Low-Dose Dioxin Reduced Glucose Uptake in C2C12 Myocytes: The Role of Mitochondrial Oxidative Stress and Insulin-Dependent Calcium Mobilization

Abstract

Chronic exposure to some environmental polluting chemicals (EPCs) is strongly associated with metabolic syndrome, and insulin resistance is a major biochemical abnormality in the skeletal muscle in patients with metabolic syndrome. However, the causal relationship is inconsistent and little is known about how EPCs affect the insulin signaling cascade in skeletal muscle. Here, we investigated whether exposure to 100 pM of 2,3,7,8-tetrachlorodibenzodioxin (TCDD) as a low dose of dioxin induces insulin resistance in C2C12 myocytes. The treatment with TCDD inhibited the insulin-stimulated glucose uptake and translocation of glucose transporter 4 (GLUT4). The low-dose TCDD reduced the expression of insulin receptor β (IRβ) and insulin receptor substrate (IRS)-1 without affecting the phosphorylation of Akt. The TCDD impaired mitochondrial activities, leading to reactive oxygen species (ROS) production and the blockage of insulin-induced Ca2+ release. All TCDD-mediated effects related to insulin resistance were still observed in aryl hydrocarbon receptor (AhR)-deficient myocytes and prevented by MitoTEMPO, a mitochondria-targeting ROS scavenger. These results suggest that low-dose TCDD stress may induce muscle insulin resistance AhR-independently and that mitochondrial oxidative stress is a novel therapeutic target for dioxin-induced insulin resistance.

Boron Compounds Mitigate 2,3,7,8-Tetrachlorodibenzo-p-dioxin-Induced Toxicity in Human Peripheral Blood Mononuclear Cells

“…TCDD acts as a potent ligand for the aryl hydrocarbon receptor (AHR), with a strong affinity, causing an increase in the production of the CYP1A enzyme and disrupting the balance of oxidation and reduction. Additionally, TCDD hinders mitochondrial functions, resulting in the generation of reactive oxygen species (ROS) [ 55 , 56 ].…”

Neuroprotective Effects of Aldehyde-Reducing Composition in an LPS-Induced Neuroinflammation Model of Parkinson’s Disease

“…TH-immunopositivity in the ST was measured by the optical density of TH-positive fibers at ×40 magnification using ImageJ software (version 1.53e, http://imageJ.nih.gov/ij, accessed on 5 December 2023, National Institutes of Health, Bethesda, MD, USA). Activated microglia and astrocytes were categorized and counted based on their morphologies as previously described [33,34] Quantitative real-time RT-qPCR was conducted using 1.5 µg of total RNA isolated using Trizol reagent (Invitrogen, Carlsbad, CA, USA) and 10 pM oligo dT primers (Invitrogen) as previously described [53]. The real-time RT-qPCR reactions were carried out with 2× AmpiGene ® qPCR green Mix Lo-ROX (Enzo Biochem, New York, NY, USA) on a Roter-Gene Q (Qiagen, Hilden, Germany).…”

“…The mRNA quantification was normalized by concurrently measuring nuclear DNA encoding 18S rRNA. Relative gene expression was determined using the 2 −∆∆ Ct method and is presented as the fold change compared to that of the control condition [53]. Primer sequences for specific genes included IL-1β (5 -tac gag ccg tag ccc aaa ca-3 and 5 -gat cgt aac gga agc gtg ga-3 for murine), IL-6 (5 -ctg gag tac cat agc tac ctg g-3 and 5 -gtc ctt agc cac tcc ttc tg-3 for murine), TNFα (5 -gcc cag acc ctc aca ctc aga t-3 and 5 -ttg tcc ctt gaa gag aac ctg-3 for murine), and antioxidant genes Nrf2 (nuclear factor (erythroid-derived 2)-like 2) (5 -tgg agg cag cca tga ctg a-3 and 5 -ctg ctt gtt ttc ggt att aag aca ct-3 for murine), NQO-1 (5 -atg gga ggt ggt cga atc tga-3 and 5 -gcc ttc ctt ata cgc cag aga tg-3 for murine), SOD (5 -gcc cgc taa gtg ctg agt c-3 and 5 -cca gaa gga taa cgg atg cca-3 for murine), HO-1 (5 -aag ccg aga atg ctg agt tca-3 and 5 -gcc gtg tag ata tgg tac aag ga-3 for murine), Sirt1 (5 -gct gac gac ttc gac gac g-3 and 5 -tcg gtc aac agg agg ttg tct-3 for murine), Sirt2 (5 -gag ccg gac cga ttc aga c-3 and 5 -aga cgc tcc ttt tgg gaa cc-3 for murine), Sirt3 (5 -tac agg ccc aat gtc act ca-3 and 5 -aca gac cgt gca tgt agc tg-3 for murine), and 18S rRNA (5 -gag cga aag cat ttg cca ag-3 and 5 -ggc atc gtt tat ggt cgg aa-3 for both human and murine).…”