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

Abstract

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.