Lactation-associated infertility in Japanese monkeys (Macaca fuscata) during the breeding season
Publication Type: |
Journal Article |
Year of Publication: |
2003 |
Authors: |
Masahiro Kondo, Hisashi Kishi, Chihiro Kojima, Wanzhu Jin, Juri Suzuki, Keiko Shimizu, Mariko Itoh, Satoshi Ohkura, Hiroko Tsukamura, Kei-Ichiro Maeda, Gen Watanabe, Kazuyoshi Taya |
Publication/Journal: |
Zoo Biology |
Publisher: |
A Wiley Company, Inc., Wiley Subscription Services |
Keywords: |
cortisol, estradiol-17β, gonadotropin, inhibin, lactation, progesterone, suckling |
ISBN: |
1098-2361 |
Abstract:
Abstract 10.1002/zoo.10073.abs To investigate the endocrine factors in Japanese monkeys (Macaca fuscata) responsible for the suppression of the estrous cycle during the first reproductive season after delivery (150–360 days postpartum), peripheral blood was taken to measure plasma concentrations of follicle stimulating hormone (FSH), luteinizing hormone (LH), progesterone, estradiol-17β, immunoreactive (ir)-inhibin, and cortisol. The results demonstrated that during the breeding season of lactating Japanese monkeys, circulating concentrations of FSH (1.7–2.7 ng/ml), LH (308.5–461.0 pg/ml), estradiol-17β (<62.6 pg/ml), and progesterone (145.0–453.0 pg/ml) remained low and were similar to the nadir levels observed during both the normal menstrual cycles and the nonbreeding season. Concentrations of ir-inhibin, which is secreted from both follicles and corpus luteum in female Japanese monkeys, were also low (300.5–585.0 pg/ml). This strongly suggests that no follicular development occurs during lactation. Serum concentrations of cortisol (261.0–519 ng/ml) were higher during lactation than during the nonbreeding season. Since babies were often seen suckling their mothers during the study, the results indicate that the increased cortisol levels were associated with suckling-induced secretion of corticotrophin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH). The results of this study indicate that a long period of postpartum infertility in lactating Japanese monkeys, with apparent inhibition of follicle growth and anovulation, is due to weak gonadotropin stimulation, which may occur as the result of a suckling stimulus. Zoo Biol 22:65–76, 2003. © 2003 Wiley-Liss, Inc.