P2.170 Thursday, Jan. 5 Influence of reproductive state on plasma corticosterone levels in free-living female fence lizards (Sceloporus undulatus). KLUKOWSKI, M; Middle Tennessee State University email@example.com
Numerous factors have been shown to alter stress responsiveness in vertebrates including age, sex, season, body condition, and social status. The potential role of reproductive state has received less attention, particularly in reptiles. Since maternal steroids may be transferred to the yolk, elucidation of the influence of reproductive state on plasma corticosterone levels has important implications for offspring development and phenotype. Here I tested whether females of differing reproductive state (early-, late-vitellogenic, or gravid) differed in baseline or stress-induced levels of plasma corticosterone. Adult female fence lizards were captured in the field and bled as quickly as possible to obtain baseline blood samples. Females were subsequently confined for one hour in a cloth bag, bled again, and then brought into the laboratory where laparotomies were performed to determine each female’s reproductive condition. Females were released the following day. Plasma triglyceride and lactate levels were measured in addition to corticosterone. Gravid females had significantly higher baseline corticosterone levels than the vitellogenic groups and exhibited the weakest stress responses in terms of both corticosterone and lactate. All three groups differed in plasma triglyceride levels with the highest levels observed in late-vitellogenic females. Altogether these results indicate a substantial influence of reproductive condition on plasma corticosterone levels in female fence lizards. In particular, whether the relatively high baseline corticosterone levels observed in gravid females is indicative of chronic stress or plays some role in reproduction deserves further study.