Regulation by Androgen of Levels of the β Subunit of Nerve Growth Factor and Its mRNA in Selected Regions of the Mouse Brain

Abstract

Our previous studies showed that the concentration of the beta subunit of nerve growth factor (beta-NGF) in nervous tissues is higher in male than in female mice. To identify the brain regions that are affected by androgens, the amounts of beta-NGF protein and its mRNAs were measured in male, female, and castrated male CD-1 mice and testicular feminization mice at 3-4 months of age. Among tissues examined, the hypophysis of males contained the highest average concentration of beta-NGF protein. In most regions of the brain, individual levels were more variable in males than in females. However, after the castration, such variations in beta-NGF levels disappeared. Average levels of beta-NGF protein in males were higher in the cerebellum (eightfold higher), olfactory bulb (12-fold higher), hypothalamus (sixfold higher), and hypophysis (72-fold higher) than those in corresponding regions of females. No significant differences were observed in levels of beta-NGF protein in the hippocampus, cerebral cortex, striatum, septum, and brainstem. The castration of male mice caused a reduction in levels of beta-NGF protein in the hypothalamus and hypophysis, but not in the cerebellum and olfactory bulb, to the female levels. The concentrations of beta-NGF protein in testicular feminization mice were similar to those in female CD-1 mice in all regions.(ABSTRACT TRUNCATED AT 250 WORDS)