Objective: To investigate the neuroprotective effect of epigallocatechin gallate(EGCG), the main extract from green tea, on the oxidative-stress-injured retinal ganglion cells.
Methods: Rat retinal ganglion cells (RGC-5) were cultured into 3 groups (normal control; H2O2; H2O2 + EGCG or Trolox or NU1025). In-situ TUNEL was used to detect the apoptosis of the RGC-5 cells. Dihydroethidium (DHE) assay was used to observe the intracellular ROS generation. The activation of nuclear enzyme, PARP-1 was quantitatively detected by Western blot and the cell viability was measured by MT method.
Results: Hydrogen peroxide reduced RGC-5 cell viability in a time-concentration-dependent manner. The treatment of 500 micromol/L H2O2 for 24 hours reduced RGC-5 cell viability by about 50% of control. Hydrogen peraoxide caused apoptosis of the RGC-5 cell, obviously increased intracellular ROS generation and up-regulated the PARP-1 expression. The pretreatment with EGCG was able to markedly reduce the number of apoptotic cells, attenuate intracellular ROS generation. Furthermore, MTT assay showed that the pretreatment with EGCG (50 micromol/L) increased the most cell viability to 87% of control, but pretreatment with Trolox (100 micromol/L) and NU1025 (100 micromol/L, a PARP-1 inhibitor) recovered the most cell viability to 62% and 71% of control respectively.
Conclusion: EGCG is able to effectively protect retinal ganglion cell against oxidative-stressed injury and can be used as a very potential neuroprotective drug.