Effects of Polygonum cuspidatum on AMPK-FOXO3α Signaling Pathway in Rat Model of Uric Acid-Induced Renal Damage

Objective: To observe the effects of Chinese medicine（CM） Polygonum cuspidatum（PC） on adenosine 5'-monophosphate-activated protein kinase（AMPK）, forkhead box O3α（FOXO3α）, Toll-like receptor-4（TLR4）, NACHT, LRR and PYD domains-containing protein 3（NLRP3）, and monocyte chemoattractant protein-1（MCP-1） expression in a rat model of uric acid-induced renal damage and to determine the molecular mechanism. Methods: A rat model of uric acid-induced renal damage was established, and rats were randomly divided into a model group, a positive drug group, and high-, medium-, and low-dose PC groups（n=12 per group）. A normal group（n=6） was used as the control. Rats in the normal and model groups were administered distilled water(10 m L·kg–1) by intragastric infusion. Rats in the positive drug group and the high-, medium-, and low-dose PC groups were administered allopurinol(23.33 mg·kg–1), and 7.46, 3.73, or 1.87 g·kg–1·d–1 PC by intragastric infusion, respectively for 6 to 8 weeks. After the intervention, reverse transcription polymerase chain reaction, Western blot, enzyme linked immunosorbent assay, and immunohistochemistry were used to detect AMPK, FOXO3α, TLR4, NLRP3, and MCP-1 m RNA and protein levels in renal tissue or serum. Results: Compared with the normal group, the m RNA transcription levels of AMPK and FOXO3α in the model group were significantly down-regulated, and protein levels of AMPKα1, pAMPKα1 and FOXO3α were significantly down-regulated at the 6 th and 8 th weeks（P<0.01 or P<0.05）. The m RNA transcription and protein levels of TLR4, NLRP3 and MCP-1 were significantly up-regulated（P<0.01 or P<0.05）. Compared with the model group, at the 6 th week, the mRNA transcription levels of AMPK in the high-and medium-dose groups, and protein expression levels of AMPKα1, p AMPKα1 and FOXO3α in the high-dose PC group, AMPKα1 and p AMPKα1 in the mediumdose PC group, and p AMPKα1 in the low-dose PC group were significantly up-regulated（P<0.01 or P<0.05）; the m RNA transcription and protein levels of TLR4 and NLRP3 in the 3 CM groups, and protein expression levels of MCP-1 in the medium-and low-dose PC groups were down-regulated（P<0.01 or P<0.05）. At the 8 th week, the m RNA transcription levels of AMPK in the high-dose PC group and FOXO3α in the medium-dose PC group, and protein levels of AMPKα1, p AMPKα1 and FOXO3α in the 3 CM groups were significantly up-regulated（P<0.01 or P<0.05）; the m RNA transcription levels of TLR4 in the medium-and low-dose PC groups, NLRP3 in the high-and low-dose PC groups and MCP-1 in the medium-and low-dose PC groups, and protein expression levels of TLR4, NLRP3 and MCP-1 in the 3 CM groups were down-regulated（P<0.01 or P<0.05）. Conclusion: PC up-regulated the expression of AMPK and its downstream molecule FOXO3α and inhibited the biological activity of TLR4, NLRP3, and MCP-1, key signal molecules in the immunoinflammatory network pathway, which may be the molecularmechanism of PC to improve hyperuricemia-mediated immunoinflammatory metabolic renal damage.