Daily gene activity in the retina occurs earlier than in the pineal gland

Daily rhythms in gene expression in the retina are phase-advanced compared to the pineal gland under varying seasonal lighting conditions.

• Gene expression profiles of several key genes were recorded in the retina and pineal gland of rats under short and long day conditions.
• All genes exhibited cyclical patterns that were phase-advanced in the retina, especially under short day conditions.
• The expression of the AA-NAT gene serves as an indicator of the output from the circadian system's pacemakers in both tissues.
• The phase relationship between AA-NAT expression in the retina and pineal gland persists even in constant darkness.
• The findings suggest that the intrinsic clock in the retina oscillates in a phase-advanced manner relative to the clock in the suprachiasmatic nucleus.

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