Danggui Sinitang Mitigates Gouty Arthritis in Rats by Regulating Autophagy via PI3K/Akt/mTOR Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo study the mechanism of Danggui Sinitang in mitigating gouty arthritis （GA） in rats by regulating autophagy via the phosphatidylinositol 3-kinase （PI3K）/protein kinase B （Akt）/mammalian target of rapamycin （mTOR） signaling pathway. MethodSixty male SD rats were randomly assigned into normal， model， colchicine （0.3 mg·kg-1）， and low-， medium-， and high-dose Danggui Sinitang （6.54， 13.08， and 26.16 g·kg-1） groups （n=10） and administrated with corresponding drugs by gavage. The rats in the normal group and model group were administrated with equal volume of normal saline by gavage for 7 days. One hour after administration on day 5， the GA model was established by injecting sodium urate suspension （50 g·L-1） into the right ankle joint of rats in other groups except the normal group， and the rats in the normal group were injected with sterile normal saline of the same volume. The swelling and pathological changes of the ankle joint were observed. The serum levels of tumor necrosis factor-α （TNF-α）， interleukin-6 （IL-6）， and IL-1β were determined. Western blot was employed to determine the protein levels of PI3K， phosphorylated PI3K （p-PI3K）， protein kinase B （Akt）， phosphorylated Akt （p-Akt）， mTOR， phosphorylated mTOR （p-mTOR）， microtubule-associated protein 1 light chain 3 Ⅱ/Ⅰ （LC3Ⅱ/Ⅰ）， autophagy effector Beclin-1， and ubiquitin-binding protein p62 in the synovial tissue. Real-time fluorescent quantitative PCR （Real-time PCR） was employed to determine the mRNA levels of PI3K， Akt， mTOR， LC3， Beclin-1 and p62. ResultCompared with the normal control， the model group showed increased joint swelling index （P<0.01）， elevated serum levels of TNF-α， IL-6， and IL-1β， inflammatory cell infiltration， and fibrous tissue hyperplasia. In addition， the model group showed up-regulated protein levels of PI3K， p-PI3K， Akt， p-Akt， mTOR， p-mTOR， and p62 and mRNA levels of PI3K， Akt， mTOR， and p62 in the synovial tissue， while it showed down-regulated protein levels of LC3Ⅱ/Ⅰ and Beclin-1 and mRNA levels of LC3 and Beclin-1 （P<0.01）. Compared with the model group， medium- and high-dose Danggui Sinitang alleviated the joint swelling （P<0.01）， lowered the serum levels of TNF-α， IL-6， and IL-1β （P<0.05）， and relieved the inflammatory cell infiltration in the synovial tissue of the ankle joint and the fibrous tissue hyperplasia. Moreover， they down-regulated the protein levels of PI3K， p-PI3K， Akt， p-Akt， mTOR， p-mTOR， and p62 and the mRNA levels of PI3K， Akt， mTOR， and p62 in the synovial tissue （P<0.05）， while they up-regulated the protein levels of LC3Ⅱ/Ⅰ and Beclin-1 and the mRNA levels of LC3 and Beclin-1 （P<0.05）. ConclusionDanggui Sinitang， especially at a high dose， can inhibit PI3K/Akt/mTOR signaling pathway to improve autophagy in the synovial tissue， thereby mitigating GA.