Fig. 2.
The effect of WIN2 is concentration dependent and solely involves CB1. A: fEPSP recordings obtained after a 35-min exposure to various concentrations of WIN2. Top: A WIN2 concentration of 0.01 μM did not alter excitatory transmission, but a clear effect was observed with 0.1 μM. Middle: The maximal effect was obtained with 1 μM WIN2, insofar as increasing the dose to 4 μM did not further alter fEPSPs. Bottom: The CB1 antagonist AM251 completely prevented the effect of the highest concentration of WIN2, confirming the sole involvement of CB1. B: Dose-response curve (logistic fit) of the WIN2 effect. WIN2 decreased fEPSPs by a maximum of 62%, with an apparent EC50 of 0.2 μM (dashed line). WIN2 did not affect fEPSPs in the presence of SR1 (open circle) or AM251 (open triangles).