The ovary is innervated by autonomic nerves in addition to being under the control of hormones. In this symposium, we will introduce our studies on regulation of ovarian estradiol secretion and ovarian blood flow by sympathetic adrenergic innervation in relation to physical stress.
In rats, sympathetic nerves reach the ovary by two routes: the superior ovarian nerve (SON) in the suspensory ligament and ovarian nerve plexus (ONP) along the ovarian artery. Of the two pathways, stimulation of the SON, but not the ONP, reduces estradiol secretion via activation of alpha2-adrenoceptors, whereas stimulation of the either nerves reduces ovarian blood flow via activation of alpha1-adrenoceptors. Reflex activation of ovarian sympathetic nerves by noxious physical stress (noxious cutaneous stimulation of a hindpaw) causes ovarian vasoconstriction and inhibition of ovarian estradiol secretion. The ovarian vasoconstrictive response is produced via reflex activation of the SON and ONP, whereas inhibition of ovarian estradiol secretion occurs as a result of reflex activation of the SON only. These results suggest that reflex activation of sympathetic nerves to the ovary by stressful physical stimulation, for example, noxious stimulation, may be involved in rapid inhibition of ovarian function in emergencies. Rapid and direct regulation of ovarian function by the autonomic nerves may be an important adaptation of female reproductive function to either internal or external environmental changes.