Summary
Melatonin is one of the most prominent hormones in the human body, known to the general public as “sleep hormone.” Melatonin is released in animals’ brains during the night time and it is associated with the sleep-wake cycle control. However, melatonin’s effects go far beyond only sleep control; it affects the immune system and blood pressure, for instance. Yet these melatonin interactions in animals’ bodies have been studied much less.
Structure, Functions, and Source
Melatonin’s molecular formula is C13H16N2O2 and its 2D chemical structure is demonstrated on the slide.
Melatonin’s main function is to synchronize central & peripheral oscillators, which implies regulation of the circadian rhythm – the human sleep-wake cycle.
Pineal gland is responsible for melatonin production in the human body.
Mode of Action
The best-characterized molecular pathway through which melatonin acts includes two types of membrane-specific receptors: high-affinity ML1 sites and low-affinity ML2 sites. The activation of ML1 receptors, which are G protein-coupled receptors, leads to an inhibition of the adenylate cyclase in target cells. The activation of ML2 receptors, currently called MT3, leads to phospho-inositides hydrolysis. In the picture, you can see the melatonin-caused activity in MT1 and MT2 – two sub-types of the ML1 receptor.
Melatonin regulates circadian rhythms such as the sleep-wake rhythm, neuroendocrine rhythms or body temperature cycles through its action on MT1 and MT2 receptors.
Deficiency-Related Diseases
Two prominent melatonin deficiency-related diseases include sleep disturbance and insomnia and depressive disorders.
Sleep disturbances can be treated by melatonin intake effectively and safely.
There is no significant evidence that melatonin intake can help with depressive disorders, yet there are many other options, including counseling, antidepressants, and even self-help, which means better time management, exercise, etc.
References
Esposito, S., Laino, D., D’Alonzo, R., Mencarelli, A., Di Genova, L., Fattorusso, A., Argentiero, A., & Mencaroni, E. (2019). Pediatric sleep disturbances and treatment with melatonin. Journal of translational medicine, 17(1), 77.
National Center for Biotechnology Information. (2022).PubChem compound summary for CID 896, melatonin.
Tordjman, S., Chokron, S., Delorme, R., Charrier, A., Bellissant, E., Jaafari, N., & Fougerou, C. (2017). Melatonin: Pharmacology, functions and therapeutic benefits.Current neuropharmacology, 15(3), 434–443.