Phospholipase A2 expression during the estrous cycle and early pregnancy
Date of Award
Master of Science
James D. Godkin
Patricia K. Tithof, Jun Lin
Acute control of prostaglandin production is essential for normal estrous cyclicity and maintenance of early pregnancy. The rate limiting step for prostaglandin production is the activation of Phospholipase A2. There are many phospholipase A2s, but few have been investigated in reproductive studies. The objective of this study was to examine PLA2 Groups IV and VI protein and mRNA expression in the uterine endometrium during the estrous cycle and early pregnancy in ewes. Ewes were monitored for estrous and uterine tissues were collected surgically on days 5 (n=3), 10(n=3) and 15(n=3) of the estrous cycle. Endometrium from pregnant animals were harvested on days 14(n=3), 15(n=1), 16(n=2), 17(n=1) or 20(n=2). Endometrial scrapings were collected in attempts to harvest luminal epithelial cells primarily and tissue samples were collected to harvest samples containing all cellular endometrial components. Samples were analyzed by western blot analysis and qRT-PCR to detect protein and mRNA expression of both PLA2s Group IV and VI. Western blot results revealed that protein expression of Group IVA was greatest on day ten of the estrous cycle but was not significantly different form days 5 and 15, possibly due to animal variation. Group IVA was significantly elevated on day 14 of pregnancy (P<0.05) and remained elevated until day 16 when it diminished and a 50kD band appeared. Group VIA analysis showed a cross-reactive 50kD band that showed no significant change. qRT-PCR analysis for Group IVA of scraping samples revealed similar findings showing not only an increase of Group IVA mRNA at pregnancy but also during day 10 of the estrous cycle (P<0.0001) but little difference was seen in tissue samples (P<0.0001). Group VIA was shown to have no mRNA difference in both tissue and scraping samples. These results suggest that PLA2 expression is not the sole regulator of prostaglandin production, but it does play an integral role that is tissue and cell type specific in both the estrous cycle and early pregnancy.
Ochs, Gregory Joseph, "Phospholipase A2 expression during the estrous cycle and early pregnancy. " Master's Thesis, University of Tennessee, 2008.