Correlation between insulin resistance and intramyocellular lipid levels in rats

Abstract

Increased intramyocellular lipid (IMCL) content has been proposed as biomarker for insulin resistance (IR). An inverse correlation between IMCL and insulin sensitivity (IS) was found in nonathletic humans, whereas in animal models only a few validation studies have been performed. The aim of this study was to investigate the interrelation between IS indices determined by the glucose clamp technique (glucose disposal (GD), exogenous glucose infusion rates (GIR)) and IMCL content in the tibialis (TIB) and the soleus (SOL) muscle obtained by magnetic resonance spectroscopy in different rat models of IR. Dietinduced insulin-resistant Wistar rats as well as genetic disease models (ZDF rats) were used. In both muscles, elevated IMCL correlated with an impaired IS in all models of IR. The correlation of IMCL with both parameters for IS was comparable in TIB and SOL. The best fit between IMCL and IS was obtained using TIB and GIR data (r ‫؍‬ -0.69, P < 0.001). Diabetic male ZDF rats exhibited comparatively low IMCL levels due to their catabolic state: exclusion of this group improved r.

Hyperglycemic diet and training alter insulin sensitivity, intramyocellular lipid content but not UCP3 protein expression in rat skeletal muscles

“…Accordingly, exercise training during the final 4 weeks of the 12-week dietary intervention increased the insulin sensitivity index proportionally to the decrease in IMCL. Therefore, our current findings corroborate earlier findings in both rodents (51) and humans (7) showing close associations between IMCL accumulation, due to an increased fat supply to muscles, and insulin sensitivity. A recent study by Holloway and co-workers have also demonstrated that as FFA transport in muscles from obese rats is increased by virtue of elevated circulating FFA concentration in conjunction with increased capacity for membrane FFA transport, the rate of intramyocellular triacylglycerol accumulation occurs at a much greater rate than the compensatory increase in the rate of mitochondrial fat oxidation (8).…”

Hyperglycemic diet and training alter insulin sensitivity, intramyocellular lipid content but not UCP3 protein expression in rat skeletal muscles

“…Accordingly, exercise training during the final 4 weeks of the 12-week dietary intervention increased the insulin sensitivity index proportionally to the decrease in IMCL. Therefore, our current findings corroborate earlier findings in both rodents (51) and humans (7) showing close associations between IMCL accumulation, due to an increased fat supply to muscles, and insulin sensitivity. A recent study by Holloway and co-workers have also demonstrated that as FFA transport in muscles from obese rats is increased by virtue of elevated circulating FFA concentration in conjunction with increased capacity for membrane FFA transport, the rate of intramyocellular triacylglycerol accumulation occurs at a much greater rate than the compensatory increase in the rate of mitochondrial fat oxidation (8).…”

Insulin Resistance, Hepatic Lipid and Adipose Tissue Distribution in HIV-Infected Men

“…IMAT is an adipose tissue depot located between muscle groups and between muscle bundles, associated with perimysium and epimysium of muscles. Although there is no report yet of a relationship between IMAT and muscle insulin sensitivity, as has been demonstrated with intramyocellular lipid [23,24], we previously reported an association between IMAT and insulin resistance in both HIV-infected and uninfected women [16]. In contrast, the current study found IMAT was not a significant predictor of hepatic lipid level, and its association with the insulin sensitivity index was not significant.…”

Effect of grapefruit juice and sibutramine on body weight loss in obese rats

“…It has been reported that sibutramine produces significant reduction of body weight when used in conjunction with caloric restriction all over the period of its administration (Florentin et al, 2007). In the present study CAF diet did not produce a significant increase in the level of serum glucose compared to normal control, but it increased the serum triglycerides level (Kuhlmann et al, 2005). These results may be attributed to hyperinsulinemia and hyperlipidemia (Akiyamaab et al, 1996).…”

Hyperglycemic diet and training alter insulin sensitivity, intramyocellular lipid content but not UCP3 protein expression in rat skeletal muscles

“…Accordingly, exercise training during the final 4 weeks of the 12-week dietary intervention increased the insulin sensitivity index proportionally to the decrease in IMCL. Therefore, our current findings corroborate earlier findings in both rodents (51) and humans (7) showing close associations between IMCL accumulation, due to an increased fat supply to muscles, and insulin sensitivity. A recent study by Holloway and co-workers have also demonstrated that as FFA transport in muscles from obese rats is increased by virtue of elevated circulating FFA concentration in conjunction with increased capacity for membrane FFA transport, the rate of intramyocellular triacylglycerol accumulation occurs at a much greater rate than the compensatory increase in the rate of mitochondrial fat oxidation (8).…”

Insulin Resistance, Hepatic Lipid and Adipose Tissue Distribution in HIV-Infected Men

“…IMAT is an adipose tissue depot located between muscle groups and between muscle bundles, associated with perimysium and epimysium of muscles. Although there is no report yet of a relationship between IMAT and muscle insulin sensitivity, as has been demonstrated with intramyocellular lipid [23,24], we previously reported an association between IMAT and insulin resistance in both HIV-infected and uninfected women [16]. In contrast, the current study found IMAT was not a significant predictor of hepatic lipid level, and its association with the insulin sensitivity index was not significant.…”

Effect of grapefruit juice and sibutramine on body weight loss in obese rats

“…It has been reported that sibutramine produces significant reduction of body weight when used in conjunction with caloric restriction all over the period of its administration (Florentin et al, 2007). In the present study CAF diet did not produce a significant increase in the level of serum glucose compared to normal control, but it increased the serum triglycerides level (Kuhlmann et al, 2005). These results may be attributed to hyperinsulinemia and hyperlipidemia (Akiyamaab et al, 1996).…”

Hyperglycemic diet and training alter insulin sensitivity, intramyocellular lipid content but not UCP3 protein expression in rat skeletal muscles

“…Accordingly, exercise training during the final 4 weeks of the 12-week dietary intervention increased the insulin sensitivity index proportionally to the decrease in IMCL. Therefore, our current findings corroborate earlier findings in both rodents (51) and humans (7) showing close associations between IMCL accumulation, due to an increased fat supply to muscles, and insulin sensitivity. A recent study by Holloway and co-workers have also demonstrated that as FFA transport in muscles from obese rats is increased by virtue of elevated circulating FFA concentration in conjunction with increased capacity for membrane FFA transport, the rate of intramyocellular triacylglycerol accumulation occurs at a much greater rate than the compensatory increase in the rate of mitochondrial fat oxidation (8).…”

Insulin Resistance, Hepatic Lipid and Adipose Tissue Distribution in HIV-Infected Men

“…IMAT is an adipose tissue depot located between muscle groups and between muscle bundles, associated with perimysium and epimysium of muscles. Although there is no report yet of a relationship between IMAT and muscle insulin sensitivity, as has been demonstrated with intramyocellular lipid [23,24], we previously reported an association between IMAT and insulin resistance in both HIV-infected and uninfected women [16]. In contrast, the current study found IMAT was not a significant predictor of hepatic lipid level, and its association with the insulin sensitivity index was not significant.…”

Effect of grapefruit juice and sibutramine on body weight loss in obese rats

“…It has been reported that sibutramine produces significant reduction of body weight when used in conjunction with caloric restriction all over the period of its administration (Florentin et al, 2007). In the present study CAF diet did not produce a significant increase in the level of serum glucose compared to normal control, but it increased the serum triglycerides level (Kuhlmann et al, 2005). These results may be attributed to hyperinsulinemia and hyperlipidemia (Akiyamaab et al, 1996).…”