Establishment Of The Model Of A Predator Stress And Its Eeffects On Oocyte Developmental Potential In Mouse

As everyone knows, stress is found everywhere in our life, inevitable. In recent years, with the development of the society, the accelerating pace of life and the happening of natural disaster, people face more and more pressure(stress). Previous studies showed that women in social life are often several, and who is also the role of all in one, not only work well, but also take care of family, so career women are more vulnerable than other people to stressors. In worst-case scenarios, even this can lead to infertility. As further research on stress and mechanism of stress disorder, more and more animal models(e.g. foot shock, restraint stress ) have emerged, but as an ideal psychological stress model, they all have some disfigurement in some degrees and cause many controversies. In addition, there are a few researchs on effect of psychological stress on female gametes development ability. Consequently, Establishing an ideal model to study the effects of psychological stress on female oocytes is imperative.In this study, a predator stress (psychological stress) system that not only avoids the physical stress and other stress factors but also allows mice free intake of feed and water was first established. Experiment mainly focused on predator stress for 24h following gonadotropin administration. To ensure good stress continuity, took four times for every cat system (i.e. change one cat every 6h). Elevated plus maze( EPM) was used to measure mouse anxiety-like behavior immediately following treatment for 15min or 17h and the mouse plasma cortisol was also measured at different time periods during predator stress, to further demonstrate the validity of our animal model as an ideal psychological stress model. At the same time , the effect of predator stress for 24h following gonadotropin stimulation on oocyte maturation, activation/fertilization, and embryo development in vitro and in vivo were then observed(investigated). The results are summarized as follows:(1) Anxiety-like behavior is produced by brief exposure of mouse (Kun Ming) to a cat, and it can be preferably maintained through all the stress process.(2) Cat-exposed to mice showed a pronounce rise in cortisol levels, and that peaked at 12h from the beginning of the predator exposure, nearly reached 4.5 times (70.16±9.10 vs 16.57±3.03 ng/ml)to contrast. With the extension of time, the cortisol levels presented downtrend, and exposure to cat for 24h, the difference was also significant. But after recovery 1h following exposure to cat for 24h, cortisol level is significantly lower than the control(3) Stimulated mice were exposed to cat for 24 h starting from 24 h after eCG injection, and the maturation, activation/fertilization were unaffected by acute predator stress ,but blastocyst development were significantly reduced.(4) Stimulated mice were exposed to cat for 24 h starting from 24 h after eCG injection, and the embryo development in vivo was not affected, but reduced the litter size or the birth weight of young.