Melatonin
Melatonin is mainly produced in the pineal gland and a small part of the retina (Cardinali, 2019). Its synthesis and release are stimulated by darkness (Cardinali, 2019). Photic signals from the retina are conducted to the pineal gland via the sympathetic nervous system. During daylight, hyperpolarization of the retina’s photoreceptor cells occurs, inhibiting norepinephrine release. On the other hand, the onset of darkness stimulates norepinephrine release and thus activates the system (Cardinali, 2019).
This hormone regulates neuroendocrine and circadian rhythms, including the sleep-wake cycle (Tordjman et al., 2017). Melatonin is also essential in early fetal development. It directly affects neuronal, glial, and placental development and has a critical role in establishing fetal diurnal rhythms (Tordjman et al., 2017). Subsequently, melatonin is an endogenous synchronizer. It reinforces the oscillations of the central biological clock. In addition, melatonin has a role in autonomic blood pressure regulation, immune system regulation, and retinal functions. It also has antioxidant properties. Further, there have been reported roles of melatonin in bone and body mass regulation. It prevents increased body fat with age and promotes bone formation and osteoblast differentiation (Tordjman et al., 2017). Finally, it has a role in sexual maturation and reproduction. It downregulates gonadotropin-releasing hormone gene expression (Tordjman et al., 2017).
Too much melatonin has the opposite effects of the intended purpose. It disrupts the circadian rhythm, making it hard for someone to sleep (Tordjman et al., 2017). Conversely, melatonin deficiency results in various diseases. Decreased melatonin is implicated in type 2 diabetes mellitus, dementia, severe pain, and mood disorders (Tordjman et al., 2017). Dysfunction in melatonin secretion is associated with deviations in the circadian rhythm’s coupling, phasing, and amplitudes.
In conclusion, melatonin is an important hormone in the human body. It has many roles, but its primary role is the regulation of the circadian rhythm.
References
Cardinali, D. P. (2019). Melatonin: Clinical perspectives in Neurodegeneration. Frontiers in Endocrinology, 10. https://doi.org/10.3389/fendo.2019.00480
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. https://doi.org/10.2174/1570159×14666161228122115
ORDER A PLAGIARISM-FREE PAPER HERE
We’ll write everything from scratch
Question 
Please pick a hormone and answer the questions below. Please do not duplicate the work of your classmates.
Hormones control a great many of the reactions involved in homeostasis. Every hormone has an organ or organ part that produces it and a target or targets. Let’s take some specific hormones and look at them in more detail. For your hormones, tell us
Melatonin
where it is produced
what stimulates its production and release
what its effects are
what happens if you have too much of it
what happens if you have too little of it
Try to follow this pattern in your initial response. The goal is to present the information in such a way that each of you can make an expanded version of the chart in the book that would include these points.
Note: if your hormone is usually referred to by its initials, you must spell out its complete name the first time you use it in your response. After that, initials are OK.
Melatonin is the topic chosen.