Gene expression in the suprachiasmatic nuclei and the photoperiodic time integration

The core of the suprachiasmatic nuclei (SCN) integrates a new photoperiod quickly, influencing the expression of clock-controlled genes.

• Daily changes in gene expression reflect integration of a new photoperiod rather than a passive light effect.
• The transition from long to short photoperiod in Syrian hamsters leads to rapid adjustments in clock gene expressions.
• Clock-controlled genes exhibit slower adaptation following changes in photoperiod compared to core clock genes.
• The pineal gland shows differential daily functioning as a result of changes in SCN activity due to photoperiod shifts.
• In hamsters exposed to a short photoperiod for 26 weeks, all analyzed genes show similar daily expression except for Clock.
• The distinct expression of Clock in the photorefractory phase suggests its potential role in this physiological state.

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