The antidepressant effect of testosterone: An effect of neuroplasticity?

•Testosterone has antidepressant effects whereby the underlying mechanisms are still unknown.•Promoted neuroplasticity and the activation of the serotonin system may underlie the antidepressant effect of testosterone.•Studies suggest that a combination of testosterone and current antidepressants enhance antidepressant-induced neurogenesis.•Testosterone actions within the HPA axis and during inflammation may additionally contribute to the mood enhancing effects.•Not only testosterone alone, but also its conversion to estradiol may contribute to the observed antidepressant effects.