Effect of Gender and Sex Hormones on Chronically Injured Nerve as a Model of Neuropathic Pain

摘要

Gender differences in pain perception are caused by differential modulating effects of estrogens and androgens. The aim of this study was to disclose any possible relation between the microscopical changes and the sex following chronic constriction injury (CCI) of the sciatic nerve. CCI model of neuropathic pain was induced in male and female Wistar rats (200-250 g) three weeks after gonadectomy. The animals were randomly assigned into groups: (1) ovariectomized females; (2) ovariectomized, estradiol treated (0.5 mg/kg, p.o. in 11 doses for 21 days) females; (3) gonadally intact males and (4) castrated males. Light microscopy and computer assisted amage analysis were applied to reveal the morphological changes. The axonal and myelin injuries are more, heavily expressed in castrated males than in ovariectomized females. However, ovariectomized and estrogen treated females show greater changes than gonadally intact males. Results show clearly that there are sex differences in the morphological changes after CCI.