The autophagic inducer and inhibitor display different activities on the meiotic and developmental competencies of porcine oocytes derived from small and medium follicles

This study aimed to examine the effect of rapamycin (autophagy inducer) and 3-methyladenine (3-MA, autophagy inhibitor) on the meiotic and developmental competencies of porcine oocytes derived from medium follicles (MF, 3-6 mm in diameter) and small follicles (SF, 1-2 mm in diameter) during in vitro maturation (IVM) process. The presence of 1 nM but not 10 nM rapamycin significantly increased the maturation rate of MF-derived oocytes (P < 0.05). However, the maturation rate of SF-derived oocytes was not affected by rapamycin at both concentrations (1 nM and 10 nM). The maturation rate of MF-derived oocytes decreased significantly (P < 0.05) in the presence of 0.2 mM but not 2 mM 3-MA than non-supplemented control. In contrast, in SF-derived oocytes, 3-MA at both 0.2 and 2 mM concentrations did not affect the maturation rates. The presence of 1 nM rapamycin significantly increased the blastocyst formation rate of MF-derived mature oocytes following parthenogenetic activation (P < 0.05). However, the blastocyst formation rate of SF-derived mature oocytes was not affected by the presence of rapamycin. The presence of 3-MA significantly reduced the blastocyst formation rate of MF-derived mature oocytes but did not change that of SF-derived oocytes. In conclusion, our study results show differences in activity of the autophagy inducer and inhibitor on the meiotic and developmental competencies of MF- and SF-derived porcine oocytes.