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[Innervation, activity rhythm and accumulation of myosin light chains in a fast muscle of chickens]
M F Gardahaut1, A Khaskiye, T Rouaud
1Groupe de Physiologie Cellulaire, Centre de Recherche de Biologie et Physico-Chimie Cellulaires, Faculté des Sciences, Nantes, France.
Insights
Neural and contractile activity rhythms influence muscle development in chicks. Slow rhythms promote slow muscle fiber development, while fast rhythms accelerate fast muscle fiber characteristics, impacting myosin light chain expression.
Area of Science:
- Muscle physiology
- Developmental biology
- Neurobiology
Context:
- The fast posterior latissimus dorsi (PLD) muscle in chicks normally downregulates slow myosin light chains (MLC) during neonatal development.
- Slow MLC constitutes a small fraction of total MLC by embryonic day 18, coinciding with the detection of LC3F.
Purpose:
- To investigate the role of neural and contractile activity rhythms in regulating MLC expression and muscle fiber type differentiation in the developing chick PLD muscle.
Summary:
- Spinal cord stimulation at a slow rhythm in chick embryos promoted slow-type PLD differentiation, inhibiting LC3F accumulation and increasing slow MLC.
- Conversely, fast rhythm stimulation accelerated LC3F accumulation.
- Post-hatching denervation studies revealed that fast rhythm stimulation maintained fast-type development, while slow rhythm stimulation induced slow-type development in denervated PLD, suggesting neural activity is crucial for muscle phenotype.
- Innervated PLD showed a diminished response to slow rhythm stimulation compared to denervated muscle.
Impact:
- These findings highlight the critical role of neural and contractile activity patterns in dictating muscle fiber type specification during embryonic and post-natal development.
- Demonstrates that the frequency of neural and/or muscle activity is a key determinant of myosin light chain expression and muscle maturation in avian skeletal muscle.
Abstract:
The fast posterior latissimus dorsi muscle (PLD) of the chick ceases to accumulate slow myosin light chains (MLC) during neonatal development. On day 18 of embryonic life slow MLC represented only 2% of total MLC, and LC3F was first detected. In chick embryo, spinal cord stimulation at a slow rhythm modifies PLD differentiation toward the slow type: LC3F did not accumulate and slow MLC increased. In contrast, stimulation at a fast rhythm accelerated LC3F accumulation. PLD denervation on day 2 after hatching inhibited the synthesis of LC3F. Direct stimulation at a fast rhythm led to post-hatching development into normal fast type while a slow rhythm influenced the development of denervated PLD towards the slow type. In innervated PLD, the effect of stimulation at a slow rhythm was less important than in denervated PLD. These results suggest that the rhythm of the neural and/or contractile activity plays an important role in the MLC expression during embryonic and post-natal development of the chicken fast muscle.