Skeletal Muscle Atrophy Induced by Dexamethasone Is Attenuated by Amino Acid Complex Supplementation in Rats

Area of Science:

• Gerontology
• Muscle Physiology
• Nutritional Biochemistry

Background:

• Aging leads to sarcopenia, characterized by muscle atrophy due to imbalanced protein synthesis and breakdown.
• Dexamethasone (Dexa) administration is a common method to induce sarcopenia in animal models.
• Amino acid complex supplementation (ACS) is being investigated for its potential to counteract muscle loss.

Purpose of the Study:

• To evaluate the efficacy of amino acid complex supplementation (ACS) in preventing and treating dexamethasone (Dexa)-induced muscle atrophy in rats.
• To determine the optimal dosage and formulation of ACS for sarcopenia treatment.
• To assess the impact of ACS on muscle mass, protein content, exercise capacity, and muscle tissue integrity.

Main Methods:

• Sprague Dawley rats were divided into seven groups, including controls and groups treated with Dexa and varying doses/formulations of ACS (100 mg, 300 mg, 500 mg, or liquid formulation).
• Supplementation and Dexa administration were conducted orally for 4 weeks.
• Exercise capacity was measured using treadmill tests (TT) and forced swimming tests (FST).
• Blood biochemical indices, total muscle protein, and muscle tissue morphology (via electron microscopy and H&E staining) were analyzed.

Main Results:

• High-dose ACS (500 mg) significantly increased exercise capacity in both TT (110% increase) and FST compared to Dexa-only treated rats.
• All ACS treatment groups showed a significant increase in total muscle protein.
• Microscopic analysis revealed that high-dose ACS preserved muscle fiber structure, including clearer M-lines and Z-lines and partially intact mitochondria, in Dexa-treated rats.

Conclusions:

• Amino acid complex supplementation (ACS) effectively mitigates muscle damage and loss in a dexamethasone-induced rat model of sarcopenia.
• A high dose of ACS demonstrated the most significant protective and restorative effects on muscle tissue.
• ACS treatment positively influenced serum indices, muscle protein mass, and histological integrity, supporting its therapeutic potential for sarcopenia.