M.S., Villanova University, 1993
M.A., Johns Hopkins University, 1994
Ph.D., Johns Hopkins University, 1998
Postdoctoral Fellow, NSF Center for Behavioral Neuroscience, Georgia State University, 1998-2001
Email address: gdemas(at)indiana.edu
The primary focus of our laboratory is the study of the interactions amoung the neuroendocrine and immune systems and behavior interactions in an ecologically relevant content.
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Seasonal trade-offs Between Reproduction and Immune Function
Many organisms, including mammals, birds and reptiles, demonstrate pronounced fluctuations in immune function across the seasons of the year. These seasonal fluctuations in immunity may have evolved as adaptive functional responses to seasonal changes in disease prevalence. The broad goal of our research is to identity the environmental and social factors contributing to seasonal changes in immunity and to determine the neuroendocrine mechanisms underlying these changes in a variety of rodent species. Current projects within the laboratory focus on: 1) the role of the pineal hormone melatonin as an endocrine mediator of immune-brain interactions; 2) the role of direct sympathetic neural connections between the brain and peripheral immune tissues (e.g., spleen, thymus), as well as neuro-immune factors (e.g., cytokines), in regulating seasonal changes in immune function; 3) The energetic costs of immunity and, specifically, the role of the adipose tissue hormone leptin in the regulation of immune function.
Neuroendocrine Regulation of Seasonal Aggression
The other broad area of interest within the laboratory is the neuroendocrine mechanisms underlying aggression. Specifically, we are interested in the role of gonadal and adrenal steroid hormones (e.g., testosterone) as well as neurally-derived steroids (e.g., dehydroepiandrosterone) in resident-intruder models of aggression. We employ both "knockout", as well as more traditional physiological manipulations, to evaluate behavioral phenotypes in several rodent species. Specific research questions are addressed from both adaptive-functional and physiological perspectives.
Students in the laboratory can expect to learn a variety of neuroendocrine and immune techniques including: cell proliferation assays, determination of antibody concentrations using enzyme-linked immunosorbant assays (ELISAs). tests of delayed-type hypersensitivity, radioimmunoassays (RIAs) to determine specific hormone concentrations, high pressure liquid chromatography (HPLC) to assess neurotransmitter levels, trans-neuronal viral tract tracing, immunocytochemistry (ICC) to localize brain receptor subtypes, as well as stereotaxic and other small animal surgeries. We also employ a variety of behavioral tests including open field and elevated plus-mazes to assess anxiety and general activity, as well as tests for aggression, reproductive behavior and circadian activity.
Our laboratory is in a unique position to apply an integrative approach to the understanding of how the brain communicates with the periphery in coordinating seasonal changes in physiology and behavior. We believe an integrative, multidisciplinary approach will allow for a biologically meaningful, ecologically relevant examination of the interactions among the neuroendocrine and immune systems and behavior.
Nelson, R.J., Demas, G.E., Huang, P.L., Fishman, M.C.. Dawson, V.L., Dawson, T.M., and Snyder, S.H. (1995). Behavioural abnormalities in male mice lacking neuronal nitric oxide synthase. Nature 378: 383-386.
Demas, G.E., Klein. S.L., and Nelson, R.J. (1996). Reproductive and immune responses to photoperiod and melatonin are linked in Peromyscussubspecies. Journal of Comparative Physiology 179: 819-825.
Nelson, R.J. and Demas, G.E. (1996). Seasonal changes in immune function. Quarterly Review of Biology 71: 511-548.
Demas, G.E.. Chefer V., Talan, M., and Nelson, R.J. (1997). Metabolic costs of mounting an antigen-stimulated antibody response in adult and aged C57BL/6J mice. American Journal of Physiology 273: R1631-R1637.
Demas, G.E., Kriegsfeld, L.J., Blackshaw, S., Nelson, R.J., and Snyder, S.H. (1999). Eliminaton of aggressive behavior in male mice lacking endothelial nitric oxide synthase. Journal of Neuroscience 19: RC30 (1-5).
Demas, G.E. (2002). Splenic denervation blocks leptin-induced enhancement of humoral immunity in Siberian hamsters. (phodopus sungorus). Neuroendocrinology 76: 178-184.
Demas, G.E. (2004). The energetics of immunity: A neuroendocrine link between energy balance and immune function.Hormones and Behavior, 46: 75-80.
Demas, G.E., Polacek, K.M., Durazzo, A., and Jasnow, A.M. (2004). Role of adrenal hormones in melatonin-induced increases in aggression in male Siberian hamsters (phodopus sungorus), Hormones and Behavior, 46: 582-591.
Demas, G.E. and Sakaria, S. (2005). Leptin mediates trade-offs between body fat and humoural immunity. Proceedings of the Royal Society B, 272: 1845-1850.
Demas, G.E., Albers, H.E., Cooper, M., and Soma, K. (2005). Novel mechanisms underlying neuroendocrine regulation of aggression: A synthesis of bird, rodent and primate Studies. In: J.D. Blaustein (Ed.) Behavioral Neurochemistry, Neuroendocrinology and Molecular Neurobiology, Kluwer Press, In press.