Figure 4

Attenuation of active lever pressing by SB206 was not reversed by the 5-HT _2C antagonist SB242. Shown are active lever presses in 15 min intervals for the first 30 min of cue reactivity (CR) testing from rats that completed interaction studies with 3.0 mg/kg SB 242084 (SB242) vs. 10.0 mg/kg SB 206553 (SB206; n = 11) or 5.0 mg/kg SB206 (n = 9; one statistical outlier removed). Rats were tested after a pretreatment of vehicle or 3.0 mg/kg SB242, and vehicle, 5.0, or 10.0 mg/kg SB206. The x-axis legend refers to time elapsed after treatment and immediately placing the subject into the operant chamber; data represent total active lever presses between 30-45 min and 45-60 min after treatment. (A) 5-HT_2C antagonism with 3.0 mg/kg SB242 had no effect on CR when administered alone and did not block the effects of 10.0 mg/kg SB206. SB206 significantly decreased active lever presses in the first 15 min of testing (***p < 0.001; Newman-Keuls comparing veh/veh vs. 10.0 mg/kg SB206) and significance was retained even following pretreatment with SB242 (***p < 0.001; comparing veh/veh vs. SB242/SB206). (B) 5-HT_2C antagonism with 3.0 mg/kg SB242 had no effect on active lever pressing when administered alone and did not block the effects of 5.0 mg/kg SB206. SB206 significantly decreased active lever presses in the first 15 min of testing (**p < 0.01; Newman-Keuls comparing veh/veh vs. 5.0 mg/kg SB206) and significance was retained following pretreatment with SB242 (***p < 0.001 comparing veh/veh vs. SB242/SB206).