Adrenergic influence on progesterone metabolism and cyclicity in the rat ovary: autotransplantation and chemical sympathectomy.

Elimination of adrenergic nerve endings by chemical sympathectomy with 6-hydroxydopamine of normally cycling rats produced no differences in the weights of body, uterus, ovaries or adrenals, but suppressed significantly proestrus/estrus stages. Unilateral fully denervated (autotransplanted) ovaries showed the following changes in [¹⁴C]progesterone metabolism: the formation of 20α-hydroxy-4-pregnen-3-one increased, whereas 5α-pregnane-3α,20α- and 3ß,20α-diol, 3α- and 3ß-hydroxy-5α-pregnan-20-one, 20α-hydroxy-5α-pregnan-3-one, an unidentified metabolite Y and a group of hydrophobic metabolites decreased dramatically. Enzyme activities could not be restored with epinephrine. Sympathectomy changed the spectrum of [¹⁴C] progesterone metabolites in the same direction, but only at diestrus and metestrus. Autotransplantation suppressed 5α-reductase, 3α- and 3ß-hydroxysteroid dehydrogenase activities (-HSD) measured by the sum of all 5α-, 3α, and 3ß-metabolites, respectively. Sympathectomy suppressed significantly 5α-reductase and 3α-HSD at metestrus. 20α-HSD was not changed in any experiment. These studies provide evidence that 5α-reductase depends on adrenergic input in ovaries of rats at metestrus, a stage of nadir of gonadotropins. During the estrous cycle 5α-reductase may be a regulatory enzyme for progesterone metabolism and also influence estradiol biosynthesis.