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Human relaxin, prolactin and placental lactogen in human intrauterine tissues

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Title:Human relaxin, prolactin and placental lactogen in human intrauterine tissues
Authors:Sakbun, Vannara
Date Issued:1991
Abstract:The human placenta, fetal membranes and decidua can be classified as endocrine glands because of their abilities to produce hormones which maintain and ensure the success of a pregnancy. These hormones may enter the maternal and/or the fetal circulatory systems to act upon distant targets while others may be produced and act locally within the intrauterine compartment. This study was designed to look at three circulatory hormones, relaxin, prolactin and placental lactogen, as bipolar hormones, local and distant. The sources of their production were studied in five different intrauterine tissues at two physiological time frames, before and after labor. The corpus luteum is the source of circulating relaxin during pregnancy. To determine whether this hormone is produced locally in intrauterine tissues, two techniques have been used, immunocytochemistry and Northern analyses. An antiserum to a synthetic l4-amino acid sequence of the connecting peptide of human relaxin and two monoclonal antibodies to human relaxin were used to immunostain fetal membranes with adherent decidua and placental trophoblast. Poly(A)+RNA prepared from five separate tissues, the amnion, chorionic membrane, decidua parietalis , basal plate and the placental trophoblast were hybridized to a 48-mer oligoprobe to human relaxin. Results from both techniques showed that the decidua parietalis and basalis, the chorion and the placental trophoblast synthesize and produce relaxin. The mRNA species in the placental trophoblast was shown to be 1.1kb, about 100 base pairs smaller than the mRNA species in other tissues, suggesting different processing mechanisms for these two mRNA species for relaxin. Comparative quantitation of mRNA levels showed that the decidua parietalis expressed the gene for relaxin more than the other tissues. Also all tissues obtained after normal spontaneous delivery had a lower capability for relaxin synthesis than tissues obtained from term elective Cesarean section. It is generally accepted that the decidua parietalis is the primary source of amniotic fluid prolactin. Whether this hormone is a product of other intrauterine tissues has not been thoroughly defined. Two polyclonal and four monoclonal antibodies were used to localize human prolactin (hPRL) in human intrauterine tissues. Northern analyses using a 48-mer oligoprobe and a 712 base pair cDNA probe for hPRL were performed to distinguish synthesized from sequestered hormone. Results showed that the decidua parietalis is indeed the major source of amniotic fluid prolactin and that the chorion laeve and the basal plate are additional sources. There was no significant difference in hPRL mRNA levels between Cesarean section and normal vaginal delivery tissues. Human placental lactogen (hPL) is one of the major hormones secreted by the placental syncytiotrophoblast and is readily detected in the maternal circulation. In this study, a specific polyclonal antibody to hPL, a 48-mer oligoprobe and a 540 base pair cDNA probe to hPL were used to investigate and determine other possible intrauterine sources of this hormone. Results showed unequivocally that the syncytiotrophoblast is the classical source of hPL. In addition, some cells of the chorionic cytotrophoblast and the basal plate also synthesized hPL. Quantitative analysis on Northern blots showed that the mRNA levels for hPL in these extra-sources were less than one percent of that in the classical source syncytiotrophoblast. It is not known whether these small amounts of hPL by these ectopic sources stay and function locally in the intrauterine tissues or whether they contribute to maternal circulation. The differential production of the three hormones by intrauterine tissues presented in this dissertation provide further definition of a paracrine/autocrine system within these tissues.
Description:Thesis (Ph. D.)--University of Hawaii at Manoa, 1991.
Includes bibliographical references (leaves 142-162)
xv, 162 leaves, bound ill. (some col.) 29 cm
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.
Appears in Collections: Ph.D. - Biomedical Sciences (Anatomy and Reproductive Biology)

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