CPT1A alters granulosa cell proliferation and steroidogenic activity in association with fatty acid oxidation during goat follicular development

Follicular development in goats relies on the extensive proliferation and hormone synthesis of granulosa cells (GCs), processes that require an adequate energy supply. Fatty acid oxidation (FAO) represents a primary energy source for granulosa cells. However, how its rate-limiting enzyme, carnitine palmitoyltransferase 1A (CPT1A), modulates granulosa cell function remains unclear. This study examined CPT1A expression in healthy and atretic follicles and investigated its association with FAO-associated gene expression, ATP generation, proliferation, steroidogenesis, and palmitic acid (PA)-induced ferroptosis-associated responses in goat granulosa cells. Compared with healthy follicles, CPT1A protein expression was significantly higher in atretic follicles. In vitro experiments demonstrated that CPT1A overexpression upregulated the expression of FAO-associated genes and elevated intracellular ATP levels, whereas CPT1A knockdown produced the opposite effects. Moreover, CPT1A expression was positively associated with granulosa cell proliferation and steroidogenesis, as evidenced by increased PCNA expression, EdU-positive rates, the expression of steroidogenesis-associated proteins, and the secretion of estradiol and progesterone. Conversely, CPT1A knockdown inhibited cell proliferation and reduced steroidogenic activity. Additionally, PA treatment increased CPT1A expression, which was accompanied by ferroptosis-associated changes, including elevated lipid peroxidation and ROS accumulation, alongside reduced GSH levels. In summary, this study reveals the critical role of CPT1A as a potential metabolic regulator in goat granulosa cells, providing new insights into the metabolic mechanisms underlying follicular development and suggesting that CPT1A may serve as a key molecular target for understanding reproductive regulation in goats.