Research interests: neuroendocrinology, neuroethology, sensory biology, comparative physiology.
Neuroendocrine Mechanisms of Seasonal Aggression in Siberian Hamsters (Phodopus sungorus)
Although most seasonally-breeding animals show elevated territorial aggression exclusively during the breeding season, some species display equivalent or increased levels of aggression outside of the breeding season, despite gonadal regression and reduced levels of circulating androgens and estrogens. Siberian hamsters (Phodopus sungorus) are an excellent model for examining how seasonal variations in photoperiod can alter the neuroendocrine mechanisms associated with territorial aggression, since these animals exhibit robust changes in morphology, physiology, and behavior on a seasonal basis. Recent work from our group has shown that non-breeding female hamsters increase aggression, serum dehydroepiandrosterone (DHEA) levels, and estrogen receptor-alpha abundance in brain nuclei associated with aggression, but not in nuclei associated with reproduction. Furthermore, exogenous administration of melatonin (MEL), an indolamine that regulates circadian and biological rhythms, elevates aggression in male and female hamsters. While these findings suggest that MEL modulates seasonal aggression, the precise mechanisms by which MEL facilitates seasonal shifts in steroid secretion to ultimately influence aggression have yet to be elucidated.
For my dissertation research, I am exploring the neuroendocrine mechanisms of territorial aggression in Siberian hamsters, with a particular emphasis on how seasonal fluctuations in melatonin secretion mediate changes in neural and adrenal androgen synthesis. Currently, I am comparing neurosteroid levels in brain regions specifically associated with aggression and reproduction in breeding and non-breeding male hamsters using liquid chromatography-mass spectrometry.