Rapid alterations of hypothalamic and hippocampal bombesin-like peptide levels with feeding status

It has been suggested that bombesin (BN)-like peptides may play a physiological role in the control of food intake. We studied the time course of changes in the levels of central BN-like peptides during a meal. Four groups of animals were used: rats that were food (but not water) deprived for 12-h period (preprandial group) and then given access to food for either 10 min (partially satiated group) or 35 min (postprandial group). The fourth group constituted nondeprived controls (ad libitum fed group). BN-like immunoreactivity (BLI) of the hypothalamus, hippocampus, and medulla was determined using a radioimmunoassay. Our data revealed that at the hypothalamus, the BLI content dropped significantly after food deprivation (preprandially), and returned to the ad libitum fed control levels after the meal (postprandially). At the hippocampus, food deprivation did not affect the BLI levels; however, food ingestion significantly elevated the BLI content within 35 min. The medullary BLI levels failed to alter in relation to the feeding status. The observed rapid alterations suggest that the hypothalamic response to food intake is satiety linked and hence lend support to the contention that BN-like peptides play a physiological role in the central regulation of ingestive behavior. The alterations noted at the hippocampus implicate physiological role of BN-like peptides in other meal-associated processes (such as memory).