اثر استرس محدود كننده نوع حاد و مزمن بر آستانه درك درد و غلظت هورمون هاي جنسي در موش هاي صحرايي سالم نر و ماده

Effects of Restraint Stress on Nociception, Serum Testosterone and Estradiol Concentration in Male and Female Rats

Introduction: In spite of numerous studies conducted on stress and stress induced analgesia, the role of sex hormones on pain perception and also the effect of stress on the reproductive system are not known well. Therefore, the aim of the present study was to determine the effects of chronic and acute restraint stress on nociception and serum level of sex hormones in male and female rats. Materials and Methods: The study was carried out on 47 rats. The animals were initially exposed to acute restraint stress (1 h) or chronic stress (two weeks-lh/day) and tail flick test was performed to evaluate nociception. Then, blood sample was taken directly from the heart and the sex hormone level of the serum was estimated by radioimmunoassy method. The results were analyzed statistically by the nonparametric Mann-whitney and Kruskal-Wallis tests. Results: In both male and female rats, acute restraint stress resulted in an increment in latency in the tail flick test. On the other hand, chronically stressed male rats presented a performance similar to that of the control group whereas chronically stressed females responded to restraint with an increase in tail flick latency. Acute and chronic restraint stress reduced testosterone level in the male rats. In female rats, the serumʹs estradiol level decreased due to acute stress but chronic stress did not influence the estradiol level. In addition, restraint stress had no effect on testosterone and estradiol level in female and male rats, respectively. Conclusion: The results reveal that nociceptive and gonadal hormoneʹs responses to acute stress are similar in both male and female rats, but in chronic stress these responses are sex dependent.