TRANSSYNAPTIC EXPRESSION OF A PRESYNAPTIC GLUTAMATE-RECEPTOR DURING HIPPOCAMPAL LONG-TERM POTENTIATION

Repetitive activation of excitatory synapses in the hippocampus produc es a persistent enhancement of synaptic efficiency known as long-term potentiation (LTP). In anesthetized and in freely moving rats, the ind uction of LTP in the perforant path led to a transient increase in the amount of messenger RNA (mRNA) coding for a presynaptic glutamate rec eptor (GR33) in dentate granule cells. The amount of GR33 mRNA was inc reased for at least 5 hours after the induction of LTP but was indisti nguishable from control values 1 day after induction. The N-methyl-D-a spartate receptor antagonist 2-aminophosphonovalerate prevented the in duction of both LTP and the increase in GR33 mRNA. The amount of GR33 protein was increased in the mossy fiber terminal zone of dentate gran ule cells 5 hours after the induction of LTP. These results suggest th at the induction of LTP in synapses at one stage in a neural network m ay lead to modification in synaptic function at the next stage in the network.