ABSTRACT
ObjectiveTo investigate the effect of Tangbikang granules on oxidative stress of sciatic nerve in diabetic rats by regulating adenylate activated protein kinase/peroxisome proliferator-activated receptor γ coactivator-1α/mitochondrial Sirtuins 3 （AMPK/PGC-1α/SIRT3） signaling pathway. MethodThe spontaneous obesity type 2 diabetes model was established using ZDF rats. After modeling， they were randomly divided into high， medium， and low dose Tangbikang granule groups （2.5， 1.25， 0.625 g·kg-1·d-1） and lipoic acid group （0.026 8 g·kg-1·d-1）， and the normal group was set up. The rats were administered continuously for 12 weeks after modeling. The blood glucose of rats was detected before intervention and at 4， 8， 12 weeks after intervention. At the 12th week， motor nerve conduction velocity （MNCV）， sensory nerve conduction velocity （SNCV）， nerve blood flow velocity， mechanical pain threshold， and thermal pain threshold were detected. The sciatic nerve was taken for hematoxylin-eosin （HE） staining to observe the tissue morphology. The ultrastructure of the sciatic nerve was observed by transmission electron microscope. The expression levels of superoxide dismutase （SOD）， malondialdehyde （MDA）， interleukin-1β （IL-1β）， and tumor necrosis factor-α （TNF-α） in sciatic nerve were determined by enzyme-related immunosorbent assay （ELISA）. The mRNA expressions of AMPKα， AMPKβ， PGC-1α， and SIRT3 in sciatic nerve were determined by real-time polymerase chain reaction （Real-time PCR）. ResultCompared with the normal group， fasting blood glucose in the model group was increased at each time point （P<0.01）. The mechanical pain threshold was decreased （P<0.05）， and the incubation time of the hot plate was extended （P<0.01）. MNCV， SNCV， and nerve blood flow velocity decreased （P<0.05）. The expression level of SOD was decreased （P<0.01）. The expression levels of MDA， IL-1β， and TNF-α were increased （P<0.01）. The mRNA expression levels of AMPKα， AMPKβ， PGC-1α， and SIRT3 were decreased （P<0.01）. The structure of sciatic nerve fibers in the model group was loose， and the arrangement was disordered. The demyelination change was obvious. Compared with the model group， the fasting blood glucose of rats in the high dose Tangbikang granule group was decreased after the intervention of eight weeks and 12 weeks （P<0.01）. The mechanical pain threshold increased （P<0.05）. The incubation time of the hot plate was shortened （P<0.01）. MNCV， SNCV， and Flux increased （P<0.05）. The expression level of SOD was increased （P<0.01）. The expression levels of MDA， IL-1β， and TNF-α were decreased （P<0.01）. The mRNA expression levels of AMPKα， AMPKβ， PGC-1α， and SIRT3 were increased （P<0.01）. The sciatic nerve fibers in the high-dose Tangbikang granule group were tighter and more neatly arranged， with only a few demyelinating changes. The high， medium， and low dose Tangbikang granule groups showed a significant dose-effect trend. ConclusionTangbikang granules may improve sciatic nerve function in diabetic rats by regulating AMPK/PGC-1α/SIRT3 signaling pathway partly to inhibit oxidative stress.