Daily Corticosterone Levels and Timing Influence Clock Gene Activity in the Male Rat Thinking Area

Adrenalectomy significantly altered clock gene expression patterns in the prefrontal cortex of male rats.

• Clock gene mRNA levels in the prefrontal cortex and suprachiasmatic nucleus displayed a diurnal pattern in sham rats, but the phase differed between these two structures.
• In adrenalectomized rats, clock gene expression patterns in the prefrontal cortex were substantially altered, indicating the influence of glucocorticoids.
• In-phase treatment with cortisol normalized the altered clock gene expression in the prefrontal cortex, while antiphasic treatment disrupted the diurnal pattern or inverted its phase.
• Cortisol condition had little effect on clock gene expression in the suprachiasmatic nucleus, suggesting region-specific responses to glucocorticoids.
• These findings highlight the potential role of cortisol in regulating the molecular clock within the prefrontal cortex, which may relate to dysfunction in mood disorders.

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