Greg Demas

Greg Demas

Associate Chair for Research, Biology

Professor, Biology


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

Research interests

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: The role of the pineal hormone melatonin as an endocrine mediator of immune-brain interactions; 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; 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: The role of the pineal hormone melatonin in mediating seasonal aggression in male and females rodents. The role of gonadal and adrenal steroids mediating social behaviors 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.


  • Frank A. Beach Award in Behavioral Neuroendocrinology, 2002
  • Fellow, American Association for the Advancement of Science (AAAS), 2013

Representative publications

Behavioural abnormalities in male mice lacking neuronal nitric oxide synthase (1995)
Randy J Nelson, Gregory E Demas, Paul L Huang, Mark C Fishman, Valina L Dawson, Ted M Dawson ...
Nature, 378 (6555), 383

Seasonal changes in immune function (1996)
Randy J Nelson and Gregory E Demas
The Quarterly review of biology, 71 (4), 511-548

Metabolic costs of mounting an antigen-stimulated immune response in adult and aged C57BL/6J mice (1997)
Gregory E Demas, Vladimir Chefer, Mark I Talan and Randy J Nelson
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 273 (5), R1631-R1637

Seasonal patterns of stress, immune function, and disease (2002)
Randy J Nelson, Gregory E Demas, Sabra L Klein and Lance J Kriegsfeld
Cambridge University Press.

Seasonal changes in adiposity: the roles of the photoperiod, melatonin and other hormones, and sympathetic nervous system (2002)
Timothy J Bartness, Gregory E Demas and C Kay Song
Experimental Biology and Medicine, 227 (6), 363-376

The energetics of immunity: a neuroendocrine link between energy balance and immune function (2004)
Gregory E Demas
Hormones and Behavior, 45 (3), 173-180

Beyond phytohaemagglutinin: assessing vertebrate immune function across ecological contexts (2011)
Gregory E Demas, Devin A Zysling, Brianna R Beechler, Michael P Muehlenbein and Susannah S French
Journal of Animal Ecology, 80 (4), 710-730

Environmental control of kisspeptin: implications for seasonal reproduction (2007)
Timothy J Greives, Alex O Mason, Melissa-Ann L Scotti, Jacob Levine, Ellen D Ketterson, Lance J Kriegsfeld ...
Endocrinology, 148 (3), 1158-1166

SCN efferents to peripheral tissues: implications for biological rhythms (2001)
TJ Bartness, CK Song and GE Demas
Journal of biological rhythms, 16 (3), 196-204

Novel mechanisms for neuroendocrine regulation of aggression (2008)
Kiran K Soma, Melissa-Ann L Scotti, Amy EM Newman, Thierry D Charlier and Gregory E Demas
Academic Press. 29 (4), 476-489

Stroke in estrogen receptor--deficient mice (2000)
Kenji Sampei, Shozo Goto, Nabil J Alkayed, Barbara J Crain, Kenneth S Korach, Richard J Traystman ...
Stroke, 31 (3), 738-744

Minireview The influence of season, photoperiod, and pineal melatonin on immune function (1995)
Randy J Nelson, Gregory E Demas, Sabra L Klein and Lance J Kriegsfeld
Journal of pineal research, 19 (4), 149-165

Spatial memory deficits in segmental trisomic Ts65Dn mice (1996)
Gregory E Demas, Randy J Nelson, Bruce K Krueger and Paul J Yarowsky
Behavioural brain research, 82 (1), 85-92

Ecoimmunology (2012)
Gregory Demas and Randy Nelson
Oxford University Press.

Short-day increases in aggression are inversely related to circulating testosterone concentrations in male Siberian hamsters (Phodopus sungorus) (2000)
Aaron M Jasnow, Kim L Huhman, Timothy J Bartness and Gregory E Demas
Hormones and behavior, 38 (2), 102-110