Comparative analysis of ACTH and oxytocinase plasma concentration during pregnancy.

INTRODUCTION: Normal function of the hypothalamo-adrenal axis is important for the regulation of feto-maternal intrauterine homeostasis including immunomodulating activity and may influence the timing of parturition. ACTH is produced during pregnancy by mother pituitary gland and by trophoblast cells, which are the place of oxytocinase production. Oxytocinase is basically secreted by syncytiotrophoblast cells and rises progressively during pregnancy until the labor. Oxytocinase may play a role as one of the main factors suppressing uterine contractions, controlling the vascular resistance and the volume of the retroplacental blood pool.

MATERIAL AND METHODS: The study group consisted of 102 patients with pregnancy following infertility treatment. The assessment was provided longitudinally in six selected groups progressively according to the gestational age. Immunoassay was used to measure ACTH plasma concentration. Oxytocinase plasma activity was established using l-cystine-di-beta-naphthylamide as a substrate.

RESULTS: Significantly increased oxytocinase plasma level was identified during pregnancy, progressive rise was observed beginning with the first trimester of pregnancy, until the labor. ACTH plasma concentration was observed to be at comparable level in the first and second trimester of pregnancy, while sudden statistically significant increase of ACTH plasma level was noted beginning with 28th week of gestation.

CONCLUSIONS: The assessment of ACTH and oxytocinase plasma concentration might be useful for the evaluation of pregnancy development.