Human endometrium contains relaxin that is progesterone-dependent.
The avidin-biotin immunoperoxidase method using two anti-porcine relaxin antisera was employed to study the occurrence of relaxin in the endometrium of 102 pre- or postmenopausal women. Relaxin was not found in the endometrium in the following conditions: 1. normal proliferative phase (n = 27), 2. cystic glandular hyperplasia (n = 12), 3. early secretory endometrium during 1-3 postovulatory days (n = 12), 4. atrophic endometrium from postmenopausal women not taking hormones (n = 7), and 5. atrophic or proliferative endometrium of women undergoing estrogen replacement therapy (n = 5). Relaxin was invariably present 1. in the secretory endometrium from natural cycles after day 3 postovulation (n = 28), 2. in the secretory endometrium of previously unovulatory premenopausal women taking progestogens (n = 6), and 3. in the secretory endometrium during the latter part of the cycle of postmenopausal women undergoing estrogen-progestogen replacement therapy (n = 5). Our results indicate that the occurrence of relaxin in the endometrium is progesterone-dependent, but the corpus luteum is not required for relaxin synthesis to occur in non-pregnant women. The timing of the appearance of relaxin in the endometrium during natural cycles coincides with implantation, thus suggesting a role for relaxin in the early events of human reproduction.
D000328:Adult; D004717:Endometrium / Q000378:metabolism* / Q000473:pathology; D004967:Estrogens / Q000008:administration & dosage; D005260:Female; D006801:Humans; D006965:Hyperplasia; D006984:Hypertrophy; D007124:Immunoenzyme Techniques; D008593:Menopause / Q000187:drug effects; D008875:Middle Aged; D010060:Ovulation; D011374:Progesterone / Q000008:administration & dosage / Q000378:metabolism*; D012065:Relaxin / Q000378:metabolism*
D004967:Estrogens; D011374:Progesterone; D012065:Relaxin