Modulation by vasoactive intestinal peptide of serotonin receptors in the dorsal hippocampus of the rat brain: an autoradiographic study.

Brain sections of 32 microns from the hippocampus were incubated with tritiated serotonin (5-HT) in the presence or absence of 10(-7) M vasoactive intestinal peptide (VIP). Sections were run for biochemical Scatchard analysis or quantitative autoradiography by means of LKB 3H-Ultrofilm. On sections from dorsal hippocampus, VIP increases the amount of 5-HT1 receptors and decreases the affinity for the ligand. Densities measurements show that this effect is located in a discrete area of the hippocampus, the dorsal subiculum. The present data suggest that some of the neurotransmitter effects of 5-HT in the central nervous system can be modulated by VIP.