VPAC₂ Receptor Activation Mediates VIP Enhancement of Population Spikes in the CA1 Area of the Hippocampus

Abstract

The receptors mediating vasoactive intestinal polypeptide (VIP) enhancement of synaptic transmission to pyramidal cell bodies were investigated. RO 25-1553 (VPAC2agonist) mimicked the excitatory effect of VIP on population spike (PS) amplitude. [K15, R16, L27] VIP (1-7)/GRF (8-27) (VPAC1 agonist) caused only a small increase in PS amplitude. The effect of VPAC2 agonist (but not of the VPAC1 agonist) persisted upon blockade of GABAergic transmission and was strongly attenuated upon inhibition of PKA. In conclusion, VPAC2 receptor activation mediates VIP enhancement of PS amplitude in the hippocampus essentially through a PKA-dependent mechanism.