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CT
 
Background & objectives: So far, various reports have been presented on the relationship between sex hormones and gender-related differences in pain and analgesia in humans and laboratory animals. The purpose of this study was to investigate the effect of testosterone hormone and spironolactone anti-androgen drug on morphine-induced analgesia in male mice using formalin test.
Methods: In this study, 80 male mice were divided into 10 groups (N=8); normal saline (control), sesame seed oil (as testosterone solvent), testosterone (5 and 10 mg/kg body weight), spironolactone, morphine, sesame seed oil + morphine, testosterone (5 and 10 mg/ kg body weight) + morphine and spironolactone + morphine. Formalin test was performed in all the mice, and data were analyzed by one-way ANOVA.
Results: The results showed that sesame seed oil + morphine (p<0.001), morphine (p<0.001), testosterone (5 mg/kg) + morphine (p<0.01) and testosterone (10 mg/kg) + morphine (p<0.001) significantly reduced acute  pain, and testosterone (5 mg/kg) (p<0.05), testosterone (10 mg/kg) (p<0.01), sesame seed oil + morphine (p<0.001), morphine (p<0.001), testosterone (5 mg/kg) + morphine (p<0.001) and testosterone (10 mg/kg) + morphine (p<0.001) significantly reduced chronic pain compared with control group. Spironolactone had no effect on pain relief in the presence and absence of morphine compared to control group.
Conclusions: It can be concluded that testosterone has analgesic effects on the chronic phase of the pain. On the other hand, spironolactone may have hyperalgesic effects due to its anti-androgenic properties.