After a Turkish scientist took Nobel Prize due to his contributions to understand clock genes,
melatonin, closely related to these genes, may begin to shine.
Melatonin, a
hormone secreted from the pineal gland at night, plays roles in regulating sleep-wake cycle, pubertal development and seasonal adaptation.
Melatonin has antinociceptive,
antidepressant,
anxiolytic, antineophobic, locomotor activity-regulating, neuroprotective, anti-inflammatory,
pain-modulating, blood pressure-reducing,
retinal, vascular, anti-
tumor and
antioxidant effects. It is related with memory, ovarian physiology, and osteoblast differentiation. Pathologies associated with an increase or decrease in
melatonin levels are summarized in the review.
Melatonin affects by four mechanisms: 1) Binding to
melatonin receptors in plasma membrane, 2) Binding to intracellular
proteins such as calmoduline, 3) Binding to
Orphan nuclear receptors, and 4)
Antioxidant effect. Receptors associated with
melatonin are as follows: 1)
Melatonin receptor type 1a: MT1 (on cell membrane), 2)
Melatonin receptor type 1b: MT2 (on cell membrane), 3)
Melatonin receptor type 1c (found in fish, amphibians and birds), 4)
Quinone reductase 2
enzyme (
MT3 receptor, a detoxification
enzyme), 5) RZR/RORĪ±:
Retinoid-related Orphan
nuclear hormone receptor (with this
receptor, melatonin binds to the
transcription factors in nucleus), and 6) GPR50: X-linked
Melatonin-related Orphan receptor (it is effective in binding of
melatonin to MT1).
Melatonin agonists such as
ramelteon,
agomelatine, circadin, TIK-301 and
tasimelteon are introduced and side effects will be discussed. In conclusion,
melatonin and related drugs is a new and promising era for medicine.
Melatonin receptors and
melatonin drugs will take attention with greater interest day by day in the future.