Daily gene activity in the eye’s clock system of mice with and without melatonin

In melatonin-deficient mice, protein levels of PER1, CRY2, and phosphorylated CREB did not show significant changes over a 16L/8D cycle.

• Both melatonin-deficient (C57BL) and melatonin-proficient (C3H) mice displayed rhythmic expression of the clock gene Per1, peaking at zeitgeber time (ZT) 08.
• Cry2 did not exhibit a similar rhythmic expression in either mouse strain.
• In C3H mice, protein levels of PER1 and CRY2 in the inner nuclear layer and ganglion cell layer showed a clear day/night rhythm, peaking at ZT14.
• Phosphorylated CREB levels peaked at the beginning of the day in C3H mice.
• Melatonin may influence the protein levels of PER1 and CRY2 and is associated with the rhythmic regulation of pCREB levels in the retina.

Simplified