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Relaxin in the Marmoset Monkey: Secretion Pattern in the Ovarian Cycle and Early Pregnancy
Relaxin is a peptide hormone with a broad range of biological activities, related not only to parturition and lactation but possibly also to decidualization, implantation, and early pregnancy. The present study was designed to investigate the secretion pattern of relaxin throughout the cycle and ear...
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Published in: | Biology of reproduction 1999-08, Vol.61 (2), p.512-520 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Relaxin is a peptide hormone with a broad range of biological activities, related not only to parturition and lactation but
possibly also to decidualization, implantation, and early pregnancy. The present study was designed to investigate the secretion
pattern of relaxin throughout the cycle and early pregnancy in the common marmoset monkey in relation to ovarian function
and the systemic hormone milieu. First, a novel relaxin ELISA was developed and validated to confirm the pattern of relaxin
secretion during pregnancy. Secondly, serum relaxin profiles were determined through nonconceptive and conceptive cycles and
analyzed in relation to the concentration of other hormones and to the development of ovarian follicles and corpora lutea
(CL). Blood samples were collected 2â3 times per week from the experimental animals and analyzed for relaxin, progesterone,
and LH. The animals from the conceptive cycles were also ultrascanned at these time points to determine the ovarian status
up to Day 25 of pregnancy. During early pregnancy, the relaxin levels in serum were approximately 1 ng/ml, increasing up to
15 ng/ml in the second trimester, at a time when progesterone levels had declined. In the third trimester, when progesterone
levels were increasing again, the levels of relaxin decreased, returning to basal levels by term of pregnancy. In early pregnancy
there was a parallel increase in both relaxin and LH/hCG, with the relaxin rise in the conceptive cycle appearing sooner than
in the nonconceptive cycle, suggesting that, like chorionic gonadotropin (CG), relaxin may be a useful and early marker for
pregnancy. Unlike the situation in the human, there was no correlation between the levels of either hormone and the number
of CL detected, infants born, mother's age, or parity. Relaxin levels increased in early pregnancy before bioactive LH/CG,
implying that relaxin is not directly regulated by this gonadotropin. Furthermore, hCG applied to nonconceptive females during
the expected time of implantation caused an increase in progesterone but not in relaxin concentrations. In summary, the results
obtained indicate that relaxin may be a reliable indicator of early pregnancy status in the common marmoset, but it is independent
of direct CG influence. |
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ISSN: | 0006-3363 1529-7268 |
DOI: | 10.1095/biolreprod61.2.512 |