Early effects of spinal cord transection on skeletal muscle properties

Area of Science:

• Physiology
• Neuroscience
• Muscle Biology

Background:

• Spinal cord transection (Tx) leads to muscle mass reduction.
• Beta-adrenergic receptor (beta-AR) activity influences muscle mass.
• The role of beta-AR signaling in post-Tx muscle changes is unclear.

Purpose of the Study:

• To investigate the acute effects of Tx on skeletal muscle mass, protein concentration, and enzyme activity.
• To determine changes in beta-AR density in response to Tx.
• To explore the relationship between muscle property alterations and beta-AR signaling post-Tx.

Main Methods:

• Female Sprague-Dawley rats underwent complete spinal cord transection (T10).
• Muscle mass, protein concentrations, and cytochrome c oxidase activity were measured at 4 and 8 days post-Tx.
• Beta-adrenergic receptor density was assessed in the gastrocnemius and triceps brachii muscles.

Main Results:

• Tx significantly decreased muscle mass and muscle-to-body mass ratios.
• Total and myofibrillar protein concentrations remained unchanged.
• Cytochrome c oxidase activity in the plantaris muscle decreased significantly post-Tx.
• Beta-AR density was unchanged in the gastrocnemius but increased in the triceps brachii.

Conclusions:

• Rapid declines in muscle mass and cytochrome c oxidase activity occur early after spinal cord transection.
• These early post-Tx muscle changes do not appear to be directly related to alterations in beta-AR density.