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Melatonin, an indoleamine, is a natural compound produced by various organisms, including bacteria and eukaryotes. [1] Its discovery in 1958 by Aaron B. Lerner and colleagues stemmed from the isolation of a substance from the pineal gland of cows that could induce skin lightening in common frogs .
Melatonin synthesis is also regulated by the nervous system. Nerve fibers in the retinohypothalamic tract connect the retina to the suprachiasmatic nucleus (SCN). The SCN stimulates the release of norepinephrine from sympathetic nerve fibers from the superior cervical ganglia that synapse with the pinealocytes.
The thyroid secretes thyroxine, the pituitary secretes growth hormone, the pineal secretes melatonin, the testis secretes testosterone, and the ovaries secrete estrogen and progesterone. [2] Glands that signal each other in sequence are often referred to as an axis, such as the hypothalamic–pituitary–adrenal axis.
The secretion of melatonin happens in a cycle. Secretion is high at night or in the absence of light and low during the day. The suprachiasmatic nucleus in the hypothalamus is responsible for this cycle of secretion from the epithalamus, specifically from the pineal gland. [ 8 ]
The pineal gland (also known as the pineal body [1] or epiphysis cerebri) is a small endocrine gland in the brain of most vertebrates.It produces melatonin, a serotonin-derived hormone, which modulates sleep patterns following the diurnal cycles. [2]
A liver segment is one of eight segments of the liver as described in the widely used Couinaud classification (named after Claude Couinaud) in the anatomy of the liver.This system divides the lobes of the liver into eight segments based on a transverse plane through the bifurcation of the main portal vein, [1] arranged in a clockwise manner starting from the caudate lobe.
Melatonin is a naturally occurring hormone produced in the brain’s pineal gland that regulates our circadian rhythm. By acting as our body’s internal clock, it helps us know when to go to bed ...
Melatonin is a naturally occurring hormone produced in the brain that is also used as a dietary supplement and medication. [ 9 ] [ 12 ] As a hormone, melatonin is released by the pineal gland and is involved in sleep–wake cycles .