Mechanisms By Which Corticotropin-Releasing Hormone Impairs Mouse Oocyte Developmental Potential During Restraint Stress

With the fast development of the society and the happening of natural disaster, thepressure that people faced is becoming stronger and stronger. Women are more susceptiblethan men to stress-related mental illness and twice as likely to experience depression. Theeffects of stress on reproduction in female have been demonstrated that stress can bringdisorder to the reproductive endocrine system, and induce anaplasia in reproductive system ofwomen. So in this research, we investigated the effect of restraint stress, the emotional stressmodle we established before, on percentages of apoptotic cumulus cells and levels of steroidhormones in ovaries and serum. Furthermore, we investigated the mechanisms of CRH inimpairing mouse oocyte developmental potential during restraint stress. Our researchdemonstrated that:（1）No difference was observed in percentages of apoptotic cumulus cells betweencontrol and stressed mice before or after culture of COCs with serum, growth factor andhormone (SGH).The difference became significant after culture without SGH.（2）The percentages of MII oocytes and actived oocytes did not differ between controland stressed mice after culture of COCs with or without SGH, percentages ofparthenogenetic blastocysts were significantly lower in stressed than in control mice aftermaturation of COCs either with or without SGH. Maternal restraint stress impaired mouseoocyte developmental potential.（3）The concentrations of cortisol increased significantly in both ovarian homogenatesand serum following restraint stress.（4）The concentrations of progesterone increased, that of estradiol decreasedsignificantly in both ovarian homogenates and serum following restraint stress. Interestingly,whereas the level of testosterone in serum increased, that in the ovary decreased significantlyfollowing stress. In a word, restraint stress affected the levels of steroid hormones. （5）The concentrations of IGF-1decreased significantly in both ovarian homogenatesand serum following restraint stress.（6）The concentrations of CRH increased significantly in both ovarian homogenatesand serum following restraint stress, which may effect the levels of steroid hormones in serumand ovaries. Furthermore, the level of CRH in oocytes increased following restraint stress，which is about1.4times of that of the control group.（7）By immunohistochemistry,we found that CRHR1was intense in the stroma cells,ina subpopulation of cells within the corpora lutea and thecal cells surrounding the antralfollicles.However, CRHR1immunostaining was the sparsely present in cumulus oophorus ofantral follicles.The level of CRHR1increased significantly in theca cells following restraintstress, which may inhibit the production of testosterone, subsequently inhibit the productionof estradiol indirectly.（8）Restraint stress increased expression of CRHR1in cumulus cells and the CRH levelin oocytes compared with control group, which may contributes to CRH signal pathway. Andthis may be responsible for the apoptosis increased and developmental potential decreased instress group when matured in incomplete culture medium.