Antioxidant enzymatic defence systems in sheep corpus luteum throughout pregnancy

Abstract

The activities of copper, zinc-superoxide dismutase (SOD1), manganese SOD (SOD2), glutathione peroxidase (GPX), glutathione reductase (GSSG-R) and glutathione S-transferase (GST) were studied in sheep corpora lutea (CL) obtained on days 15, 40, 60, 80 and 128 of pregnancy. Maintained enzymatic activity of SOD1, SOD2, GPX, GSSG-R and GST were found in the sheep CL throughout pregnancy. Enzymatic activity of SOD1, GPX and GST increased significantly from day 15 to day 40 of pregnancy, and thereafter remained constant until day 128. SOD2 and GSSG-R activities were not different between any days of pregnancy examined. Apoptotic luteal cells identified by the terminal deoxynucleotidyl transferase-mediated fluoresceindUTP nick-end labelling were very rarely observed, and their incidence (less than 0.5%) was not different between days of pregnancy. These results showed that the activities of antioxidant enzymes in the sheep CL are subject to major changes during early pregnancy, suggesting that the CL of early pregnancy may be rescued from luteolysis through increasing activities of key antioxidant enzymes and inhibition of apoptosis. Maintained levels of antioxidant enzymes in the CL throughout pregnancy may be linked to reactive oxygen species continuously generated in the steroidogenically active luteal cells, and may be involved in the maintenance of luteal steroidogenic activity and cellular integrity.

Ovine corpus luteum proteins, with functions including oxidative stress and lipid metabolism, show complex alterations during implantation

“…Our finding of a significant increase in SOD2 expression in ovine CL in the late luteal phase agrees with the previous findings that CL SOD2 activity increases from mid luteal to late luteal phase in women (Sugino et al 2000) and sheep (Al-Gubory et al 2005). Moreover, SOD2 expression in CLs of pregnant ewes on days 12, 16 and 20 did not alter, in agreement with the previous findings for SOD2 activity (Al-Gubory et al 2004). SOD2 mRNA is induced in the rat CL by inflammatory cytokines (Sugino et al 1998), which are involved in CL regression (Niswender et al 2000).…”

“…Increased expression of GSTA1 in CL from day 12 to day 16 of pregnancy (this study) is likely an important mechanism protecting the early developing CL against ROS-mediated cell damage. This agrees with the observations that ovine CL GST activity significantly increases from day 15 to day 40 of pregnancy (Al-Gubory et al 2004).…”

The Influence of Dehydroepiandrosterone on Early Pregnancy in Mice

“…During normal pregnancy, an increased antioxidant status has been reported [17] . Moreover, it has been proposed that the activities of antioxidant enzymes in the corpus luteum are subject to major changes during early pregnancy, suggesting that the corpus luteum of early pregnancy may be rescued from luteolysis through increasing activities of key antioxidant enzymes or metabolites and inhibition of apoptosis [18] .…”

Improvement of Conception in Sheep Using Different Hormonal Treatments during Mating and their Influence on the Antioxidant Status

“…Previous reports showed that the activities of antioxidant enzymes in the sheep corpus luteum (CL) are subject to major changes during early pregnancy, suggesting that the CL of early pregnancy may be rescued from luteolysis through increasing activities of key antioxidant enzymes and inhibition of apoptosis. Maintained levels of antioxidant enzymes in the CL throughout pregnancy may be linked to reactive oxygen species continuously generated in the steroidogenesis activity of luteal cells, and may be involved in the maintenance of luteal steroidogenic activity, cellular integrity and preventive to oxidative stress, improving pregnancy outcomes [27]. Even though the total antioxidant levels were not significantly different, some changes for single antioxidants such as vitamin E, as well as neuroendocrinology-related CART level [28].…”