Inhibition of vasopressin secreting neurons of the paraventricular nucleus by gastric distension in rats

Abstract

The effects of gastric distension on the neural activity of vasopressin (AVP) secreting neurons of the paraventricular nucleus (PVN) were examined in rats anesthetized with urethane alpha - chloralose. Sixteen putative AVP neurons were identified on the basis of phasically firing patterns. About half of the putative AVP neurons (7/16) were inhibited by gastric distension, while distension of the intraperitoneal balloon had no effect. Severing of the left cervical vagus trunk greatly reduced the inhibitory response. In contrast, the gastric distension had no effect on most non-phasically firing neurons (55/66). These data indicate that sensory information originating from the gastric mechanoreceptors selectively inhibits the activity of PVN AVP secreting neurons and suggest that gastric afferent information is important in the rapid inhibition of AVP release after drinking.