cjs-202302-0001 ArticleInAPeriodical 2023 Czech Journal of Animal Science 68 2 53-63 Ji-HyeLee ChoSeok-Hyun Sang-HwanKim Effects of apoptosis by 20α-hydroxysteroid dehydrogenase activity on corpus luteum formation during early pregnancy in cattle 20α-hydroxysteroid dehydrogenase (20α-HSD) is a member of the aldo-keto reductase family. These enzymes play a pivotal role in regulating steroid hormones, such as androgens, oestrogen, and progesterone, and are, therefore, considered vital targets for determining whether a pregnancy is maintained. In this study, we investigated the association between 20α-HSD and apoptosis-related genes in luteal tissues (at 30, 60, and 90 days of gestation) and cells from early gestation in cattle. The corpus luteum altered the number of large lutein cells from 30-90 days. The change in the junction of the connective tissue appeared to affect the density of the corpus luteum. In addition, 20α-HSD was detected in the corpus luteum and cultured cells during early pregnancy, in contrast to the results of previous studies. The overall expression pattern of the 20α-HSD and Casp-3 proteins was lower on day 50 of gestation than on days 30 and 90. However, the 20α-HSD expression gradually increased from 30 to 90 days of gestation. When the 20α-HSD protein was increased to 0.5 μg/ml, 1 μg/ml, and 1.5 μg/ml in the luteal cells collected on day 30 of pregnancy, apoptosis was analysed after 48 hours. 20α-HSD generated in the cells was confirmed, and the concentration gradually decreased as the concentration increased. However, the expression of Casp-3 showed an overall similar expression pattern. Notably, the 20α-HSD and Casp-3 proteins were lowest at 1.5 μg/ml supplemented with 20α-HSD, with higher levels in the cytosol than in the cytoplasm. These results suggest that 20α-HSD plays a role in maintaining normal pregnancy, particularly by regulating the progesterone concentrations during luteal cell development.