Metabolomic Response of Skeletal Muscle to Aerobic Exercise Training in Insulin Resistant Type 1 Diabetic Rats

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.

Effects of low-intensity exercise on contractile property of skeletal muscle and the number of motor neurons in diabetic rats

The mode of diabetes-induced muscle and motor neuron damage depends on the type of muscle and motor neuron. One of the purposes of exercise therapy for diabetes is to improve blood glucose levels; however, information on the effects of low-intensity exercise on muscle and motor neuron disorders remain unknown. Therefore, this study aimed to examine the effects of low-intensity exercise on diabetes-induced muscle and motor neuron damage in a rat model of type 1 diabetes mellitus. We subjected adult male Wistar rats treated with streptozotocin to develop type 1 diabetes and age-matched rats to low-intensity treadmill exercise for 12 weeks. We recorded electrically evoked maximum twitch tension in leg muscles, and examined the number of motor neurons and cell body sizes. Low-intensity exercise ameliorated the prolonged half-relaxation time and the decreased numbers of the retrograde-labeled motor neurons observed in the soleus muscle of type 1 diabetic rats. However, no effect was observed in the diabetic group, as atrophy was not improved and the twitch force in the medial gastrocnemius muscle was decreased in the diabetic group. In addition, there was no improvement in the blood glucose levels after exercise. These data indicate that low-intensity exercise may relieve the onset of muscle and motor neuron damage in the soleus muscle of type 1 diabetic rats.

Highlighting the novel effects of high-intensity interval training on some histopathological and molecular indices in the heart of type 2 diabetic rats

Background

Type 2 diabetes is one of the most common metabolic diseases in recent years and has become an important risk factor for cardiovascular disorders. The first goal is to reduce type 2 diabetes, and in the case of cardiovascular disease, the second goal is to reduce and manage that disorder.

Materials and methods

The rats were divided into 4 groups: Healthy Control (n=8), Diabetes Control (n=8), Diabetes Training (n=8), and Healthy Training (n=8). The protocol consisted of 8 weeks of High-intensity interval (5 sessions per week), where the training started with 80% of the peak speed in the first week, and 10% was added to this speed every week. To measure the level of B-catenin, c-MYC, GSK3B, and Bcl-2 proteins using the western blot method, cardiac pathological changes were measured using hematoxylin and eosin staining, Masson's trichrome and PAS staining and apoptosis using the TUNEL method.

Findings

Histological results showed that diabetes causes significant pathological hypertrophy, fibrosis, and severe apoptosis in heart tissue. HIIT training significantly reduced pathological hypertrophy and fibrosis in heart tissue, and the rate of cardiomyocyte apoptosis was greatly reduced. This research showed that diabetes disorder increases the levels of B-catenin and c-Myc proteins and causes a decrease in the expression of GSK3B and Bcl-2 proteins. After eight weeks of HIIT training, the levels of B-catenin and c-Myc proteins decreased significantly, and the levels of GSK3B and Bcl-2 proteins increased.

Conclusion

This study showed that HIIT could be a suitable strategy to reduce cardiomyopathy in type 2 diabetic rats. However, it is suggested that in future studies, researchers should perform different intensities and exercises to promote exercise goals in type 2 diabetic cardiomyopathy.

Assessment of executive function in a rodent model of Type 1 diabetes

This study examined the impact of Type 1 Diabetes Mellitus (T1DM) on executive function using a series of operant conditioning-based tasks in rats. Sprague Dawley rats were randomized to either non-diabetic (n = 12; 6 male) or diabetic (n = 14; 6 male) groups. Diabetes was induced using multiple low-dose streptozotocin injections. All diabetic rodents were insulin-treated using subcutaneous insulin pellet implants (9-15 mM). At week 14 of the study, rats were placed on a food restricted diet to induce 5-10 % weight loss. Rodents were familiarized and their set-shifting ability was tested on a series of tasks that required continuous adjustments to novel stimulus-reward paradigms in order to receive food rewards. Results showed no differences in the number of trials, nor number and type of errors made to successfully complete each task between groups. Therefore, we report no differences in executive function, or more specifically set-shifting abilities between non-diabetic and diabetic rodents that receive insulin.

