We investigated whether central histamine is responsible for the reduction in food intake by GLP-1. The inhibitory effect of GLP-1 on eating was attenuated by histamine depletion and the blockade of histamine HI-receptors. These results suggests that activation of histamine H1-receptors may contribute to the inhibitory effect of GLP-1 on feeding. Histamine levels were unexpectedly decreased by GLP-1 infusion in the hypothalamus. The local injection of GLP-1 into the hypothalamus might cause feeding-stimulatory processes that reduce histamine release.