The Effects of Separate and Combined Stress during Pregnancy on Motor Learning of Offspring of Rats

Today, due to the modern industrial life of human beings, stress has become prevalent among them and they will suffer from its complications. Exposure to stress during pregnancy can change many babie's normal physiological processes. The separate and combined effects of three common types of prenatal stress were investigated on motor learning of male offspring of rats. In the present study, pregnant NMRI rats were used. Except the control group, the other groups were stressed on the eighth day of gestation for 10 days. The motor learning of 40 male offspring rats were tested using the rotarod performance test 75 days after the experiment. The length of time that each rat could maintain its balance was recorded automatically. The study groups included control, electromagnetic field stress (intensity 1.2 mT, 50 Hz), immobility stress (for 0.5 hour - 2 times/day), social stress (6 rats kept in a small cage), and combined stress (all 3 of the above stresses). Data were analyzed by using multiple comparisons and Tukey’s tests. The motor balance of the combined stress group was lower than the control, at first timing of the first test day (P < 0.05). In the next few days of the test, the effects of stress on learning of experimental groups were not similar. Combined stress reduced motor learning. Learning fluctuations were higher in electromagnetic field stress group compared to the other groups. The results of our study showed that prenatal combined stress can reduce motor learning of children.