Effects of Post-Weaning Differential Housing on Serum Testosterone Levels in Male Mice throughout Aging : Endocrinology

概要

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The influence of differential housing (1, 2, 5 or 10 per cage) on serum testosterone (T) levels was studied in male ICR mice from 21days to 550days of age. In socially-housed individuals, the circulating T levels were lowered with increasing group size from 60 to 200days of age. Peak T levels in groups of 2, 5 and 10 males were 5.55, 4.09 and 2.65ng/ml, respectively. However, individual T levels showed great variations ranging from 1.67 to 20.49ng/ml within a cage. Suppressive effect was exclusively focused on a few members in each cage, and intensified with increasing group size throughout 200days of age. But the difference of serum T levels among different group sizes and the individual variations within a cage were gradually decreased with age since 300days of age. On the other hand, singly-housed individuals showed different age-associated changes in serum T levels from those of socially-housed ones. These results suggest that (1) testicular endocrine function may be greatly influenced by grouping size from sexually maturing period through adult life in male mice, (2) this effect is concentrated on a few members within a cage, and (3) singly-housing condition may be qualitatively different from socially-housing condition.
社団法人日本動物学会の論文
1989-04-15