Tetrahydro-beta-carbolines elevate plasma prolactin in male rats

The effects of systemic administration of three tetrahydro-beta-carbolines (TH beta C's) on plasma prolactin were determined in male rats. After intraperitoneal administration, 6-methoxy-TH beta C (6-MeO-TH beta C; 80 mg/kg) significantly elevated prolactin levels for 6 min. After intravenous administration via an indwelling jugular cannula, 6-MeO-TH beta C (20 mg/kg but not 2.0 mg/kg), TH beta C (20 mg/kg) and 6-OH-TH beta C (20 mg/kg) all produced a significant elevation in plasma prolactin for 30 min. with the latter compound effective for 60 min. Previous evidence indicated that the TH beta C's interact relatively selectively with the serotonergic neurotransmitter system to increase serotonergic function. Thus, the present data are consistent with previous studies which indicated that increased serotonergic activity resulted in enhanced prolactin secretion.