Abstract: Objective To investigate the effect of fluctuant high blood glucose on observing the changes of pathology and BCL-2 ,BAX expression in neurons of the hippocampus from diabetic rats. Methods The diabetic rat models were produced by injection with l％ streptozotocin(STZ),followed by insulin administration . regular insulin were used to set up fluctuant high glucose group model. After 12 experimental weeks, the express of Fas protein in hippocampus was studied by immunohistochemistry , changes of pathology and ultrastructure were observed by using light microscopes and electron microscopes in three groups .Results：Compared with those in N group，the expression of BCL-2 in pyramidal cells of diabetic rat's hippocampus was lower，while that of BAX was higher (P<0.01)．The pathologic changes of retrogression were significantly serious．The pathologic changes in RDM group were more serious in fluctuant high blood glucose rats group (P<0.05) Conclusion Fluctuant high blood glucose induces more apoptosis in hippocampal neurons cells .The expression of BCL-2, BAX may be one of the mechanism that hippocampus neuron injury in diabetic rats was aggravated.

Key words: Bcl-2, Bax, fluctuant high blood, diabetes mellitus, hippocampus, apoptosis