Effect of Combined Exercise Versus Aerobic-Only Training on Skeletal Muscle Lipid Metabolism in a Rodent Model of Type 1 Diabetes

The Effects of Resistance Exercise Training on Skeletal Muscle Metabolism and Insulin Resistance Development in Female Rodents with Type 1 Diabetes

The etiology of insulin resistance (IR) development in type 1 diabetes mellitus (T1DM) remains unclear; however, impaired skeletal muscle metabolism may play a role. While IR development has been established in male T1DM rodents, female rodents have yet to be examined in this context. Resistance exercise training (RT) has been shown to improve IR and is associated with a lower risk of hypoglycemia onset in T1DM compared to aerobic exercise. The purpose of this study was to investigate the effects of RT on IR development in female T1DM rodents. Forty Sprague Dawley eight-week-old female rats were divided into four groups: control sedentary (CS; n = 10), control trained (CT; n = 10), T1DM sedentary (DS; n = 10), and T1DM trained (DT; n = 10). Multiple low-dose streptozotocin injections were used to induce T1DM. Blood glucose levels were maintained in the 4-9 mmol/l range with intensive insulin therapy. CT and DT underwent weighted ladder climbing 5 days/week for six weeks. Intravenous glucose tolerance tests (IVGTT) were conducted on all animals following the six-week period. Results demonstrate that DS animals exhibited significantly increased weekly blood glucose measures compared to all groups including DT (p < 0.0001), despite similar insulin dosage levels. This was concomitant with a significant increase in insulin-adjusted area under the curve following IVGTT in DS (p < 0.05), indicative of a reduction in insulin sensitivity. Both DT and DS exhibited greater serum insulin concentrations compared to CT and CS (p < 0.05). DS animals also exhibited significantly greater glycogen content in white gastrocnemius muscle compared to CS and DT (p < 0.05), whereas DT and DS animals exhibited greater p-Akt: Akt ratio in the white vastus lateralis muscle and citrate synthase activity in the red vastus lateralis muscle compared to CS and CT (p < 0.05). These results indicate that female rodents with T1DM develop poor glycemic control and IR which can be attenuated with RT, possibly related to differences in intramyocellular glycogen content.

The influence of exercise training versus intensive insulin therapy on insulin resistance development in type 1 diabetes

The etiology of insulin resistance (IR) in Type 1 Diabetes (T1D) is unclear; however, intramyocellular lipids (IMCL) are likely contributors. While exercise lessens IR and IMCL content; T1D patients elevate glycemia to offset exercise-induced hypoglycemic risk. The preferred treatment for T1D patients is tight glucose management through intensive insulin therapy (IIT); however, IIT is accompanied with a sedentary lifestyle. The purpose of this study was to examine IR development and IMCL in combined exercise (DARE; aerobic/resistance) and IIT-treated T1D animals. 76 rats were divided into control sedentary (C), diabetic sedentary (CD), diabetes sedentary intensive insulin therapy (DIT) and DARE groups. Following streptozotocin (STZ), glycemia was maintained at either 9-15 mM (CD, DARE) or 5-9 mM (DIT) using insulin. DARE alternated between running and weighted climbing for 12 weeks. Results demonstrate that DARE exhibited reduced onset of IR compared with C, DIT and CD, indicated by increased glucose infusion rate (hyperinsulinemic-euglycemic-clamp). A shift in lipid metabolism was evident whereby diacylglycerol was elevated in DIT compared to DARE, while triacylglycerol was elevated in DARE. These findings indicate enhanced IMCL metabolism and the sequestration of fat as neutral triacylglycerol leads to reduced IR in DARE. In contrast, IIT and sedentary behavior leads to diacylglycerol accumulation and IR.

The Effects of Exercise Training on Glucose Homeostasis and Muscle Metabolism in Type 1 Diabetic Female Mice

