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. Author manuscript; available in PMC: 2009 Apr 1.
Published in final edited form as: Neuropsychopharmacology. 2007 Jun 20;33(5):1137–1148. doi: 10.1038/sj.npp.1301477

Figure 2.

Figure 2

Effect of repeated pretreatment with methylphenidate (2.5 mg/kg; n=8) or saline (n=6) on nicotine self-administration at a unit dose of 0.03 mg/kg/infusion. Data points represent the mean (±SEM) number of reinforcers earned across 3 baseline (Base), 12 drug pretreatment and 3 saline (Sal) sessions. Asterisks indicate a significant difference from the number of infusions earned during the respective final baseline session (*p<.01). Hache symbols indicate a significant difference from the number of infusions earned by saline-treated rats on the corresponding session (#p<.01).