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Published on: December 16, 2022
Mice, melatonin and the circadian system
1Dr. Senckenbergische Anatomie, Fachbereich Medizin, J.W.-Goethe Universität, Theodor-Stern-Kai 7, D-60590 Frankfurt/Main, Germany. korf@em.uni-frankfurt.de
Abstract:
Melatonin effects are discussed by reviewing results from mice with intact or disrupted melatonin signaling. Melatonin, the neuroendocrine hand of the clock produced in the pineal gland during night, acts upon two receptor subtypes. Melatonin receptors are found in the suprachiasmatic nuclei (SCN), hypophysial pars tuberalis (PT) and adrenal gland. In SCN, melatonin interacts with PACAP, a neuropeptide of the retinohypothalamic tract. Moreover, melatonin acts on the SCN to modulate the activity of the sympathetic nervous system. Melatonin is not required to maintain rhythmic clock gene expression in SCN. By contrast, the rhythmic clock gene expression in PT depends on a melatonin signal interacting with adenosine. Melatonin may also affect clock gene protein levels in the adrenal cortex and influence adrenal functions. In conclusion, melatonin may serve the synchronization of peripheral oscillators by interacting with other neuroactive substances. A stress-reducing potency of melatonin needs to be explored in further studies.
Insights
Melatonin influences circadian rhythms by acting on receptors in the brain and adrenal glands. It synchronizes peripheral clocks, but its role in stress reduction requires further investigation.
Area of Science:
- Neuroendocrinology
- Chronobiology
- Molecular Biology
Background:
- Melatonin, a pineal gland hormone, regulates circadian rhythms.
- It exerts its effects through two receptor subtypes.
- Melatonin signaling is crucial for various physiological processes.
Purpose of the Study:
- To review the effects of melatonin on circadian clock gene expression.
- To investigate melatonin's interaction with other signaling pathways.
- To understand melatonin's role in peripheral oscillator synchronization.
Main Methods:
- Review of studies on mice with intact or disrupted melatonin signaling.
- Analysis of melatonin receptor distribution and function.
- Examination of melatonin's interaction with PACAP and adenosine.
Main Results:
- Melatonin is not essential for suprachiasmatic nuclei (SCN) clock gene rhythmicity.
- Rhythmic clock gene expression in the pituitary pars tuberalis (PT) depends on melatonin signaling.
- Melatonin may influence adrenal gland functions and clock gene expression.
Conclusions:
- Melatonin synchronizes peripheral oscillators through interactions with neuroactive substances.
- Further research is needed to explore melatonin's stress-reducing potential.
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