Expression of adrenomedullin in the human corpus luteum

Abstract

Objective: Adrenomedullin (AM) is a potent hypotensive peptide found in human pheochromocytoma tissue. In the present study, the expression of AM mRNA in the human ovary was examined. Design: Ovarian mRNA was analyzed in the follicle, the corpus luteum of mid-luteal phase, and early pregnancy. Setting: Gunma University School of Medicine, Gunma, Japan. Patient(s): Premenopausal women with histologically normal ovary who were undergoing salpingoophorectomy. Intervention(s): The dominant follicle and corpora lutea were isolated and total RNA was extracted from these tissues. Main Outcome Measure(s): Northern blot analysis of AM, receptor activity–modifying protein 2 (RAMP2), and LH/hCG receptor mRNA in human samples. Result(s): An AM mRNA transcript of 1.6 kilobases (kb) was detected in corpus luteum tissue; this transcript was identical to that which has been detected in placenta and fetal membrane. The AM and LH/hCG receptor mRNA levels were low in the mature follicle but increased in the corpus luteum of the mid-luteal phase and were maintained during early pregnancy. A single transcript of 0.8 kb for RAMP2 was also seen in the follicle and corpus luteum, the level of RAMP2 mRNA was relatively high in the preovulatory follicle and RAMP2 was present in the corpus luteum. Conclusion(s): The expression of AM, its receptor, and LH/hCG receptor may be an important component in the process of development and differentiation of the corpus luteum.