Influence of different prenatall stress on the Pain Induced by formalin in Rat

Due to different types of stress، it is important to recognize its adverse effects on the nervous system. This study was done to investigate the effect of three types of common stresses in modern living environment i. e. electromagnetic waves، immobilization and disturbance، individually and combined on pain threshold in infant rats. In this experimental study، 40 pregnant female Sprague rats and all their male infants were studied. Female rats were divided into 5 control، electromagnetic stress، immobilization stress، disturbance stress and combined stress groups. From eighth day of gestation، pregnant rats of stress groups were exposed to stress for 10 consecutive days. 75 days postpartum (after maturity)، male rats were subjected to formalin pain test. Measuring the pain intensity was done via scale «zero» (putting the feet on the ground completely)، «1» (putting the paw on the ground)، «2» (raising the feet) and «3» (biting or licking the feet). Data were analyzed using one-way ANOVA and Tukey''s post hoc tests. The mean of pain severity at the acute phase of the formalin test between each stress groups and the control group was not significant (p>0. 05). The mean of pain severity of the interphase stage of the formalin test was significant only between the electromagnetic stress and the control groups (p<0. 05). The mean of pain severity at the chronic stage of formalin test was significant between each of the combined stress (p<0. 01) and the immobility stress (p<0. 05) groups and the control group. Stress during pregnancy affects the pain behavior of the mature rats.