Photoperiodic Effects on Immune Function

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

The goal of this research is to document the effects of photoperiod (day length) on immune function. Dr. Nelson's previous studies have indicated that high energetic demands can compromise immune function. Field studies also suggest that immune function, assessed indirectly, is compromised when energy requirements are high, especially during the winter. The proposed research examines how animals predict the onset of winter with photoperiodic information, and use this information to bolster immune function prior to the immunosuppressive effects of winter. The proposed studies will directly assess immune function among individuals under various energetic challenges or in different reproductive states. Both cell-mediated and humoral immunity will be examined. In some experiments, the effects of natural energetic stressors on immune function will be examined, whereas in other experiments, pharmacological manipulation of metabolic fuel availability will test the role of these metabolic fuels on immune function. The significance of this work lies in its potential contribution to understanding how natural stressors influence immune function, and to determining the effects of certain hormones, leptin and melatonin, in mediating these effects. Many people experience compromised immune function when exposed to stressors. By studying how rodents naturally cope with seasonally-recurring stressors, physiological coping mechanisms might be discovered that could help in the development of treatments aimed at preventing immunosuppression during stress among people. The development of such therapies (e.g., melatonin treatment regimens or gene therapy) would benefit people who function under energetically-demanding conditions (such as military, firefighters, or medical doctors) who are at risk for many stress-related illnesses. From an evolutionary perspective, these studies also provide a mechanistic link between life history strategies and reproductive and survival costs.