Developing of a Muscle Atrophy Model

Abstract

Muscle atrophy is one of the most important and frequent problems observed in patients in Intensive Care Units following a surgery, immobilization, extended periods of bed rest as well as in sports medicine. All of these involves loss of muscle mass and decreased muscle strength which increases the risk for future health problems. Immobilization changes the function as well as structure of the peripheral neuromuscular system, and alters both protein degradation and synthesis. Therefore, effective therapeutic strategies to treat muscle wasting induced by immobilization are urgently required but first is necessary to validate and standardize the immobilization technique. In this work we develop a reproducible well‐characterized injury model using a modified Thomas‐ splint validated with mechanical force measurements, histology (H&E and NADH), morphology and ultrasound imaging. Forty young Wistar male rats were divided into two groups: 1) Control‐ no immobilized extremities (CON; n=10) and 2) Unilateral right hindlimb immobilization at 3, 7 or 14 days (Im 3, Im 7, Im 14; n=10 for each group). Results showed a significant increment in body weight for Im 7 and Im 14 compared to CON. Experiments performed in tibialis anterior (TA) of Im muscle showed morphological changes in muscle weight and muscle diameter compared to CON confirmed by Ultrasound imaging. These changes were accompanied with a decrement in peak isometric tetanic force (Po) of immobilized muscles of 20%, 41% and 28% at 3, 7 and 14 days post injury, respectively. Fatigue time for all Im muscles was higher than CON ones (Im 3= 23%, Im 7=33% and Im 14=42%). Metabolic changes using NADH technique denoted an early increase of oxidative fibers and a decrement of glycolytic fibers at 7 days post‐injury compared to CON. In here, we developed, standardized and characterized an immobilization technique that can be used as a first approach to use effective therapeutic strategies to avoid muscle atrophy.Support or Funding InformationSupported partially by UNAM ‐PAPIIT RA207818 and CONACyT AI‐S‐17636 to KPGP.