Corticosterone rhythm of mouse adrenal in relation to serum corticosterone and sampling

Abstract

Under conditions standardized for light-synchronized periodicity analysis the corticosterone content of mouse adrenals undergoes significant 24-hour periodic changes. In mature males of the B1 stock, glandular hormone content fluctuates by approximately 50% around its day-mean, accounting amplitude-wise for about one-half of the periodic change in blood hormone. Peak corticosterone content in the adrenal occurs at ≈16:00, if mice are kept on a regimen providing for light from 06:00 to 18:00, alternating with 12 hours of darkness. As to timing, the daily corticosterone peak in the gland corresponds roughly to that in serum, when sampling is done at 4-hour intervals in the absence of stimulation other than daily routine. The correlation between physiologic 24-hour changes of corticosterone in adrenal and serum is positive and statistically significant. This correlation may be altered by the conditions of sampling, e.g. by the repeated exposure of mice to man.