RESUMO
In vivo, the temperature inside preovulatory follicles of cows is approximately 1 °C lower than rectal temperature. However, standard bovine oocyte in vitro maturation (IVM) protocols use 38.5 °C based on rectal temperature. This study evaluated the effect of reducing IVM temperature to 37.5 °C on the proteomic profile of oocytes compared to the routine 38.5 °C. Nuclear maturation rate and cumulus cell (CC) expansion (30 COCs per group, 21 replicates) were assessed by observing the first polar body and using a subjective scoring method (0-4). Total nitrite concentrations in the culture medium were measured using the Griess method. Differential proteomics was performed using LC-MS/MS on pooled oocyte samples (500 matured oocytes per group, three replicates), followed by gene ontology enrichment, protein-protein interaction, and putative miRNA target analyses. No significant differences were observed between the groups in nuclear maturation, CC expansion, or nitrite concentration (P > 0.05). A total of 806 proteins were identified, with 7 up-regulated and 12 down-regulated in the treatment group compared to the control. Additionally, 12 proteins were unique to the control group, and 8 were unique to the treatment group. IVM at 37.5 °C resulted in the upregulation of proteins involved in protein folding and GTP binding, and the downregulation of enzymes with oxidoreductase activity and proteins involved in cytoskeletal fiber formation. Furthermore, 43 bovine miRNAs potentially regulating these genes (DES, HMOX2, KRT75, FARSA, IDH2, CARHSP1) were identified. We conclude that IVM of bovine oocytes at 37.5 °C induces significant proteomic changes without impacting nuclear maturation, cumulus cell expansion, or nitrite concentration in the IVM medium.
Assuntos
Técnicas de Maturação in Vitro de Oócitos , Oócitos , Proteômica , Animais , Bovinos , Técnicas de Maturação in Vitro de Oócitos/veterinária , Oócitos/fisiologia , Feminino , Temperatura , ProteomaRESUMO
A L-arginina (L-arg) é o principal precursor da síntese do NO, contudo, é precursora também da síntese de creatina, agmatina, ureia, síntese proteica, L-ornitina, poliaminas, L-prolina e L-glutamato. Nesta breve revisão, vamos falar de alguns resultados que estão sendo obtidos sobre o papel da L-arg na capacitação de espermatozoides bovinos e seu impacto na produção in vitro de embriões. Estudos in vitro mostraram que a adição de L-arg ao meio de capacitação espermática está associada a um aumento na produção de NO, que se correlaciona com aumento da motilidade e vigor, integridade da membrana plasmática e acrossomal, atividade mitocondrial, capacitação espermática, peroxidação lipídica, bem como com a produção de blastocistos. Além disso, a adição da L-arg ao meio de capacitação in vitro, altera o perfil de proteínas importantes ligadas ao processo de capacitação, fertilização e desenvolvimento embrionário inicial. Estes efeitos da L-arg são GMPc dependentes e independentes. Na maturação in vitro, entretanto, embora já tenham sido encontrados bons resultados com o uso do L-arg, mais estudos são necessários para determinar a concentração ideal a ser adicionada ao meio de maturação in vitro e seu impacto na produção de blastocistos. Visto que a pré-capacitação de espermatozoides induzida pela heparina em presença de L-arg foi o método mais eficiente na produção in vitro de embriões, sugerimos sua utilização. Mais pesquisas sobre o metabolismo da L-arg no espermatozoide e CCOs de bovinos durante eventos ligados à fertilização são necessários para se identificar novas vias que atuem nestas etapas in vitro visando o aumento da percentagem e qualidade de embriões bovinos produzidos in vitro.
L-arginine (L-arg) is the main source of NO synthesis; however, it is also a precursor of the synthesis of creatine, agmatine, urea, protein synthesis, L-ornithine, polyamines, L-proline, and Lglutamate. In this brief review, we will discuss some results obtained previously about the role of L-arg in the capacitation of bovine sperm and its impact on in vitro embryo production. In vitro studies have shown that the addition of L-arg to the sperm capacitation medium is associated with an increase in NO production, which in controlled levels is related to an increased motility and vigor, plasma and acrosomal membrane integrity, mitochondrial activity, sperm capacitation, peroxidation lipids, as well as with the blastocyst production. Furthermore, the addition of L-arg to the in vitro capacitation medium alters the profile of important proteins linked to the capacitation process, fertilization, and early embryonic development. These effects of L-arg are cGMP dependent and independent. In in vitro maturation, however, although good results have already been found with the use of L-arg, further studies are needed to determine the ideal concentration to be added to the in vitro maturation medium and its impact on the production of blastocysts. Since heparin-induced pre-capacitation of spermatozoa in the presence of L-arg was the most efficient method for in vitro embryo production, we suggest its use. More research on L-arg metabolism in bovine sperm and OCCs during events related to fertilization is needed to identify new pathways that act in these in vitro steps aiming to increase the percentage and quality of bovine embryos produced in vitro.