Possible role of PPARγ in the negative regulation of ovulatory cascade andluteal development in rats

[摘要] Peroxisome proliferator-activated receptor γ (PPARγ), a member of a nuclear receptorfamily, has been shown to be implicated in various reproductive processes. Here, weevaluated possible roles of PPARγ in ovulation and luteal development in agonadotropins-primed immature rat model. Immunoreactive PPARγ was expressed in granulosacells of eCG-stimulated mature follicles, and its expression level decreased followingovulatory hCG stimulus. Intra-bursal treatment with rosiglitazone (a PPARγ agonist)simultaneously with subcutaneously administered hCG blocked the induction ofcyclooxygenase-2 and steroidogenic acute regulatory protein (StAR) in preovulatoryfollicles. Consistently, tissue levels of their respective products, prostaglandin (PG)E2 and progesterone (P4), were reduced, leading to significantly decreasedovulation rate. GW9662, a PPARγ antagonist, was almost ineffective to alter those values.Local treatment with rosiglitazone 24 hr after hCG administration caused reductions in thesize, StAR expression and P4 secretion of corpus luteum 48 hr later. Obtained data arepossible functional evidence with rats for granulosa cell PPARγ as a negative regulator ofPG and P4 synthesis during follicle rupture and transformation to luteal tissue.LH/hCG-induced decreases in PPARγ expression and its activity would be an early componentin the proper induction of following ovulatory cascade and luteal development.

[学科分类] 兽医学

[关键词] luteal formation;ovulatory cascade;PPARγ;rat;rosiglitazone