Rapamycin Rescues the Poor Developmental Capacity of Aged Porcine Oocytes

Abstract

Unfertilized oocytes age inevitably after ovulation, which limits their fertilizable life span and embryonic development. Rapamycin affects mammalian target of rapamycin (mTOR) expression and cytoskeleton reorganization during oocyte meiotic maturation. The goal of this study was to examine the effects of rapamycin treatment on aged porcine oocytes and their in vitro development. Rapamycin treatment of aged oocytes for 24 h (68 h in vitro maturation [IVM]; 44 h+10 μM rapamycin/24 h, 47.52±5.68) or control oocytes (44 h IVM; 42.14±4.40) significantly increased the development rate and total cell number compared with untreated aged oocytes (68 h IVM, 22.04±5.68) (p<0.05). Rapamycin treatment of aged IVM oocytes for 24 h also rescued aberrant spindle organization and chromosomal misalignment, blocked the decrease in the level of phosphorylated-p44/42 mitogen-activated protein kinase (MAPK), and increased the mRNA expression of cytoplasmic maturation factor genes (MOS, BMP15, GDF9, and CCNB1) compared with untreated, 24 h-aged IVM oocytes (p<0.05). Furthermore, rapamycin treatment of aged oocytes decreased reactive oxygen species (ROS) activity and DNA fragmentation (p<0.05), and downregulated the mRNA expression of mTOR compared with control or untreated aged oocytes. By contrast, rapamycin treatment of aged oocytes increased mitochondrial localization (p<0.05) and upregulated the mRNA expression of autophagy (BECN1, ATG7, MAP1LC3B, ATG12, GABARAP, and GABARAPL1), anti-apoptosis (BCL2L1 and BIRC5; p<0.05), and development (NANOG and SOX2; p<0.05) genes, but it did not affect the mRNA expression of pro-apoptosis genes (FAS and CASP3) compared with the control. This study demonstrates that rapamycin treatment can rescue the poor developmental capacity of aged porcine oocytes.

Effect of L-carnitine supplementation on maturation and early embryo development of immature mouse oocytes selected by brilliant cresyle blue staining

“…GDF-9 (a member of the transforming growth factor-β family: TGF-β) is an oocyte-secreted growth factor that plays essential roles in oocyte maturation, cumulus expansion, and oogenesis [47]. It has been shown that the cytoplasmic maturation can be assayed through the expression of GDF-9 and GSH levels [38,47,48]. Exposure of COCs during oocyte maturation to oocyte-secreted factors (OSFs) such as GDF-9 significantly enhanced oocyte developmental competence [49].…”

Allicin protects porcine oocytes against damage during aging in vitro

“…Moreover, these factors are important determinants of the efficiency of embryo production in vitro. Indeed, these parameters decrease when oocytes are exposed to stresses such as aging (Lee et al, ), oxidative stress induced by H 2 O 2 or sodium fluoride (Liang et al, ; Yazaki, Hiradate, Hoshino, Tanemura & Sato, ), and heat stress induced by high temperature (Gharibzadeh et al, ). In this study, oocyte survival and PB extrusion rates were lower in the 0 AL group than in the control group, and these decreases were prevented in the 1 AL group (Table ).…”

“…Spindle microtubules span from centrosomes to centromeres and regulate the cell cycle by arranging the chromosomes (Rienzi et al, ). When a matured oocyte is not fertilized, the ultrastructures of centrosomes and microtubules are disrupted, leading to spindle abnormalities and chromosome unpacking (Lee et al, ; Saito et al, ). We found that the percentage of oocytes with normal spindles decreased upon in vitro aging, and that allicin treatment prevented this decrease (Figure ).…”

“…Oocyte quality is a key factor determining embryo competency, regardless of whether maturation occurs under normal or stress conditions. Oocytes whose quality is decreased by aging or exposure to oxidative stress have a reduced developmental potential (Lee et al, ; Liang et al, ). Consistent with this, we found that the blastocyst formation rate was significantly lower in the 0 AL group than in the 1 AL group.…”

“…Very little information is available about antiaging effectors in oocytes, and the mechanism for rescuing or preventing oocyte aging Several studies have investigated the degradation of oocyte quality with aging time. Embryos from oocytes aged for more than 48 hr rarely develop into blastocysts (Lee et al, 2014;Miao et al, 2018;Němeček, Dvořáková, Heroutová, Chmelíková, & Sedmíková, 2017). Although aging for 24 hr also decreases oocyte competence, this effect can be recovered by antiaging systems (Lee et al, 2014;Ma, Zhang, Zhang, Han, & Rui, 2015).…”