Apelin-12 exerts neuroprotective effect against ischemia-reperfusion injury by inhibiting JNK and P38MAPK signaling pathway in mouse

Objective: Cerebral ischemia is a common Neurological Disease, and its pathological process remains elusive. This study focused on the protective mechanism of Apelin-12 protein on the nervous system of mice during cerebral ischemia-reperfusion injury through JNK and P38MAPK signaling pathway.

Materials and methods: The mouse model with an ischemia-reperfusion injury in middle cerebral artery was prepared by the modified thread-occlusion method and divided into 4 groups randomly. Before implantation of the mice, we assessed the neurological function and evaluated the cerebral edema by the wet-dry weight method. Lactate Dehydrogenase (LDH) kit was used to assess the degree of cell injury. Malondialdehyde (MDA) kit was used to measure the level of neuron MDA. Immunohistochemistry was performed to evaluate the neuronal cell in the ischemic brain. Protein expressions of JNK and P38MAPK and apoptosis-related molecules, including Bax, Bcl-2, Caspase-3, and cleaved Caspase-3, were measured by Western blot assay.

Results: After focal cerebral ischemia-reperfusion, a significant decrease in neurobehavioral score, brain edema and neuron injury in mice occurred. Apelin-12 significantly improved the neurobehavioral score of the mice with ischemia-reperfusion injury, alleviated brain edema and the damage to neurons. In addition, Apelin-12 inhibited the morphological changes and Apoptosis of neuronal cells in the ischemic penumbra of mice. Apelin-12 could downregulate the expression of Bax and Caspase-3, inhibit the activity of Caspase-3 and upregulate the expression of Bcl-2, an anti-apoptotic protein. A significant reduction in the protein expression of p-JNK and p-p38 was observed in the Apelin-12 group compared with that in the I/R or Vehicle group (p<0.05).

Conclusions: When an ischemia-reperfusion injury occurred, Apelin-12 can inhibit the JNK and P38MAPK signaling pathway of the apoptosis-related MAPKs family, thus offering protection to neurons.