Although exercise training is an important recommendation for the management of type 1 diabetes (T1D), most of the available research studies predominantly focus on male subjects. Given the importance of sex as a biological variable, additional studies are required to improve the knowledge gap regarding sex differences in T1D research. Therefore, the purpose of this study was to examine the role of exercise training in mediating changes in glucose homeostasis and skeletal muscle metabolism in T1D female mice. Female mice were injected with streptozotocin (STZ) to induce T1D. Two weeks after STZ injection, control (CON) and STZ mice were exercise trained on a treadmill for 4 weeks. Aerobic exercise training failed to improve glucose tolerance, prevent the decrease in body weight and adipose tissue mass, or attenuate muscle atrophy in T1D female mice. However, insulin sensitivity was improved in T1D female mice after exercise training. Aerobic exercise training maintained skeletal muscle triglyceride content but did not prevent depletion of skeletal muscle or liver glycogen in T1D mice. Gene expression analysis suggested that T1D resulted in decreased glucose transport, decreased ketone body oxidation, and increased fatty acid metabolism in the skeletal muscle, which was not altered by exercise training. These data demonstrate that 4 weeks of aerobic exercise training of a moderate intensity is insufficient to counteract the negative effects of T1D in female mice, but does lead to an improvement in insulin sensitivity.

Regular combined training and vitamins modulated the apoptosis process in diabetic rats: Bioinformatics analysis of heart failure's differential genes expression network correlated with anti-apoptotic process

The apoptosis process could impose significantly by hyperglycemia. According to in silico language processing and high throughput raw data analysis, we recognized hub molecular mechanisms involved in the pathogenesis of diabetic hearts and suggested a new pharmaceutical approach for declining myocardial programed cell death. Fifty male Sprague-Dawley rats were classified into five groups: healthy rats as control, diabetic rats, diabetic combined resistance/endurance training, diabetic rats which consumed supplementation vitamins E and C, and the combined supplementation and training. Here, we calculated changes in gene expression based on artificial intelligence methods and evaluated gene expression in apoptotic influencing combined training and antioxidants vitamins consumption in heart injured models by streptozotocin via Real-Time PCR. Moreover, we assessed the binding affinity of the 3D structure of small molecules on macromolecule SIRT3 to a new compound pharmaceutical suggesting the decline in cell death program. The computational intelligence surveys revealed that the apoptosis process was a remarkable pathomechanism in the abnormality function of heart tissue in diabetic conditions. Furthermore, we showed that synchronizing antioxidant vitamin consumption and regular combined training could significantly decrease irreversible myocardial cell death in diabetic myocardiopathy. Hence, levels of antiapoptotic mRNA were modified in the combined training/vitamin consumption group compared with other classifications. We found that regular combined exercise and vitamin consumption could reverse the apoptosis process to enhance the survival of cardiac muscle cells in diabetes conditions. PRACTICAL APPLICATIONS: Machine learning and system biology indicated that the apoptosis process is a vital pathomechanism of hyperglycemia-induced heart failure. Sirt3/Fas/Bcl-2/Cycs and Bax, as a critical network of apoptosis, play an essential role in heart failure induced by hyperglycemia. Moreover, Type 2 diabetes and obesity increase the risk of heart failure by increasing high blood sugar levels. We calculated the binding power of the vitamins E and C on SIRT3 protein based on the drug software. In addition, this study assessed that regular combined training and vitamin consumption had an antiapoptotic effect. Also, our data might improve the hyperglycemia state.

The impact of concurrent training and antioxidant supplementation on the factors associated with the ocular lens opacity in diabetic rats

The current study was aimed to investigate the protective effect of vitamins C and E (VCE) supplementation, exercise, and their concurrent application against cataract incidence in the diabetic rats. The obtained results indicated that different supplementation and training treatments were capable to preserve the lens transparency in the diabetic rats. Also, upon applying different supplementation and training treatments, the level of glutathione (GSH) and activity of antioxidant enzymes in the diabetic rats was preserved approximately close to their control levels. In addition, different treatments were capable to maintain the structural integrity of the lens proteins in diabetic rats. Moreover, VCE supplementation, exercise and their simultaneous application prevented lens crystallins of diabetic rats against fibrillation and formation of the increased oligomeric sizes. The results of this study signify the importance of antioxidant supplementation and exercise in reducing the detrimental effects of hyperglycemia on the eye lenses.

The effects of exercise training versus intensive insulin treatment on skeletal muscle fibre content in type 1 diabetes mellitus rodents

BACKGROUND

Intensive-insulin treatment (IIT) strategy for patients with type 1 diabetes mellitus (T1DM) has been associated with sedentary behaviour and the development of insulin resistance. Exercising patients with T1DM often utilize a conventional insulin treatment (CIT) strategy leading to increased insulin sensitivity through improved intramyocellular lipid (IMCL) content. It is unclear how these exercise-related metabolic adaptations in response to exercise training relate to individual fibre-type transitions, and whether these alterations are evident between different insulin strategies (CIT vs. IIT).

