Untersuchung TNF-[alpha]-vermittelter Effekte auf präovulatorische Ovarien von Jungsauen

The process of ovulation has been linked to an inflammatory reaction, which includes the infiltration of different leukocyte populations into the tissue of mature Graafian follicles, the activation of resident immune cells and the local production of cytokines. Hypothetically, cytokines produced in the nearby uterus may reach the ovary via a so called counter current transfer, in parts where the uterus vein is neighboured by the arteria ovarica. In the present study, we tested the hypothesis that TNF-α reaching the porcine ovary via the arteria ovarica triggers resident mast cells and thereby induces degranulation and mediator secretion which eventually promote preovulatory events. A bilateral surgical approach in the pig using 14 spontaneous cycling gilts was used. Recombinant porcine TNF-α at 2 or 20 ng in one ml was injected into the ovarian artery of one side and PBS into the contralateral side up to 10 h after the detection of oestrus. The ovaries were ectomized 45 min later. Follicular fluid was aspirated and analysed for histamine concentrations. Ovarian tissue was dissected into four regions to be analysed by histology, immunohistochemistry and quantitative RT-PCR. The Pappenheim stain was used for the quantitative analysis of mast cells. Immunohistochemistry was performed using specific anti-TNF-α and anti-TNF-α receptor I antibodies. The mRNA expression of eight chemokines, cytokines and enzymes (TNF-α, GM-CSF, TGF-s, IL-10, CXCL8, IL-6, PTGS2, lipoxygenase-5) was analysed by qRT-PCR. An in vivo model for delivering cytokine-mediated effects to the porcine ovary was established successfully. In this study no evidence was found for a direct action of mast cell-mediated TNF-α dependent effects on preovulatory follicles. Nontheless, we cannot rule out, that TNF-α may influence preovulatory follicles in the porcine system - a variety of cells located in ovarian tissue may act as a target for direct TNF-α mediated effects. The selective upregulation of the pro-inflammatory PTGS2 and the selective down-regulation of other pro-inflammatory mediators (TNF-α, CXCL8) caused by TNF-α-application indicates that the ovulatory cascade is not a classical inflammatory response.