Permanent semi-microelectrodes were implanted in the ventromedial hypothalamus (VMH), lateral hypothalamus (LH), amygdala (AMYG), medial forebrain bundle (MFB), anterior hypothalamus (AH), inferior colliculus (IC), and caudate nucleus (CN). Average evoked responses were recorded simultaneously from the above sites in freely behaving rats before and after administration of pentagastrin (100 μg/kg), secretin 1 μg/kg or cholecystokinin octapeptide (CCK-OP) (1 μg/kg) in search of satiety signal. Gastrin and secretin had little effect while it appears that CCK may perform a regulatory function in a neurohumoral feedback mechani