Changes in Plasminogen Activity in Uterus Tissue during the Estrous Cycle in the Pigs

This study investigated the changes of plasminogen activators (PAs) activity, expression and localization of tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) during the estrous cycle in pigs. Estrous cycle was sorted into three group by pre-ovulation (Pre-Ov), post-ovulation (Post-Ov) and early to mid-luteal stages (Early to mid-L). Analysis for immunohistochemistry was confirmed by location of tPA and uPA. Porcine uterus tissue was cut into $1{\times}1$ cm squares, and were incubated in DMEM/F-12 medium for 1 h at $38^{\circ}C$, 5% $CO_2$ for measurement of PA activity. Western blotting was implemented for measurement of PA quantity. In results, the blood vessels and secretory glands were increased in Post-Ov stage than Pre-Ov and Early to mid-L stages. The tPA and uPA was located mainly within lumen of blood vessels and secretory glands. The PA activity in Post-Ov ($0.99{\pm}0.03$) stage were significantly (p<0.01) higher than Pre-Ov stage ($0.51{\pm}0.03$) and Early to mid-L stage ($0.21{\pm}0.04$). Expression of PAs were significantly (p<0.05) higher in Early to mid-L stage than other stages. These results indicate that PAs activity and expression may change in uterus tissue during the estrous cycle in pigs.