Palmitate increases superoxide production through mitochondrial electron transport chain and NADPH oxidase activity in skeletal muscle cells

Abstract

The effect of unbound palmitic acid (PA) at plasma physiological concentration range on reactive oxygen species (ROS) production by cultured rat skeletal muscle cells was investigated. The participation of the main sites of ROS production was also examined. Production of ROS was evaluated by cytochrome c reduction and dihydroethidium oxidation assays. PA increased ROS production after 1 h incubation. A xanthine oxidase inhibitor did not change PA-induced ROS production. However, the treatment with a mitochondrial uncoupler and mitochondrial complex III inhibitor decreased superoxide production induced by PA. The importance of mitochondria was also evaluated in 1 h incubated rat soleus and extensor digitorum longus (EDL) muscles. Soleus muscle, which has a greater number of mitochondria than EDL, showed a higher superoxide production induced by PA. These results indicate that mitochondrial electron transport chain is an important contributor for superoxide formation induced by PA in skeletal muscle. Results obtained with etomoxir and bromopalmitate treatment indicate that PA has to be oxidized to raise ROS production. A partial inhibition of superoxide formation induced by PA was observed by treatment with diphenylene iodonium, an inhibitor of NADPH oxidase. The participation of this enzyme complex was confirmed through an increase of p47(phox) phosphorylation after treatment with PA.

Omega-3 fatty acids differentially modulate enzymatic anti-oxidant systems in skeletal muscle cells

“…Similar results were observed by our previous studies (Lambertucci et al 2008) using primary cultures of skeletal muscle cells treated with palmitic acid. Rossary et al (2007) also observed an increased ROS production using fibroblasts treated with 15 μM of DHA for 4 h (even using a shorter fatty acid concentration and incubation time).…”

“…Fluorescent microscopy was used to measure fluorescent signal which was quantified using ImageJ 1.46r (Wayne Rasband, NIH, USA) using two photos per well selected at random. Palmitic acid at 100 μM was used as positive control for superoxide production as shown in previous studies (Lambertucci et al 2008(Lambertucci et al , 2012.…”

Hemin Improves Insulin Sensitivity in Skeletal Muscle in High Fat–Fed Mice

“…Although the cause of the increased oxidative stress in high-fat diet-induced obesity is not completely understood, one possible reason is the increased supply of free fatty acids to the cells from triglyceride. Incubation of the skeletal muscle with palmitate for 1 h induces superoxide production in the skeletal muscle (26), and high-fat meal for 5 days in lean humans increases mitochondria hydrogen peroxide production and reduces antioxidants capacity (27). Fat content in thigh muscle are negatively correlated with insulin sensitivity in obese type 2 diabetic patients (28), and diet restriction reduces triglyceride levels and oxidative stress in skeletal muscle, which is associated with improved insulin sensitivity in Goto-Kakizaki rats (29).…”

Wogonin ameliorates lipotoxicity-induced apoptosis of cultured vascular smooth muscle cells via interfering with DAG-PKC pathway

“…The effect of FFA on ROS production has been examined in numerous cell types [50,51] . ER stress and ROS are proposed to be involved in cell death.…”