COX-2 Immunostaining Is Increased in LE During Early Pregnancy
The intensity of the red staining (Fig. 2) in the concep-tus, LE, and S was evaluated by image analysis (Fig. 3, BD). COX-2 staining linearly decreased with time (Fig. 3B) in the conceptus between d18P and d30P (R2 = 0.3, slope = —4, P < 0.005). In the LE, on the other hand, no significant effect of day was observed (Fig. 3C) during the cycle (regression analysis, P > 0.5), even though COX-2 intensity appeared stronger at d16C, the day of luteolysis. However, COX-2 was significantly stimulated during pregnancy (Fig. 3C) in the LE from d7P to d30P (R2 = 0.20, slope = 10, P < 0.005).
COX-2 was expected to follow the pattern of IFN-т production, thus being weakly expressed at d7P, increasing through d21P, and decreasing afterward. When examined separately by regression analysis, the up-regulation through time was confirmed between d7P and d21P (R2 = 0.4, slope = 19, P < 0.0005) but not between d21P and d30P, which rather showed a decreasing tendency, a regression plot with a negative slope (R2 = 0.1, slope = -13, P > 0.1). When d7, d16, and d18 were compared across status (pregnant vs. cyclic) by regression analysis, no effect of status was found (P > 0.1). In the S (Fig. 3D), no significant effect of day on COX-2 staining was observed either during the cycle or the pregnancy (regression analysis, P > 0.1). When d7, d16, and d18 were compared across status (pregnant vs. cyclic), again no effect of status was found (regression analysis, P > 0.1).