Changes in the Sensitivity of Adrenergic Receptors in the Oviduct During Early Gestation in the Rabbit

There is evidence to indicate that the transport of an egg through the rabbit oviduct is controlled through an interaction of the sympathetic nervous system and ovarian hormones. The effect of norepinephrine (NE) on the contractility of the oviduct during the first 8 days of gestation was studied using the rabbit perfused oviduct. The sensitivity of the α-adrenergic receptors of the oviduct to NE decreased progressively during early gestation. This was reflected in a potency change and a decrease in the maximal response obtained. These data support the concept that an isthmic sphinctering effect mediated by the autonomic nervous system may play a role in the regulation of egg transport through the oviduct. Blood pressure responses to NE did not change during early pregnancy except that the responses to NE were significantly enhanced immediately after mating. This suggests that the sensitivity changes to autonomic agents during early gestation may be selective for reproductive tissues.