Evidence for vagal involvement in the eating elicited by adrenergic stimulation of the paraventricular nucleus.
We examined the role of the vagus nerves in mediating the eating and preprandial drinking seen after injection of norepinephrine (NE) into the region of the paraventricular hypothalamic nucleus of satiated rats. Complete subdiaphragmatic vagotomy (confirmed by gastric secretion tests) abolished the NE-elicited eating response, whether the diet used was lab chow, milk, or a milk-chow misture, and attenuated, by 38%, the NE-elicited drinking response. These effects occurred independently of changes in body weight or daily food intake imposed by vagal surgery. The vagotomized rats retained the capacity to rapidly increase eating in response to food deprivation or insulin injection challenges, indicating that the effect of vagotomy on NE-induced eating was not due to some non-specific impairment. Efferent vagal blockade of intact rats with systemic injections of atropine methyl nitrate (0.4 mg/kg) prior to central NE infusions yielded similar results. Finally-selective section of the coeliac branch of the vagus produced a 49% reduction of NE, elicited eating, as compared with a 29% reduction in water intake, while selective section of the gastric plus hepatic vagal branches, leaving only the coeliac branch intact, did not significantly affect either ingestive response. Both of these selectively vagotomized groups displayed an unimpaired capacity to increase food intake in response to systemic insulin injections. These results suggest participation of efferent vagal mechanisms in the adrenergic feeding, and, to a lesser extent, drinking phenomena and are consistent with a particular role for some function under coeliac vagal control (perhaps insulin secretion) in modulating the effects of NE on feeding behavior.
D000818:Animals; D004326:Drinking / Q000187:drug effects; D004435:Eating / Q000187:drug effects*; D007031:Hypothalamus / Q000502:physiology*; D007328:Insulin / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D013238:Stereotaxic Techniques; D014630:Vagus Nerve / Q000502:physiology*
D007328:Insulin; D009638:Norepinephrine