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Female Reproductive Tract; |
Departments of Physiology3 and Anatomy,4 Centre of Heart, Brain, Hormone and Healthy Aging,5 Centre of Reproduction, Development and Growth,6 Faculty of Medicine, The University of Hong Kong, Hong Kong, China
ABSTRACT
The present study demonstrates the expression of adrenomedullin (ADM) in the reproductive system of the female rat and its effect on the secretion of estradiol and progesterone. Ovarian ADM and Adm mRNA levels were decreased at estrus, whereas oviductal Adm mRNA levels were low at proestrus. Both tissues were shown to coexpress mRNAs encoding the calcitonin receptor-like receptor and receptor activity-modifying protein 1 (Ramp1), Ramp2, and Ramp3. Gel filtration chromatography of ovarian extracts showed two peaks, with the predominant one eluting at the position of authentic rat ADM (1–50) at estrus and at the position of ADM precursor at diestrus. Positive ADM immunostaining was localized in the granulosa and theca cells of the follicle and corpora lutea of the ovary. Adrenomedullin inhibited FSH-induced estradiol secretion in 2-day-old follicles and also suppressed eCG-stimulated progesterone release in corpora lutea. The inhibitory effect of ADM on the follicles and the corpora lutea was abolished by calcitonin gene-related peptide (8–37) and ADM (22–52), respectively. The presence of ADM and the gene expression of ADM and its receptor components in the female reproductive system suggest a paracrine effect of ADM on ovarian steroidogenesis.
estradiol, follicle-stimulating hormone, human chorionic gonadotropin, ovary, progesterone
1Substantially supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (HKU 7736/07M).
Correspondence: 2W.S.O., Department of Anatomy, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Rd., Pokfulam, Hong Kong, China. FAX: 852 28170857; e-mail: owaisum{at}hkucc.hku.hk
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