Ovarian nerve extracts influence androgen production by cultured ovarian thecal cells

There is growing evidence that ovarian steroidogenesis is controlled not only by pituitary gonadotropins but also by ovarian nerves. Nerves reach the ovary via the plexus nerve and via the superior ovarian nerve (SON), which runs in the suspensory ligament, and innervate theca cells of all sizes of follicles. To investigate the role of ovarian nerves in steroidogenesis we have examined the effects of adding an extract of SON from adult rats on androgen production by cultured porcine theca cells. Addition of SON extract to cultured theca interna from 3 to 6 mm diameter follicles of prepubertal gilts significantly inhibited (p less than 0.05) LH-stimulated androstenedione production in a dose-dependent manner; significant inhibition (10.8%) occurred with the addition of the extract of 2 mg of SON/ml culture medium, and near maximal inhibition (83%) resulted when the SON extract was increased to 60 mg SON/ml. Extracts of sciatic nerves, used as non-ovarian nerve controls, failed to inhibit, and in fact significantly increased (p less than 0.05) androstenedione production over the same concentration range of neural tissue extract. The inhibitory effect of the SON extract was unaffected by chymotrypsin digestion or by the presence of the beta-adrenergic antagonist propranolol (10(-6) M), but was removed by charcoal treatment. These results suggest that the nervous system has the potential for modulation of follicular steroid biosynthesis via direct innervation of the ovaries, in addition to the well-established indirect mechanism of neural control exerted via the hypothalamic-pituitary system.