Synthesis and release of prostaglandins D2 and E2 by rat uterine tissue throughout the sex cycle. Effects of 17-beta-estradiol and progesterone.

The synthesis and release of prostaglandins (PGs) D2 and E2 by rat uterine tissue was studied during the whole sex cycle. The PGs released into the bathing solution after 60 min of incubation were measured by specific radioimmunoassays. It was found that PGD2 released at diestrous was significantly higher than at proestrous and estrous. We also observed that PGE2 produced at diestrous was significantly higher than at proestrous and estrous, i.e. both PGs follow the same pattern of production throughout the sex cycle, but in all cases the uterine strips released higher amounts of PGE2 than of PGD2. The influence of the sex hormones on PGD2 and PGE2 synthesis, was also studied. We observed that the treatment of ovariectomized rats with 17-beta-estradiol decreased significantly the synthesis and release of PGD2 and PGE2. On the other hand, progesterone treatment did not modify the production of PGE2 but decreased significantly the synthesis of PGD2. In conclusion, in the present study we have found that PGD2 and PGE2 production varied similarly during the sex cycle and that 17-beta-estradiol negatively regulates their synthesis. In addition, we have found that progesterone depressed only PGD2 synthesis without affecting PGE2 production.