Expression and localization of 20α-hydroxysteroid dehydrogenase (20α-HSD) in porcine reproductive tissues during pregnancy

• Pig 20α-HSD mRNA was the highest expression in the placenta on day 30 of pregnancy and in the ovary during pre-parturition.
• Pig 20α-HSD protein in the reproductive tissues was similar to that of 20α-HSD mRNA.
• Pig 20α-HSD protein was localized in the trophoblast villus in the placenta.
• It was highly expressed in the glandular epithelial cells of the endometrium and the luminal epithelial cells of the uterus.

The aims of this study were to determine the specific site of 20α-HSD expression in the reproductive tissues on day 30 of pregnancy and during pre-parturition. 20α-HSD mRNA was demonstrated to have the highest expression in the placenta on day 30 of pregnancy and in the ovary during pre-parturition. Weak mRNA expression was observed in the uterus and ovary on day 30 of pregnancy. However, the mRNA was not expressed in the oviduct on day 30 of pregnancy. The mRNA was also specifically detected in the placenta on day 30 of pregnancy by northern blot analysis. Western blot analysis indicated that the expression pattern of the 20α-HSD protein in the reproductive tissues was similar to that of 20α-HSD mRNA. Immunohistochemical analysis also revealed that the pig 20α-HSD protein was localized in the trophoblast villus in the placenta on day 30 of pregnancy. It was highly expressed in the glandular epithelial cells of the endometrium and the luminal epithelial cells of the uterus. The 20α-HSD protein was highly localized in the large luteal cells of the ovary on day 30 of pregnancy and during pre-parturition.Taken together, our study demonstrated that the pig 20α-HSD mRNA and protein are mainly localized in the trophoblast villus in the placenta on day 30 of pregnancy. The expression of the protein is also localized in the large luteal cells of the ovary. In addition, the protein is highly expressed in the glandular epithelial cells of the endometrium and the luminal epithelial cells of the uterus.