Atropine fails to block the overconsumption of sugar solutions by hypothalamic hyperphagic rats.

Adult female Sprague-Dawley rats given bilateral parasagittal knife cuts in the medial hypothalamus (VMH group) were hyperphagic and became obese on a chow diet, compared with sham-operated controls. VMH Ss also overconsumed, relative to controls, sucrose and glucose solutions during 30-min/day tests. Pretreating VMH and control Ss with atropine methyl nitrate (1.0, 5.0, or 10.0 mg/kg) reduced their intake of the sugar solutions in 3 of 5 experiments, and in all experiments it suppressed their 24-hr chow intake. However, VMH Ss continued to drink more of the sugar solutions than the controls after all atropine treatments, and in 3 of 4 experiments their hyperphagia on the chow diet was not blocked by the atropine. Results do not support the hypothesis that vagally stimulated insulin release or other cholinergically mediated cephalic responses of digestion are essential for the expression of hypothalamic hyperphagia and finickiness. (44 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)