MOORE, F.L.*: Ultimate and proximate mechanisms that control the stress-induced inhibition of reproductive behaviors.

When animals confront harsh or threatening conditions, they frequently respond with rapid changes in behavior, for example, switching from courtship behavior to survival behaviors such as hiding or fleeing. Stress hormones regulate this shift in behavioral state. Behavioral studies in an amphibian model, the roughskin newt (Taricha granulosa), demonstrate that acute stress triggers the secretion of corticosterone and that the elevated corticosterone concentration causes a rapid suppression of reproductive behaviors. This behavioral response to corticosterone works through a non-genomic pathway that involves a membrane-associated corticosteroid receptor (mCR) in the G-protein coupled receptor superfamily (Orchinik et al., 1991). The mCR protein has an apparent mass of 63 kDa (Evans et al., 2000a). The mCR binding site is highly selective, recognizing only two steroids (corticosterone and cortisol) and a subset of kappa-selective ligands (Orchinik et al., 1991; Evans et al. 2000b). These binding data are consistent with behavioral and physiological studies showing that corticosterone and specific kappa ligands trigger similar responses. Our working hypothesis is that the mCR is structurally related to a kappa opioid-like receptor. (Supported by NSF grant IBN 9319633)