Effects of pretreatment with JNJ16259685 and vehicle on cocaine self-administration under a second-order schedule of intravenous drug delivery. A, JNJ16259685 dose-response curve; the empty bar shows the effects of the JNJ16259685 vehicle. B, cocaine dose-response function after pretreatment with JNJ16259685 or vehicle. C, number of injections/session self-administered during cocaine availability. D, within-session analyses showing the effects of pretreatment with JNJ16259685 or vehicle on the rate of responding during sequential components of cocaine self-administration sessions. *, p < 0.05, effects of pretreatment with JNJ16259685 compared with vehicle, Bonferroni t test.