Diurnal variation in CREB phosphorylation and PER1 protein levels in lactotroph cells of melatonin-proficient C3H and melatonin-deficient C57BL mice: similarities and differences

At night, the percentage of lactotroph cells showing positive nuclear pCREB and PER1 immunoreaction is significantly smaller in melatonin-deficient C57BL mice compared to melatonin-proficient C3H mice.

• Melatonin deficiency affects the activity of lactotroph cells in the pituitary gland.
• C57BL mice exhibit reduced levels of phosphorylated CREB (pCREB) and PER1 proteins at night compared to C3H mice.
• In both mouse strains, pCREB levels are lowest in the early morning and peak in the late night.
• C57BL mice show drastically reduced PER1 levels in the early afternoon, indicating a disruption in the normal rhythmic pattern.
• The differences in pCREB and PER1 levels suggest distinct melatonin-regulated signaling pathways in lactotroph cells.

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