Molecular strategies for identifying the roles of steroids in behavior

Molecular investigations of sex hormone effects in brain tissue have revealed that the behavioral actions of these steroids are not likely to be limited to simple reproductive behaviors (Ogawa et al, Endocrine Society, 1995). For example, the estrogen receptor “knockout” male mouse shows surprisingly normal libido but is massively deficient in its aggressive behaviors and has female-typical exploratory behaviors. Moreover, hormone-influenced genes affect behavior through routes both indirect and direct, during development and during adulthood. Among human patients, Kallmannʹs Syndrome (Crowley and Jamieson, Endocrine Review, 1992) will be used as an example of indirect influences of a gene on libido, acting through a complex causal chain.