Blockade of the histamine H1-receptor in the rat ventromedial hypothalamus and feeding elicitation.

All H1-, but no H2-antagonists infused into the rat third cerebroventricle, induced feeding during the early light, but not during the early dark, reflecting a concentration of hypothalamic histamine. Bilateral microinfusion identified the ventromedial hypothalamus (VMH), but not the lateral hypothalamus or the paraventricular nucleus, as a main locus for the induction of feeding by an H1-antagonist. The effect was completely abolished when brain histamine was decreased by pretreatment with alpha-fluoromethylhistidine. Hypothalamic neuronal histamine suppresses food intake, at least in part, through H1-receptors in the VMH.