Effects of glucocorticoids on brain protection and cerebrospinal fluid immunoglobulin levels in rats with Streptococcus pneumoniae meningitis
Objective:To investigate the effect of glucocorticoids on brain injury in rats with Streptococcus pneumoniae(SP)meningitis,as well as the changes of cerebrospinal fluid immunoglobulin levels under this effect.Methods:A total of 40 SD rats were divided into control group,model group,low-dose methylprednisolone sodium succinate group(Low-MSS)and high-dose methylpred-nisolone sodium succinate group(High-MSS)according to random table method,with 10 rats in each group.Except for the control group,SP meningitis models were established in other groups.Rats in Low-MSS group and High-MSS group were injected with methyl-prednisolone sodium succinate by tail vein at doses of 5 mg/kg and 10 mg/kg,respectively,once a day for 21 days.Neurobehavioral scores of rats after modeling were performed by Loeffler method;contents of immunoglobulin IgA,IgM and IgG in cerebrospinal fluid of rats were detected by immunoturbidimetry;levels of inflammatory cytokines TNF-α,IL-6 and IFN-γ in supernatant of rats brain ho-mogenate were determined by ELISA;HE staining was used to detect pathological changes of rats brain tissue;Nissl staining was used to detect the number of neuronal cells in rats brain tissue;TUNEL staining was used to detect the number of apoptotic cells in rats brain tissue;immunofluorescence staining was used to detect expressions of GFAP and S-100b,the marker proteins of rat brain tissue injury.Results:Before SP injection,there was no difference in neurobehavioral scores between control group and model group(P>0.05),at 24 h,48 h and 72 h after SP injection,neurobehavioral scores in model group were significantly lower than those in control group(P<0.05).Compared with control group,contents of IgA,IgM and IgG in cerebrospinal fluid of rats in model group were in-creased,and contents of TNF-α,IL-6 and IFN-γ in supernatant of the brain homogenate were also increased,the tissue was obviously damaged,accompanied by a large number of inflammatory cells infiltration,the number of neuronal cells were decreased,the number of apoptotic cells were increased,and the fluorescence density values of S-100b and GFAP were increased(P<0.05);compared with model group,contents of IgA,IgM and IgG in cerebrospinal fluid of rats in Low-MSS group and High-MSS group were decreased,and contents of TNF-α,IL-6 and IFN-γ in brain homogenate supernatant were also decreased(P<0.05),brain tissue damage was alleviated,inflammatory cell infiltration was significantly reduced,neuronal cells were increased,the number of apoptotic cells were decreased,and the fluorescence density values of S-100b and GFAP were also decreased(P<0.05).In addition,the improvement effect of various indexes and brain tissue damage in High-MSS group was better than that in Low-MSS group,and the difference were statistically signifi-cant(P<0.05).Conclusion:Glucocorticoid methylprednisolone sodium succinate can effectively improve the brain tissue damage in SP meningitis rats,regulate the levels of immunoglobulin IgA,IgM and IgG,and has a protective effect on SP meningitis rats.
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