Metabolismo de lipídios em complexo cumulus-ovócito durante a maturação in vitro em suínos

Abstract

The swine species has physiological similarities with humans and is therefore widely used in genomic editing studies focusing on research related to human diseases and xenotransplantation. However, in vitro embryo production (IVEP) of pigs, necessary for genomic editing studies, has a low efficiency due, among other things, to the competence of the oocytes, which affects in vitro maturation (IVM). It is known that oocytes from prepubertal females are less competent, however, the reasons remain not fully understood. Many studies have related lipid metabolism to oocyte competence, as it is an important energy source for gamete maturation. Therefore, understanding how the female's age affects the lipid metabolism of the cumulus-oocyte complex during IVM is necessary for adapting and improving IVM protocols. In pubertal females, which have more competent oocytes, the gamete showed an accumulation of lipids during IVM, which, apparently, is a result of the contribution of cumulus cells and follicular fluid composition. Furthermore, the lipophagy pathway in these gametes seems to be active for maintaining lipid homeostasis to avoid lipid excess during IVM and lipotoxicity during early embryonic development. On the other hand, the less competent oocytes, belonging to the prepubertal gilts, presented opposite mechanisms to those presented by the cyclic sows in relation to the lipid metabolism. In these gametes, there was a decrease in the amount of lipids during IVM, which indicates an active lipolytic activity. However, the lipophagy pathway is apparently silenced or reduced, indicating that, in porcine oocytes, lipolysis and lipophagy may be opposite pathways, but both contribute to maintaining the amount of lipids. The presented results show that, in fact, the oocytes of pre-pubertal gilts are not yet ready to be matured, as they have not acquired competence during the final stages of folliculogenesis. Therefore, these gametes need new in vitro maturation protocols that guarantee a more similar behavior to competent gametes.