Abstract
To investigate the role of locally produced prostaglandin F2α (PGF2α) in luteal function, luteal PGF2α and plasma levels of progestins, progesterone, and 20α-hydroxypregn-4-en-3-one (20α-OHP) were measured during pseudopregnancy in PMSG-primed immature rats. Plasma pro-gesterone increased from the basal level at 0700 h on day 1 of diestrus (D1) and reached the peak level at 1800 h on D2. The plateau level was maintained until D6 and decreased to the basal level on D7. 20α-OHP in plasma increased temporally from D1 to D3 and showed a gradual increase until D8. PGF2α content in the corpus luteum was low (5.2-7.7 pg/CL) until D3 and increased significantly (P<0.05) on D4 and D5. After that, luteal PGF2α declined to a basal level as low as that before D3. These results show that a rise in luteal PGF2α preceded the decline of progesterone levels and suggest that the increase in endogenous PGF2α may initiate the functional regression of the corpus luteum in immature pseudopregnant rats.
