We investigate the effect of endoplasmic reticulum (ER) stress inhibitor treatment during parthenogenetic activation of oocytes on the ER stress generation, apoptosis, and in vitro development of parthenogenetic porcine embryos. Porcine in vitro matured oocytes were activated by 1) electric stimulus (E) or 2) E+10 μM Ca-ionophore (A23187) treatment (EC). Oocytes were then treated by ER stress inhibitors such as salubrinal (200 nM) and tauroursodeoxychloic acid (TUDCA, 100 μM) for 3 h prior to in vitro culture. Parthenogenetic embryos were sampled to analyze ER stress and apoptosis at the 1-cell and blastocyst stages. The x-box binding protein 1 (Xbp1) mRNA and ER stress-associated genes were analyzed by RT-PCR or RT-qPCR. Apoptotic gene expression was analyzed by RT-PCR. At the 1-cell stage, although no difference was observed in Xbp1 splicing among treatments, BiP transcription level in the E group was significantly reduced by salubrinal treatment, and GRP94 and ATF4 transcription levels in EC group were significantly reduced by all treatments (p<0.05) compared to control. In the EC group, both apoptotic genes were reduced by ER stress inhibitor treatments compared to control (p<0.05) except Caspase-3 gene by TUDCA treatment. These results suggest that the treatment of ER stress inhibitor during parthenogenetic activation can reduce ER stress, and thereby reduce apoptosis and promote in vitro development of porcine parthenogenetic embryos.

ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
  1. Chemicals
  2. Collection and in vitro maturation of oocytes
  3. Parthenogenetic activation and ER stress inhibit
or treatment
  4. In vitro culture and sampling
  5. Isolation of mRNA and cDNA synthesis
  6. RT-PCR and RT-qPCR
  7. Statistical analysis
 RESULTS
  1. ER-stress generation in 1-cell embryos
  2. Apoptosis in 1-cell embryos
  3. ER stress generation and apoptosis in blastocysts
  4. In vitro development of parthenogenetic embryos
 DISCUSSION
 REFERENCES

• Hye-Bin Park(College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University)
• Mi-Jeong Kim(College of Animal Life Sciences, Kangwon National University)
• Bae-Dong Jung(College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University)
• Seunghyung Lee(College of Animal Life Sciences, Kangwon National University)
• Choon-Keun Park(College of Animal Life Sciences, Kangwon National University)
• Boo-Keun Yang(College of Animal Life Sciences, Kangwon National University)
• Hee-Tae Cheong(College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University) Corresponding Author