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. Author manuscript; available in PMC: 2022 Jul 1.
Published in final edited form as: Neuropharmacology. 2021 May 11;192:108599. doi: 10.1016/j.neuropharm.2021.108599

Figure 1. Fentanyl self-administration in rats.

Figure 1.

Dose-response curves showing total lever responses (A), total infusions (B), and total fentanyl infused (C) in rats self-administering different unit doses of fentanyl on a FR5 schedule (a=significant increase compared to 0.001 μg/kg/infusion fentanyl; b=significant increase compared to 0.125 μg/kg/infusion fentanyl; c=significant increase compared to 1.25 μg/kg/infusion fentanyl; d=significant increase compared to 2.5 μg/kg/infusion fentanyl: p<0.05, Bonferroni; n=11/treatment). Total lever responses (D) and total fentanyl infusions (E) were significantly decreased in rats (n=11/treatment) pretreated with buprenorphine compared to vehicle-treated controls (*p<0.05, Bonferroni).