Effect of Chaihu Shugansan on Mitochondrial Function and Mitophagy in Gastric Tissue of Rats with Functional Dyspepsia / 中国实验方剂学杂志

ABSTRACT

Objective:To observe the effects of Chaihu Shugansan on gastric motility and mitochondrial function and mitophagy in rats with functional dyspepsia （FD） and to preliminarily reveal its mechanism in preventing and treating FD. Method:Thirty-two SD rats of SPF grade were randomly divided into the normal group， model group， Chaihu Shugansan （4.8 g·kg^-1） group， and domperidone group （4.5 mg·kg^-1） after one week of adaptive feeding， with eight rats in each group. Rats in all groups except for the normal group were exposed to modified tail-clamping stimulation for inducing FD. Four weeks later， the semi-solid nutritive medium was used to observe the gastric emptying rate of FD rats， and the serum citrate synthase （CS）， motilin （MTL）， and gastrin （GAS） were detected by enzyme-linked immunosorbent assay （ELISA）. The pathological changes in gastric tissue were observed by hematoxylin-eosin （HE） staining， the mitochondrial characteristics by transmission electron microscopy， and the expression of microtubule-associated protein light chain 3 （LC3） and voltage-dependent anion-selective channel 1 （VDAC1） by immunofluorescence co-localization. The mitochondria were extracted from fresh gastric tissue for measuring the reactive oxygen species （ROS）， malondialdehyde （MDA）， and superoxide dismutase （SOD） levels using the biochemical kits. The mitochondrial LC3， yeast Atg6 homologous（Beclin1）， and p62 protein expression was assayed by Western blot. Result:Compared with the normal group， the model group exhibited significantly reduced gastric emptying rate （<italic>P</italic><0.01） and serum CS， MTL， and GAS levels （<italic>P</italic><0.01）. HE staining showed no pathological changes like erosion or ulcer in the gastric tissue of rats in each group. However， the mitochondria in the gastric tissue were observed swollen and dilated under the transmission electron microscope， and vacuolar lesions appeared. The co-expression of LC3 with VDAC1 increased significantly （<italic>P</italic><0.01）. The mitochondrial ROS and MDA levels were elevated significantly （<italic>P</italic><0.01）， while SOD content was significantly reduced （<italic>P</italic><0.01）. The protein expression levels of LC3 and Beclin1 were significantly up-regulated （<italic>P</italic><0.05， <italic>P</italic><0.01）， whereas p62 protein expression was down-regulated significantly （<italic>P</italic><0.01）. Compared with the model group， Chaihu Shugansan and domperidone elevated the gastric emptying rate （<italic>P</italic><0.05） and serum CS， MTL， and GAS levels （<italic>P</italic><0.05， <italic>P</italic><0.01）. It was observed under the transmission electron microscope that the mitochondrial nuclear membrane of the gastric tissue was intact， with clear structure and high density of mitochondrial cristae， and mitochondrial fission and fusion were observed in some parts. The co-localization area of LC3 and VDAC1 was significantly reduced （<italic>P</italic><0.01）. The mitochondrial ROS and MDA levels declined significantly （<italic>P</italic><0.05， <italic>P</italic><0.01）， whereas SOD level rose （<italic>P</italic><0.05）. The protein expression levels of LC3 and Beclin1 were significantly down-regulated （<italic>P</italic><0.05， <italic>P</italic><0.01）， while that of p62 was obviously up-regulated （<italic>P</italic><0.01）. Conclusion:The mechanism of Chaihu Shugansan in preventing and treating FD may be related to the improvement of mitochondrial function and the inhibition of mitophagy in gastric tissue.