The postnatal development of VIP binding sites in rat forebrain and hindbrain

Abstract The specific binding of 125 I-labeled vasoactive intestinal peptide (VIP) to brain membranes from the forebrain and hindbrain regions of 2 to 37-day postnatal rats was measured. In both regions of the brain, VIP binding was low but detectable two days after birth and rose markedly between postnatal days 7 and 17. This increase in VIP binding with age correlates well with observed increases in VIP-stimulated adenylate cyclase activity [19] and increases in VIP content as determined by radioimmunoassay [1, 7, 14, 15, 20]. In hindbrain, the density of VIP binding sites was substantially higher than the forebrain at two days, while at 37 days, they were about equal, suggesting that the hindbrain regions may mature neurochemically prior to the forebrain. Total binding sites for forebrain and hindbrain were about equal at birth for both brain regions, while forebrain had a substantially greater number of sites at 37 days postnatal. The presence of VIP binding sites in both forebrain and hindbrain early in postnatal development suggests that VIP may play a role in development of the brain.