Circadian Variation in Placental and Hepatic Clock Genes in Rat Pregnancy

Both zones of the rat placenta express all seven canonical clock genes but show limited circadian variation.

• The junctional and labyrinth zones of the rat placenta exhibit marked differences in clock gene expression.
• Unlike maternal liver, the placental expression of clock genes does not display significant circadian variation.
• Pregnancy leads to notable changes in clock gene expression in maternal liver, with specific genes showing altered peak levels.
• Fetal liver expresses all clock genes, but exhibits less circadian variation compared to maternal liver.
• Maternal corticosterone levels show clear circadian variation, while fetal corticosterone levels remain stable throughout the day.

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