Objective      To observe the activating features of astrocytosis in a cuprizone (CPZ)-induced demyelination model of mice at different ages and their correlation with demyelination.       Methods      Six-week old and 9-month old male C57BL/6 mice were enrolled in this study and served as 6-week group and 9-month group

respectively. A mouse model of CPZ-induced acute demyelination was established. Six weeks after 0.2%CPZ treatment

whether the model was successfully established was observed by measuring the body weight and luxol fast blue (LFB) staining. Expression of glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP) in corpus callosum and cortex from 6-week group and 9-month group was detected by immunohostochemistry and Western blotting

respectively.       Results      Six weeks after 0.2%CPZ treatment

the number of GFAP positive cells in corpus callosum and cortex from 6-week group was significantly increased (P0.01)

while the expression of MBP significantly decreased (P0.01); the number of GFAP positive cells in corpus callosum from 9-month group was significantly increased (P0.05)

while the expression of MBP significantly decreased (P0.05). The number of GFAP positive cells was significantly greater and the expression level of MBP was significantly lower in 6-week group than in 9-month group (P0.01).       Conclusion      Activation of astrocytes is more significant in 6-week old mice and positively related with myelin sheath damage. It may be one of the important reasons for myelin sheath damage.