# Protective Efficacy of Lactobacillus plantarum Postbiotic beLP-K in a Dexamethasone-Induced Sarcopenia Model

## TL;DR

This study shows that a postbiotic from Lactobacillus plantarum helps prevent muscle loss caused by dexamethasone in both cells and rats.

## Contribution

The novel contribution is demonstrating the protective effects of beLP-K against DEX-induced sarcopenia through molecular and physiological mechanisms.

## Key findings

- beLP-K reduced muscle protein degradation markers like FoxO3α, MAFbx/atrogin-1, and MuRF1.
- Rats treated with beLP-K showed increased muscle mass, weight gain, and improved grip strength.
- beLP-K administration was associated with reduced DEX-induced weight loss and muscle atrophy.

## Abstract

Sarcopenia is characterized by a reduction in muscle function and skeletal muscle mass relative to that of healthy individuals. In older adults and those who are less resistant to sarcopenia, glucocorticoid secretion or accumulation during treatment exacerbates muscle protein degradation, potentially causing sarcopenia. This study assessed the preventive effects and mechanisms of heat-killed Lactobacillus plantarum postbiotic beLP-K (beLP-K) against dexamethasone (DEX)-induced sarcopenia in C2C12 myotubes and Sprague-Dawley rats. The administration of beLP-K did not induce cytotoxicity and mitigated cell damage caused by DEX. Furthermore, beLP-K significantly reduced the expression of forkhead box O3 α (FoxO3α), muscle atrophy f-box (MAFbx)/atrogin-1, and muscle RING-finger protein-1 (MuRF1), which are associated with muscle protein degradation. DEX induced weight loss in rats; however, in the beLP-K group, weight gain was observed. Micro-computed tomography analysis revealed that beLP-K increased muscle mass, correlating with weight and grip strength. beLP-K alleviated the DEX-induced reduction in grip strength and increased the mass of hind leg muscles. The correlation between beLP-K administration and increased muscle mass was associated with decreased expression levels of muscle degradation-related proteins such as MAFbx/atrogin-1 and MuRF1. Therefore, beLP-K may serve as a treatment for sarcopenia or as functional food material.