Journal article
Effects of dexamethasone on fibre subtypes in rat muscle
Neuropathology and Applied Neurobiology, Vol.7(5), pp.381-398
1981
Abstract
The extent to which dexamethasone treatment produced atrophy of fast-twitch (EDL) and slow-twitch (SOL) muscles in the rat was investigated. The mean weight of steroid-treated EDL muscles was decreased as compared to normal, whereas SOL muscles from normal and dexamethasone-treated animals showed no significant difference. Muscle fibre diameters also showed comparatively minor changes in SOL, which consists of Type 1 (slow oxidative) and Type 2A (fast oxidative/glycolytic) fibres. Rat EDL contains, in addition to Type 1 and Type 2A fibres, two sub-populations of fast glycolytic fibres (Types 2B and 2B'). These fibre types showed the most severe degree of atrophy both after dexamethasone treatment and after denervation. The mean ratio of the weights of denervated to innervated EDL muscles was lower in steroid-treated rats than in normal animals suggesting that the atrophy produced by steroid treatment in conjunction with denervation was more than simply additive. Analysis of the proportions of histochemical fibre types in SOL and EDL showed that dexamethasone treatment produced no major alterations in the fibre type constitution of these muscles. However, further histochemical studies showed that there was relatively severe impairment of myophosphorylase activity in Type 2B' (fast glycolytic) fibres as compared to other fibre types; conversely Type 1 fibres frequently contained increased myophosphorylase. Levels of β-hydroxybutyrate dehydrogenase were low in both normal and steroid-treated EDL but high in SOL which also showed higher general oxidative activity. It is suggested that the particular susceptibility of fast glycolytic fibres to atrophy as a result of steroid treatment may be linked to: 1 the relatively severe reduction of myophosphorylase activity in these fibres and 2 their comparative inability to utilize alternative energy sources, especially substrates derived from free fatty acids.
Details
- Title
- Effects of dexamethasone on fibre subtypes in rat muscle
- Authors/Creators
- I. Livingstone (Author/Creator) - Muscular Dystrophy Group Research Laboratories, Regional Neurological Centre, Newcastle General Hospital, Newcastle upon TyneM.A. Johnson (Author/Creator) - Muscular Dystrophy Group Research Laboratories, Regional Neurological Centre, Newcastle General Hospital, Newcastle upon TyneF.L. Mastaglia (Author/Creator) - Muscular Dystrophy Group Research Laboratories, Regional Neurological Centre, Newcastle General Hospital, Newcastle upon Tyne
- Publication Details
- Neuropathology and Applied Neurobiology, Vol.7(5), pp.381-398
- Publisher
- Wiley
- Identifiers
- 991005543726807891
- Copyright
- 1981 Blackwell Scientific Publications
- Murdoch Affiliation
- Murdoch University
- Language
- English
- Resource Type
- Journal article
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- Citation topics
- 1 Clinical & Life Sciences
- 1.255 Musculoskeletal Disorders
- 1.255.1081 Microgravity Muscle Adaptation
- Web Of Science research areas
- Clinical Neurology
- Neurosciences
- Pathology
- ESI research areas
- Neuroscience & Behavior