Indomethacin, ketoprofen and corpus luteum regression in the guinea-pig

1 The accelerated regression of the corpora lutea normally produced by glass beads inserted unilaterally into the uterus of the guinea-pig early in the oestrous cycle was prevented when the beads were filled with indomethacin or ketoprofen. 2 Luteal regression was enhanced by the placement of beads in both horns of the uterus. When empty beads were placed in one horn of the uterus and drug-filled beads in the other, indomethacin blocked regression in both ovaries whereas ketoprofen was ineffective. 3 Indomethacin probably blocks luteal regression by inhibition of prostaglandin syntheses in the uterus.