Abstract:

Objective To investigate the protective effect of prunetin on the neurons in the rats with cerebral ischemia reperfusion injury （CIRI）， and to clarify its possible mechanisms. Methods Thirty-six SD rats were randomly divided into sham operation group， model group， low dose of prunetin group （3.5 mg·kg^-1）， medium dose of prunetin group （7.0 mg·kg^-1）， high dose of prunetin group （14.0 mg·kg^-1）， and positive drug edaravone （Eda） group （n=6）. Zealonga method was used to evaluate the neurological function damage of the rats in various groups； open field experiment was used to evaluate the autonomous motor function； Triphenyltetrazolium chlorde （TTC） staining was used to evaluate the areas of cerebral infarction of the rats in various groups； HE staining and Nissl staining were used to observe the pathomorphology of brain tissue of the rats in various groups. Additionally，twenty-one SD rats were randomly divided into sham operation group， model group， prunetin group， c-Jun N-terminal kinase （JNK） inhibitor group， p38 inhibitor group， JNK inhibitor+prunetin group， and p38 inhibitor+prunetin group （n=3）. TUNEL staining was used to detect the positive rates of apoptosis of neurons of the rats in various groups； Western blotting method was used to detect the expression levels of apoptosis-related proteins and JNK/p38 signaling pathway-related proteins in brain tissue of cerebral infarction side of the rats in various groups. Results Compared with sham operation group， the neurological deficit score of rats in model group was significantly increased （P<0.001）， the total motor distance was shortened （P<0.001）， and the ratio of cerebral infarction area was increased （P<0.001）. In sham group，the neuronal structure in the rat brain tissue was clear and well-organized， with an abundance of Nissl bodies and no apparent pathological changes observed. Compared with model group， the neurological deficit scores of the rats in medium and high doses of prunetin groups were decreased （P<0.05）， total motor distances of rats were increased （P<0.05）， and the cerebral infarction areas of rats were decreased（P<0.05）； the neurons showed disarrayed arrangement， cytoplasmic condensation， nuclear consolidation， and lysing and deletion of Nissl bodies were decreased. Compared with sham operation group， the positive rate of apoptosis of neurons in model group was significantly increased （P<0.001）， the expression level of B-cell lymphoma-2（Bcl-2）， Bcl-2-associated X protein（Bax） and cleaved Caspase-3 proteins in brain tissue of the rats were significantly increased （P<0.05 or P<0.01）. Compared with model group， the positive rats of apoptosis of neurons of the rats in prunetin group were decreased （P<0.05）， the expression level of Bcl-2 protein in brain tissue of the rats was increased （P<0.001）， and the expression levels of Bax and cleaved Caspase-3 proteins were significantly decreased（P<0.05）. Compared with inhibitor groups， the positive rates of apoptosis of neurons in inhibitor+prunetin groups were decreased （P<0.01）， and the expression levels of p-JNK and p-p38 proteins in brain tissue of the rats as well as the ratios of p-JNK/JNK and p-p38/p38 were decreased （P<0.05）. Conclusion Prunetin has the effect of reducing the neurological function damage， decreasing the area of cerebral infarction， reducing the pathological damage， and inhibiting neuronal apoptosis in the rats， and its mechanism may be related to inhibiting neuronal apoptosis through regulating the JNK/p38 signaling pathway.

Key words: Prunetin, Cerebral ischemia-reperfusion injury, Apoptosis, C-Jun N-terminal kinase, Neurons