Role of EAAT2 in cannabinoid receptor 2 activation-induced attenuation of microglial injury caused by glutamate

Objective To evaluate the role of excitatory amino acid transporter 2 (EAAT2) in cannabinoid receptor 2 (CB2 receptor) activation-induced attenuation of microglial injury caused by glutamate. Methods N9 microglial cells were divided into 4 groups (n=26 each) using a random number table method: control group (group Con), glutamate group (group Glu), CB2 receptor agonist AM1241 plus glutamate group (group AM1241+ Glu) and AM1241 plus EAAT inhibitor TBOA plus glutamate group (group AM1241+ TBOA+ Glu). The cells were routinely cultured for 30 h in group Con.In group Glu, the cells were routinely cultured for 6 h, and then were incubated for 24 h in the culture medium containing glutamate 10 mmol/L.In group AM1241+ Glu, the cells were incubated for 4 h in the culture medium containing AM1241 2 μmol/L, and then were routinely cultured for 2 h, and then were incubated for 24 h in the culture medium containing glutamate 10 mmol/L.In group AM1241+ TBOA+ Glu, the cells were incubated for 4 h in the culture medium containing AM1241 2 μmol/L and TBOA 100 μmol/L, and then were routinely cultured for 2 h, and then were incubated for 24 h in the culture medium containing glutamate 10 mmol/L.The cell viability was measured by MTT assay, the activity of lactic dehydrogenase (LDH) in supernatant was determined using colorimetric method, and the expression of EAAT2 was determined by Western blot. Results Compared with group Con, the cell viability was significantly decreased and LDH activity was increased in Glu, AM1241+ Glu and AM1241+ TBOA+ Glu groups, and the expression of EAAT2 was significantly up-regulated in Glu and AM1241+ Glu groups (P 0.05). Compared with group AM1241+ Glu, the cell viability was significantly decreased, LDH activity was increased, and the expression of EAAT2 was down-regulated in group AM1241+ TBOA+ Glu (P<0.05). Conclusion The mechanism by which the activation of CB2 receptor attenuates microglial injury caused by glutamate is related to up-regulating the expression of EAAT2. Key words: Excitatory amino acid transporter 2; Receptor, cannabinoid, CB2; Glutamic acid; Microglia