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.

Hepatic Metabolic Profiling of Lifelong Exercise Training Rats

Regular physical exercise has been investigated as a primary preventive measure of several chronic diseases and premature death. Moreover, it has been shown to synchronize responses across multiple organs. In particular, hepatic tissue has proven to be a descriptive matrix to monitor the effect of physical activity. In this study, we performed an untargeted metabolomics-based analysis of hepatic tissue extracts from rats that have undergone either lifelong or chronic exercise training. For this purpose, 56 hepatic samples were collected and were analyzed by UHPLC-TOF-MS in negative ionization mode. This approach involved untargeted metabolite detection on hepatic tissue extracts accompanied by an in-house retention time/accurate mass library enabling confident metabolite identification. Unsupervised (PCA) and supervised (OPLS-DA) multivariate analysis showed significant metabolic perturbation on a panel of 28 metabolites, including amino acids, vitamins, nucleotides, and sugars. The training regime employed in this study resulted in a probable acceleration of the bioenergetic processes (glycolysis, glycogen metabolism), promoted catabolism of purines, and supplied biosynthetic precursors via the pentose phosphate pathway and pentose and glucuronate interconversions. Overall, the applied methodology was able to discriminate the different training schedules based on the rat liver metabolome.

Protective effects of physical activity against health risks associated with type 1 diabetes: “Health benefits outweigh the risks”

The magnitude of diabetes mellitus (DM) has increased in recent decades, where the number of cases and the proportion of the disease have been gradually increasing over the past few decades. The chronic complications of DM affect many organ systems and account for the majority of morbidity and mortality associated with the disease. The prevalence of type 1 DM (T1DM) is increasing globally, and it has a very significant burden on countries and at an individual level. T1DM is a chronic illness that requires ongoing medical care and patient self-management to prevent complications. This study aims to discuss the health benefits of physical activity (PA) in T1DM patients. The present review article was performed following a comprehensive literature search. The search was conducted using the following electronic databases: “Cochrane Library”, Web of Science, PubMed, HINARI, EMBASE, Google for grey literature, Scopus, African journals Online, and Google Scholar for articles published up to June 21, 2021. The present review focused on the effects of PA on many outcomes such as blood glucose (BG) control, physical fitness, endothelial function, insulin sensitivity, well-being, the body defense system, blood lipid profile, insulin resistance, cardiovascular diseases (CVDs), insulin requirements, blood pressure (BP), and mortality. It was found that many studies recommended the use of PA for the effective management of T1DM. PA is a component of comprehensive lifestyle modifications, which is a significant approach for the management of T1DM. It provides several health benefits, such as improving BG control, physical fitness, endothelial function, insulin sensitivity, well-being, and the body defense system. Besides this, it reduces the blood lipid profile, insulin resistance, CVDs, insulin requirements, BP, and mortality. Overall, PA has significant and essential protective effects against the health risks associated with T1DM. Even though PA has several health benefits for patients with T1DM, these patients are not well engaged in PA due to barriers such as a fear of exercise-induced hypoglycemia in particular. However, several effective strategies have been identified to control exercise-induced hypoglycemia in these patients. Finally, the present review concludes that PA should be recommended for the management of patients with T1DM due to its significant health benefits and protective effects against associated health risks. It also provides suggestions for the future direction of research in this field.

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.

Protocol for parallel proteomic and metabolomic analysis of mouse intervertebral disc tissues

The comprehensiveness of data collected by "omics" modalities has demonstrated the ability to drastically transform our understanding of the molecular mechanisms of chronic, complex diseases such as musculoskeletal pathologies, how biomarkers are identified, and how therapeutic targets are developed. Standardization of protocols will enable comparisons between findings reported by multiple research groups and move the application of these technologies forward. Herein, we describe a protocol for parallel proteomic and metabolomic analysis of mouse intervertebral disc (IVD) tissues, building from the combined expertise of our collaborative team. This protocol covers dissection of murine IVD tissues, sample isolation, and data analysis for both proteomics and metabolomics applications. The protocol presented below was optimized to maximize the utility of a mouse model for "omics" applications, accounting for the challenges associated with the small starting quantity of sample due to small tissue size as well as the extracellular matrix-rich nature of the tissue.

