Increased visceral pain responsiveness in female mice compared to male mice afer partial sciatic nerve ligation

Neuropathic pain which is a chronic pain causes hyperalgesia due to peripheralm nerve damage.the relation between neuropathic pain and hyperalgesia and the response to treatment in case of somatic and inflammatory pain have been investigated previuosly.however the response of visceral pain in peripheral neuropathy and the possible gender differences in visceral pain response and gender differnces are evaluated in albino male and female mice,using partial sciatic nerve ligation(PSNL) model.male and female mice were divided as intact,sham and PSNL groups.visceral pain was induced by intraperitoneal(i.p) administration of 0.6% of acetic acid and 20 in sham and PSNL mice.the number of abdominal contractions for a period of 15 minutes was measured in each experimented group as an indicator of visceral pain.the results showed that there was no significant differences in abdominal contractions of intact and sham operated male and female mice.the abdominal contractions in male PSNL mice was decreased signifigantly and in female PSNL mice was increased significantly as compared to male and female sham-operated mice respectively.the obdominal contractions in PSNL male and female mice showed a significant difference with sham operated mice 20 days after surgery i.e. male PSNL group showed significant decrease and females showed a significant increase in abdominal contractions as compared to sham0operated mice.the mean abdominal contractions in female PSNL mice were significantly higher than males in 20 th days of experiment.In summary,the results of this study showed that the female mice are a better model in hyreralgesia studies for visceral pain due to secondary hyperalgesia.the geneder differences in the response to visceral pain can be related to the effect of sex hormones in pain transmission or in structural differences in male and female mice which could result in secondary hyperalgesia in female mice.