Experiments performed by Wang et al. have indicated that in subacute cerebral ischemia, activated microglia exert a neuroprotective role through balancing the expressions of GDNF and TNF-α, whereas the inhibition of microglial activation by poly [ADP-ribose] polymerase 1 (PARP-1), the co-activating factor of nuclear factor NF-κB signaling pathway, attenuates GDNF production [117]. This evidence concerns the gene GDNF and brain ischemia.