Figure 5.
Pharmacological induction of LTD by NMDA is reversed by D1/D5R activation. A, NMDA (20 μm, 2 min; n = 5) induced a response that was typified by a near-complete depression of synaptic transmission followed by a rapid recovery to a transient potentiated state. When applied twice at 45 min intervals, the NMDA treatment led to a stable LTD after the second application. B, Application of SKF 38393 (100 μm, 40 min; n = 6) immediately after the second NMDA application completely prevented the development of LTD from the potentiated state, with synaptic transmission returning only to baseline levels. C, Delayed application of SKF 38393 (100 μm, 40 min; n = 4) 60 min after the second NMDA application did not reverse the LTD. D, Isoproterenol (1 μm, 40 min; n = 3) delivered immediately after the second NMDA application did not prevent the development of LTD or return it to baseline transmission levels. Waveforms are as in Figure 1.