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Title: Relaxin and prolactin secretion from the human decidual cell : regulation in vitro 
Author: Hijazi, Mai M
Date: 1992
Abstract: A cell immunoblot technique originally designed for the study of prolactin secretion by rat pituitary cells has been modified and evaluated for the study of relaxin and prolactin accumulation and secretion from individual human decidual cells in vitro. Prolactin has been studied extensively in the human decidua, however nothing is known about the regulation of relaxin secretion. Macrophages were shown to make up 25% and chorionic cytotrophoblasts 10% of the cells in the decidual cell preparation. The decidual cells analyzed were selected by size and absence of immunostaining with macrophage and cytotrophoblast cell markers. Relaxin and prolactin intracellular accumulation and secretion were detected immunocytochemically as intracellular and extracellular staining respectively and were quantitated with an IBAS Kontron image analysis system. Relaxin secretion was detected after 15 min of incubation and was unaffected by cycloheximide suggesting release of preformed hormone. Prolactin on the other hand was only detected intracellularly up to 18 h and this was decreased by cycloheximide suggesting new production synthesis. Relaxin intracellular accumulation and secretion were significantly increased when the cells were incubated with added porcine relaxin, H2 synthetic human relaxin and Hl recombinant human relaxin. Porcine relaxin was slightly more potent than human H2 relaxin, which was more potent than the Hl synthetic peptide in increasing its own synthesis and secretion in vitro. Human and porcine insulins also significantly increased relaxin intracellular and extracellular staining. Preliminary results of added IGF-l and EGF showed stimulatory effects on relaxin intracellular and extracellular staining, but these results were not dose-dependent and are therefore questionable. Exogenous prolactin had both stimulatory and inhibitory effects on relaxin accumulation and secretion, and caused a significant increase in prolactin accumulation without affecting its secretion. The results suggest that relaxin and prolactin may be autocrine hormones in the human decidua, and the effects of relaxin treatment provide indirect evidence for the presence of relaxin receptors on the decidual cells. Preliminary results of treatment with insulin, IGF-l and EGF also suggest that these hormones may act as paracrine regulators of decidual relaxin synthesis and secretion.
Description: Thesis (Ph. D.)--University of Hawaii at Manoa, 1992. Includes bibliographical references. Microfiche. xiii, 191 leaves, bound ill. 29 cm
URI: http://hdl.handle.net/10125/9426
Rights: All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.

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