Meeting Abstract
Environmental factors and subsequent hormonal changes can regulate the development of various physiological systems. Steroid hormones are known to affect significantly the reproductive system in seasonal breeders, but effects on the GI tract have not been as extensively studied. The present studies examined whether corticosterone or estradiol affect GI development and reproduction in juvenile male and female rice rats. Rice rats were subjected to subcutaneous Silastic implants of corticosterone or estradiol from 21-56 days of age. The following masses were examined: body, testes, seminal vesicles, Harderian glands (males only), spleen (males only), female reproductive tract, and wet (W) and dry (D) masses of the stomach (St), small intestine (SI), cecum (Ce), and colon (Co). In addition, small intestine and colon lengths were measured. Corticosterone had no effect on body mass or any reproductive or GI variable examined in males or females. Estradiol, on the other hand, increased female reproductive tract mass, WSt, WSI, DSt, and DSI masses relative to animals with empty implants, but decreased SI and Co lengths. These data show that estradiol most dramatically affects reproduction and GI development in females, but that corticosterone was without effect on any reproductive or GI endpoints in either sex. It was hypothesized that changes in the GI tract may be a necessary mechanism for coping with likely seasonal changes in metabolic requirements brought about by changes in steroid hormone levels. We are currently examining the effects of reducing steroids via ovariectomy on these same variables in females.
