Changes of norepinephrine levels, tyrosine hydroxylase and dopamine-beta-hydroxylase activities after castration and testosterone treatment in vas deferens of adult rats

Norepinephrine levels and tyrosine hydroxylase and dopamine-beta-hydroxylase activities have been used to evaluate the effect of castration and testosterone treatment on the sympathetic innervation of the adult vas deferens. Castration was followed by a decrease in both norepinephrine content and tyrosine hydroxylase activity, even though the changes were not concomitant. Treatment of castrated animals with testosterone reversed the effect of castration on organ weight and norepinephrine content, but only a short-lasting increase in tyrosine hydroxylase activity occurred at the beginning of testosterone treatment. In contrast, the testosterone-induced recovery of norepinephrine content observed at this time was accompanied by a marked increase in dopamine-beta-hydroxylase activity. The results suggest that in rat vas deferens, norepinephrine levels are under androgenic control and that this regulation mainly involves changes in dopamine-beta-hydroxylase activity rather than a modulation of tyrosine hydroxylase.