Effect of Exposure to Chronic Heterogeneous Sequential Stress during Prenatal on Formalin-Induced Nociceptive Behaviour in Adult Offspring in Rats

There are different kinds of stress on mothers during prenatal period. The present study investigated the effects of exposure to chronic heterogeneous sequential stress during prenatal period on formalin-induced nociceptive behavior in adult offspring. In the present study، animals were divided in stressed and non-stressed groups and their offspring divided in male and female groups. Heterogeneous sequential stress including food deprivation، water deprivation، restraint، restraint at room temperature، restraint at 4◦C، forced swimming and social isolation were applied during days 9 to 19 of gestation. Formalin test as chemical model and hot-plate as thermal pain model were used in rats. Chronic heterogeneous sequential stress increased the nociceptive behaviors in male rats in first part and in female rats in second part of phase 2 of formalin test compared with controls. The result of this study showed that chronic heterogeneous sequential stress in rats increased the nociceptive behaviours in second phase of formalin test in a gender-dependent order; which suggested chronic heterogeneous sequential stress may be useful in evaluating the basic mechanism of exposure to chronic heterogeneous sequential stress during prenatal period on in adult offspring.