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P A Y W A L L E D S O U R C E : Mechanisms of Ageing and Development
Highlights
• Caloric restriction (CR) can improve health, but its effects are age-dependant.
• Old mice showed greater weight loss compared to adult mice after ten-week 30% CR
• Old mice did not differ from adult mice in extent of muscle wasting or improvement in glucose tolerance after CR
• CR was associated with increase in specific force of extensor digitorum muscle (EDL), but not soleus (SOL) muscle
• CR lead to muscle weakening in both adult and old mice
Abstract
Caloric restriction (CR) can improve health, but its effects are age-dependant. We studied effects of ten-week 30% CR on skeletal muscles of adult (7-month old) and old (24-month old) C57BL/6 J mice. Old mice were heavier than adult mice (36.1 ± 4.0 g versus 32.9 ± 2.3 g, p < 0.05, respectively), but lost more weight (34.7 ± 6.0% versus 23.9 ± 3.3%, p < 0.001, respectively) during CR. Old mice did not differ from adult mice in extent of hind-limb muscle wasting or improvement in glucose tolerance after CR.
Ageing and CR had an additive effect on increase in percentage of type 1 fibres in the soleus (SOL) muscle. CR was associated with greater atrophy of fast-twitch extensor digitorum longus (EDL) compared to slow-twitch SOL muscle. Old mice showed reduced gene expression of lysosomal markers, p62 and LC3B, while CR tended to upregulate the proteolysis genes. CR was also associated with increase in specific force of EDL muscle, but did not affect it in SOL muscle. In summary, ten-week CR induces only limited improvements in skeletal muscle function, but leads to significant muscle wasting and weakness in both adult and old mice.
Outline
1. Introduction
2. Methods
2.1. Animals and experiments
2.2. Physical activity
2.3. Glucose tolerance and serum IGF-1
2.4. Muscle contractile properties
2.5. Muscle fibre properties
2.6. Succinate dehydrogenase (SDH) activity
2.7. Quantitative PCR
2.8. Data analysis
3. Results
3.1. Body mass, heart and muscles
3.2. Molecular markers
3.3. Physical activity
3.4. Metabolic markers
3.5. Muscle fibre type composition and size
3.6. Muscle contractile properties
4. Discussion
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Edited by Engadin, 29 July 2020 - 08:27 PM.
