PEA ameliorates chronic hyperalgesia in HbSS mice. (A-B) PEA intraperitoneal (IP) dose-dependently reduced hyperalgesia in male HbSS mice in response to mechanical and cold stimulation with maximal effect at 1 hour and 72 hours of daily treatment with 20 mg/kg per day dose. (C) PEA did not affect measures of musculoskeletal hyperalgesia in male HbSS or HbAA mice. (D-F) Optimized PEA dose (IP, 20 mg/kg per day) in female mice significantly ameliorated mechanical and cold hyperalgesia 1 hour and 72 hours after start of treatment compared with vehicle and BL measures, and musculoskeletal hyperalgesia was reduced at 72 hours in PEA-treated mice compared with vehicle. (G) PEA (IP, 20 mg/kg per day) treatment significantly ameliorated nonevoked cold hyperalgesia in a thermal place preference test, indicated by increased time spent in a cold chamber, 1 hour after initial dose and after 3 days of daily treatment compared with vehicle-treated HbSS mice. No effects were observed in male or female control mice with treatments. Mean ± SD. In panels A-G, data were analyzed using repeated measures 2-way ANOVA and the Tukey post hoc multiple comparisons test. ∗Indicates a difference compared with time-matched vehicle; †indicates a difference compared with respective BL. ∗,†P < .05; ∗∗,††P < .01; ∗∗∗,†††P < .001; ∗∗∗∗,††††P < .0001. Age: 3.5 to 5.0 months. For panels A-C: PEA male, HbSS vehicle, n = 4; HbSS 3 mg/kg, n = 4; HbSS 20 mg/kg, n = 4; HbSS 30 mg/kg, n = 5; HbAA vehicle, n = 5; HbAA 30 mg/kg, n = 6; panels D-G: PEA female, HbAA vehicle, n = 11; HbAA 20 mg/kg, n = 6; HbSS vehicle, n = 8; HbSS 20 mg/kg, n = 12. BW, body weight; PWF, paw withdrawal frequency; Tx, treatment; VF, von Frey.