Comparative studies on the circadian rhythm of corticosterone, lipid and cholesterol levels in adrenals and blood of rats.

The time-dependent relationship of corticosterone, lipids and cholesterol over a 48-hr period was studied in the adrenals and blood of rats. In addition an attempt was made to determine whether there was a reciprocal dependence among these compounds and also a correlation between corticosterone and cholesterol in the adrenals and blood. Corticosterone and cholesterol exhibit a circadian rhythm in the adrenals and blood. The same is true for lipids in the serum. A reciprocal dependence between the compounds in the adrenals and blood could not be demonstrated. Only the time-dependent processes of the corticosterone content in the adrenals and plasma are well correlated with each other. High levels of these steroids in the adrenals are associated with high levels of these steroids in the plasma and vice versa. An inverse correlation between corticosterone and cholesterol exists in the adrenals and in blood. Maximal levels of corticosterone correspond to minimal levels of cholesterol and vice versa.