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. Author manuscript; available in PMC: 2010 Nov 1.
Published in final edited form as: Pharmacol Biochem Behav. 2009 Aug 22;94(1):204–210. doi: 10.1016/j.pbb.2009.08.011

Figure 2.

Figure 2

Cumulative infusions of saline did not significantly alter baseline rates of responding maintained by a fixed-interval schedule of stimulus termination in four squirrel monkeys (A). Cumulative doses of cocaine (0.03-1.0 mg/kg) produced a typical inverted-U shaped dose effect curve (B). Both 0.1 and 0.3 mg/kg cocaine produced significant increases in rates of responding. LY379268 (1.0-3.0 mg/kg) pretreatments did not significantly alter rates of responding maintained by a fixed-interval stimulus-termination schedule when repeated injections of saline were administered (A,C). However, a 5-min LY379268 pretreatment produced a downward shift of the cocaine dose effect curve (B). In contrast, a 30-min pretreatment time was ineffective in attenuating the behavioral-stimulant effects of cocaine (D). Abscissae: drug dose or saline infusion. Ordinates: rates of responding expressed as a percent of baseline control rates.