A critical role of a facilitatory presynaptic kainate receptor in mossy fiber LTP

The mechanisms involved in mossy fiber LTP in the hippocampus are not well established. In the present study, we show that the kainate receptor antago nist LY382884 (10 muM) is selective for presynaptic kainate receptors in th e CA3 region of the hippocampus. At a concentration at which it blocks moss y fiber LTP, LY382884 selectively blocks the synaptic activation of a presy naptic kainate receptor that facilitates AMPA receptor-mediated synaptic tr ansmission. Following the induction of mossy fiber LTP, there is a complete loss of the presynaptic kainate receptor-mediated facilitation of synaptic transmission. These results identify a central role for the presynaptic ka inate receptor in the induction of mossy fiber LTP. In addition, these resu lts suggest that the pathway by which kainate receptors facilitate glutamat e release is utilized for the expression of mossy fiber LTP.