Effects of metformin on adrenal steroidogenesis in women with polycystic ovary syndrome.

OBJECTIVE: To determine whether the administration of metformin, an insulin-sensitizing agent, is followed by changes in adrenal steroidogenesis in women with polycystic ovary syndrome (PCOS). DESIGN: Prospective trial. SETTING: Department of Obstetrics and Gynecology, University of Siena, Siena, Italy. PATIENT(S): Fourteen women with PCOS. INTERVENTION(S): Blood samples were obtained before (-15 and 0 minutes) and after (15, 30, 45, and 60 minutes) the administration of ACTH (250 microg). Metformin then was given at a dosage of 500 mg three times a day for 30-32 days, at which time the pretreatment study was repeated. MAIN OUTCOME MEASURE(S): The adrenal androgen responses to ACTH before and after treatment with metformin. RESULT(S): Ovulation occurred in two women (14%) in response to metformin treatment. A significant reduction in basal concentrations of free testosterone and a significant increase in concentrations of sex hormone-binding globulin were observed. The administration of metformin was associated with a significant reduction in the response of 17alpha-hydroxyprogesterone, testosterone, free testosterone, and androstenedione to ACTH. The ratio of 17alpha-hydroxyprogesterone to progesterone, which indicates 17alpha-hydroxylase activity, and the ratio of androstenedione to 17alpha-hydroxyprogesterone, which indicates 17,20-lyase activity, were significantly lower after a month of metformin treatment, indicating a reduction in the activities of these enzymes. CONCLUSION(S): The administration of metformin to unselected women with PCOS led to a reduction in the adrenal steroidogenesis response to ACTH. This finding supports the hypothesis that high insulin levels associated with PCOS may cause an increase in plasma levels of adrenal androgens.

Metformin treatment reduces ovarian cytochrome P-450c17alpha response to human chorionic gonadotrophin in women with insulin resistance-related polycystic ovary syndrome.

It has recently been proposed that hyperinsulinaemic insulin resistance and increased ovarian cytochrome P-450c17alpha activity, two features of the polycystic ovary syndrome (PCOS), are pathogenetically linked. The aim of the present study was to test the hypothesis of the linkage between hyperinsulinaemia and supranormal activity of cytochrome P-450c17alpha using the human chorionic gonadotrophin (HCG) challenge, which is a more direct ovarian stimulus than gonadotrophin-releasing hormone (GnRH) in detecting modifications in ovarian steroidogenesis. Eleven women with insulin resistance-related PCOS were studied. HCG (10 000 IU) was given i.m., and blood samples were obtained 0, 8, 12, 16 and 24 h thereafter. Next day, metformin was given at a dose of 500 mg three times a day for 30-32 days, at which time the pretreatment study was repeated. Two women ovulated after metformin treatment. The administration of metformin was associated with a decrease in area under the curve for insulin during a 2h, 75g oral glucose tolerance test, in plasma free testosterone concentrations and an increase in plasma sex hormone binding globulin concentration. The plasma 17-hydroxyprogesterone response to HCG was significantly lower after metformin treatment. The present study gives a direct demonstration that metformin leads to a reduction in stimulated ovarian cytochrome P-450c17alpha activity in women with polycystic ovary syndrome.