OBJECTIVETo evaluate the protective effect of quercetin against lipopolysaccharide (LPS)-induced cardiac injury in mice.

METHODSC57BL/6J mice were randomized into 4 groups to receive intraperitoneal injection of saline (negative control) or LPS (20 mg/kg), or fed with quercetin (100 mg/kg for 7 days) with or without subsequent LPS injection (quercetin+LPS group and quercetin control group, respectively). Six hour after LPS injection, the mice were tested for cardiac function with an echocardiograph, and the protein expressions of Bax, Bcl-2, iNOS, and eNOS in the myocardium were evaluated with Western blotting; serum NO concentration was also measured. The survival of the mice within 5 days after LPS injection was recorded to draw the survival curve.

RESULTSQuercetin pretreatment significantly improved the cardiac function of LPS-challenged mice (P<0.05), and attenuated LPS-induced increment in myocardial iNOS expression and decrement in eNOS level. LPS significantly increased the myocardial Bax expression and slightly decreased Bcl-2 expression; quercetin pretreatment decreased Bax expression to the control level and significantly lowered Bax/Bcl-2 ratio as compared with the LPS group. Serum NO level was significantly increased by nearly 2.5 folds in LPS-challenged mice, but was markedly decreased with quercetin pretreatment (P<0.05). The 5-day survival rate of LPS-treated mice was 10%, which was increased to 45% in quercetin- pretreated mice (P<0.05).

CONCLUSIONQuercetin can alleviate LPS-induced cardiac dysfunctions in mice to increase their survival rate following LPS challenge.