Supersensitivity to norepinephrine or dopamine antagonists after knife cuts that produce aphagia and adipsia in rats.

Aphagia and adipsia of equivalent duration were produced by knife cuts along the lateral border of the hypothalamus (PH cuts), or the medial surface of the globus pallidus (MP cuts) in male albino rats. Striatal dopamine (DA) was reduced by 75% in animals with PH cuts but only 50% by MP cuts. Hypothalamic norepinephrine was reduced 25% by PH cuts and was unaffected by MP cuts. Aphagia and adipsia were positively correlated with DA depletions only in rats with PH cuts. Presurgical catecholamine depletions produced by chronic injections of alpha-methyl-p-tyrosine did not alter the duration of aphagia or adipsia resulting from these knife cuts. However, following recovery of ingestive behavior, rats with PH and MP cuts were supersensitive to the anorexic effects of the dopamine-beta-hydroxylase inhibitor, diethyldithiocarbamate. Exaggerated anorexia was also observed after DA blockade by haloperidol or alpha-adrenergic blockade by phenoxybenzamine. The most pronounced effects of catecholamine blockade were observed in rats with PH cuts.