Protective Effect of l-Theanine on Cadmium-Induced Apoptosis in PC12 Cells by Inhibiting the Mitochondria-Mediated Pathway

l-Theanine is an amino acid derivative from green tea. The present work was aimed at the effect of l-theanine on neuron-like rat pheochromocytoma (PC12) cells stimulated with cadmium chloride. Treatment with l-theanine before cadmium exposure increased cell viability; the experiments of Annexin V/PI staining indicated that l-theanine inhibited cadmium-induced cell apoptosis. Meanwhile, l-theanine decreased ROS production and protected from cadmium-induced disruption of mitochondrial transmembrane potential. Compared with cadmium-treated cells, l-theanine could also decrease the ratio of Bax/Bcl-2, as well as the level of cleaved caspase-9, caspase-3 and poly(ADP-ribose) polymerase. Furthermore, l-theanine depresses cadmium-induced up regulation of phosphorylations of PI3K/Akt, MAPK ERK1/2, and JNK signaling. These data suggest that l-theanine pretreatment reduces severity of cadmium toxicity probably via antioxidant action. Therefore, it may be concluded that l-theanine could be exploited for prevention of cadmium-induced diseases.