The goal of Drs. Hillgarth and Potts research is to better understand how androgens play a role in regulating immunological defenses and reproductive behaviors. High testosterone is associated with high social and mating success in males, and yet this steroid is immunosuppresive. Why does testosterone have this paradoxical effect? One possible explanation is that testosterone plays a role in allocating energy and resources between reproductive and immunological functions. For example, if a male becomes infected, then he must initiate an immune response to survive. However, since immune responses are metabolically expensive, infected males must divert energy from less vital needs, such as maintaining social status and costly mating displays. This reallocation may be accomplished by adjusting testosterone levels, since males exhibit a decrease in testosterone levels during infection. Previous studies by these investigators on mice living in naturalistic enclosures, found that dominant males were successful in all mating attempts with females and they exhibited the highest levels of testosterone; however it is unclear if this was due to increased exposure or reduced immunity. To address these problems, Drs. Hillgarth and Potts propose to conduct experiments in which they manipulate testosterone levels and immune competence to determine (1) whether testosterone increases dominance or vice versa; (2) whether dominant males are immunologically impaired; (3) whether increasing testosterone increases susceptibility to parasites; and (4) whether males adaptively adjust their testosterone levels and social status if they are immunologically challenged. Besides allowing us to determine if testosterone modulates immune and behavioral functions, this work will provide an interdisciplinary link between the traditionally separate fields of behavior, immunology and endocrinology.
