Stimulation of basolateral amygdaloid serotonin 5-HT2C receptors promotes the induction of long-term potentiation in the dentate gyrus of anesthetized rats

We have previously found that the induction of hippocampal long-term potentiation (LTP) is modulated by neuron activities in the basolateral amygdala (BLA). However, little is known about what neurotransmitter system in the BLA contributes to modulation of hippocampal LTP. In the present study, we investigated possible involvement of BLA serotonergic system in the induction of LTP at the perforant path (PP)-dentate gyrus (DG) granule cell synapses of anesthetized rats. The induction of PP-DG LTP was significantly inhibited by intra-BLA injection of the 5-HT2 receptor antagonist cinanserin (25-50 nmol), but not by intra-BLA injection of the 5-HT1,7 receptor antagonist methiothepin (50 nmol), the 5-HT3 receptor antagonist ondansetron (50 nmol) or the 5-HT4 receptor antagonist RS23597-190 (100 nmol). In addition, intra-BLA injection of the 5-HT2C receptor agonist MK212 (50 nmol) facilitated the induction of PP-DG LTP. These results suggest that the induction of PP-DG LTP is promoted by activation of 5-HT2C receptors in the BLA.