Protective effect of puerarin against burn-induced heart injury in rats

Abstract

The present study evaluated the potential protective effects of puerarin and its associated mechanism on burn-induced myocardial damage. A total of 40 healthy adult Wistar rats were randomly divided into four groups: i) Sham; ii) burn; iii) burn + puerarin; and iv) puerarin. Serum levels of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α) and IL-6 were measured using ELISA. Myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels were determined in myocardial homogenates using a commercial assay kit. TUNEL staining and western blot analysis of cleaved and pro-caspase-3 were also performed to assess apoptosis. Activation of p38-MAPK, ERK, JNK and AKT were measured using western blot analysis. Left ventricular systolic pressure, maximum rates of increase/decrease in left ventricular pressure, creatine kinase MB activity and cardiac troponin T levels were found to be altered in the burn group 12 h after burn, which were reversed by puerarin treatment. Injection of puerarin following burn injury also reduced heart water content. Serum levels of IL-1β, TNF-α and IL-6 were significantly higher in the burn group compared with those in the sham group. Puerarin treatment reduced serum levels of IL-1β, TNF-α and IL-6, in addition to reducing MPO activity and MDA levels in myocardial tissues. Puerarin inhibited the activation of caspase-3, p38, ERK and JNK following severe burn, but elevated Akt activation following severe burn. In conclusion, puerarin improved cardiac function in rats following severe burn injury, which may be due to reduced myocardial injury, inhibition of cardiomyocyte apoptosis and reduced oxidative inflammatory stress; the MAPK and AKT signaling pathways are proposed to the underlying mechanism of these findings.

Keywords: burns; cardiac dysfunction; inflammation; myocardial injury; p38-MAPK; puerarin.

Figure 1

Puerarin attenuated severe burn-induced acute myocardial injury. All parameters were evaluated 12 h after burn injury. (A) Effects of puerarin treatment on LVSP, (B) +dP/dt_max, and (C) -dP/dt_max. (D) Effects of puerarin treatment on serum CK-MB levels and (E) cTnT levels. (F) Effects of puerarin treatment on myocardial water content (%). Values above the bars are the mean values. n=10 in each group. ^**P<0.01 and ^*P<0.05. LVSP, left ventricular systolic pressure; +dP/dt_max, maximum rates of increase in left ventricular pressure; -dP/dt_max maximum rates of reduction in left ventricular pressure; CK-MB, creatin kinase MB; cTnT, cardiac tronponin.

Figure 2

Puerarin attenuated severe burn-induced cardiac inflammation and oxidative stress. (A) Effects of puerarin treatment on serum TNF-α, (B) IL-1β, and (C) IL-6 levels. (D) Effects of puerarin treatment on MPO activity and (E) MDA content in myocardial tissue. Values above the bars represent the mean values. n=10 in each group. ^**P<0.01 and ^*P<0.05. IL, interleukin; TNF-α, tumor necrosis factor-α; MPO, myeloperoxidase; MDA, malondialdehyde.

Figure 3

Puerarin attenuated severe burn-induced cardiomyocyte apoptosis in myocardial tissues. (A) Effects of puerarin treatment on cardiomyocyte apoptosis as determined by TUNEL staining. (B) Effects of puerarin treatment on cardiomyocyte apoptosis as determined by western blot analysis of caspase-3 activation. Values above the bars represent mean values. n=10 in each group. ^**P<0.01.

Figure 4

Effects of puerarin on MAPK and Akt signaling following severe burn injury. (A) Representative blot images showing the levels of ERK, p38-MAPK, JNK and Akt phosphorylation and the expression of corresponding total proteins in myocardial tissues 12 h following burn injury. (B) Semi-quantitative densitometric results from (A), displaying the calculated ratios of p-ERK/ERK, p-p38-MAPK/p38-MAPK, p-JNK/JNK and p-Akt/Akt. Values above the bars represent mean values. n=10 in each group. ^**P<0.01 and ^*P<0.05.