Vascular effects of oxytocin on human middle cerebral artery determined by transcranial Doppler sonography.

Neurohypophysial hormones may exert regulatory influences on cerebral blood flow. This double-blind cross-over study in healthy humans (n = 6) examined effects of oxytocin (OX) on blood flow in the middle cerebral artery (MCA) by transcranial Doppler sonography. Compared to placebo, intravenous infusion of OX (0.5 IU, within 2.5 min via a forearm catheter) reduced blood flow velocity (V) within 10 min after the start of the infusion (P < 0.05). The pulsatility index (PI) was at the same time increased following OX (P < 0.05). The effects of OX were not accompanied by changes in expiratory endtidal pCO2 or blood pressure. But, heart rate was slightly enhanced immediately after infusion of OX (P < 0.05). The changes in MCA blood flow velocity following OX could reflect a vasoconstrictory effect on small cerebral resistance vessels or a vasodilating effect on the large cerebral arteries.

RCT Entities:   Population Interventions Outcomes