Delta9-tetrahydrocannabinol increase plasma testosterone concentrations in mice S Dalterio, A Bartke and D Mayfield ABSTRACT Oral administration of delta 9-tetrahydrocannabinol had a biphasic effect on plasma testosterone concentrations in male mice, causing rapid sustained increases at low doses and subsequent decreases at higher doses. In hypophysectomized and intact mice receiving gonadotropins (human chorionic gonadotropin), treatment with delta 9-tetrahydrocannabinol maintained higher plasma testosterone concentrations. Thus, this cannabinoid may interact with gonadotropin and directly influence testicular steroidogenesis in vivo.