Histamine Inhibits Eating without Altering Postprandial Satiety in Rats

Exogenous histamine decreases food intake and injection of H-1 antagonists increases food intake in rats. Previous work has focused on the effect of relatively large doses of histamine on eating behavior, and have not measured the effect of histamine on postprandial satiety behaviors. This work measures the effect of small and large doses of histamine and investigates the effects of an H-1 receptor antagonist on eating, drinking and postprandial satiety behavior. Twelve adult male Sprague-Dawley rats not food deprived were tested eating Nilla Wafer cookies with or without water following subcutaneous injections of .625 mg/Kg histamine, 10 mg/Kg histamine or 0.9% NaCl vehicle. The second experiment tested the effects of the H-1 antagonist dexbrompheniramine (DXB); 1 mg/Kg administered 10 minutes prior to .625 mg/Kg or 10 mg/Kg histamine on eating, drinking and satiety behavior. The 10 mg/Kg histamine inhibited eating and increase water intake, but failed to alter behavioral satiety measures. The .625 mg/Kg histamine stimulated drinking, but did not affect food intake or satiety. When DXB was given prior to histamine it reduced histamine-induced drinking, but did not affect food intake or satiety measures. These results demonstrate that exogenous histamine can inhibit eating without changing postprandial satiety, challenging the notion that endogenous histamine contributes to satiety for food in rats.