POTENTIALLY BENEFICIAL CARDIOVASCULAR EFFECTS OF MELATONIN ADMINISTRATION IN WOMEN

The cardiovascular effects induced by the daytime administration of me latonin (1 mg) were compared to those of placebo in 12 young women. In order to eliminate cardiovascular effects due to fluctuating endogeno us sex steroids, all women were taking a fixed dose of monophasic cont raceptive pill. In comparison to placebo, the administration of melato nin reduced, within 90 min, the pulsatility index of the internal caro tid artery, evaluated by color Doppler ultrasound (P<0.01), as well as both systolic and diastolic blood pressure evaluated in supine positi on (P<0.01). Supine catecholamine levels were not significantly modifi ed, but norepinephrine levels evaluated after 5 min of standing positi on were significantly reduced (P<0.02). These data suggest that in wom en the administration of 1 mg of melatonin may exert beneficial effect s on blood vessels.