Gegen Qinliantang and Its Combinations Inhibit Oxidative Stress Injury in Ulcerative Colitis Rats by Regulating Nrf2/NQO1 Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the underlying mechanism of Gegen Qinliantang （GGQL） in the treatment of ulcerative colitis （UC） in rats and discuss the effects of modification of GGQL on its efficacy. MethodThe UC model was induced in rats by free access to 5% dextran sulfate sodium in saline solution. Male SD rats were randomly divided into a normal group， a model group， a positive control group （sulfasalazine enteric-coated tablets， 350 mg·kg-1）， a GGQL group （17 g·kg-1）， a Glycyrrhizae Radix et Rhizoma （GR）-absent GGQL group （17 g·kg-1）， a Puerariae Lobatae Radix （PLR）-absent GGQL group （17 g·kg-1）， a GR-PLR group （17 g·kg-1）， and a Scutellariae Radix （SR）-Coptidis Rhizoma （CR） group （17 g·kg-1）. The in vitro antioxidant activities of GGQL and its combinations were evaluated by 2，2-diphenyl-1-picrylhydrazyl （DPPH）， 2，2′-azino-bis（3-ethylbenzothiazoline-6-sulfonic acid） （ABTS）， and fluorescence recovery after photobleaching （FRAP） methods. The degree of colonic tissue injury in each group was evaluated based on the weight changes of rats， the length of the colon， the colon sections， and hematoxylin-eosin （HE）-stained histopathologic sections. The serum levels of myeloperoxidase （MPO）， lipid peroxide （LPO）， malondialdehyde （MDA）， total superoxide dismutase （T-SOD）， catalase （CAT）， and reduced glutathione （GSH） were measured by colorimetry. The mRNA and protein expression of nuclear factor-erythroid 2 related factor （Nrf2）， quinone oxidoreductase 1 （NQO1）， and heme oxygenase-1 （HO-1） in colon tissues was detected by real-time fluorescence-based quantitative polymerase chain reaction （Real-time PCR） and Western blot， respectively. ResultCompared with the normal group， the model group showed colonic mucosal necrosis， inflammatory infiltration， increased serum levels of MPO， LPO， and MDA （P<0.01）， blunted activities of T-SOD， CAT， and GSH （P<0.01）， decreasing trend of mRNA expression of Nrf2， NQO1， and HO-1， reduced expression of Nrf2 protein （P<0.01）， and decreasing trend of expression of NQO1 and HO-1 proteins. Compared with the model group， the GGQL and its combination groups showed improved pathological injury and morphological structure of colon tissues in UC rats， reduced serum levels of MPO， LPO， and MDA （P<0.05）， potentiated T-SOD activity （the PLR-absent GGQL group）， CAT activity （the GR-absent GGQL group and the SR-CR group）， and GSH activity （P<0.01）， and increased mRNA and protein expression of Nrf2， NQO1， and HO-1 in colon tissues. The difference in the GGQL group was significant （P<0.05）. ConclusionGGQL has a restorative effect on the pathological injury of UC rats， and its mechanism may be related to the activation of the Nrf2 signaling pathway and inhibition of oxidative stress response. The absence of PLR or only presence of SR and CR has a great impact on the treatment of UC. The results can provide references for the clinical rational medication of Chinese medicine and the research on the mechanism of compound combinations.