Abstract
Secretin stimulates the accumulation of cyclic AMP (half maximally stimulating concentration: 10-20 nM) in cultured mouse brain cells mainly consisting of glioblasts. Vasoactive intestinal peptide (VIP) is much less potent in raising the level of cyclic AMP in these cultures. The effect of secretin but not that of VIP is inhibited by secretin-(5-27), a synthetic antagonist of secretin. Stimulation of the adrenergic alpha-receptors and the adenosine A1-receptors present on the cells attenuates the increase in cyclic AMP evoked by secretin and VIP. Somatostatin at low concentrations inhibits the accumulation of cyclic AMP (half-maximally inhibitory concentration: 3 nM), in the absence or presence of secretin, VIP, or isoproterenol. The results suggest that secretin might regulate the concentration of cyclic AMP in brain and provoke the question of a possible involvement of glial cells in the action of peptide hormones in the brain.