Atuação da Oncostatina e da Leptina na regulação folicular e luteal em bovinos

Abstract

The Janus Kinase 2 (JAK2)/ Signal Transducer and Activator of Transcription 3 (STAT3) is an intracellular pathway that mediates extra cellular signals to several cell types and tissues and can be activated by several molecules. In the ovaries, recent studies demonstrated that there is a great presence of phosphorylated STA3 in subordinate follicles in process of apoptosis. The hypothesis of this study is that this route can be activated by OSM or leptin and initiate the process of apoptosis mediated by STAT3. OSM is a cytokine of the IL-6 family, mainly produced by macrophages and is involved in hematopoiesis, inflammation, central nervous system development, but its role in the ovary is still unknown. No OSM relative transcription was detected during divergence and ovulation, but its receptor was present during the luteal phase, when both were expressed and regulated after treatment with PGF. Incubation of granulosa cells with OSM modulated the relative transcription of OSMR and XIAP, as well as the ratio between the BAX/BCL2 genes. Leptin is primarily secreted by adipocytes and involved in energy balance, being responsible for satiety, acting in the central nervous system, inflammation, bone formation, angiogenesis, fetal development and reproduction. However, its function is still not well defined and the literature is somewhat controversial regarding to its function in the ovaries. Immunohistochemistry revealed greater intensity of leptin and its receptor in subordinate follicles, as well as a change in the relative transcription of LEPROT, ADIPOR1, ADIPOR2 genes in dominant and subordinate follicles. Intrafollicular injection of leptin (100 or 1000ng / ml) in vivo had no effect under ovulation. There was no change in the relative transcription of steroidogenesis-related genes in granulosa cells cultured in vitro.