Effect of gonadectomy on gender differences of thermal pain sense threshold in rat

Abstract

the previous studies have been suggested that to tolerance,sensitivity and pain threshold are different between men and women.these differences can be affected by various factors.in this study,the effect of gonadectomy on gender differences in thermal pain sense threshold was tested hot plate method in rats.therefore the reaction time(the delay occurred in response to thermal stimulus)at zero,15 and 30 minutes was registrates.mean of those 3 values was respected as thermal pain sense threshold.then the gonads were occluded and the pain sense threshold at 7th ,21st and 35th days was measured.the results showed no gender differences before gonadectomy.however after gonadectomy the thermal pain threshold was decreased in both sexes and reached to its minimum value on 21st day and retuned to basal value on day 35 in both sexes.although this reduction was more dominant in males,ni significant difference was observed between sexes.Gonadectomy in males caused a significant reduction of pain threshold in 1th and 21st days.Gonadectomy in females had no effect.in conclusion it seems that female sex hormones have no effect on thermal pain threshold ,but testosterone was effective.since pain sense threshold was also retuened to basal value in male rats,we concluded that stimulatory effect of testosterone (up to day 21) may be more important than is organizational effect appear after 30th day.