Uterine tissues of pregnant rats were extracted to define any changes to the proportions of collagens types I, III and V. The total concentration of extracted collagen was determined in tissue samples from implant and adjacent non-implant (NI) sites. Extracts were also subjected to polyacrylamide gel electrophoresis (PAGE), immunoblotting and gel densitometry to define the collagen types and to determine their relative proportions. By relating the proportions to the collagen concentrations in the extracts, type I was found to be the predominant collagen in both tissue regions although the concentration in the implant sites was lower than that in the NI sites. The concentration of Type I collagen decreased significantly over the period of observation in both implant and NI sites. Although the concentrations of collagen type III and type V also decreased in the implant sites, they did not alter in the NI sites. The results demonstrate that shortly after the initiation of implantation the uterus responds to the presence of the implanting embryo by decreasing the concentration of all three types of collagen. This indicates that their metabolism may, in part, be regulated by similar mechanisms. Furthermore, it was evident that a decrease in the concentration of collagen type I was initiated in uterine areas that, at the time of sampling, were not directly involved with implantation. During the study, it was found that the alpha 1 chain of collagen type V separated into two distinct bands when run on gels containing 3.8 M urea.(ABSTRACT TRUNCATED AT 250 WORDS)
Collagen concentrations at implantation sites in the rat uterus were found to be significantly decreased compared with concentrations in adjacent non-involved uterine tissue in early pregnancy (75% by Day 11). The decrease in collagen was most marked in primary decidua and was also observed to a lesser extent (20%) in myometrium at the implantation site. There was a decrease of 20% in the concentration of total proteins at Day 7 (as measured by the ninhydrin method) and a slight increase in water content (2%) at Days 6 and 7. The differences in total protein and water content were transient, but the difference in collagen was maintained throughout early pregnancy. The localized changes in collagen content observed in this study, along with previously reported morphological changes in fibrillar and basement-membrane collagens in the uterus, give support to a theory of remodelling in early pregnancy involving simultaneous synthesis and degradation of extracellular proteins during decidualization.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.