PURPOSE

This study examined glycogen and fat content in skeletal muscle fibres of diabetic rats following exercise-training.

METHODS

Male Sprague-Dawley rats were divided into four groups: Control-Sedentary, CIT- and IIT-treated diabetic sedentary, and CIT-exercised trained (aerobic/resistance; DARE). After 12 weeks, muscle-fibre lipids and glycogen were compared through immunohistochemical analysis.

RESULTS

The primary findings were that both IIT and DARE led to significant increases in type I fibres when compared to CIT, while DARE led to significantly increased lipid content in type I fibres compared to IIT.

CONCLUSIONS

These findings indicate that alterations in lipid content with insulin treatment and DARE are primarily evident in type I fibres, suggesting that muscle lipotoxicity in type 1 diabetes is muscle fibre-type dependant.

Optimal exercise intensity and volume to impact rats with Traditional Chinese Medicine phlegm-dampness constitution

Objective

We aim to investigate the effects of different exercise intensities and volumes on Phlegm-dampness constitution (PDC).

Methods

The rats were fed with high-fat food and lived in 75%–85% humidity for 6 weeks to establish the model of PDC. Then PDC rats were screened and intervened by varying exercise intensities for 8 weeks. Weight, constitution scores, blood and liver tissues were collected to detect the concentration of serum total cholesterol (Tch), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), homocysteine (Hcy), blood glucose (GLU), alanine transaminase (ALT) and percentage of lipid droplet area in liver tissue (PLDA).

Results

The weight, Tch, TG, HDL-C, LDL-C, Hcy, GLU, and ALT of rats in moderate-intensity exercise group returned to normal. The rats with high-intensity or low-intensity exercise did not recover as well as moderate-intensity.

Conclusion

Different exercise intensities and volumes have different effects on PDC, moderate-intensity exercise over an 8-week intervention is most appropriate.

GCN2 Deficiency Enhances Protective Effects of Exercise on Hepatic Steatosis

Background

Combined aerobic and resistance training has been demonstrated to benefit glycemic control and reverse nonalcoholic fatty liver disease in childhood obesity. General control nonderepressible 2 (GCN2) deficiency has been reported to attenuate hepatic steatosis and insulin resistance. However, whether GCN2 impacts the positive effects of combined aerobic and resistance exercise remains unknown.

Objectives

To investigate whether combined aerobic and resistance exercise improves hepatic steatosis and glucose intolerance and the role GCN2 plays in mediating the metabolic regulation of exercise.

Methods

Wild-type (WT) and GCN2 knockout (GCN2KO) mice were fed a high-fat diet (HFD) for 25 weeks. The WT and GCN2KO mice performed exercise (treadmill running + ladder climbing) during the last eight weeks. Their body and liver weights, their triglyceride content, and their levels of aspartate transaminase (AST), alanine transaminase (ALT), and blood glucose were measured, and the expressions of proteins involved in the GCN2/eIF2α/ATF4 pathway and the glucolipid metabolism-related proteins (e.g., p-AMPK, SIRT1, PPARα, PGC-1α, GLUT4, and p-GSK-3β) were determined.

Results

The body weight of WT and GCN2KO mice continued to increase until the end of the experiment. The liver weights, hepatic triglyceride content, and AST and ALT levels of the exercised mice were significantly reduced compared to those of the sedentary mice. Exercise improved blood glucose levels and glucose clearance ability in the WT mice, but the glucose intolerance of GCN2KO mice was not improved. Exercise increased PGC-1α, GLUT4, and p-GSK-3β expressions in the WT rather than the GCN2KO mice. Interestingly however, exercise-trained GCN2KO mice were better protected against hepatic steatosis with downregulated expressions of p-eIF2α and ATF4, upregulated expressions of p-AMPK and SIRT1, and the presence of PPARα in the liver, compared to the exercised WT mice.

Conclusion

Combined aerobic and resistance exercise had positive effects on hepatic steatosis and the control of glucose intolerance. GCN2 was found to be necessary for exercise-induced improved glucose intolerance. However, the better efficacy in improving hepatic steatosis by exercise in the GCN2-deficient mice enhanced liver lipid metabolism, at least partially, via the AMPK/SIRT1/PPARα pathway.