The research on sex differences in nociception and antinociception as well as sex and gender differences in
pain and
analgesia is a maturing field. There is a vast literature showing experimental and clinical
pain suppressive effects induced by
minocycline, especially in inflammatory
pain. However, as far as we know, possible qualitative or quantitative sex differences in those effects remained to be examined. By employing the
formalin test, which has two phases of experimental
pain behavior that models
nociceptive pain (i.e., first phase) and inflammatory
pain (i.e., second phase), we initially evaluated the effect induced by
minocycline in female or male C57BL/6 mice. The treatment reduced the second phase of licking behavior in both females and males, and the effects were quantitatively similar in both sexes. Likewise, the same sex-independent effect was observed in Swiss mice, suggesting a genotype-unspecific sex-independent effect. While
minocycline is already being tested in clinical trials, this appears to be the first preclinical investigation of sex differences in the experimental
pain suppressive effects induced by this widely studied drug. The independence of sex in the antinociceptive effect induced by
minocycline may be hopefully translated to gender-independent
analgesic effects, which would be surely promising in a therapeutic paradigm.