Role of nitric oxide on uterine and ovarian prostaglandin synthesis during luteolysis in the rat

MOTTA, ALICIA BEATRIZ; FRANCHI ANA MARIA; GIMENO MARTA

PROSTAGLANDINS LEUKOTRIENES AND ESSENTIAL FATTY ACIDS

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 1997 vol. 56 p. 265 - 269

0952-3278

In previous studies in our laboratory, we demonstrated that oxytocin (oxy) augmented prostaglandin F2~(PGF2~) synthesis via enhancing the uptake of Ca2+ by uterine tissue. On the other hand, we have shown that oxyenhances PGF2~ synthesis in uterine and ovarian tissues during the corpus luteum (CL) regression in the rat. In thepresent study we explore the possible relation between endogenous nitric oxide (NO) and oxy on PGs synthesisduring the luteolytic phase in the rat. The experiments were done in uterine and ovarian preparations isolated frompseudopregnant (psp) rats during the luteolytic phase. Tissues were incubated "in vitro" with 1)- oxy (50 mU/ml), 2)-NMMA (NG-monomethyI-L-arginine), a potent NOs inhibitor (300 uM), and 3)- both reagents (oxy + NMMA). NMMAdecreases the synthesis of both PGs (PGE and PGF2~,) and oxy enhances PGF2~ synthesis in uterine and ovariantissue. When reagents were used in combination (oxy + NMMA), we found different results in uterus and ovaries; i.e.,in uterine tissue the NO inhibition did not affect the increase of PGF2~ synthesis by oxy. Meanwhile, in ovaries the oxyeffect over the PGF2~ synthesis was not seen when NOs was inhibited. Probably oxy acts via different mechanisms onPGF2~ synthesis in uterine and ovarian tissue. This assumption was confirmed when the NOs activity in both tissues(uterine and ovarian) was measured after oxy treatment. We found that oxy enhanced the NOs activity in ovariantissues from psp rats but did not modify the enzyme activity in uterine tissue.