The endocannabinoid system: an ancient signaling involved in the control of male fertility.

The effects of cannabinoids on human health have been known since the antiquities when the extract of the plant Cannabis sativa was used because of its psychoactivity. The scientific story of the cannabinoids started in the 1960s with the isolation and characterization of the active component of the plant. After the synthesis of cannabinoid analogues, the analysis of structure-effect relationships was implemented, and this had a similar effect to a positive "Pandora's box" opening. To date, numerous roles have been ascribed to the "endocannabinoid system." Here we describe its involvement in the control of male reproduction, taking into consideration possible evolutionary speculations. Indeed, the endocannabinoid system is a very ancient signaling system, being clearly present from the divergence of the protostomian/deuterostomian.