Pineal gland melatonin production

Melatonin is /V-acetyl-5-methoxytryptamine (Figure 16-2), a simple methoxylated and /V-acetylated product of serotonin found in the pineal gland. It is produced and released primarily at night and has long been suspected of playing a role in diurnal cycles of animals and the sleep-wake behavior of humans. 

The production of melatonin varies over the course of a day. Darkness stimulates the pineal gland to produce melatonin, while the presence of light inhibits the release of this hormone. Melatonin levels are so low during the day lime that they are almost immeasurable. The amount of melatonin starts to increase around 9 p.m. or 10 p.m. 

The most well-known effect of melatonin is that it regulates the sleep cycle. Production of melatonin by the pineal gland increases with darkness. Increased melatonin levels, in turn, promote sleep. 

The natural production of melatonin by the pineal gland peaks at the age of only four or five years of age. Since a decrease in its production occurs during sexual maturation, researchers warn that taking it during adolescence may have a detrimental effect on puberty. 

Have not finished, or even started, puberty. The decreased production of melatonin by the pineal gland that occurs during late childhood and early adolescence may be linked to sexual maturation. 

Selective serotonin reuptake inhibitors (SSRIs) are a type of antidepressant that stimulates the pineal gland s ability to produce melatonin. Antipsychotic drugs also have this effect. Other medicines have the opposite effect. Certain types of medicines used to treat cardiovascular disease called beta blockers reduce the production of melatonin by the pineal gland. Nonsteroidal antiinflammatories, which are used to treat pain and/or fever,... 

N-Acetyltransferase uses acetyl-CoA to acetylate the amino moiety of arylal-kylamines. In mammalian pineal gland, this enzyme catalyzes the production of N-acetyl-5-hydroxytryptamine, which is the precursor of melatonin. It is also involved in the inactivation of monoaminergic neurotransmitters in insects. 

HT is converted to melatonin in the pineal gland under the influence of darkness, and its production is controlled by a circadian temperature rhythm and synchronized by the light-dark cycle. Several studies have reported reduced and earlier secretion of... 

Although serotonin has gained much recognition over the years, more recently another tryptophan-related compound, melatonin, has been gaining notoriety. L-tryptophan is the precursor and serotonin an intermediary product for melatonin synthesis in the pineal gland.11 In the following section on melatonin, a brief review of its actions and relationships to L-tryptophan and melatonin is given. 

Melatonin T-helper cells bear G-protein coupled melatonin cell membrane receptors and activation of melatonin receptors, induce the release of T-helper cell type 1 (Thl) cytokines such as interferon-y(IFN-Y) and IL-2. Melatonin also stimulates the release of novel opioid cytokines, which cross-react immunologicaUy with both IL-4 and dynorphin B. Melatonin may enhance the production of IL-6 from human monocytes. Conversely, IFN-yand various colony-stimulating factors may feedback to modulate melatonin production by the pineal gland [14]. 

Melatonin, a naturally occurring amide, is a hormone that is synthesized hy the pineal gland from the amino acid tryptophan. Melatonin regulates the dark-light clock that governs such things as the sleep-wake cycle, body temperature, and hormone production. 

CytosoUc phospholipase Aj (EC 3.1.1.4) mRNA levels in the rat pineal gland showed an off-phase diurnal pattern in relation to melatonin levels (Li et al. 2000). Intravenous administration of isopre-naline, which has been shown to elevate melatonin production, also decreased the level of cytosolic phosphoUpase Aj mRNA significantly. Direct administration of melatonin to rats by intravenous injection decreased the levels of cytosoHc phospholipase Aj protein and mRNA in rat pineal glands. 

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