The effects of differential grouping on endocrine function of mature male albino mice

Abstract

Mature male albino mice of the Tuck TT strain and of proved fertility were isolated or housed in groups of 2, 4, 8 or 16. After 21 days of such treatment, plasma samples were obtained both by rapid decapitation and via the jugular vein following 2 min of ether stress. Body weights and weights of various endocrine glands were obtained from mice of each category of housing. The results indicated that mice maintained as pairs showed a more pronounced increase in adrenocortical function and a greater decline in gonadal activity as compared with single animals than some of the more densely crowded groups. Apart from the paired mice, however, there was a general increase in adrenocortical activity and a decline in gonadal function proportional to the increase in group size (as shown by Christian). The results are interpreted on the basis of the increased social stress to which the subordinate mouse is subjected.