Effects Of Intrathecal Isoflurane Administration On Nociception In The Rat Spinal Cord And Research On Its Mechanism

With technology developing quickly, the drugged state is still obscure which is not same as dormancy, without memoy, without instinct, without pain. The general anesthesia includes analgesia, sedation, muscle relaxation and immobility in response to pain. In previous studies, the four elements were mixed. It mixed multiple effects so that we can not know the mechanisms inhalation anesthetics produce anti-nociception.Objective:In our study, we administered isoflurane by intrathecal administration directly to the spinal cord for the first time. By using behavioral, immunohistochemistry and RT-PCR research works, we studied below problems:1.Can isoflurane liquid and emulsified isoflurane exert antinociceptive effects at the spinal level?2. Can isoflurane liquid and emulsified isoflurane alter Fos protein and the c-fos expression in the dorsalhorn of spinal cord? Our results can provide direct evidence that inhalation anesthetics produce anti-nociception at the spinal level.Methods:We observed the change of the number of flinches of the injected paw of intrathecal isoflurane liquid and emulsified isoflurane. Moreover, the rat's paw withdrawal threshold for mechanical stimuli and latency forheat stimuli were measured. At the same time, we also observed the effects of isoflurane liquid and emulsified isoflurane on Fos protein and the c-fos expression in the dorsalhorn of spinal cord by using immunohistochemistry technique.Results:A: Intrathecal isoflurane liquid(50μl/kg and 25μl/kg) and emulsified isoflurane(50μl/kg and 25μl/kg) can inhibit the flinching induced by formalin.B: Intrathecal isoflurane liquid(50μl/kg and 25μl/kg) and emulsified isoflurane(50μl/kg and 25μl/kg) can prolong the rat's paw withdrawal latency forheat stimuli.C: Intrathecal isoflurane liquid(50μl/kg and 25μl/kg) and emulsified isoflurane(50μl/kg and 25μl/kg) can increase the rat's paw withdrawal threshold for mechanical stimuli.D: Intrathecal isoflurane liquid(50μl/kg and 25μl/kg) and emulsified isoflurane(50μl/kg and 25μl/kg) can inhibit Fos protein expression in the dorsalhorn of spinal cord.E: The c-fos expression in groups of the intrathecal administration of isoflurane liqid or emulsified isoflurane was lower than that of group of the intrathecal administration of saline significantly.Conclusion:The results indicate that intrathecal administration of isoflurane liquid or emulsified isoflurane exert antinociceptive effects at the spinal level.