# Effects of Aging in Combination with High-Fat or Ketogenic Diet on Skeletal Muscle Atrophy Following Denervation in C57BL/6J Mice

## TL;DR

This study shows that aging, not diet, affects muscle atrophy after nerve damage in mice.

## Contribution

It reveals that high-fat or ketogenic diets do not influence denervation-induced muscle atrophy.

## Key findings

- Denervation-induced atrophy was greater in gastrocnemius than soleus muscles.
- Muscle atrophy was greater in adult than old mice, regardless of diet.
- High-fat and ketogenic diets reduced IGF-1 levels in gastrocnemius muscles.

## Abstract

Objectives: The aim of this study was to investigate the effect of the interaction between aging and high-fat diet (HFD) or ketogenic diet (KD) on denervation-induced muscle atrophy. Methods: In this study, 6-, 19- and 27-month-old male mice were studied after 12 weeks’ exposure to a regular chow diet, RD (kcal distribution: 13% fat, 57% carbohydrate, 30% protein), HFD (kcal distribution: 60% fat, 20% carbohydrates, 20% protein), or KD (kcal distribution: 80% fat, <1% carbohydrates, 20% protein). Gastrocnemius (GAS) and soleus (SOL) muscles were left denervated during the last 6 weeks of this 12-week dietary intervention (n = 10 for each group). Results: Denervation-induced atrophy was greater (p < 0.001) in GAS compared to SOL. There were no differences between type 1 and type 2 muscle fiber atrophy in adult SOL muscle. Muscle atrophy did not depend on the diet and was greater in adult than old mice. Both HFD and KD feeding reduced IGF-1 levels (p < 0.01) in GAS muscle compared with the RD independently of age. Myostatin levels in GAS muscle increased (p < 0.01) with age independently of the diets. Conclusions: Denervation-induced muscle atrophy does not depend on dietary fat intake and proceeds at a slower rate in old mice compared to adult mice.