Effects of total and selective abdominal vagotomies on water intake in rats

Abstract

To determine if the decreased water intake of abdominal vagotomized rats in the presence and absence of food could be localized to a specific branch of the abdominal vagus, we measured the drinking response of rats that had undergone gastric vagotomy, hepatic vagotomy, coeliac vagotomy or a combined coeliac-hepatic vagotomy. The major results were: (1) gastric vagotomized rats drank less than rats that had had sham operations in the previous 24 h with and without food present; (2) hepatic vagotomized rats drank as much as sham operation rats in the presence or absence of food, but drank more than sham operation rats after 17 h water deprivation; (3) coeliac vagotomized rats drank normally in all tests; (4) combined coeliac and hepatic vagotomized rats drank normally except in a 2 h liquid food-related drinking test in which they drank more than sham operation rats; (5) no selective or total, abdominal vagotomized rat drank less than sham operation rats in response to 17 h water deprivation. Thus, gastric vagotomy was the selective vagotomy that most closely mimicked the effects of total abdominal vagotomy on drinking. In demonstrating that increases, decreases, or normal water intake depended on the specific vagal branch(es) disconnected and the specific dipsogenic test, these results refute the opinion that decreased drinking after abdominal vagotomy is simply the result of non-specific effects of vagal surgery. Finally, the normal water intake after water deprivation in total, gastric, and coeliac vagotomized rats in these experiments challenges the current theory that drinking after water deprivation is primarily due to osmotic thirst because previous experiments have shown that total, gastric, and coeliac vagotomized rats drink less than normal to the osmotic challenge produced by acute administration of hypertonic saline.