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. Author manuscript; available in PMC: 2010 Oct 28.
Published in final edited form as: Neuropharmacology. 2007 Aug 15;53(6):771–782. doi: 10.1016/j.neuropharm.2007.08.004

Figure 2.

Figure 2

Effect of l-THP on cocaine self-administration under PR reinforcement. Panel A shows representative records of an individual animal illustrating a reduction in the PR break-point for cocaine self-administration from 62 after vehicle (1 ml sterile water, i.p.; upper trace) to 32 after l-THP (3 mg/kg i.p., 30 min prior to test; lower trace) pretreatment. Each vertical line indicates a cocaine infusion (0.5 mg/kg/infusion). The number between the vertical lines indicates the work demand (progressively increased PR ratio, i.e., number of lever presses) for a subsequent cocaine infusion. The PR breakpoint was defined as the highest completed work requirement (lever-presses) to receive the last cocaine infusion. Panel B depicts the percent changes in break-point for cocaine self-administration after each dose of l-THP pretreatment. *p<0.05, ** p<0.01, *** p<0.001, when compared to the vehicle (0 mg/kg l-THP) pretreatment group.