Opposite daily patterns of two key clock genes in the brain’s timekeeping center and body tissues of rats

Circadian expression of BMAL1 mRNA peaks at the time of dark-light transition in the suprachiasmatic nucleus.

• BMAL1 mRNA exhibits a circadian expression pattern in the suprachiasmatic nucleus (SCN) that is out of phase with rPer1 and rPer2.
• No circadian oscillation for rat Clock mRNA was detected in this study.
• BMAL1 mRNA also shows circadian expression in peripheral tissues, including brain (excluding the SCN), eye, heart, kidney, and lung.
• The expression levels of BMAL1 and rPer2 mRNA are correlated across different tissues.
• The findings suggest that BMAL1 mRNA may play a significant role in regulating the circadian expression of per homologue genes in mammals.

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