Sino-aortic baroreceptors are not involved in the potentiation of vasopressin or oxytocin secretion observed after noxious stimuli in the rat.

The possibility that arterial baroreceptors may be involved in the potentiation of vasopressin or oxytocin secretion observed after noxious stimuli was tested in male rats after sino-aortic denervation (SAD). There was no significant difference in plasma level of vasopressin or oxytocin between the SAD and the corresponding sham-operation control (SHAM) groups with or without electric shocks. An i.p. injected alpha 1-adrenergic receptor antagonist, prazosin, decreased arterial blood pressure both in the SAD and in the SHAM groups. However, the increased levels of these hormones after prazosin were significantly lower in the SAD than in the SHAM groups. Reflexly evoked tachycardia after prazosin occurred in the SHAM but not in the SAD groups. These results suggest that afferent neural signals originating from arterial baroreceptors are not involved in potentiation of vasopressin and oxytocin secretion after noxious stimuli in the rat.