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Title:The use of monoclonal antibodies specific for rat relaxin to study the physiological roles of relaxin in pregnant rats
Author(s):Hwang, Jiuan-Jiuan
Doctoral Committee Chair(s):Sherwood, O. David
Department / Program:Department of Physiology and Biophysics
Department of Molecular and Integrative Physiology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Biology, General
Biology, Animal Physiology
Biology, Zoology
Abstract:The purpose of the present research was to determine the physiological roles of endogenous relaxin in pregnant rats by passive immunization with a monoclonal antibody specific for rat relaxin (MCA1). Recently, Lao Guico-Lamm and Sherwood demonstrated that rats treated with MCA1 throughout the second half of pregnancy exhibited prolonged delivery and reduced pup survival at birth compared to controls.
I first examined the hypothesis that the influence of endogenous relaxin on birth is attributable, at least partly, to its effects on the cervix. The initial study showed that cervices obtained on day 22 of pregnancy from rats treated with MCA1 throughout the second half of pregnancy were markedly smaller and less extensible than cervices from controls. The second study demonstrated that rats treated with MCA1 during only the last three days of pregnancy, the so-called antepartum period, exhibited prolonged delivery and reduced cervical growth and softening compared to controls. However, passive immunization of relaxin during the antepartum period has less profound effects on cervical growth and softening and litter delivery than did passive immunization of relaxin throughout the second half of pregnancy. Collectively, studies 1 and 2 provided strong support for the hypothesis that relaxin enables rapid and safe delivery of the pups, at least partly, by promoting growth and softening of the cervix.
The second study also demonstrated that pups born of relaxin deficient rats exhibited reduced weight and postpartum survival rate. Accordingly, I examined the hypothesis that endogenous relaxin contributes to the development of the mammary apparatus and lactational performance. On day 22 rats treated with MCA1 throughout the second half of pregnancy exhibited smaller nipples and abnormal morphology of the mammary glands compared to controls. Furthermore, MCA1-treated rats, cesarean sectioned near term, showed poor lactational performance towards foster pups born of untreated intact rats as judged by pup growth and survival.
In conclusion, the present research establishes two vital physiological needs for endogenous relaxin during pregnancy. Relaxin promotes not only the cervical growth and softening required for birth but also the development of the mammary apparatus essential for growth and survival of the young during lactation.
Issue Date:1990
Rights Information:Copyright 1990 Hwang, Jiuan-Jiuan
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9114275
OCLC Identifier:(UMI)AAI9114275

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