Involvement of L-type Ca2+ channels in the induction of long-term potentiation in the basolateral amygdala-dentate gyrus pathway of anesthetized rats.

We have recently found that synaptic pathway from the basolateral amygdala (BLA) to the dentate gyrus (DG) displays N-methyl-D-aspartate (NMDA) receptor-independent form of long-term potentiation (LTP), which should be a valuable model for elucidating neural mechanisms linking emotion and memory. To explore its cellular mechanisms, we investigated the effects of L-type Ca(2+) channel blockers on LTP in this pathway of anesthetized rats. Intraperitoneal administration of verapamil (3-30 mg/kg) or diltiazem (6-20 mg/kg) significantly impaired the induction of LTP following high-frequency stimulation. When verapamil was administered after high-frequency stimulation, it did not affect the pre-established LTP. These results suggest that activation of L-type Ca(2+) channels is necessary for the induction of LTP in the BLA-DG pathway.