The circadian rhythm of glucocorticoids is regulated by a gating mechanism residing in the adrenal cortical clock

Clock gene expression was detected in the outer adrenal cortex, suggesting its involvement in regulating gluco- and mineral corticoid biogenesis.

• The adrenal gland contains a circadian clock that may influence metabolic and physiological rhythms.
• In mice lacking a circadian clock, regulation of the hypothalamus/pituitary/adrenal axis was disrupted.
• Organ culture and tissue transplantation indicate that the adrenal clock may control glucocorticoid production in response to ACTH.
• The adrenal circadian clock can be synchronized by light exposure.
• Analysis of gene expression revealed genes that may play roles in steroid hormone production, linked to the adrenal clock's regulation of ACTH response.

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