Therapeutic Effect of Buyang Huanwutang on Diabetic Peripheral Neuropathy and Dosage of Astragalus in Prescription： Based on SIRT1/p53-mediated Apoptosis / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the neuroprotective effect of Buyang Huanwutang （BYHW） on diabetic peripheral neuropathy （DPN） rats by regulating SIRT1/p53 pathway and to clarify the mechanism and the dosage of astragalus in the prescription. MethodA total of 90 SD rats were randomized into control group， DPN group， DPN + BYHW containing 120 g Astragalus （at 15 g·kg-1·d-1） （BYHW120 group）， DPN + BYHW containing 60 g Astragalus （at 8.75 g·kg-1·d-1） （BYHW60 group）， DPN + BYHW containing 30 g Astragalus （at 5.625 g·kg-1·d-1） （BYHW30 group）， and DPN + α-lipoic acid （at 60 mg·kg-1·d-1） （ALA group）. Standard diet was given to rats in the control group and high-carbohydrate/high-fat diet and streptozotocin （ip） were used to induce diabetes in rats in other groups. The administration lasted 12 weeks. After the intervention， mechanical pain threshold and nerve conduction velocity were detected. The L4-5 dorsal root ganglions were stained with haematoxylin-eosin （HE） and toluidine blue to observe the pathological changes， and the apoptosis of nerve cells was detected by terminal deoxynucleotidal transferase-mediated dUTP-biotin nick end labeling （TUNEL） assay. Cleaved cysteinyl aspartate-specific proteinase-3 （Caspase-3）， and the main proteins in the SIRT1/p53 pathway， such as silencing information regulator 2 related enzyme 1 （SIRT1）， acetyl-p53， dynamin-related protein 1 （Drp1）， Bcl-2 associated X protein （Bax）， and B-cell lymphoma-2 （Bcl-2）， were detected by immunohistochemistry and Western blot. ResultCompared with the control group， the DPN group presented increase in blood glucose （P<0.01）， decrease in nerve conduction velocity and mechanical pain threshold （P<0.01）， rise of the percentage of positive cells （TUNEL assay， the same below） and the expression of cleaved Caspase-3 （P<0.01）， drop in the expression of SIRT1 （P<0.01）， and elevation of acetyl-p53， Drp1， and Bax/Bcl-2 ratio （P<0.01）. Cleaved Caspase-3， acetyl-p53， Drp1， and Bax/Bcl-2 ratio in each administration group decreased as compared with those in the DPN group （P<0.01）. Nerve conduction velocity， mechanical pain threshold （P<0.05， P<0.01）， and the percentage of positive cells （P<0.05， P<0.01） increased in the administration groups as compared with those in the DPN group except for the BYHW30 group， and BYHW120 group and ALA group showed the increase in SIRT1 （P<0.05， P<0.01）. Nerve conduction velocity， mechanical pain threshold， and SIRT1 expression were lower （P<0.05， P<0.01） and expression of cleaved Caspase-3 was higher （P<0.01） in the BYHW60 and BYHW30 groups than in the BYHW120 group. The percentage of positive cells and the expression of acetyl-p53 were higher in the BYHW30 group than in the BYHW120 group （P<0.01）. ConclusionBYHW inhibits apoptosis and exerts therapeutic effect on DPN by regulating the SIRT1/p53 pathway. The therapeutic effect is related to the dosage of Astragalus in the prescription. BYHW containing 120 g Astragalus suppresses p53-dependent apoptosis more significantly than Buyang Huanwutang containing 60 g and 30 g of Astragalus.