Author

• parvin Zareian

Abstract

Introduction: In spite of numerous studies have been done about stress and stress induced analgesia , the role of sex hormones on pain perception and effect of stress on reproductive system had not been known as well. Therefore , the aim of the present experiment was investigation about the effects of chronic and acute restraint stress on nociception and serum level of sex hormones in male and female rats.

 Methods: The study was carried out on 147 rats. Animals were initially submitted to acute restraint stress (1 h) or chronic stress (two weeks-1h/day). Then, submitted to tail flick test to evaluate nociception. After that blood sample was taken directly from the heart and serum sex hormones level was estimated by radioimmunoassy method. Results were analysed statiscally by the nonparametric Mann-whitney and Kruskal-Wallis tests.

Results: In both male and female rats, acute restraint stress resulted to increment in latency in the tail flick test. On the other hand chronically stressed male rats presented a performance similar to the control group. Whereas chronically stressed females responed to restraint with a increase in tail flick latency. Acute and chronic restraint stress reduced testosterone level in male rats. In female rats , serum estradiol level decreased by acute stress but chronic stress did not influence on estradiol level. In addition restraint stress had not effect on testosterone and estradiol level in females and male rats respectively.

Discussion : The results show that nociceptive and gonadal hormone responses to acute stress are similar in both male and female rats but in chronic stress these responses are sex dependent.

Keywords

• Restraint stress
• nociception
• Estradiol
• Testosterone