Sites of action of brain-gut peptides in cultured neurons of rat brainstem.

Using cultures of dissociated neurons from the lower brainstem of 14- to 15-day-old rat embryos, we studied a site of action of a brain-gut peptide by determining whether neuronal responses to a test peptide are abolished or not after replacement of normal medium with low Ca2+- high Mg2+ medium. VIP, secretin and CCK-4 may act on the postsynaptic membrane, while motilin and neurotensin may act on the presynaptic terminal. Somatostatin and bombesin may work either presynaptically or postsynaptically.