Metabolomics of Aerobic Exercise in Chronic Stroke Survivors: A Pilot Study

BACKGROUND

Understanding the metabolic response to exercise may aid in optimizing stroke management. Therefore, the purpose of this pilot study was to evaluate plasma metabolomic profiles in chronic stroke survivors following aerobic exercise training.

METHODS

Participants (age: 62 ± 1 years, body mass index: 31 ± 1 kg/m², mean ± standard error of the mean) were randomized to 6 months of treadmill exercise (N = 17) or whole-body stretching (N = 8) with preintervention and postintervention measurement of aerobic capacity (VO₂peak). Linear models for microarray data expression analysis was performed to determine metabolic changes over time, and Mummichog was used for pathway enrichment analysis following analysis of plasma samples by high-performance liquid chromatography coupled to ultrahigh resolution mass spectrometry.

RESULTS

VO₂peak change was greater following exercise than stretching (18.9% versus -.2%; P < .01). Pathway enrichment analysis of differentially expressed metabolites results showed significant enrichment in 4 pathways following treadmill exercise, 3 of which (heparan-, chondroitin-, keratan-sulfate degradation) involved connective tissue metabolism and the fourth involve lipid signaling (linoleate metabolism). More pathways were altered in pre and post comparisons of stretching, including branched-chain amino acid, tryptophan, tyrosine, and urea cycle, which could indicate loss of lean body mass.

CONCLUSIONS

These preliminary data show different metabolic changes due to treadmill training and stretching in chronic stroke survivors and suggest that in addition to improved aerobic capacity, weight-bearing activity, like walking, could protect against loss of lean body mass. Future studies are needed to examine the relationship between changes in metabolomic profiles to reductions in cardiometabolic risk after treadmill rehabilitation.

The Effects of Caffeine on Metabolomic Responses to Muscle Contraction in Rat Skeletal Muscle

Exercise has beneficial effects on our health by stimulating metabolic activation of skeletal muscle contraction. Caffeine is a powerful metabolic stimulant in the skeletal muscle that has ergogenic effects, including enhanced muscle power output and endurance capacity. In the present study, we aim to characterize the metabolic signatures of contracting muscles with or without caffeine stimulation using liquid chromatography-mass spectrometry and capillary electrophoresis coupled to mass spectrometry. Isolated rat epitrochlearis muscle was incubated in the presence or absence or of 3 mM caffeine for 30 min. Electrical stimulation (ES) was used to induce tetanic contractions during the final 10 min of incubation. Principal component analysis and hierarchical clustering analysis detected 184 distinct metabolites across three experimental groups—basal, ES, and ES with caffeine (ES + C). Significance Analysis of Microarray identified a total of 50 metabolites with significant changes in expression, and 23 metabolites significantly changed between the ES and ES + C groups. Changes were observed in metabolite levels of various metabolic pathways, including the pentose phosphate, nucleotide synthesis, β-oxidation, tricarboxylic acid cycle, and amino acid metabolism. In particular, D-ribose 5-phosphate, IMP, O-acetylcarnitine, butyrylcarnitine, L-leucine, L-valine, and L-aspartate levels were higher in the ES + C group than in the ES group. These metabolic alterations induced by caffeine suggest that caffeine accelerates contraction-induced metabolic activations, thereby contributing to muscle endurance performance and exercise benefits to our health.

Effects of noopept on cognitive functions and pubertal process in rats with diabetes

AIM

Type 1 diabetes (T1DM) is a common chronic disease in childhood. Increasing insulin resistance in puberty gives rise to higher doses of insulin usage in treatment. Of this reason new approaches in treatment are needed. Noopept researches suggest it to have anti-diabetic properties. We tried to determine the effects of noopept on pubertal diabetes.

