Objective To explore the expression and significance of protein tyrosine phosphatase SHP2 in experimental bacterial meningitis.Methods A juvenile rat bacterial meningitis model was established by direct intraeisternal injection with Streptococcus pneumoniae. Uninfected control animals were mock-infected with sterile saline.The transcription and expression of SHP2 were detected by reverse transcription-polymerase chain reaction(RT-PCR),Western blot and immunohistochemistry techniques respectively at 1,3,7 and 14 days after infection.White blood cell(WBC)count,concentration of tumor necrosis factor-alpha(TNF-α)in cerebrospinal fluid(CSF)were also measured.Variables that were not normally distributed were compared by the Kruskal-Wallis test.Multiple comparison used Student-Newman-Keuls(SNK).The association between variables was assessed by using the Pearson correlation coefficient.Results Compared with uninfected controls,rats with bacterial meningitis showed a significant upregulation of SHP2 at both mRNA and protein levels(F=12.74,P<0.01;F=198,P<0.01).S HP2 mRNA levels peaked at 3 days after infection increasing more than five fold and remained at high levels at 7 days.In parallel,SHP2 protein levels began to increase at 3 days after infection,reaching a maximal increase of nearly nine fold at 7 days and remained at high levels at 14 days. Immunohistochemical analysis of SHP2 expression in the juvenile rat brain demonstrated that SHP2 labelling cells,identified as neuronal and glial cells,widely distributed in the cerebral cortex and the increased immunoreactive cells around the third ventricle were mainly glial cells.In addition,the protein levels of SHP2 and WBC counts were significantly correlated with each other(r=0.77,P<0.01),while there were no significant correlations between levels of SHP2 and TNF-a (r=0.08,P>0.05).Conclusions SHP2 may participate the pathological progress of the bacterial meningitis,restrating the inflammation and accelerating the renovation,so it can be regard as an index to measure the state of the illness.