Summary: To explore the effect of different concentrations of corticosterone (CORT) on primary cultured hippocampal neurons and their Ca~2+ /CaMKⅡ expression and possible mechanism, the changes of hippocampal neurons were observed in terms of morphology, activity of cells, cell death, concentrations of cytosolic free calcium, and the expression of CaMKⅡ by using MTT assay, flow cytometry, fluorescent labeling of Fura-2/AM and Western blotting after 10~-7 , 10~-6 and 10~-5 mol/L of CORT was added to culture medium, The evident effect of 10~-6 and 10~-5 mol/L of CORT on the morphology of hippocampal neuron was found. Compared with control neurons, the activity of the cells was markedly decreased and [Ca~2+ ]_i increased in the neurons treated with 10~-6 and 10~-5 mol/L of CORT, but no change was observed in the neuron treated with 10~-7 mol/L of CORT. The death was either by way of apoptosis or necrosis in the cells treated with 10~-6 and 10~-5 mol/L of CORT respectively. The correlation analysis showed that a reverse correlation existed between [Ca~2+ ]_i and the expression of CaMKⅡ. Either apoptosis or necrosis occurs in the hippocampal neurons treated with CORT. The increased hippocampal [Ca~2+ ]_i is both the result of CORT impairing the hippocampal neurons and the cause of the apoptosis of hippocampal neurons and the decreased CaMKⅡ expression. Summary: To explore the effect of different concentrations of corticosterone (CORT) on primary cultured hippocampal neurons and their Ca ~ 2 + / CaMKII expression and possible mechanism, the changes of hippocampal neurons were observed in terms of morphology, activity of cells, cell death , concentrations of cytosolic free calcium, and the expression of CaMKII by using MTT assay, flow cytometry, fluorescent labeling of Fura-2 / AM and Western blotting after 10 ~ -7, 10 ~ -6 and 10 ~ -5 mol / L of The evident effect of 10 ~ -6 and 10 ~ -5 mol / L of CORT on the morphology of hippocampal neuron was found. Compared with control neurons, the activity of the cells was markedly decreased and [Ca ~ 2 +] _i increased in the neurons treated with 10 ~ -6 and 10 ~ -5 mol / L of CORT, but no change was observed in the neuron treated with 10 ~ -7 mol / L of CORT. The death was either by way of apoptosis or necrosis in the cells treated with 10 ~ -6 and 10 ~ -5 mol / L of CORT respectively. The correla tion analysis showed that a reverse correlation existed between [Ca ~ 2 +] _i and the expression of CaMKII. Either apoptosis or necrosis occurs in the hippocampal neurons treated with CORT. The increased hippocampal [Ca ~ 2 +] _i is both the result of CORT impairing the hippocampal neurons and the cause of the apoptosis of hippocampal neurons and the decreased CaMKII expression.