Induction of LTD in the adult hippocampus by the synaptic activation of AMPA/kainate and metabotropic glutamate receptors

It has been suggested that the induction of long-term depression (LTD) may be developmentally regulated since LTD can be readily induced by LFS in sli ces from young but not adult animals. However, we have recently reported th at paired pulse low frequency stimulation (PP-LFS) can reliably induce LTD in the CA1 region of adult hippocampal slices. We now describe the role of glutamate receptors in the induction of LTD in adult hippocampus. The induc tion of LTD was prevented by the combined application of AMPA/kainate and m etabotropic glutamate (mGlu) receptor antagonists (CNQX and LY341495). Howe ver, LTD was not blocked by the co-application of NMDA and mGlu receptor an tagonists nor by the co-application of NMDA and AMPA/kainate receptor antag onists. Taken together, the above results suggest that activation of either AMPA/kainate or mGlu receptors is sufficient to induce LTD. Therefore, the se results suggest that PP-LFS can efficiently activate AMPA/kainate and mG lu receptors in order to induce long-lasting synaptic depression in the CAI region of the adult hippocampus in vitro. (C) 1999 Elsevier Science Ltd. A ll rights reserved.