Fig. 9.
cGMP production inhibits the induction of LTP during long trains of TPS. (A) The guanylyl cyclase inhibitor ODQ enables the induction of LTP by a long train of TPS (900 pulses). While TPS had little lasting effect on synaptic strength in vehicle control experiments (open symbols, n=10), it induced significant LTP in slices pretreated in ACSF containing 10 μM ODQ for 20 min prior to TPS (filled symbols, n=10). (B) Summary of the effects of ODQ on TPS-induced LTP. Blocking guanylyl cyclase had no effect on the induction of LTP by brief trains of TPS (150 pulses, fEPSPs were potentiated to 155±14% of baseline in control experiments and were potentiated to 159±9% of baseline in slices bathed in ACSF containing 10 μM ODQ, n=5 for both) but significantly enhanced the induction of LTP by a long train of TPS (900 pulses, * P<0.01 compared with control).