Autophagy Enhancing Contributes to the Organ Protective Effect of Alpha-Lipoic Acid in Septic Rats

Abstract

Alpha-lipoic acid (ALA) reportedly has protective effects against sepsis, which is a leading cause of mortality worldwide and is associated with multiple organ dysfunction. The present study aimed to investigate further the possible action mechanisms of ALA. Male Sprague-Dawley rats were subjected to cecal ligation and puncture (CLP) in order to establish a sepsis model. The rats received an oral gavage of 200 mg/kg ALA or saline immediately after surgery. The heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP) and maximum rising and lowering rates of left ventricular pressure (±dp/dt) were examined for assessing the cardiac function. Blood urea nitrogen (BUN) and serum creatinine levels were assessed for evaluating renal function. Neutrophil gelatinase-associated lipocalin (NAGL) was examined for reflecting acute renal injury. Histopathological alterations of the small intestine were examined by hematoxylin-eosin staining. The ultrastructure of the small intestine and kidney was observed under electron microscopy. The levels of autophagy- and inflammation-associated proteins were determined via western blot analysis. The binding of nuclear factor-kappa B (NF-κB) to DNA was tested via an electrophoretic mobility shift assay. Cell apoptosis was examined using TUNEL staining. ALA treatment improved the survival rate, restored the loss of body weight and pro-inflammatory cytokines production in the serum of CLP-induced septic rats. ALA improved the cardiac and renal functions, downregulated the expression levels of interleukin-1β, tumor necrosis factor-α, and inducible nitric oxide synthase in the myocardium and small intestine of septic rats. ALA treatment also inactivated the NF-κB signaling pathway in the small intestine. An examination of autophagy showed that ALA increased the LC3II/I ratio, upregulated Atg5, Atg7, and beclin-1 and downregulated p62 protein levels in the myocardium, kidney, and small intestine of septic rats, and further promoted autophagosome accumulation in the kidney and small intestine. In addition, ALA could also reduce cell apoptosis in myocardium, kidney and small intestine tissues. These effects can be completely or party inhibited by 3-MA. Our findings suggest that autophagy enhancing may contribute to the organ protective effect of ALA in septic rats.

Alpha-Lipoic Acid Protects Cardiomyocytes against Heat Stroke-Induced Apoptosis and Inflammatory Responses Associated with the Induction of Hsp70 and Activation of Autophagy

“…It is demonstrated that inhibition of autophagy accelerated apoptosis and disturbed immunity as well as increased ROS production [43], suggesting that autophagy plays an important role in the inhibition of apoptosis and inflammation. The causal relationship of ALA and autophagy was demonstrated in recent literature that ALA activated autophagy and reduced NF- κ B signaling as well as apoptosis to exert the protective effects in the myocardium of septic rats [44]. However, these effects were significantly eliminated by the administration of autophagy inhibitor 3-methyladenine (3-MA), suggesting that enhancement of autophagy played a critical role in the protective effect of ALA in alleviation of acute inflammation.…”

TUNEL Assay: A Powerful Tool for Kidney Injury Evaluation

“…This is perhaps because cells are considered dead independent of the intensity of the TUNEL signal, as a cell cannot be “more dead” if the TUNEL staining is more intense. Although it is difficult to compare studies that use a wide variety of methods to quantify TUNEL results, the amount of TUNEL-positive cells in control animals is usually below 2% [ 75 , 99 , 100 , 116 , 126 ]. Acute injury is associated with a ~5–40× increase in TUNEL-positivity [ 79 , 126 , 127 ].…”

“…Although it is difficult to compare studies that use a wide variety of methods to quantify TUNEL results, the amount of TUNEL-positive cells in control animals is usually below 2% [ 75 , 99 , 100 , 116 , 126 ]. Acute injury is associated with a ~5–40× increase in TUNEL-positivity [ 79 , 126 , 127 ]. During chronic injury, the increase in TUNEL-positive cells is slightly lower, ~2–20-fold, [ 29 , 43 , 65 ] compared to untreated controls.…”

Inhibited histone deacetylase 3 ameliorates myocardial ischemia–reperfusion injury in a rat model by elevating microRNA‐19a‐3p and reducing cyclin‐dependent kinase 2

“…The cardiac function also can be evaluated by hemodynamic indicators such as LVEDP, LVSP, + dp/dt max and − dp/dt max. 25 Our outcomes reflected that I/R increased LVEDP level and decreased levels of LVSP, + dp/dt max and − dp/dt max; HDAC3/CDK2 inhibition or miR-19a-3p upregulation reduced LVEDP level and promoted levels of LVSP, + dp/dt max and − dp/dt max; the effects of silencing HDAC3 was eliminated by miR-19a-3p antagomir (Figure 3a-d).…”