Effect of cage population density on plasma corticosterone and peripheral lymphocyte populations of laboratory mice (1989)

Peng, X., Lang, C. M., Drozdowicz, C. K. et al.

Abstract

Groups were formed of 2, 4 or 8 animals in cages with a floor areas of 390 sq.cm. The results of this study suggest that population density of 4 mice per cage induced minimal stress compared to that induced by the population density of 2 or 8 mice per cage. Since stress is known to induce alteration in a variety of biological functions, the population density of mice per cage should be considered in the interpretation of research data. .... There was no significant difference of plasma corticosteroid concentration in all the 3 groups on day 14 suggesting that social hierarchy development might play a more important role to animal stress than the population density in this study. It is possible that fighting between mice within newly assigned groups was the main cause of the elevated corticosteroide concentration.