Study On The Medical Ozone In Alleviating Formalin Induced Inflammatory Pain

Objective: To observe the effects of medical ozone（O₃）on the activation of microglia and the expression of TNF-α,IL-1β and MCP-1 in the spinal dorsal horn of formalin-induced inflammatory pain rats,and to explore the mechanism of ozone to alleviate inflammatory pain.Methods: Adult male SD rats were randomly divided into 4 groups:（1）Control group（group C）: Normal saline（100μl）was injected subcutaneously into the plantar surface of rats.（2）Formalin group（group F）: 2% formalin（100μl）was injected subcutaneously into the plantar surface of rats and normal saline（10μl）was intrathecally injected.（3）Minocycline group（group MI）: After the establishment of inflammatory pain model,rats were given intrathecal injection of MI（5ug/ul,10μl）.（4）Ozone group（group O₃）: After the establishment of inflammatory pain model,the plantar surface of rats was injected subcutaneously with O₃（30ug/ml,50μl）.Each group contained 10 rats.Mechanical withdrawal threshold（mechanical withdrawal,threshold,MWT）and thermal withdrawal latency（thermal withdrawal,latency,TWL）were measured at 0h（before modeling）,1 h,3h,12 h,1d,3 d and 5 d（after intrathecal injection）.The expression of OX42（the specific marker protein of microglia）in the dorsal horn of rat spinal cord was observed by Western blot.Finally,ELISA method was used to detect the expression of TNF-,IL-1 and MCP-1in the spinal dorsal horn of rats.Results:（1）Behavioral: There was no significant difference in MWT and TWL of rats in group C at each time point（P > 0.05）.MWT and TWL of rats in group F,group MI and group O₃ were significantly lower than the basal line（0h,P < 0.05）.MWT and TWL of rats in group F were marked higher than those in group MI and group O₃（P < 0.05,n = 10）.（2）Western blot: Compared with group C,the expression of OX42 in group F,group MI and group O₃ was significantly increased（P < 0.05）.Compared with group F,the expression of OX42 in group MI and group O₃ were significantly decreased（P < 0.05,n =10）.（3）ELISA: Similarly,the expression levels of MCP-1,IL-1β and TNF-α in spinal dorsal horn of rats in group F,MI and O₃ were significantly higher than those in group C（P < 0.05）.Compared with group F,the expression of MCP-1,IL-1β and TNF-α in group MI and group O₃ were significantly decreased（P < 0.05,n = 10）.Conclusion:（1）Microglia,TNF-α,IL-1β and MCP-1 in the spinal dorsal horn of rats are involved in the regulation of formalin-induced inflammatory pain.（2）Plantar surface injection of medical ozone can significantly attenuate formalin-induced inflammatory pain.（3）Medical ozone may down-regulate the expression of TNF-α,IL-1β and MCP-1 by inhibiting the activation of microglia in the spinal dorsal horn,to alleviate the formalin-induced pain response.