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Endometrial expression of progesterone receptor and uteroglobin genes during early pregnancy in the rabbit
Author(s) -
GutierrezSagal Ruben,
PerezPalacios Gregorio,
Langley Elizabeth,
Pasapera Ana Maria,
Castro Ivone,
Cerbón Marco Antonio
Publication year - 1993
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.1080340303
Subject(s) - uteroglobin , endometrium , immunostaining , biology , endocrinology , progesterone receptor , medicine , gene expression , messenger rna , uterus , pregnancy , andrology , gene , immunohistochemistry , estrogen receptor , immunology , biochemistry , genetics , cancer , breast cancer
Abstract The progesterone receptor (PR) plays a pivotal role in the maturation process of the secretory endometrium, implantation and maintenance of pregnancy in rabbits. To determine the dynamics of PR gene expression and its physiological significance, the endometrial expression of PR and PR mRNA were evaluated and compared with the expression of the progesterone‐regulated uteroglobin (UG) gene during 0–5 days post‐coitus in rabbits. The results of immunoblot experiments indicated the presence of PR in endometrial cell extracts from days 1–4 of pregnancy with maximum PR immunostaining on day 2, followed by a marked diminution until its complete disappearance on day 5. When endometrial PR mRNA content was assessed by Northern blots, the results were similar to those of PR immunostaining, with maximal concentrations on the second day after mating. However, PR mRNA levels were still high on day 3, despite the concomitant decrease in immunostainable PR. Endometrial UG gene expression, on the other hand, exhibited a different time sequence. Thus, the UG content in uterine flushings progressively increased from day 3 after mating, reaching maximal levels on the fifth day. The endometrial UG mRNA content presented a similar profile, as its maximum concentration occurred on days 4–5. The overall results indicate that endometrial PR is down‐regulated at both the mRNA and protein levels, possibly by endogenous progesterone during early pregnancy. The striking observation that maximal expression of endometrial UG gene products occurred when PR and its mRNA are no longer detectable suggests an important role for this progesterone‐binding uterine protein during the preimplantation period. © 1993 Wiley‐Liss, Inc.