Mechanism of Tang Luo Ning effect on attenuating of oxidative stress in sciatic nerve of STZ-induced diabetic rats

Abstract

Ethnopharmacological relevance: Tang Luo Ning recipe (TLN), a traditional Chinese herbal medicine based on Huangqi Guizhi Wuwu decoction, has been used clinically to treat diabetic peripheral neuropathy in China. However, the effect of TLN on diabetic peripheral neuropathy is unclear. The objective of this study was to determine the main components in TLN and to investigate the effects of TLN on oxidative stress in diabetic peripheral neuropathy rats.

Materials and methods: The effect of TLN on oxidative stress was investigated in streptozocin (STZ)-induced diabetic rats. Fasting blood glucose, body weight, thermal perception threshold test and motor and sensory nerve conduction velocity of sciatic nerve were measured. Sciatic nerve morphology was observed by Haematoxylin and eosin staining and under transmission electron microscope. T-AOC was measured by colorimetric assay. ROS were measured using enzyme-linked immunosorbent assay. Nrf2 and γGCS protein levels were measured by Western blot analysis. The expression of Bcl2, Bax and Cyto C were examined by immunohistochemistry.

Results: TLN markedly improved the neurological function including thermal perception threshold and nerve conduction velocity of DPN rats. Haematoxylin and eosin (HE) and transmission electron microscopy (TEM) staining results showed that TLN attenuated axon atrophy and demyelination in DPN rats. Moreover, TAOC were increased, whereas ROS content was decreased after treatment with TLN in rats with DPN. Furthermore, TLN increased protein levels of Nrf2, γGCS and Bcl2, and decreased Bax and Cyto C expression.

Conclusions: TLN improved neurological function to prevent diabetic peripheral neuropathy by attenuating oxidative stress through Nrf2 and Bcl2 activation.

Keywords: Albiflorin (PubChem CID: 24868421); Astragaloside A (PubChem CID: 45006101); Bax; Bcl-2; Calycosin (PubChem CID: 5280448); Chlorogenic acid (PubChem CID: 1794427); Diabetic peripheral neuropathy; Ellagic acid (PubChem CID 5281855); Ginkgolide C (PubChem CID: 9867869); Nrf2; Oxidative stress; Oxypaeoniflora (PubChem CID: 21631105); Paeoniflorin (PubChem CID: 53384387); Rosmarinic acid (PubChem CID 5281792); Salvianolic acid A (PubChem CID 5281793); Salvianolic acid B (PubChem CID: 6441188); γGCS.