It has been well documented that the activation of c-Jun N-terminal
protein kinase (JNK) pathway and
caspase-3 signal are involved in the delayed neuronal cell death in
cerebral ischemia. In this study, we first detected the activation pattern of JNK signaling including mixed lineage
kinase (MLK)3,
mitogen-activated protein kinase kinase (MKK)7 and JNK3 in hippocampal CA1 and CA3/DG regions at various time points after 15 min of
ischemia. These results indicated that
cerebral ischemia induced the continuous activation of MLK3/MKK7/JNK3 cascade, which all had two active waves only in the CA1 region. We also detected the phosphorylation of JNK substrates c-Jun and Bcl-2, and the activation of a key
protease of
caspase-3 in CA1 region, which only had one active peak, respectively. Because
K252a has recently been shown to be a potent inhibitor of MLK3 activity both in vivo and in vitro, we further examined the possible effects and mechanism of this interesting
drug in
cerebral ischemia. In our present paper, we found that administration of
K252a 20 min prior to
ischemia inhibited MLK3/MKK7/JNK3 signaling, Bcl-2 phosphorylation, the activation of c-Jun and
caspase-3, but had no significant effects on these
protein expressions. Additionally, pretreatment of
K252a significantly increased the number of the surviving CA1 pyramidal cells at 5 days of reperfusion. Our results suggest that
K252a play a neuroprotective role in ischemic injury via inhibition of the JNK pathway, involving the death effector of
caspase-3. Thus, JNK signaling may eventually emerge as a prime target for novel therapeutic approaches to treatment of
ischemic stroke, and
K252a may serve as a potential and important
neuroprotectant in therapeutic aspect in
ischemic stroke.