Associate Professor
Member, CISAB and Program in Neuroscience

Ph.D., Johns Hopkins University, 1998
Postdoctoral Fellow, NSF Center for Behavioral Neuroscience, Georgia State University, 1998-2001

Program Affiliation: Evolution, Ecology and Behavior

Research Groups Affiliation: Behavior

Phone: 812/856-0158
Fax: 812/855-6705
Email Greg

Demas Lab website

The primary focus of our laboratory is the study of neuroendocrine-immune interactions and behavior in an ecologically relevant context.

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 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, 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.

The other broad area of interest within the laboratory is the neuroendocrine mechanisms underlying aggression. Specifically, we are interested in the role of steroid hormones (e.g., testosterone, cortisol) as well as "neurosteroids" (e.g., DHEA) in resident-intruder models of aggression and other social behaviors. We employ both "knockout" animal models, 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. Current projects focus on:

1. The role of the pineal hormone melatonin in mediating seasonal aggression in male and females rodents.
2. The role of gonadal and adrenal steroids mediating social behaviors
3. Neurosteroid modulation of aggression

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, hymolytic complement, bacterial kliing, enzyme immunoassays (EIAs) 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 to assess anxiety, general activity, aggression and reproductive behavior.

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.

Demas, G.E., Albers, H.E., Cooper, M. and Soma, K.K. (2007). 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.

Zysling, D.A. and Demas, G.E. (2006). Metabolic stress differentially affects humoral immunity in long- and short-day housed Siberian hamsters (Phodopus sungorus), Journal of Comparative Physiology B, In press.

Greives, T. J., Mason, A.O., Scotti, M.-A., Levine, J., Ketterson, E. D. Kriegsfeld, L. J. and Demas, G. E. (2006). Environmental control of kisspeptin: implications for seasonal reproduction. Endocrinology, In revision.

Demas, G.E. and Sakaria, S. (2005). Exogenous leptin attenuates lipectomy-induced decreases in humoral immunity, Proceedings of the Royal Academy of Sciences B, 272:1845-1850.

Wen, J., Hotchkiss, A., Demas, G.E. and Nelson, R.J. (2004). Photoperiod affects neuronal nitric oxide synthase and aggressive behavior in male Siberian hamsters (Phodopus sungorus), Journal of Neuroendocrinology , 16:916-921.

Demas, G.E. (2004). The energetics of immunity: A neuroendocrine link between energy balance and immune function. Hormones and Behavior, 43: 75-80.

Demas, G.E., Polacek, K.M., Durazzo, A. and Jasnow, A.M. (2004). Adrenal hormones mediate melatonin-induced increases in aggression in male Siberian hamsters (Phodopus sungorus), Hormones and Behavior , 46:582-591.

Demas, G.E., Drazen, D.L. and Nelson, R.J. (2003). Reduction in total body decreases humoral immunity, Proceedings of the Royal Society of Sciences B , 270:905-911.

Nelson, R.J., Demas, G.E., Klein, S.L., & Kriegsfeld, L.K. (2002). Seasonal Patterns of Stress, Immune Function and Disease. Cambridge University Press: Cambridge, UK.

Demas, G.E. (2002). Splenic denervation blocks leptin-induced enhancement of humoral immunity in Siberian hamsters (Phodopus sungorus) , Neuroendocrinology, 76:178-184.