Effect of castration on the smooth muscle cells of the internal sex organs of the rat: influence of the smooth muscle on the sympathetic neurons innervating the vas deferens, seminal vesicle and coagulating gland.

Wet weights of vas deferens, seminal vesicle and coagulating gland were reduced by almost 80 to 90% 10 weeks after castration. Endogenous norepinephrine content and dopamine-beta-hydroxylas activity of these tissues were also reduced to the same degree. One week after castration there was approximately a 50% loss in the weight of all three organs. However, this was accompanied by an equal reduction in norepinephrine content and dopamine-beta-hydroxylase activity only in the vas deferens. Two weeks later the degree of reductions in wet weight, norepinephrine content and dopamine-beta-hydroxylase activity was almost identical for all three organs. Treatment of 40-day castrate rats with testosterone (10 mg/kg s.c.) not only restored the wet weights of the internal sex organs to normal but their norepinephrine content and dopamine-beta-hydroxylase activity as well. Castration of immature rats (10-14 days old) resulted in retardation of growth of the vas deferens and seminal vesicle by 90-95%, and similar reductions in norepinephrin content and dopamine-beta-hydroxylase activity, when compared to the tissues of control littermates on the 90th postoperative day. Histological examination of normal and castrate rats indicated that, along with a reduction in epithelial cells, the smooth muscle cells of the vas deferens, seminal vesicle and coagulating gland was markedly reduce in size as well. Administration of testosterone completely reversed these changes. Furthermore, deoxyribonucleic acid content of the seminal vesicle and coagulating gland was reduced by 50% after castration and then restored to control level after testosterone treatment. Taken together, it seems that atrophy of the internal sex organs following castration is a combined effect of reduction in size and number of smooth muscle cells. Therefore, it is concluded that any alteration in the size of smooth muscle cells or loss of such cells of the internal sex organs indirectly influences their sympathetic nerves in such a manner that norepinephrine concentrations, and thereby the density of innervation, are maintained at normal levels.