[Muscle atrophy in microgravity and during its simulation].

Area of Science:

• Space Biology
• Physiology

Background:

• Space flight leads to skeletal muscle atrophy due to unloading.
• Previous models for simulating microgravity effects have limitations.

Purpose of the Study:

• To compare morphological changes in rat skeletal muscles after actual space flight and simulated microgravity.
• To evaluate the efficacy of different simulation models.

Main Methods:

• Comparative analysis of hindlimb muscles from space-flown rats and rats subjected to different simulation methods (immobilization, clinostatting, tail suspension).
• Morphological assessment of skeletal muscle changes.

Main Results:

• Space flight induced hindlimb muscle atrophy, primarily affecting slow anti-g muscles, and hemodynamic changes.
• Immobilization and clinostatting were inadequate models.
• Tail suspension effectively mimicked microgravity-induced muscle atrophy.
• Younger rats showed a stronger and earlier response to hindlimb unloading than older rats.
• Gender did not significantly affect skeletal muscle response to suspension.

Conclusions:

• Tail suspension is a valid model for studying microgravity-induced skeletal muscle atrophy.
• Age influences the response of hindlimb muscles to unloading.
• Hormonal differences do not alter the fundamental response of skeletal muscles to unloading in male and female rats.