Figure 9.

The alpha 1 antagonist prazosin prevented the depressive effects of NE on P-FS synapses. A and B, Representative samples show the effects of prazosin and prazosin + NE on EPSC amplitude and synaptic failure. Prazosin (1 μM) itself slightly decreased the amplitude of EPSC and NE also exhibited slightly depressive effect on the EPSC amplitude when co-applied with prazosin. There was a trend of decreasing EPSC amplitudes in prazosin + NE and in wash but the number of synaptic failures did not show clear change. C, Cumulative probabilities of the first EPSC amplitudes in prazosin, prazosin + NE, and wash exhibited small shifts to the left but not significant compared to baseline (P > 0.05 for all). D, Prazosin and prazosin + NE slightly decreased the first EPSC amplitudes but not significant compared to baseline (n = 7, P > 0.05 for both). E, The CVs of the first EPSC amplitudes of prazosin and prazosin + NE were also slightly increased but not significant compared to baseline EPSC (P = 0.769 and P = 0.085, respectively). F, G, H and I, The first EPSC amplitudes in the P-FS pairs in baseline, prazosin, prazosin + NE, and wash period were binned and fitted with Gaussian function. The synaptic failures in prazosin and prazosin + NE were slightly increased during the drug application but overall not significant (P = 0.570 and P=0.132, respectively, compared with baseline and P = 0.147 between prazosin and prazosin + NE; two-way ANOVA F = 2.239, P = 0.149). Gaussian fit showed that the peak values of EPSC in prazosin and prazosin + NE shifted from 20 pA in baseline to 15 and 10 pA, respectively and returned to 15 pA in wash.