High-fat diet-induced met-hemoglobin formation in rats prone (WOKW) or resistant (DA) to the metabolic syndrome: effect of CoQ10 supplementation

The Paradox of Coenzyme Q10 in Aging

Coenzyme Q (CoQ) is an essential endogenously synthesized molecule that links different metabolic pathways to mitochondrial energy production thanks to its location in the mitochondrial inner membrane and its redox capacity, which also provide it with the capability to work as an antioxidant. Although defects in CoQ biosynthesis in human and mouse models cause CoQ deficiency syndrome, some animals models with particular defects in the CoQ biosynthetic pathway have shown an increase in life span, a fact that has been attributed to the concept of mitohormesis. Paradoxically, CoQ levels decline in some tissues in human and rodents during aging and coenzyme Q₁₀ (CoQ₁₀) supplementation has shown benefits as an anti-aging agent, especially under certain conditions associated with increased oxidative stress. Also, CoQ₁₀ has shown therapeutic benefits in aging-related disorders, particularly in cardiovascular and metabolic diseases. Thus, we discuss the paradox of health benefits due to a defect in the CoQ biosynthetic pathway or exogenous supplementation of CoQ₁₀.

Aspalathin-Rich Green Rooibos Extract Lowers LDL-Cholesterol and Oxidative Status in High-Fat Diet-Induced Diabetic Vervet Monkeys

Type 2 diabetic patients possess a two to four-fold-increased risk for cardiovascular diseases (CVD). Hyperglycemia, oxidative stress associated with endothelial dysfunction and dyslipidemia are regarded as pro-atherogenic mechanisms of CVD. In this study, high-fat diet-induced diabetic and non-diabetic vervet monkeys were treated with 90 mg/kg of aspalathin-rich green rooibos extract (Afriplex GRT) for 28 days, followed by a 1-month wash-out period. Supplementation showed improvements in both the intravenous glucose tolerance test (IVGTT) glycemic area under curve (AUC) and total cholesterol (due to a decrease of the low-density lipoprotein [LDL]) values in diabetics, while non-diabetic monkeys benefited from an increase in high-density lipoprotein (HDL) levels. No variation of plasma coenzyme Q10 (CoQ₁₀) were found, suggesting that the LDL-lowering effect of Afriplex GRT could be related to its ability to modulate the mevalonate pathway differently from statins. Concerning the plasma oxidative status, a decrease in percentage of oxidized CoQ₁₀ and circulating oxidized LDL (ox-LDL) levels after supplementation was observed in diabetics. Finally, the direct correlation between the amount of oxidized LDL and total LDL concentration, and the inverse correlation between ox-LDL and plasma CoQ₁₀ levels, detected in the diabetic monkeys highlighted the potential cardiovascular protective role of green rooibos extract. Taken together, these findings suggest that Afriplex GRT could counteract hyperglycemia, oxidative stress and dyslipidemia, thereby lowering fundamental cardiovascular risk factors associated with diabetes.

Biochemical responses to cadmium exposure in Oncorhynchus mykiss erythrocytes

Cd is known for its carcinogenic effects, however its mechanism of toxicity and in particular its ability to promote oxidative stress is debated. In fact, although it is considered a redox-inactive metal, at high concentration Cd was shown to promote indirectly oxidative stress. In this study we investigated metal accumulation in ex vivo exposed trout (Oncorhynchus mykiss) erythrocytes and Cd dose-dependent effect in terms of RBC viability, cytosolic and mitochondrial ROS levels as well as its effects on mitochondrial membrane depolarization, hemoglobin stability and precipitation. In the concentration range used, Cd did not affect cell viability. However, metal accumulation was associated with an increase in all oxidative indexes evaluated, except mitochondrial superoxide anion production that, on the contrary, was significantly decreased, probably due to a lowered respiration rate associated with interference of Cd with complex I, II and III, as suggested by the observed Cd-dependent mitochondrial membrane depolarization. On the other hand, hemoglobin destabilisation seems to be the major trigger of oxidative stress in this cell type.

Effect of different metals on oxidative state and mitochondrial membrane potential in trout erythrocytes

Homeostasis of metal ions is critical for life and excessive exposure can promote cellular damage that could be due to oxidative damage. In this context we evaluated the effects of three different elements (copper, zinc and aluminum) on oxidative stress and mitochondrial functionality in nucleated trout erythrocytes (Oncorhynchus mykiss). Flowcytometric measurements using MitoProbe and DCFDA-H₂ as fluorescent probes, indicated that redox active copper was able to influence all the biological parameters considered while redox inert, zinc and aluminum, show no significant effects. Toxicity of Al and Zn represent a debated argument and their ability to interact with other endogenous metal ions/metal binding proteins could play a role modulating their cellular toxicity.

Coenzyme Q and Its Role in the Dietary Therapy against Aging

Coenzyme Q (CoQ) is a naturally occurring molecule located in the hydrophobic domain of the phospholipid bilayer of all biological membranes. Shortly after being discovered, it was recognized as an essential electron transport chain component in mitochondria where it is particularly abundant. Since then, more additional roles in cell physiology have been reported, including antioxidant, signaling, death prevention, and others. It is known that all cells are able to synthesize functionally sufficient amounts of CoQ under normal physiological conditions. However, CoQ is a molecule found in different dietary sources, which can be taken up and incorporated into biological membranes. It is known that mitochondria have a close relationship with the aging process. Additionally, delaying the aging process through diet has aroused the interest of scientists for many years. These observations have stimulated investigation of the anti-aging potential of CoQ and its possible use in dietary therapies to alleviate the effects of aging. In this context, the present review focus on the current knowledge and evidence the roles of CoQ cells, its relationship with aging, and possible implications of dietary CoQ in relation to aging, lifespan or age-related diseases.

TRAM1 protect HepG2 cells from palmitate induced insulin resistance through ER stress-JNK pathway

Excess serum free fatty acids (FFAs) are fundamental to the pathogenesis of insulin resistance. Chronic endoplasmic reticulum (ER) stress is a major contributor to obesity-induced insulin resistance in the liver. With high-fat feeding (HFD), FFAs can activate chronic endoplasmic reticulum (ER) stress in target tissues, initiating negative crosstalk between FFAs and insulin signaling. However, the molecular link between insulin resistance and ER stress remains to be identified. We here reported that translocating chain-associated membrane protein 1 (TRAM1), an ER-resident membrane protein, was involved in the onset of insulin resistance in hepatocytes. TRAM1 was significantly up-regulated in insulin-resistant liver tissues and palmitate (PA)-treated HepG2 cells. In addition, we showed that depletion of TRAM1 led to hyperactivation of CHOP and GRP78, and the activation of downstream JNK pathway. Given the fact that the activation of ER stress played a facilitating role in insulin resistance, the phosphorylation of Akt and GSK-3β was also analyzed. We found that depletion of TRAM1 markedly attenuated the phosphorylation of Akt and GSK-3β in the cells. Moreover, application with JNK inhibitor SP600125 reversed the effect of TRAM1 interference on Akt phosphorylation. The accumulation of lipid droplets and expression of two key gluconeogenic enzymes, PEPCK and G6Pase, were also determined and found to display a similar tendency with the phosphorylation of Akt. Glucose uptake assay indicated that knocking down TRAM1 augmented PA-induced down-regulation of glucose uptake, and inhibition of JNK using SP600125 could block the effect of TRAM1 on glucose uptake. These data implicated that TRAM1 might protect HepG2 cells against PA-induced insulin resistance through alleviating ER stress.