Male and female mammals exhibit distinctive masculine or feminine behavior patterns. The developmental cause of many of the sexually dimorphic behaviors has been shown to be the exposure of the male brain to testosterone during the perinatal period. Most of these behavior patterns involve the hypothalamus, and this region of the brain exhibits a sexual dimorphism in terms of histology and synaptic connections. These anatomical features are also dependent on the organizing influence of perinatal testosterone. There are reasons to think that the anatomical and behavioral differences between male and female brains may be caused by or result in different patterns of proteins in the two brains. Since many key regulatory steps in metabolism involve phosphorylated proteins, this class of proteins would most likely show differences. We have recently demonstrated distinct male and female patterns of cytosolic protein phosphorylation patterns in the preoptic-hypothalamus region of the rat. Furthermore, the ontogeny of the male pattern was also shown to require the presence of testosterone during the postnatal period. This study proposes to investigate the molecular differences between male and female brains by identifying the soluble and membrane phosphoproteins and the soluble and membrane protein kinases in the adult rat hypothalamus and cortex from both sexes. The results of this study may identify specific molecules whose adult status is dependent on the postnatal action of testosterone. This study will also serve as a foundation for the identification of specific molecules that are different in male and female brains which may play an important role in the differential effects of drugs, behavior modifications, and disease between males and females.
