Mechanism of Salvianolate in Inducing Autophagy in Podocytes of Rats with Membranous Nephropathy via AMPK/SIRT1/PGC-1α Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo observe the effect of salvianolate on the protein expressions of adenosine monophosphate （AMP）-activated protein kinase （AMPK）， silent information regulator 1 （SIRT1） and peroxisome proliferator-activated receptor-γ coactivator-1α （PGC-1α）， autophagy and apoptosis in kidney tissue of rats with membranous nephropathy （MN）， and to explore its possible molecular mechanism against MN. MethodEighty male SD rats were randomly divided into normal group， model group， benazepril hydrochloride group （10 mg·kg-1）， and salvianolate low-， medium-， and high-dose groups （16.7， 33.3 and 66.7 mg·kg-1）. The rats were modeled by injection of cationized bovine serum albumin （C-BSA） into the tail vein. After successful modeling， rats in the administration groups were given corresponding doses of drugs for 4 consecutive weeks， and then 24-hour urine， serum and kidney tissue were collected for the detection of 24-hour urinary protein （UTP）， blood urea nitrogen （BUN）， serum creatinine （SCr）， interleukin-6 （IL-6）， tumor necrosis factor-α （TNF-α）， C reactive protein （CRP）， glutathione peroxidase （GSH-Px）， superoxide dismutase （SOD）， and malondialdehyde （MDA）. The pathological changes of kidneys were observed by light microscope， electron microscope and immunofluorescence. Western blot was used to detect the protein expressions of phospho-AMPK （p-AMPK）， AMPK， phospho-SIRT1 （p-SIRT1）， SIRT1 and PGC-1α in rat kidney tissue. The protein expressions of autophagy-specific gene （Beclin-1）， microtubule-associated protein 1 light chain 3 （LC3） Ⅱ， ubiquitin-binding protein （p62）， B cell lymphoma （Bcl-2）， Bcl-2-associated X （Bax）， and cysteine aspartic protease-7 （Caspase-7） in rat kidney tissue were determined by immunohistochemistry （IHC）. ResultCompared with the conditions in the normal group， the levels of UTP， IL-6， TNF-α， CRP and MDA in the model group were increased （P<0.05） while the levels of SOD and GSH-Px were decreased （P<0.05）， and there was no difference in BUN and SCr. Compared with the model group， the administration groups had lowered UTP， IL-6， TNF-α， CRP and MDA （P<0.05） while elevated SOD and GSH-Px （P<0.05）. It could be seen from hematoxylin and eosin （HE） staining， Masson staining， immunofluorescence and electron microscopy that the pathological damage of rat kidney tissue in the model group was significant， but after treatment with benazepril hydrochloride and salvianolate， the pathological damage of kidney cells was gradually improved. The expressions of p-AMPK/AMPK， p-SIRT1/SIRT1， PGC-1α， Bcl-2， Beclin-1 and LC3Ⅱ in rat kidney in the model group were lower than those in the normal group （P<0.05） while the expressions of Bax， Caspase-7 and p62 were higher （P<0.05）. Compared with the model group， benazepril hydrochloride group and salvianolate groups had an up-regulation in the expressions of p-AMPK/AMPK， p-SIRT1/SIRT1， PGC-1α， Bcl-2， Beclin-1 and LC3Ⅱ in the kidney （P<0.05） while a down-regulation in the expressions of Bax， Caspase-7 and p62 （P<0.05）. ConclusionThe protective effect of salvianolate on the kidneys of MN rats may be related to the activation of AMPK/SIRT1/PGC-1α signaling pathway， the up-regulation of autophagy and the reduction of apoptosis.