Role of AMPK pathway in lead-induced endoplasmic reticulum stress in kidney and in paeonol-induced protection in mice.

Paeonol is a natural flavonoid isolated from Moutan Cortex, which has been found to exhibit antioxidant, anti-apoptotic, anti-aging and anti-inflammatory bioactivities. Herein, we investigated the nephroprotective efficacy of paeonol against Pb-induced toxicity and elucidated the potential mechanisms. The results revealed that paeonol significantly ameliorated renal dysfunction and histology changes of Pb-treated mice. Paeonol inhibited oxidative stress and increased activities of antioxidant enzyme in the kidneys of Pb-treated mice. Paeonol decreased the nuclear factor-κB activation and over-production of inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). Paeonol suppressed endoplasmic reticulum (ER) stress in kidneys of in the Pb treatment group and primary kidney mesangial cells. Moreover, paeonol increased the denosine 5'-monophosphate-activated protein kinase (AMPK) phosphorylation and decreased the activations of glycogen synthase kinase-3 (GSK-3), protein kinase RNA-like ER kinase (PERK), inositol-requiring protein-1 (IRE1), c-jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). These results were further confirmed in primary kidney mesangial cells. Taken together, these findings indicate that paeonol could protect kidney form Pb-induced injury by inhibiting oxidative stress, ER stress and inflammation via the AMPK and GSK-3 pathway. Paeonol might be a potential therapeutic agent to inhibit ER stress-associated inflammation in lead-stimulated kidneys.