Under the stressed condition, a complex feedback mechanism for stress is activated to maintain homeostasis of the body and secretes several stress hormones. But these stress hormones impair synthesis and secretion of the reproductive hormones, followed by suppression of ovarian function. Cytochrome P450 1A2 (CYP1A2) plays a major role in metabolizing exogenous substances and endogenous hormones, and its expression is recently identified at not only the liver but also several organs with respect to the pancreas, lung and ovary. Although the expression of CYP1A2 can be also affected by several factors, understanding for the changed pattern of the ovarian CYP1A2 expression upon stress induction is still limited. Therefore, CYP1A2 expression in the ovaries from immobilization stress-induced rats were assessed in the present study. The stress-induced rats in the present study exhibited the physiological changes in terms of increased stress hormone level and decreased body weight gains. Under immunohistological observation, the ovarian CYP1A2 expression in both control and the stressed ovary was localized in the antral to pre-ovulatory follicles. However, its expression level was significantly (p < 0.01) higher in the stress-induced group than control group. In addition, stress-induced group presented more abundant CYP1A2-positive follicles (%) than control group. Since expression of the ovarian CYP1A2 was highly related with follicle atresia, increased expression of CYP1A2 in the stressed ovary might be associated with changes of the ovarian follicular dynamics due to stress induction. We hope that these findings have important implications in the fields of the reproductive biology.

ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
CONFLICTS OF INTEREST
ACKNOWLEDGEMENTS
AUTHOR CONTRIBUTIONS
AUTHOR’S POSITION AND ORCID NO
REFERENCES

• Jong-Chan Hwang(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea)
• Hwan-Deuk Kim(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea, Department of Veterinary Research, Daegu Metropolitan City Institute of Health & Environment, Daegu 42183, Korea)
• Byung-Joon Park(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea)
• Ryoung-Hoon Jeon(College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Su-Min Baek(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea)
• Seoung-Woo Lee(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea)
• Min Jang(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea)
• Seul-Gi Bae(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea)
• Sung-Ho Yun(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea)
• Jin-Kyu Park(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea)
• Young-Sam Kwon(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea)
• Seung-Joon Kim(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea)
• Won-Jae Lee(College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea) Corresponding author