تفاوت وابسته به جنس در روند پيدايش درد نوروپاتيك ناشي از بستن عصب سياتيك در موش سوري

Sex-related differences in development of hyperalgesia induced by sciatic nerve ligation in mice

Introduction: In normal animals, neuropathic pain arising from sciatic nerve ligation injury can result in increased sensitivity to both noxious (hyperalgesia) and non-noxious stimuli (allodynia) and are accompanied by a number of neuroplastic alternations at the level of spinal cord including upregulation of neurotransmitters including dynorphin, neuropeptide Y and cholecystokinin. Some research studies have been shown that the mechanisms underlying neuropathic pain processing differed as a function of gender and gonadal hormone status. However, the effect of nerve injury on acute nociception and sex-related differences in time-course of hyperalgesia has not been extensively studied. Materials and Methods: A model of peripheral nerve injury was used to study gender differences in the progression of chronic constriction injury induced hyperalgesia in male and female mice. Nerve ligation injury was produced by unilateral ligation around the left common sciatic nerve. Animals were examined for response to acute nociception daily during the three postoperative weeks. In this regard, the latency of tail flick response (TFL) was measured in control group and at set intervals (2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 days after sciatic ligation as ligated or surgery without ligation as sham groups in both sexes) by using an automated analgesia meter. Results: In the absence of nerve injury, intact (8.4±0.95 Sec) and sham (8.35±0.3 Sec) males responded faster than control (8.7±0.99 Sec) and sham (8.9±0.34 Sec) females to a thermal nociceptive stimulus. However, there were no significant differences between groups and both sexes. Significant hyperalgesia was developed in ligated male and female mice, as compared to control and sham groups, within 10 days after sciatic nerve injury (P<0.01). However, it elongated for six days in males and more that 10 days in females. On the other hand, TFL in males (4.9±0.1 Sec) reduced significantly (P<0.05) more than that in females (6.8±0.17 Sec). Conclusion: These data suggest that mechanisms underlying chronic nociceptive processing differ as a function of gender and it may be related to gonadal hormone status.