Effect Of Intravenous Flurbiprofen Axetil On NO/cGMP Content In Spinal Cord Of Rat With Formalin Pain

Objective:This study is to investigate the pain-relieve mechanism of flurbiprofen axetil through observing the pain response of rats after formalin injection,measuring NO and cGMP content in spinal cord,and observing the intervention of flurbiprofen axetil to them.Methods:24 adult Sprague-Dawley rats were randomly divided into 4 groups(n=6 in each group):normal control group(group A),formlin control group(group B),formlin+lipoids microballoons group(group C),and flurbiprofen axetil test group(group D).The rats in group A were put to death to get the spinal cord right after completing the direct observation of behavior.The rats in group B,C,D received subcutaneous injection of 5%formalin 100ul into the plantar surface of the right hind-paw.Pain response was record for a period of 60 minutes after the injection of formlin.All rats were put to death to get the spinal cord right after record the pain response.Pain intensity scoring(PIS)was utilized to assess pain behavior.The spinal cord content of nitric oxide(NO)and cyclic guanosinemonophosphate(cGMP)were respectively measured by applying nitrate reductase method and radioimmunoassay.Results:1.The subcutaneous injection of formalin produced a biphasic pain response in rats.Compare to group A,PIS of group B,C and D was decreased markedly.PIS between B and C have no significant difference.Compare to group B and C,PIS of group D was decreased markedly in the second period of rats' formalin pain.2.NO and cGMP content in the spinal cord of group B,C,D was higher than that in group D.The difference in the statistics was significant.NO and cGMP content between B and C have no significant difference.Compare to group B and C,NO and cGMP content of group D was increased markedly.3.There is positive correlation between the content of NO and cGMP.Conclusions:1.Intravenous administration of flurbiprofen axetil provide significant antinociception in rats' formalin pain.2.The inhibition of NO-cGMP pathway is one of the antinociception mechanisms for intravenous administration of flurbiprofen axetil.