Bombesin-stimulated acetylcholine release from myenteric plexus neurons

The ability of bombesin to stimulate acetylcholine release from guinea pig myenteric plexus neurons was studied using a primary neuronal culture system. Bombesin caused dose-dependent increases in [3H]-acetylcholine (ACh) release from guinea pig myenteric plexus neurons. ACh release in response to 0.5 mM bombesin (160 +/- 12% of control) was blocked by exposure to a calcium-free medium (116 +/- 13%) by nifedipine (101 +/- 11%) and by omega conotoxin (107 +/- 10%). Bombesin-stimulated ACh release was inhibited the protein kinase C inhibitor, H7, but was not affected by inhibitors of the cAMP signaling pathway. Interactions with inhibitory neuropeptides was implied by sensitivity of bombesin-stimulated ACh release to neuropeptide Y and galanin. The findings suggest that bombesin activation of protein kinase C in myenteric neurons results in increased acetylcholine release.