Serine Supplementation Alleviates Doxorubicin-Induced Oxidative Damage in Skeletal Muscle of Mice

Evaluation of skeletal muscle function in male rats with doxorubicin-induced myopathy following various exercise techniques: the significant role of glucose transporter 4

A common anthracycline antibiotic used to treat cancer patients is doxorubicin (DOX). One of the effects of DOX therapy is skeletal muscle fatigue. Our goal in this research was to study the beneficial effect of exercise on DOX-induced damaged muscle fibers and compare the effect of different exercise strategies (prophylactic, post- toxicity and combined) on DOX toxicity. Five groups were created from 40 male rats: group I, control group; group II, DOX was administered intraperitoneally for 2 weeks over 6 equal injections (each 2.5 mg/kg); group III, rats trained for 3 weeks before DOX; group IV, rats trained for 8 weeks after DOX; and group V, rats were trained for 3 weeks before DOX followed by 8 weeks after. Measures of oxidative damage (H2O2, catalase), inflammation (TNF-α), and glucose transporter 4 (GLUT4) expression on skeletal muscle were assessed. Also, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) was estimated. Skeletal performance was evaluated by contraction time (CT), half relaxation time (1/2 RT), and force-frequency relationship by the end of this research. The current study demonstrated a detrimental effect of DOX on skeletal performance as evidenced by a significant increase in CT and 1/2 RT compared to control; in addition, H2O2, TNF-α, and HOMA-IR were significantly increased with a significant decrease in GLUT4 expression and catalase activity. Combined exercise therapy showed a remarkable improvement in skeletal muscle performance, compared to DOX, CT, and 1/2 RT which were significantly decreased; H2O2 and TNF-α were significantly decreased unlike catalase antioxidant activity that significantly increased; in addition, skeletal muscle glucose metabolism was significantly improved as GLUT4 expression significantly increased and HOMA-IR was significantly decreased. Exercise therapy showed significant improvement in all measured parameters relative to DOX. However, combined exercise therapy showed the best improvement relative to both pre-exercise and post-exercise groups.

An insight into role of amino acids as antioxidants via NRF2 activation

Oxidative stress can affect the protein, lipids, and DNA of the cells and thus, play a crucial role in several pathophysiological conditions. It has already been established that oxidative stress has a close association with inflammation via nuclear factor erythroid 2-related factor 2 (NRF2) signaling pathway. Amino acids are notably the building block of proteins and constitute the major class of nitrogen-containing natural products of medicinal importance. They exhibit a broad spectrum of biological activities, including the ability to activate NRF2, a transcription factor that regulates endogenous antioxidant responses. Moreover, amino acids may act as synergistic antioxidants as part of our dietary supplementations. This has aroused research interest in the NRF2-inducing activity of amino acids. Interestingly, amino acids' activation of NRF2-Kelch-like ECH-associated protein 1 (KEAP1) signaling pathway exerts therapeutic effects in several diseases. Therefore, the present review will discuss the relationship between different amino acids and activation of NRF2-KEAP1 signaling pathway pinning their anti-inflammatory and antioxidant properties. We also discussed amino acids formulations and their applications as therapeutics. This will broaden the prospect of the therapeutic applications of amino acids in a myriad of inflammation and oxidative stress-related diseases. This will provide an insight for designing and developing new chemical entities as NRF2 activators.

Exploring the Muscle Metabolomics in the Mouse Model of Sepsis-Induced Acquired Weakness

Background/Aim

We aimed to identify the differentially expressing metabolites (DEMs) in the muscles of the mouse model of sepsis-induced acquired weakness (sepsis-AW) using liquid chromatography-mass spectrometry (LC-MS).

Materials and Methods

Sepsis by cecal ligation puncture (CLP) with lower limb immobilization was used to produce a sepsis-AW model. After this, the grip strength of the C57BL/6 male mice was investigated. The transmission electron microscopy was utilized to determine the pathological model. LC-MS was used to detect the metabolic profiles within the mouse muscles. Additionally, a statistically diversified analysis was carried out.

Results

Compared to the sepsis group, 30 DEMs, including 17 upregulated and 13 down-regulated metabolites, were found in the sepsis-AW group. The enriched metabolic pathways including purine metabolism, valine/leucine/isoleucine biosynthesis, cGMP-PKG pathway, mTOR pathway, FoxO pathway, and PI3K-Akt pathway were found to differ between the two groups. The targeted metabolomics analysis explored significant differences between four amino acid metabolites (leucine, cysteine, tyrosine, and serine) and two energy metabolites (AMP and cAMP) in the muscles of the sepsis-AW experimental model group, which was comparable to the sepsis group.

Conclusion

The present work identified DEMs and metabolism-related pathways within the muscles of the sepsis-AW mice, which offered valuable experimental data for diagnosis and identification of the pathogenic mechanism underlying sepsis-AW.