Androgens modulate structure and function of the suprachiasmatic nucleus brain clock

Area of Science:

• Neuroscience
• Chronobiology
• Endocrinology

Background:

• Gonadal hormones, particularly androgens, are known to influence circadian rhythms.
• Androgen receptors are present in the suprachiasmatic nucleus (SCN), the brain's master clock.
• The role of androgens in SCN neural plasticity remains largely unexplored.

Purpose of the Study:

• To investigate the impact of androgens on the structure and function of the mouse SCN.
• To examine how gonadectomy (GDX) affects SCN circuitry, clock gene expression, and behavioral responses to light.

Main Methods:

• The study utilized gonadectomy (GDX) in mice to remove gonadal hormone production.
• Changes in SCN structure (glial fibrillary acidic protein, synaptophysin, postsynaptic density 95) were assessed.
• Light-induced clock gene expression (mPer1, mPer2) and behavioral phase shifts were measured at different circadian times.
• Dihydrotestosterone (DHT) was used to treat GDX animals to assess androgen's role.

Main Results:

• GDX led to increased glial fibrillary acidic protein and decreased synaptophysin and postsynaptic density 95 in the SCN.
• The effects of GDX on light-induced clock gene expression were phase-dependent.
• GDX altered behavioral responses to light, causing larger phase delays at CT13.5.
• DHT treatment reversed the structural and functional changes induced by GDX.

Conclusions:

• Androgens play a crucial role in regulating the structural integrity of the mouse SCN.
• Androgens modulate molecular and behavioral responses to light, impacting circadian rhythmicity.
• These findings highlight the importance of androgens in SCN plasticity and circadian clock function.