SMITH, M.C.*; SHAH, P.J.; MORENO, V.N.; TALLIS, M.D.; GALATI, L.D.; PROPPER, C.R.; Northern Arizona University, Flagstaff: Effects of a Common Pesticide on Behavior and Adrenal Hormone Secretion in an Amphibian

Pesticides and other human-made compounds in our environment are known to have profound effects on the reproductive system. Yet, little is known about the potential for endocrine disruption of other hormonal systems such as those that regulate the stress response. In this study, we examined the effects of the common pesticide, endosulfan, on general behavioral activity, feeding behavior, and corticosterone (B) levels in the anuran amphibian, Rana catesbeiana. Animals were kept for 8 days in 1 l of dechlorinated tap water containing 0, 1, 5, or 10 ppb endosulfan dissolved in 10 ul of acetone. On day 4, the water was changed and the animals were redosed. On day 5, they were tested for general activity and presentation of release calls. On day 6 their feeding behavior was evaluated. On day 8, the animals were weighed and killed, and plasma (for B and adrenocorticotropin concentration determination), interrenals (for steroidogenic factor 1; SF-1 protein concentration determination), and pituitaries (also for SF-1 determination) were collected. There were no differences among groups in the animals’ overall condition (SVL/wt), general activity or release call presentation. In a five minute feeding test, all animals ate the same number of crickets; however the 5 ppb treatment group had an overall lower capture success rate (crickets caught/capture attempt; P=0.02). Although not significant (P=0.058), this group also tended to have lower plasma B levels. These results suggest that exposure to environmentally relevant doses of a common pesticide may impact both behavior and hypothalamic-pituitary-adrenal axis function. Supported by Proposition 301 Funding to CRP and NSF REU Grant #DBI-9988009 to NAU.