Finasteride, a 5alpha-Reductase Enzyme Inhibitor, Alone and in Synergism with a Neurosteroid, Reduces Responsiveness to Nociceptive Stimuli in Male Rats

The study investigated the effects of finasteride, a 5alpha-reductase inhibitor, on pain modulation in male rats, both alone and in combination with testosterone. Finasteride alone, administered in doses ranging from 5-300 mg/kg, showed significant analgesic effects in the chronic pain model (formalin test) but not in the acute pain model (tail-flick test). When combined with testosterone, finasteride significantly enhanced antinociceptive effects in both pain models. The findings suggested that finasteride not only has its own analgesic properties but also enhances the pain-relieving effects of testosterone, indicating an interaction between the neurosteroid and the enzyme inhibitor in modulating pain.