L-Carnitine Modulates Oocyte Development and Cumulus Expansion in Tropical Ruminants: Experimental and Bioinformatics Insights.

This study investigates the effects of L-carnitine on nuclear maturation and fertilization in cattle and goat oocytes. Ovaries were collected from females with poor reproductive efficiency in the tropical climate, and cumulus-oocyte complexes (COCs) were retrieved from large antral follicles. COCs were cultured with varying concentrations of L-carnitine (0, 0.5, 1, and 1.5 mg/mL for goats; 0, 0.25, 0.375, and 0.5 mg/mL for cattle). Cumulus expansion and nuclear maturation were assessed, while bovine oocytes underwent in vitro fertilization. Here, L-carnitine enhanced cumulus expansion and nuclear maturation, with the highest maturation rates at 1 mg/mL in goats and 0.375 and 0.5 mg/mL in cattle. Fertilization rates in cattle improved with L-carnitine supplementation, particularly at 0.375 and 0.5 mg/mL. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses revealed that L-carnitine modulates pathways related to oxidative stress reduction, glucose metabolism, and mitochondrial function. Protein-protein interaction network analysis identified key regulatory genes, including SOD2, SIRT3, IGFBP3, PRL, NOS2, NOX4, SOD1, HMOX1, LEP, and AKT1, which may mediate L-carnitine's effects on oocyte maturation and fertilization. In conclusion, L-carnitine supplementation enhances oocyte competence possibly by improving cellular metabolism and reducing oxidative stress, providing valuable insights for optimizing assisted reproductive technologies in ruminants.