Effects of housing density on mouse physiology and behavior in the NASA Animal Enclosure Module simulators

Area of Science:

• Space biology and physiology
• Animal welfare science
• Microgravity research

Background:

• The Animal Enclosure Module (AEM) is crucial for studying microgravity's effects on animal physiology and behavior during space flight.
• Understanding optimal housing conditions is essential for animal well-being in space missions.
• Previous research, including NASA workshops, has highlighted the need for standardized rodent cage sizing.

Purpose of the Study:

• To compare the health and well-being of mice housed at varying densities within AEM simulators (AEMS).
• To establish a comprehensive stress assessment battery (SAB) for evaluating mouse health in simulated space environments.
• To determine if specific population densities in AEMS lead to stressful conditions for the animals.

Main Methods:

• Development and application of a stress assessment battery (SAB) including appearance, behavior, consumption, weight changes, organ weights, and blood/plasma analyses.
• Comparison of mice housed in AEM simulators (AEMS) at different densities against mice in standard vivarium shoebox cages (VSBC).
• Inclusion of physiological and histological measures such as plasma corticosterone, total protein, leukocyte counts, and gastric histology.

Main Results:

• The developed stress assessment battery (SAB) provided a comprehensive evaluation of mouse health and well-being.
• Initial findings suggest that varying housing densities within AEMS did not induce significant stress indicators compared to control VSBC.
• Detailed physiological and behavioral data were collected to establish baseline health parameters for future space flight studies.

Conclusions:

• The stress assessment battery (SAB) is a viable tool for monitoring animal health in simulated spaceflight environments.
• Current housing densities tested in AEM simulators (AEMS) appear to be well-tolerated by mice.
• Further research is warranted to fully understand the long-term effects of microgravity and varying densities on animal physiology and behavior.