The effect of oxytocin infusion on adenohypophyseal function in man.

The responses of the adenohypophyseal hormones adrenocorticotrophin (ACTH), growth hormone (GH), thyroid stimulating hormone (TSH), prolactin, luteinizing hormone (LH) and follicle stimulating hormone (FSH) to sub-maximal doses of hypothalamic releasing factors were studied in six lean male volunteers (age 23-35 years) with and without infusions of oxytocin (OXT). OXT infusion (mean plasma concentration 133.6 +/- 2.6 pmol/l) completely inhibited the plasma ACTH responses to corticotrophin releasing hormone (CRH) (saline, peak increment ACTH 1.61 +/- 0.75 pmol/l; OXT, peak increment ACTH - 0.04 +/- 0.28 pmol/l; P less than 0.05). OXT infusion had no significant effect on the GH response to growth hormone releasing hormone (GHRH), the TSH and prolactin responses to thyrotrophin releasing hormone (thyroliberin, TRH) or the LH and FSH responses to gonadotrophin releasing hormone (luteoliberin, GnRH). The data support a role for OXT in the modulation of ACTH secretion in man.