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. Author manuscript; available in PMC: 2022 Dec 1.
Published in final edited form as: Drug Alcohol Depend. 2021 Sep 24;229(Pt A):109101. doi: 10.1016/j.drugalcdep.2021.109101

Figure 1. Fentanyl (FTY) differentially affects locomotor activity (LMA) in female and male rats.

Figure 1.

(A) A schematic of the timeline of the open field experiment. Rats were first tested for LMA following saline or fentanyl (20 μg/kg) subcutaneous injection. After 1 week of daily injections, LMA was tested in rats given repeated fentanyl, acute fentanyl (i.e., rats given saline through days 1–7 and fentanyl on day 8 only), or saline-control. (B) Only female rats, given fentanyl injection on day 1 had elevated LMA compared to saline-control or acute fentanyl that received saline on day 1 (*p < 0.05). No significant changes were observed in male rats on day 1. (C) After 8 days of repeated fentanyl administration, female rats showed elevated LMA compared to saline-control (****p < 0.0001) or to acute fentanyl (**p < 0.01). Additionally, female rats given acute and chronic fentanyl had significantly more LMA than males of the same treatment groups (***p < 0.001 and ****p < 0.0001, respectively). (D) Only female rats showed a time-dependent increase in locomotor activity for rats given fentanyl daily for 8 days (chronic) when data are normalized to respective group saline-control data (*p < 0.05). Graphs display means ± SEM, with points on bar charts representing individual values.