DANTROLENE INHIBITS LONG-TERM DEPRESSION AND DEPOTENTIATION OF SYNAPTIC TRANSMISSION IN THE RAT DENTATE GYRUS

The involvement of Ca release from intracellular stores in the inducti on of long-term depression and depotentiation of excitatory synaptic t ransmission was investigated in the rat dentate gyrus using dantrolene , an agent known to block Ca release via the ryanodine receptor. In co ntrol slices, low-frequency stimulation (1 Hz for 15 min) induced robu st long-term depression of baseline field excitatory postsynaptic pote ntials and depotentiation of previously established long-term potentia tion. Dantrolene (50 mu M) was found to block completely both long-ter m depression of baseline responses and depotentiation. Moreover, long- term potentiation induced by high-frequency stimulation was enhanced i n the presence of dantrolene.