Fig 2. PD149163 alters the pattern of operant responding for METH in mice.

An examination of the pattern of responding during the 2-hour operant self-administration session revealed that METH intake was primarily decreased through attenuated behavior early in the session. (A) The latency from the start of the session until the first infusion of METH was significantly increased following PD149163 administration at both doses tested. * P < 0.05, ** P < 0.001 versus saline, Dunnett’s multiple comparison test. (B) The percent of total infusions earned during the first hour of the session was significantly decreased at both doses of PD149163 tested. ** P < 0.001, *** P = 0.0001 versus saline, Dunnett’s multiple comparison test. (C) PD149163 did not significantly alter the number of bouts of METH self-administration (defined as 2 or more infusions with less than 120 s between infusions; P = 0.055, One-way RM ANOVA), although there was a trend towards a decreased number of bouts. (D) A sample raster plot showing METH infusions (displayed as dots) during the self-administration session for one mouse following saline, 0.05, and 0.1 mg/kg PD149163, showing the delay in responding following PD149163 treatment. (E) A heat map analysis for all mice showing the number of nose pokes in 30 minute bins during the 2-hour self-administration session. Nose poking in the active hole (warmer colors) was delayed with increasing doses of PD149163.