REPRODUCTIVE FUNCTIONS ILLUSTRATING DIRECT AND INDIRECT EFFECTS OF GENES ON BEHAVIOR

Effects of gene products on reproductive behavior which are relatively direct include those of the estrogen receptor and progesterone recept or. For example, work with estrogen receptor-deficient (ERKO) female m ice has extended previous evidence contributing to the neurochemical a nalysis of lordosis behavior. On the other hand, sex differences in be havior present a classic example of indirect effects of genes on behav ior. Work with ERKO male mice shows the necessity of ER gene expressio n for normal masculinization of the brain. In particular, behavioral a ssay results distinguish apparent motivational performance of ERKO mal es from male mating reflexes: the former is similar to that of wild-ty pe males in important respects, while the latter are deficient in ERKO males. The present paper first reviews a small number of clear geneti c contributions to reproductive behaviors, and then reports one experi ment pertinent to the interpretation of the behavioral status of ERKO male mice. (C) 1996 Academic Press.