Figure 7.
The cannabinoid CB1 receptor agonist, CP55940, inhibits vesicular release evoked with 2 Hz stimulation. A, Comparison of control group data (Fig. 3D) from slices pretreated with 250 nm agatoxin and five slices (384 boutons) treated first with 1 μm CP55940 and then with CP55940 plus the CB1 antagonist, AM251, at 4 μm. CP55940 slowed the release elicited by 2 Hz stimulation, and this was prevented by AM251. B, CP55940 increased the percentage of nondestaining boutons over control levels. AM251 plus CP55940 treatment prevented the increase in numbers of nondestaining boutons. C, For the boutons that did destain in CP55940, the distribution of τdestain was shifted toward longer values, an effect that was also prevented by AM251. CP55940 had no effect on mean destaining (D), number of nondestaining boutons (E), or τdestain (F) in four conotoxin-treated slices (136 boutons). Control data are from Figure 6G. Stimulation is indicated by the black bar in A and D.