Luteinising hormone receptor kinetic and LH-induced prostaglandin production throughout the oestrous cycle in porcine endometrium

The present studies were performed to determine the LH/hCG receptor concent ration and to evaluate the LH effect on prostaglandin production in porcine endometrium throughout the oestrous cycle. LH/hCG receptors in cell membra ne preparations of the endometrium were found from days 12-14 and 15-16 of the oestrous cycle but not in preparations from days 6-7 and 18-20 using th e ligand radioreceptor assay. Western blot analysis revealed, however, that the endometrium from all stages of the oestrous cycle contains a 75-kDa im munoreactive LH receptor protein similar to corpora lutea. The incubation o f endometrial explants with LH (0, 1, 10 and 100 ng.mL(-1)) resulted in an increase of 13,14-dihydro-15-keto-PGF(2 alpha) accumulation in a dose-depen dent manner on days 5, 10, 14 and 16 of the oestrous cycle. The most effect ive dose was 10 ng LH.mL(-1) on days 5-16, but the strongest effect was fou nd on days 14 and 16(7.40 +/- 0.14 versus 12.75 +/- 1.40 and 5.67 +/- 0.35 versus 9.4 +/- 1.25 ng.100 mg(-1) tissue/6 h, respectively; P < 0.01). It w as also observed that 10 and 100 ng.mL(-1) of LH significantly increased cy clo-oxygenase expression to 135.2 and 123.5 % respectively, above the contr ol value (P < 0.01) on day 16 of the oestrous cycle. Our data suggest that LH receptors are of physiological significance in the porcine endometrium, since LH induces cyclooxygenase synthesis and increases prostaglandin produ ction. (C) Inra/Elsevier, Paris.