MAIN METHOD

The research was made with 60 prepubertal, 28 day-old, male, Sprague Dawley rats. The rats were divided into randomised 6 groups (n = 10/group). i) Control, ii) Diabetes Control, iii) Noopept Control, iv) Diabetes + Noopept, v) Diabetes + Insulin, vi) Diabetes + Insulin + Noopept. T1DM model was induced by streptozotocin on postnatal 28th day. 0.5 mg/kg noopept and 1 IU insulin were administered intraperitoneally for 14 days. Blood glucose and body weight measurements, puberty follow-up and MWM tests were performed. Hippocampus, hypothalamus and testis were evaluated histologically. Hypothalamic GnRH and kisspeptin were studied immunohistochemically. Serum LH, FSH and insulin, hippocampal homogenate NGF and BDNF levels were determined by ELISA.

KEY FINDINGS

Delayed puberty was normalized by noopept (p < 0.05). Blood glucose levels were lower in noopept-administered diabetic groups (p < 0.05). Noopept decreased HOMA-IR in insulin administered diabetic group (p < 0.05). Number of degenerated cells in hippocampus and testis were higher in diabetes control group when compared with other groups (p < 0.05). GnRH immunoreactivity in Diabetes + Noopept group was increased when compared to insulin + noopept group (p = 0.018). There was no difference in kisspeptin, serum LH, FSH, hippocampal NGF-BDNF levels and spatial learning assessment among groups (p > 0.05).

SIGNIFICANCE

Noopept may have positive effect in treatment of pubertal diabetes.

Untargeted metabolomics reveals N, N, N-trimethyl-L-alanyl-L-proline betaine (TMAP) as a novel biomarker of kidney function

The diagnosis and prognosis of chronic kidney disease (CKD) currently relies on very few circulating small molecules, which can vary by factors unrelated to kidney function. In end-stage renal disease (ESRD), these same small molecules are used to determine dialysis dose and dialytic clearance. Therefore, we aimed to identify novel plasma biomarkers to estimate kidney function in CKD and dialytic clearance in ESRD. Untargeted metabolomics was performed on plasma samples from patients with a single kidney, non-dialysis CKD, ESRD and healthy controls. For ESRD patients, pre- and post-dialysis plasma samples were obtained from several dialysis modalities. Metabolomics analysis revealed over 400 significantly different features in non-dialysis CKD and ESRD plasma compared to controls while less than 35 features were significantly altered in patients with a single kidney. N,N,N-trimethyl-L-alanyl-L-proline betaine (TMAP, AUROC = 0.815) and pyrocatechol sulfate (AUROC = 0.888) outperformed creatinine (AUROC = 0.745) in accurately identifying patients with a single kidney. Several metabolites accurately predicted ESRD; however, when comparing pre-and post-hemodialysis, TMAP was the most robust biomarker of dialytic clearance for all modalities (AUROC = 0.993). This study describes TMAP as a novel potential biomarker of kidney function and dialytic clearance across several hemodialysis modalities.

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

OBJECTIVES

Abnormal skeletal muscle lipid metabolism is associated with insulin resistance in people with type 1 diabetes. Although lipid metabolism is restored with aerobic exercise training, the risk for postexercise hypoglycemia is increased with this modality. Integrating resistance and aerobic exercise is associated with reduced hypoglycemic risk; however, the effects of this exercise modality on lipid metabolism and insulin resistance remain unknown. We compared the effects of combined (aerobic + resistance) versus aerobic exercise training on oxidative capacity and muscle lipid metabolism in a rat model of type 1 diabetes.

METHODS

Male Sprague-Dawley rats were divided into 4 groups: sedentary control (C), sedentary control + diabetes (CD), diabetes + high-intensity aerobic exercise (DAE) and diabetes + combined aerobic and resistance exercise (DARE). Following diabetes induction (20 mg/kg streptozotocin over five days), DAE rats ran for 12 weeks (5 days/week for 1 hour) on a motorized treadmill (27 m/min at a 6-degree grade), and DARE rats alternated daily between running and incremental weighted ladder climbing.

