Follicular Atresia in Buffalo: Cocaine- and Amphetamine-Regulated Transcript (CART) and the Underlying Mechanisms

Simple Summary In the present study, we aimed to explore the potential local regulatory role of the cocaine- and amphetamine-regulated transcript (CART) signaling pathway in granulosa cell (GC) apoptosis, which is a key mechanism promoting follicular atresia in several animal species, including buffalo. Our results showed how CART activity adversely influences buffalo GC viability by affecting estradiol production and enhancing apoptosis. The regulatory mechanism by which CART can affect GC apoptosis entails the modulation of the AKT/GSK3 beta/beta-catenin pathway, a key intracellular signaling pathway essential for cell viability. In conclusion, this study provides valuable insights into the intricate mechanisms governing ovarian follicle development and granulosa cell function. These findings have implications for reproductive biology not only for buffalo but also for different species.Abstract Atresia is a process in ovarian follicles that is regulated by hormone-induced apoptosis. During atresia, granulosa cell (GC) apoptosis is a key mechanism orchestrated through diverse signaling pathways. Cocaine- and amphetamine-regulated transcript (CART) signaling within ovarian GCs has been demonstrated to play a key role in the regulation of follicular atresia in cattle, pigs, and sheep. The present work aimed to investigate the potential local regulatory role of CART in GC apoptosis-induced follicular atresia in buffalo, focusing on the modulation of the AKT/GSK3 beta/beta-catenin signaling pathways, which are the intracellular signaling pathways involved in cell viability. Our findings revealed increased expression of CARTPT and BAX and decreased levels of AKT, beta-catenin, and CYP19A1 genes in atretic follicles compared to healthy follicles. Subsequently, CART treatment in the presence of FSH inhibited the FSH-induced increase in GC viability by reducing estradiol production and increasing apoptosis. This change was accompanied by an increase in the gene expression levels of both CARTPT and BAX. At the protein level, treatment with CART in the presence of FSH negatively affected the activity of AKT, beta-catenin, and LEF1, while the activity of GSK3 beta was enhanced. In conclusion, our study shows how CART negatively influences buffalo GC viability, underlying the modulation of the AKT/GSK3 beta/beta-catenin pathway and promoting apoptosis-a key factor in follicular atresia.