ABSTRACT
ObjectiveTo explore the mechanism of Naozhenning on learning and memory ability and neuron damage in hippocampal CA1 region of post-concussion syndrome model rats based on mitochondrial function. MethodMultiple cerebral concussion （MCC） was induced in SPF Wistar rats with the free-fall impact method. Then the model rats were randomly classified into model group （equivalent volume of distilled water）， piracetam （0.43 g·kg-1， ig） group， and low-， medium-， and high-dose NZN （5.4， 10.8， 21.6 g·kg-1， respectively， ig） groups， with 10 rats in each group， and another 10 normal rats were included in the normal control group （equivalent volume of distilled water）. The administration lasted 14 days and then relevant indexes were detected. Morris water maze test was used to observe the changes of learning and memory ability in each group， such as escape latency， residence time in primary quadrant， and times of crossing platform. The pathological changes of hippocampal CA1 region were observed based on hematoxylin-eosin （HE） staining and Nissl staining. The ultrastructure of mitochondria was observed under the transmission electron microscope （TME） and the activity of mitochondrial respiratory chain complex Ⅰ was detected by colorimetry. The content of adenosine triphosphate （ATP） was determined by fluorescence probe and mitochondrial membrane potential （MMP） by fluorescein enzyme-linked fluorescence immunoassay. ResultCompared with the normal control group， the model group showed long escape latency， short residence time in target quadrant， few times of crossing the platform， significant decrease in counts of neurons and Nissl bodies in hippocampal CA1 region， damage of neuronal morphology and mitochondrial structure， and significant reduction of MMP and the content of mitochondrial ATP and respiratory chain complex I （P<0.05， P<0.01）. The NZN groups demonstrated short escape latency， long residence time in target quadrant， increased times of crossing the platform， small number of neurons and Nissl bodies in hippocampal CA1 region， alleviated damage of neuronal morphology and mitochondrial structure， and increase in MMP and the content of mitochondrial ATP and respiratory chain complex I （P<0.05， P<0.01）. ConclusionNZN can improve the learning and memory ability of MCC rats by improving mitochondrial structure and function and alleviating hippocampal neuron injury.