Tumor necrosis factor-alpha gene expression in mouse oocytes and follicular cells

Abstract

Ovarian cells that transcribe and translate the gene for tumor necrosis factor alpha (TNF alpha) were identified in the adult cyclic mouse by using in situ hybridization and immunocytochemistry. TNF alpha mRNA was observed in > 97% and protein was contained in approximately 53% of the oocytes of healthy follicles with two or more layers of granulosa cells, but neither was detectable in oocytes of primordial follicles and follicles with a single layer of granulosa cells. In early atretic follicles, only 13% contained TNF alpha protein and 40% contained TNF alpha mRNA. In late stages of atresia, intense immunoreactive TNF alpha was observed in all of the oocytes, but TNF alpha mRNA was present in only 13%. In approximately 85% of follicles, theca and/or granulosa cells exhibited TNF alpha mRNA hybridization signals. Macrophage-like cells within the interstitium were positive for TNF alpha mRNA and protein. In corpora lutea, luteal cells and macrophage-like cells contained TNF alpha message, while only the latter lineage contained immunoreactive TNF alpha. Hybridization signals and immunoreactivity were more intense in older corpora lutea than in corpora lutea of the present cycle. Northern blot analysis revealed a 2.2-kb TNF alpha mRNA in the ovary that was unchanged relative to 28S rRNA (constitutive RNA) during the cycle. Similarly, TNF alpha hybridization signals and immunoreactivity did not appear to change throughout the cycle. These results indicate that TNF alpha gene transcription in the oocyte coincides with the synthesis of immunoreactive TNF alpha and that these complex biochemical processes occur at distinct steps of follicular development in the mouse.(ABSTRACT TRUNCATED AT 250 WORDS)