Daily corticosterone rhythm modulates pineal function through NFκB-related gene transcriptional program

Area of Science:

• Endocrinology
• Chronobiology
• Molecular Biology

Background:

• Melatonin and glucocorticoids are crucial hormones regulating daily rhythms and immune responses.
• Corticosterone and melatonin exhibit distinct nocturnal patterns, with potential interactions between adrenal and pineal glands.
• Inflammatory conditions suggest a link where corticosterone may enhance melatonin synthesis via NFκB inhibition.

Purpose of the Study:

• To elucidate the crosstalk between adrenal and pineal glands under physiological conditions.
• To investigate the influence of corticosterone rhythm on pineal gland gene expression and melatonin synthesis.
• To understand the role of NFκB in mediating glucocorticoid effects on nocturnal melatonin production.

Main Methods:

• Gene expression analysis of defense response genes in the rat pineal gland at darkness onset.
• Pharmacological inhibition of glucocorticoid receptors using mifepristone.
• Assessment of Aanat gene expression and nocturnal melatonin synthesis.

Main Results:

• A significant reduction in 70 out of 84 defense response genes was observed at darkness onset.
• Mifepristone administration altered the expression of 13 genes and impaired nocturnal melatonin synthesis.
• Corticosterone rhythm was shown to modulate pineal gland phenotype, including Aanat expression.

Conclusions:

• The daily rhythm of corticosterone influences the pineal gland's response to darkness.
• Glucocorticoids regulate nocturnal melatonin synthesis through the NFκB transcriptional pathway.
• This highlights a coordinated regulation of the pineal gland by both the central clock and adrenal hormones.