SYNTHESIS AND RELEASE OF PROSTAGLANDINS D-2 AND E(2) BY RAT UTERINE TISSUE THROUGHOUT THE SEX CYCLE - EFFECTS OF 17-BETA-ESTRADIOL AND PROGESTERONE

The synthesis and release of prostaglandins (PGs) D-2 and E(2) 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 PGD(2) released at diestrous was significantly higher than at proestrous and estrous. We also observed that PGE(2) 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 the cases the uterine strips released higher amounts of PGE(2) than of PGD(2). The influence of the sex hormones on PGD(2) and PGE(2) synthesis, was also studied. We observed that the treatment of ovariectomized rats with 17-beta-estradiol decreased significantly the synthesis and release of PGD(2) and PGE(2). On the other hand, progesterone treatment did not modify the production ofPGE(2) but decreased significantly the synthesis of PGD(2). In conclusion, in the present study we have found that PGD(2) and PGE(2) 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 PGD(2) synthesis without affecting PGE(2) production.