Abstract: Objective To investigate the activation characteristics of microglia(MG) in the rats striatum with MA-induced neurotoxicity.Methods Male Wistar rats were divided randomly into control group(n=24) and experimental group(n=24).The rats of experimental group were injected intraperitoneally with MA(15 mg/kg×8 injections,at 12 hours interval).The rats of control group were administrated with saline.The tissues of striatum of two rat groups were harvested at 0.5 d,1 d,2 d,3 d,4 d,5 d,6 d and 7 d post initial administrations of MA or saline.The structure changes were observed by transmission electron mi-croscopy and CD-11b immunohistochemistry.The ratio of activated MG was calculated and statistically analyzed.Results In the control group,the morphological characteristics of the MG showed that the cell bodies were small with slender processes,high electronic density nucleus,and fewer organelles known as the "fork-type".In contrast,the MG in the MA-induced neurotoxicity group displayed larger cell body,shorter cell processes or disappeared,lower electronic density nucleus and rich organelles,resembling "bush-like" or "amoeba-like".The ratio of activated MG in control group was below 0.15 at all time-points,whereas in the experimental group,the ratio of activated MG increased significantly from day 1 to day 7(P<0.001).Conclusion The continuous MA stimulation of the CNS results in prominent MG activation.

Key words: forensic pathology, methamphetamine, striatum, microglia, rats