The effects of alpha-lipoic acid on diabetic myopathy

Assessment of Calf Skeletal Muscle in Male Type 2 Diabetes Mellitus Patients With Different Courses Using T1ρ Mapping

CONTEXT

The current clinical methods for detecting skeletal muscle complications of type 2 diabetes mellitus (T2DM) are invasive and insensitive. There is an urgent need for noninvasive assessment of skeletal muscle microstructure changes during the disease progression and treatment to assist the clinical management.

OBJECTIVE

This work aimed to investigate the T2DM caused changes in the fast-twitch tibialis anterior (TA) and slow-twitch soleus (SOL) skeletal muscles using T1ρ magnetic resonance imaging (MRI).

METHODS

This cross-sectional study took place from December 2014 to December 2020 at Zhongda Hospital Southeast University. A total of 26 new-onset and 15 long-term T2DM patients were enrolled, with the addition of 20 young and 13 older healthy volunteers as age-matched controls. T1ρ relaxation times of SOL and TA muscles in different groups were measured. Parametric and nonparametric tests were used to analyze the relationship between the T1ρ values in SOL and TA muscles and the length of illness, level of fasting blood glucose, and status of homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

T1ρ relaxation times of SOL and TA muscles both of new-onset and long-term T2DM patients were significantly higher than those of the young (P < .01, P < .05) and older healthy controls (P < .05, P < .01). Positive correlations were observed between the T1ρ relaxation times of the TA or SOL and the duration of T2DM (R2 = 0.420, R2 = 0.326), the level of fasting blood glucose (R2 = 0.253, R2 = 0.071) and HOMA-IR (R2 = 0.232, R2 = 0.414).

CONCLUSION

Quantitative MRI measurement of T1ρ provides a noninvasive tool to assess T2DM-induced changes in the skeletal muscles of T2DM patients.

Rehabilitation of Individuals With Diabetes Mellitus: Focus on Diabetic Myopathy

Diabetes mellitus (DM) is a chronic metabolic disease characterized by high blood glucose levels, causing serious damage to the cardiovascular, respiratory, renal and other systems. The prevalence of type 2 diabetes mellitus (T2DM) was 6.28% in 2017, considering all age groups worldwide (prevalence rate of 6,059 cases per 100,000), and its global prevalence is projected to increase to 7,079 cases per 100,000 by 2030. Furthermore, these individuals are often affected by diabetic myopathy, which is the failure to preserve muscle mass and function in the course of DM. This happens in type 1 diabetes mellitus (T1DM) and T2DM. As skeletal muscle plays a key role in locomotion and glucose homeostasis, diabetic myopathy may contribute to additional complications of the disease. In addition, chronic hyperglycemia is associated with lung functional changes seen in patients with DM, such as reduced lung volumes and compliance, inspiratory muscle strength, and lung elastic recoil. Thus, the weakness of the inspiratory muscles, a consequence of diabetic myopathy, can influence exercise tolerance. Thus, moderate strength training in T2DM can contribute to the gain of peripheral muscle strength. Although the literature is robust on the loss of mass and consequent muscle weakness in diabetic myopathy, triggering pathophysiological factors, the impact on functional capacity, as well as the prescription of physical exercise for this condition deserves to be further explored. This review aims to explore the consequences of diabetic myopathy and its implication in rehabilitation from prescription to safety in the practice of physical exercises for these individuals.

Alpha-lipoic acid could attenuate the effect of chemerin-induced diabetic nephropathy progression

Objective(s):

Chemerin is associated with insulin resistance, obesity, and metabolic syndrome. α-lipoic acid (α-LA) is a potent antioxidant involved in the reduction of diabetic symptoms. This study aimed to investigate the relationship between chemerin and P38 MAPK in the progression of diabetic nephropathy (DN) and examine the effects of α-LA on chemerin-treated human mesangial cells (HMCs).

Materials and Methods:

HMCs were transfected with a chemerin-overexpressing plasmid. HMCs were also treated with high-glucose, chemerin, α-LA, PDTC (pyrrolidine dithiocarbamate ammonium, NF-κB p65 inhibitor), and/or SB203580 (P38 MAPK inhibitor). Cell proliferation was tested using the Cell Counting Kit-8 assay. Collagen type IV and laminin were tested by ELISA. Chemerin expression was detected by qRT-PCR. The chemerin receptor was detected by immunohistochemistry. Interleukin-6 (IL-6), tumor necrosis factor-a (TNF-α), nuclear factor-κBp-p65 (NF-κB p-p65), transforming growth factor-β (TGF-β), and p-P38 mitogen-activated protein kinase (p-P38 MAPK) were evaluated by western blot.

Results:

High-glucose culture increased the expression of the chemerin receptor. α-LA inhibited HMC proliferation. Chemerin overexpression increased collagen type IV and laminin expression. P38 MAPK signaling was activated by chemerin, resulting in up-regulation of IL-6, TNF-α, NF-κB p-p65, and TGF-β. SB203580, PDTC, and α-LA reversed the effects of chemerin, reducing IL-6, TNF-α, NF-κB p-p65, and TGF-β expression.

Conclusion:

Chemerin might be involved in the occurrence and development of DN. α-LA might prevent the effects of chemerin on the progression of DN, possibly via the P38 MAPK pathway.

