Meeting Abstract
P3.33 Saturday, Jan. 5 Effects of food restriction on immune function in long- and short-day housed Siberian hamsters (Phodopus sungorus) ZYSLING, D.A.*; DEMAS, G.E.; Department of Biology, Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA; Department of Biology, Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA dzysling@indiana.edu
Many non-tropical organisms must contend with extreme seasonal fluctuations in their respective environments and thus physiological and behavioral adaptations have evolved in order to maintain a positive energy balance year-round. These adaptations include seasonal changes in reproduction and immunity. Photoperiod is the primary signal animals use to predict environmental changes. Exposure to short day lengths inhibits reproductive activity and triggers gonadal regression, decreases body mass and food intake, and suppresses various aspects of immunity. Despite accumulating evidence for seasonal changes in immune function, little is known regarding how seasonal changes in energy availability or reproduction may mediate seasonal changes in immunity. The goal of this study was to determine the effects of food restriction on photoperiodic changes in immune function. Specifically, long- and short-day housed Siberian hamsters received either a 30% food restriction or were fed ad lib for 2 weeks. Restriction values were calculated based on baseline levels of food intake for each animal, as determined by a 10-day assessment of ad lib intake. Immune responses were quantified by measuring anti-keyhole limpet hemocyanin (KLH) antibodies and bacterial killing ability. Body mass was measured over the course of the experiment and at the conclusion of the study necropsies were performed and final gonadal and fat pad masses were recorded. Data will be discussed in the context of energetic trade-offs between competing physiological functions. Additionally, the role of these trade-offs in mediating seasonal responses will be reviewed.
