ZYSLING, D.A.*; KETTERSON, E.D.; DEMAS, G.E.; Indiana University; Indiana University; Indiana University: Effects of 2-DG induced metabolic stress on immune function in long- and short-day housed Siberian hamsters Phodopus sungorus

Individuals of many species are faced with marked seasonal variation in environmental conditions and must adapt to potentially large fluctuations in energy availability and expenditure. Seasonal changes in immunity have likely evolved as an adaptive mechanism to cope with such stressors. In addition, these changes may be constrained by seasonal fluctuations in energy availability. Mounting an appropriate immune response is energetically costly; increased immunity likely utilizes resources that could be otherwise allocated to other functions. Furthermore, accumulating evidence suggests that short �winter-like� days can attenuate the symptoms of infection, presumably to optimize energy expenditure and survival. The goal of this study was to assess the role of energetic trade-offs associated with seasonal variation in immune response. In addition to body fat stores, metabolic fuels such as glucose may affect immune function in seasonally breeding rodents. In this study we experimentally reduced glucose availability via repeated injections of the metabolic inhibitor 2-deoxy-D-glucose (2-DG) in long-day and short-day housed Siberian hamsters (Phodopus sungorus) and then examined antigen-specific (i.e., KLH) antibody production. We found that 2-DG-induced metabolic stress decreased antibody response in long-day animals compared with saline-injected controls. In contrast, no difference was observed between treatment groups in short-days. These data suggest that, although immune function is compromised during metabolic stress in long-days, short-day lengths may buffer organisms against this effect. This effect may be due to differential responsiveness of long- and short-day hamsters to metabolic stress, mediated by changes in adrenal hormones; these data will be discussed.