Fig. 1From: Examination of sex and minocycline treatment on acute morphine-induced analgesia and inflammatory gene expression along the pain pathway in Sprague–Dawley ratsMean percent effectiveness of acute morphine analgesia in male and female rats. Male and female rats were treated with either 4 mg/kg or 8 mg/kg of morphine sulfate subcutaneously. Morphine analgesia was measured using a hot plate set at 52.5 °C. The latency to respond to the heat with a rear paw shake or lick was recorded 20, 40, 60, 90, and 120 min post morphine administration. a Morphine produced significantly greater analgesia in males than females at a dose of 4 mg/kg (repeated-measures ANOVA: asterisk represents main effect of sex: F 1,15 = 21.22; p = 0.00040). b Morphine produced significantly greater analgesia in males than females at a dose of 8 mg/kg (repeated-measures ANOVA: asterisk represents main effect of sex: F 1,15 = 49.95; p < 0.001)Back to article page