Testosterone effects on development of vasopressin messenger RNA expression in the bed nucleus of the stria terminalis and medial amygdaloid nucleus in male rats.

To study whether testicular secretions in development have a permanent influence on vasopressin (AVP) messenger RNA expression in the bed nucleus of the stria terminalis (BST) and medial amygdaloid nucleus (MA), male rats that were castrated neonatally or in adulthood were compared after both were similarly treated with testosterone. Males castrated neonatally had fewer cells that were labeled for AVP mRNA and a less density of grains per labeled cell in the BST and MA than males castrated in adulthood. These data indicate that testicular secretions in early development have an organizational effect on AVP mRNA expression in the BST and MA, and this effect was accomplished not only by determining the number of cells that produce AVP, but also by influencing the ability of each individual cell to produce AVP.