Spaceflight and the rodent skeleton: A perspective.

Area of Science:

• Space Biology
• Skeletal Physiology
• Comparative Biology

Background:

• The skeleton is a gravity-sensitive organ whose structure-function relationships are altered by spaceflight.
• Model organisms are crucial for understanding human physiological responses to extreme environments like space.
• Small rodents have been extensively used to study skeletal adaptations to spaceflight over the past five decades.

Purpose of the Study:

• To review the use of rodents in understanding skeletal responses to spaceflight.
• To evaluate rodent models for predicting human skeletal adaptation to microgravity.
• To identify challenges and limitations in spaceflight research using rodents.

Main Methods:

• Analysis of studies using rodents exposed to spaceflight.
• Emphasis on changes in bone mass, architecture, quality, and cellular mechanisms.
• Evaluation of rodent model strengths, limitations, and experimental challenges in spaceflight.

Main Results:

• Spaceflight significantly impacts bone accrual and turnover, generally leading to reduced bone mass compared to controls.
• Observed skeletal responses in rodents are not uniform, with cellular and molecular mechanisms largely unknown.
• Distinguishing microgravity effects from other spacecraft environment factors is challenging.

Conclusions:

• Rodent studies offer insights into mammalian skeletal adaptation to microgravity but have limitations.
• Species-specific differences in skeletal maturation, metabolism, and physiology necessitate caution when comparing rodents to humans.
• Further research is needed to elucidate the precise mechanisms of skeletal adaptation to spaceflight.