RESULTS

After training, DAE showed reduced muscle CD36 protein content and lipid content compared to CD (p≤0.05). DAE rats also had significantly increased citrate synthase (CS) activity compared to CD (p≤0.05). DARE rats showed reduced CD36 protein content compared to CD and increased CS activity compared to CD and DAE rats (p≤0.05). DARE rats demonstrated increased skeletal muscle lipid staining, elevated lipin-1 protein content and insulin sensitivity (p≤0.05).

CONCLUSIONS

Integration of aerobic and resistance exercise may exert a synergistic effect, producing adaptations characteristic of the "athlete's paradox," including increased capacity to store and oxidize lipids.

The combination of four analytical methods to explore skeletal muscle metabolomics: Better coverage of metabolic pathways or a marketing argument?

OBJECTIVES

Metabolomics is an emerging science based on diverse high throughput methods that are rapidly evolving to improve metabolic coverage of biological fluids and tissues. Technical progress has led researchers to combine several analytical methods without reporting the impact on metabolic coverage of such a strategy. The objective of our study was to develop and validate several analytical techniques (mass spectrometry coupled to gas or liquid chromatography and nuclear magnetic resonance) for the metabolomic analysis of small muscle samples and evaluate the impact of combining methods for more exhaustive metabolite covering.

DESIGN AND METHODS

We evaluated the muscle metabolome from the same pool of mouse muscle samples after 2 metabolite extraction protocols. Four analytical methods were used: targeted flow injection analysis coupled with mass spectrometry (FIA-MS/MS), gas chromatography coupled with mass spectrometry (GC-MS), liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS), and nuclear magnetic resonance (NMR) analysis. We evaluated the global variability of each compound i.e., analytical (from quality controls) and extraction variability (from muscle extracts). We determined the best extraction method and we reported the common and distinct metabolites identified based on the number and identity of the compounds detected with low analytical variability (variation coefficient<30%) for each method. Finally, we assessed the coverage of muscle metabolic pathways obtained.

RESULTS

Methanol/chloroform/water and water/methanol were the best extraction solvent for muscle metabolome analysis by NMR and MS, respectively. We identified 38 metabolites by nuclear magnetic resonance, 37 by FIA-MS/MS, 18 by GC-MS, and 80 by LC-HRMS. The combination led us to identify a total of 132 metabolites with low variability partitioned into 58 metabolic pathways, such as amino acid, nitrogen, purine, and pyrimidine metabolism, and the citric acid cycle. This combination also showed that the contribution of GC-MS was low when used in combination with other mass spectrometry methods and nuclear magnetic resonance to explore muscle samples.

CONCLUSION

This study reports the validation of several analytical methods, based on nuclear magnetic resonance and several mass spectrometry methods, to explore the muscle metabolome from a small amount of tissue, comparable to that obtained during a clinical trial. The combination of several techniques may be relevant for the exploration of muscle metabolism, with acceptable analytical variability and overlap between methods However, the difficult and time-consuming data pre-processing, processing, and statistical analysis steps do not justify systematically combining analytical methods.

Serum metabolomic response to exercise training in spontaneously hypertensive rats

Chronic aerobic exercise training exhibits blood pressure protective effects, but the mechanism in metabolic level remains largely unclear. This study aims to investigate the effect of exercise training from serum metabolic profiles on the development of hypertension in spontaneously hypertensive rats (SHRs). Exercise training was performed, and the serum metabolites were measured by integrating gas chromatography-mass spectrometer and correlation-based network analysis. After a period of 6 weeks of chronic aerobic exercise training, systolic blood pressure was significant lower in the exercise training group (SHR + EX) rats than the control group (SHR). Principal component analysis indicated a clearly separation of metabolomic profiles between SHR + EX and SHR. Nineteen of 63 metabolites in serum were identified (P < .05, variable importance in projections > 1, false discovery rate < 0.1), including fatty acids, amino acids, and others. Lower levels of six fatty acids were observed in SHR + EX. Besides, pathway analysis indicated a significant alteration of fatty acid metabolism. The correlation-based (Pearson correlation coefficient > 0.83) network of serum metabolites revealed a decreased correlation linkage of SHR + EX than SHR rats. Higher activities of hexokinase, citrate synthase, aspartate aminotransferase, and alanine aminotransferase were detected in liver, left ventricle, and skeletal muscle of SHR + EX groups. In summary, these findings provided essential biochemistry information about the metabolic alteration to exercise training in SHR, which may in part explain the protective effect of exercise in hypertensive individuals.