Effects of the Combination of β-Hydroxy-β-Methyl Butyrate and R(+) Lipoic Acid in a Cellular Model of Sarcopenia

: Sarcopenia is a clinical problem associated with several pathological and non-pathological conditions. The aim of the present research is the evaluation of the pharmacological profile of the leucine metabolite β-hydroxy-β-methyl butyrate (HMB) associated with the natural R(+) stereoisomer of lipoic acid (R(+)LA) in a cellular model of muscle wasting. The C2C12 cell line is used as myoblasts or is differentiated in myotubes, sarcopenia is induced by dexamethasone (DEX). A Bonferroni significant difference procedure is used for a post hoc comparison. DEX toxicity (0.01-300 µM concentration range) is evaluated in myoblasts to measure cell viability and caspase 3 activation after 24 h and 48 h; cell incubation with 1 µM DEX for 48 h is chosen as optimal treatment for decreasing cell viability and increasing caspase 3 activity. R(+)LA or HMB significantly prevents DEX-induced cell mortality; the efficacy is improved when 100 µM R(+)LA is combined with 1 mM HMB. Regarding myoblasts, this combination significantly reduces DEX-evoked O2- production and protein oxidative damage. During the early phase of myotube formation, the mixture preserves the number of myogenin-positive cells, whereas it completely prevents the DEX-dependent damage in a later phase of myotube differentiation (7 days), as evaluated by cell diameter and percentage of multinucleated cells. R(+)LA in association with HMB is suggested for sarcopenia therapy.

Alpha-lipoic acid preserves skeletal muscle mass in type 2 diabetic OLETF rats

Background

Increased oxidative stress and impaired antioxidant defense are important mechanisms in the pathogenesis of diabetic myopathy. Alpha-lipoic acid (ALA) has been indicated as a weight-loss treatment in rodents and humans, but studies are limited. In the present study, we aimed to determine the influence of ALA, a potent biological antioxidant, on metabolic and growth processes in diabetic rat skeletal muscle.

Methods

Male 25-week-old type 2 diabetic rats (OLETF) were randomly divided into two groups, a control group (OLETF-C) and an ALA-treated group (OLETF-ALA) supplemented with 100 mg/kg ALA for 8 weeks. Age-matched, healthy, nondiabetic LETO (LETO-C) rats were used as controls.

Results

At 32 weeks of age, body weight was decreased by 6.8%, and the areas under the curve of IP-GTT, fasting glucose, and insulin were less in OLETF-ALA rats compared with OLETF-C rats. ALA significantly preserved muscle mass and enhanced muscle fiber cross-sectional area and fiber frequency percentage in the skeletal muscle of OLETF rats. Although the activation of myoD, myogenin, and myostatin in gastrocnemius muscle was significantly inhibited in OLETF-ALA rats relative to OLETF-C rats, there were no differences in the expression levels of muscle atrogin-1 and MuRF1 between the two groups. ALA treatment significantly increased the levels of phosphorylated 5'-AMPK, SIRT1, and PGC-1α, as well as the levels of phosphorylated AKT, mTOR, and p70S6 kinase in OLETF-ALA rats compared with OLETF-C rats. In contrast, the levels of phosphorylated p38 MAPK, IRS-1, and FOXO1 were decreased in OLETF-ALA rats compared with OLETF-C rats.

Conclusions

ALA treatment preserved mass in the gastrocnemius muscles of OLETF rats. ALA significantly upregulated the AMPK/SIRT1/PGC-1α and AKT/mTOR/p70S6K signaling pathways in OLETF rat skeletal muscle. Therefore, ALA may be a potential therapeutic intervention for skeletal muscle loss in animal models of insulin resistance.

Diabetes Treatment in the Elderly: Incorporating Geriatrics, Technology, and Functional Medicine

PURPOSE OF REVIEW

The current approach to diabetes in the elderly incorporates components from the comprehensive geriatric approach. The most updated guidelines from the American Diabetes Association reflect influence from the consensus made in 2012 with the American Geriatrics Society. Notably, the framework included the evaluation for geriatric syndromes (falls and urinary incontinence), functional and cognitive abilities. The goal for this review is to provide an updated summary of treatment strategies for community-dwelling older adults. We identified the need to expand our approach by addressing innovative approaches and scientific concepts from telemedicine, functional medicine, and geriatrics.

RECENT FINDINGS

Findings on cardiovascular protection with sodium-glucose co-transporter 2 inhibitors (SGLT-2i) and some glucagon-like peptide 1 receptor agonists (GLP-1RA) support their use for older patients with diabetes. However, careful consideration for agent selection must incorporate the presence of geriatric issues, such as geriatric syndromes, or functional and cognitive decline, as they could increase the risk and impact adverse reactions. Telemedicine interventions can improve communication and connection between older patients and their providers, and improve glycemic control. Functional medicine concepts can offer additional adjuvant strategies to support the therapeutic interventions and management of diabetes in the elderly. A systematic review confirmed the efficacy and safety of metformin as first-line therapy of type 2 diabetes in the older adult, but multiple reports highlighted the risk for vitamin B12 deficiency. Randomized controlled trials showed the efficacy and safety of antihyperglycemic agents in the elderly, including some with longer duration and lesser risk for hypoglycemia. Randomized clinical trials showed cardiovascular protection with SGLT-2i (empagliflozin, canagliflozin) and GLP-1RA (liraglutide, semaglutide). The most current guidelines recommend addressing for geriatric syndromes, physical and cognitive function in the elderly, in order to individualize targets and therapeutic strategies. Clinicians managing diabetes in the elderly can play a major role for the early detection and evaluation of geriatric issues in their patients. Telemedicine interventions improve glycemic control, and certain functional medicine strategies could be adjuvant interventions to reduce inflammation and stress, but more studies focused on the elderly population are needed.