Maternal Control of the Fetal and Neonatal Rat Suprachiasmatic Nucleus

A 6-hour delay in the dark period can reset the molecular clock in the fetal suprachiasmatic nucleus (SCN) within 5 days.

• Rhythms in clock gene expression in the rat SCN begin to develop at embryonic day 20 and progress until postnatal day 10.
• Adult rats exposed to a 6-hour delay in darkness show a significant phase delay in locomotor activity within 3 days.
• Pregnant rats exposed to this delay at embryonic day 18 cause a delay in c-fos and Avp expression rhythms in newborn pups at postnatal days 0-1.
• At embryonic day 20, the same delay leads to changes in Per1 and Per2 expression rhythms in pups by postnatal days 3 and 6.
• Phase shifts in the fetal SCN can occur even when molecular oscillations are minimal, indicating early developmental plasticity.

AI simplified