Changes in plasma adrenomedullin levels during the menstrual cycle

We investigated whether the levels of adrenomedullin, a novel peptide produ ced by several tissues, including the pituitary gland, change during the ov arian cycle. We studied 13 healthy women with regular menstrual cycles. Pla sma samples were collected at 7, 14, 21 and 28 days of the ovarian cycle an d assayed for adrenomedullin 1-52 using a specific RIA. LH, FSH, 17 beta-es tradiol, and progesterone concentrations were also determined. The adrenome dullin profile during ovarian cycle was similar to that of LH; plasma adren omedullin increased from 10.9 pg/ml at the 7th day to 15.1 pg/ml at the 14t h, and decreased to 8.5 pg/ml in the subsequent menses. The changes in plas ma adrenomedullin were related to changes in LH and 17 beta-estradiol. The cause of the increase in adrenomedullin levels during the late follicular p hase of the menstrual cycle is not clear. Since it has been demonstrated th at adrenomedullin is involved in the regulation of hypothalamus-pituitary-a drenal gland and its secretion is regulated by sex hormones we speculate th at adrenomedullin could also play a role in regulating the hypothalamus-pit uitary-ovary feedback. Alternatively it may be involved in the regulation o f fluid and electrolyte homeostasis during the menstrual cycle. (C) 2000 El sevier Science B.V. All rights reserved.