Weight and regulatory deficits in vagotomized rats: A reexamination

Abstract

Subdiaphragmatic vagotomy can produce deficits in body weight and regulatory behaviors in rats, but these occur only under specific conditions. Body weight deficits were found in vagotomized male rats eating a liquid diet or a wet mash diet, but did not appear in vagotomized male rats eating pellets. Vagotomized female rats did not show body weight deficits on any of the three diets. However, vagotomized female rats did show a small body weight deficit if access to pelleted food was delayed by 24 hr after surgery. With delayed postsurgical access to food, vagotomized female rats showed no body weight deficits when compared to pair-fed controls. In no case was there a significant reduction in food intake after vagotomy, in contrast to observations made on rabbits. In tests of fluid regulation, female rats were subjected to overnight food deprivation, hypertonic saline injections, or polyethylene glycol injections. Vagotomized female rats consumed less water over a 2-hr period after saline injections, but they failed to show deficits in a 30-min period after saline injections. Further, they showed no deficit on the other two tests. Deficits in body weight and fluid intake regulation reported after vagotomy in rats may be explained most parsimoniously as consequences of gastrointestinal malaise rather than as consequences of metabolic, hormonal, or central neurologic changes.