Effects of space flight conditions on the function of the immune system and catecholamine production simulated in a rodent model of hindlimb unloading.
The rodent model of hindlimb unloading has been successfully used to simulate some of the effects of space flight conditions. Previous studies have indicated that mice exposed to hindlimb-unloading conditions have decreased resistance to infections compared to restrained and normally housed control mice.


OBJECTIVE
The purpose of this study was to clarify the mechanisms involved in resistance to infection in this model by examining the effects of hindlimb unloading on the function of the immune system and its impact on the production of catecholamines.


METHODS
Female Swiss Webster mice were hindlimb-unloaded during 48 h and the function of the immune system was assessed in spleen and peritoneal cells immediately after this period. In addition, the kinetics of catecholamine production was measured throughout the hindlimb-unloading period.


RESULTS
The function of the immune system was significantly suppressed in the hindlimb-unloaded group compared to restrained and normally housed control mice. Levels of catecholamines were increased in the hindlimb-unloaded group and peaked at 12 h following the commencement of unloading.


CONCLUSIONS
These results suggest that physiological responses of mice are altered early after hindlimb unloading and that catecholamines may play a critical role in the modulation of the immune system. These changes may affect the ability of mice to resist infections.
Aviles
Hernan
H
Department of Biology, Binghamton University, Binghamton, NY 13902-6000, USA. haviles@binghamton.edu
Belay
Tesfaye
T
Vance
Monique
M
Sonnenfeld
Gerald
G
D000818:Animals; D002395:Catecholamines / Q000097:blood / Q000276:immunology / Q000378:metabolism*; D005260:Female; D019417:Hindlimb Suspension / Q000009:adverse effects*; D007107:Immune System / Q000276:immunology / Q000503:physiopathology*; D007108:Immune Tolerance / Q000276:immunology*; D007113:Immunity, Innate / Q000276:immunology; D051379:Mice; D023421:Models, Animal; D015213:Neuroimmunomodulation / Q000502:physiology; D013026:Space Flight; D015854:Up-Regulation / Q000276:immunology; D016474:Weight-Bearing / Q000502:physiology; D018474:Weightlessness Simulation / Q000009:adverse effects*
D002395:Catecholamines