Effects And Mechanisms Of Action Of Restraint Stress On Oocyte Developmental Potential In The Mouswe

In this study, a restraint (psychological stress) system that allows mice free intake of feed and water while restrains their movement was first established. Effects of restraint stress applied during the pro-estrus of an intact estrous cycle or at different time periods following gonadotropin stimulation on oocyte maturation, activation/fertilization, and embryo development in vitro and in vivo were then observed. The mechanism by which restraint stress affects oocyte developmental potential was finally analyzed by measuring the FSH level in serum and observing oocyte in vitro fertilization and embryo development following restraint stress or cortisol administration. The results indicate that restraint stress applied to the female during oocyte growth and maturation increased the plasma level of cortisol while reduced oocyte developmental potential. Injection of cortisol in a proper dosage also decreased oocyte developmental potential. In intact cyclic mice, the reduced oocyte developmental potential following restraint stress was associated with an increase in cortisol but a decrease in FSH in plasma. However, injection of cortisol did not reduce the plasma level of FSH in the intact cyclic mice and in gonadotropin-stimulated mice, oocyte developmental potential was impaired by restraint stress despite over doses of FSH administration, suggesting that it is possible that cortisol (or restraint stress itself) damages the oocyte independently of the hypothalamic-pituitary-gonadal (HPG) axis.