Effects of prostaglandin F2 alpha and its synthesis inhibitor indomethacin on corporaluteal functions in pseudopregnant rats.

ABSTRACT

The effects of PGF2 alpha and its synthesis inhibitor indomethacin on corporaluteal (CL) functions were studied in adult pseudopregnant rats. The CL functions were assessed by studying the duration of pseudopregnancy and histological changes in the ovary. Administration of PGF2 alpha (4 mg/kg BW) significantly (P less than 0.001) shortened the duration of pseudopregnancy. Histological examination of ovaries revealed regressed CL. Administration of indomethacin, on the other hand, significantly (P less than 0.001) prolonged the duration of pseudopregnancy. Histological examination of ovaries revealed large and well formed CL, the diameters of which were significantly (P less than 0.05) increased. Administration of indomethacin and PGF2 alpha simultaneously, however, keeps the duration of pseudopregnancy within normal limit. Further, the shortening in the duration of pseudopregnancy by PGF2 alpha alone was completely reversed by exogenous administration of progesterone. Since PGF2 alpha shortens and indomethacin (an inhibitor of PGF2 alpha synthesis) prolongs the duration of pseudopregnancy, it is concluded that PGF2 alpha acts as a luteolytic agent in rats. The mechanism of luteolysis is most likely to be due to decrease plasma progesterone level. An estimation of blood progesterone level after administration of PGF2 alpha to pseudopregnant rats is therefore, suggested.