[Intravenous injection of synthetic oxytocin induces a decrease of cortisol plasma level in normal man].

The influence of a i.v. injection of 2 I.U. of synthetic oxytocin (Oxy, Syntocinon) on plasma cortisol has been tested in 6 normal volunteers (age 22 to 33) and compared to a similar saline injection in a blind, cross-over design. Before injection basal cortisol is similar in Oxy (12.1 +/- 2.3 micrograms/100 ml M +/- Se) and saline (11.7 +/- 3.5) groups; in the Oxy group a significant (2 p less than 0.01) decrease of cortisol was noticed from the 45th min until the end of the test (120 min): the last mean level being 5.2 +/- 0.9 in the Oxy group compared to 12.9 +/- 1.8 in the saline group (2 p less than 0.005). Although the mechanism of action of Oxy on cortisol plasma levels remains to be investigated our results are in agreement with a proper action of Oxy and vasopressin at the level of the corticotroph cells or with a proper action of Oxy or of one of its metabolite (Pro-Leu-Gly-NH2 for example) on proopiomelanocorticotropic function.