Aerobic Endurance Training Does Not Protect Bone Against Poorly Controlled Type 1 Diabetes in Young Adult Rats

Streptozotocin (STZ)-induced type 1 diabetes mellitus (T1DM) decreases trabecular bone volume and bone strength in rodents. The current study investigated the potential protective effects of aerobic endurance training (AET) on bone in STZ-induced T1DM young adult rats. Sixty-four 8-week-old male Sprague-Dawley rats were randomly divided into 4 groups of 16: control non-T1DM sedentary (CS) and exercised (CX), T1DM sedentary (DS) and exercised (DX). Blood glucose was maintained at 9-15 mmol/L using subcutaneously implanted insulin pellets (Linplant, Linshin Canada, Inc.). AET was performed at ~75-85% VO_2max for 1 h/day, 5 day/week for 10 weeks. Areal and volumetric bone mineral density (aBMD and vBMD; excised femur) were measured using dual-energy X-ray absorptiometry (DXA; QDR 4500A) and micro computed tomography (μCT; Aloka). Bone strength was tested using a 3-point bending test (Instron 5544 Load Frame). Two-way ANOVA was used to test for T1DM and exercise differences followed by Tukey's HSD tests for interaction effects; significance was set at P < 0.05. T1DM had lower body weight (18.0%), aBMD (8.6%), cortical vBMD (1.6%), trabecular vBMD (2.1%), maximum load at break (22.2%), and increased elastic modulus (11.3%) vs. control (P < 0.001). Exercise in T1DM further decreased body weight (4.7%) vs. sedentary (P = 0.043) and maximum extension during the bending test that demonstrated DX was increased (7.3%) vs. CX (P = 0.033). There were no other beneficial effects of exercise on bone. These results suggest that 10 weeks of AET in rats do not have protective effects on bone in the short term and that T1DM rats have compromised bone health.

Impact of Exercise and Aging on Rat Urine and Blood Metabolome. An LC-MS Based Metabolomics Longitudinal Study

Aging is an inevitable condition leading to health deterioration and death. Regular physical exercise can moderate the metabolic phenotype changes of aging. However, only a small number of metabolomics-based studies provide data on the effect of exercise along with aging. Here, urine and whole blood samples from Wistar rats were analyzed in a longitudinal study to explore metabolic alterations due to exercise and aging. The study comprised three different programs of exercises, including a life-long protocol which started at the age of 5 months and ended at the age of 21 months. An acute exercise session was also evaluated. Urine and whole blood samples were collected at different time points and were analyzed by LC-MS/MS (Liquid Chromatography–tandem Mass Spectrometry). Based on their metabolic profiles, samples from trained and sedentary rats were differentiated. The impact on the metabolome was found to depend on the length of exercise period with acute exercise also showing significant changes. Metabolic alterations due to aging were equally pronounced in sedentary and trained rats in both urine and blood analyzed samples.

Impact of exercise on fecal and cecal metabolome over aging: a longitudinal study in rats

Aim: Physical exercise can reduce adverse conditions during aging, while both exercise and aging act as metabolism modifiers. The present study investigates rat fecal and cecal metabolome alterations derived from exercise during rats’ lifespan. Methods & results: Groups of rats trained life-long or for a specific period of time were under study. The training protocol consisted of swimming, 15–18 min per day, 3–5 days per week, with load of 4–0% of rat's weight. Fecal samples and cecal extracts were analyzed by targeted and untargeted metabolic profiling methods (GC–MS and LC–MS/MS). Effects of exercise and aging on the rats’ fecal and cecal metabolome were observed. Conclusion: Fecal and cecal metabolomics are a promising field to investigate exercise biochemistry and age-related alterations.