Neurochemical effects of buspirone in rat hippocampus: Evidence for selective activation of 5HT neurons

The effect of buspirone on neurotransmitter systems in rat hippocampus has been evaluated in vitro and in vivo. In vitro buspirone does not affect the specific binding of ³H-flunitrazepam, ³-GABA, ³H-dexetimide, but displaces ³H-5HT binding with nanomolar affinity. Oral administration of buspirone does not modify the hippocampal concentrations of GABA, acetylcholine, choline and of ³H-flunitrazepam specifically bound in vivo, but results in a dose-dependent reduction of 5HIAA and noradrenaline concentrations. While the effect on noradrenaline is also obtained in striatum of buspirone-treated animals, the effect on 5HIAA shows a regional specificity. The in vitro and in vivo data suggest that buspirone specifically activates 5HT neurons in hippocampus, and are compared with those obtained with diazepam.