Melatonin synthesis

The rate of melatonin synthesis is controlled primarily by the release of noradrenaline from sympathetic fibres originating in the superior cervical ganglion. The activity of these neurons and, consequently, the synthesis and release of melatonin, follows a circadian rhythm such that sympathetic input and melatonin synthesis are both increased in the dark. This coupling with the light cycle certainly involves the SCN since destruction of this nucleus greatly reduces the fluctuations in melatonin production. Moreover, retrograde transneural tracing has shown that there is a neuronal pathway... 

The circadian pattern of pineal NAT activity and consequently melatonin secretion is controlled by the suprachiasmatic nuclei (SCN) as it is abolished by lesions of the SCN, the major circadian oscillator (Klein and Moore 1979). Thus, the environmental L/D cycle acts as the pervasive and pre-eminent Zeitgeber that regulates melatonin synthesis (Scheer and Czeisler 2005). 

Carrillo-Vico, A., Calvo, J. R., Abreu, P. el al. (2004). Evidence of melatonin synthesis by human lymphocytes and its physiological significance possible role as intracrine, autocrine, and/or paracrine substance. FASEB J. 18, 537-9. 

Conti, A., Conconi, S., Hertens, E. et al. (2000). Evidence for melatonin synthesis in mouse and human bone marrow cells. J. Pineal Res. 28, 193-202. 

Tosini, G. Menaker, M. (1998). The clock in the mouse retina melatonin synthesis and photoreceptor degeneration. Brain Res. 789, 221-8. 

Deficiency of essential amino acid precursors in the diet can cause a dysregulation of neurotransmitter activity (e.g, L-tryptophan deficiency causes a decrease in 5-HT and melatonin synthesis and activity). Deficiency in essential fatty acids (e.g, omega-3 fatty acids) can cause a dysregulation of neurottansmitter... 

Quera Salva MA, Lainey E, Leger D, Santos C, Billiard M. 2001. [Delayed wakefulness-sleep rhythm syndrome and melatonin. Synthesis of existing studies] In French. Rev Neurol (Paris) 157 S126-129. 

Pyridoxine plays a role in (1) the control of the hypothalamo-pituitary end-organ system, (2) melatonin synthesis, and (3) convulsive seizure activity. Neurological deficits resulting from pyridoxine deficiency can largely be explained by decreased activity of glutamic acid decarboxylase, 5-hydroxytryptophan decarboxylase, and ornithine decarboxylase (Dakshinamurti et al., 1990). The products of these... 

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. 

Opioid involvement in the control of melatonin synthesis and release Stankov, B. Esposti, D. Esposti, G. Lucini, V. Mariani, M. Cozzi, B. Scaglione, F. Fraschini, F. 

In healthy human volunteers the subchronic administration of a standardized Hypericum extract induced a significant augmentation of nocturnal melatonin synthesis and suppressed production of cortisol [231]. A drop of serum corticosteron concentrations has also been... 

Another system that may contain a pacemaker is the avian pineal gland, which generates a circadian rhythm in melatonin the rhythm has also been observed in pineal cell cultures (see fig. 11.1) (Binkley, Riebman Reilly, 1978 Takahashi, Hamm Menaker, 1980 Takahashi et al., 1989). Melatonin is involved in the control of the sleep-wake cycle, and so analogues of the hormone are currently being developed for the prevention of jet lag. A circadian rhythm of activity has been demonstrated for the enzyme N-acetyltransferase, which catalyses an early step in melatonin synthesis (Binkley, 1983). 

Measurement of melatonin synthesis has been reported as a potential surrogate marker to quantify the effect of LNAAs on the brain [39], Melatonin is only synthesized in the brain from serotonin (e.g., urinary sulfatoxymelatonin) [40] and may reflect effects of diet intervention. In a... 

Yano S, Moseley K, Azen C. Large neutral amino acid supplementation increases melatonin synthesis in phenylketonuria a new biomarker. J Pediatr. 2013 162(5) 999-1003. 

The intracellular signal transduction pathway mediating the inhibitory effects of glutamate on melatonin secretion seems to be coimected to metabotropic receptors (Petralia et al. 1996) since in rat pinealocytes activation of the glutamate metabotropic receptor 3 has been reported to inhibit melatonin synthesis by decreasing cyclic AMP levels and arylalkylamine N-acetyltransferase activity (Yamada et al. 1998). 

Hydroxytryptamine is deaminated oxidatively to 5-hydroxyindole acetic acid. In addition, 5-hydroxytryptamine is catabolized in substantially smaller amounts by reduction to the corresponding alcohol, 5-hydroxytryptophol, (1868-70) is excreted in the free form and combined as the glucuronide or sulphate. 7V-Methylation of 5-hydroxytryptamine gives iV-methylsero-tonin, which can be methylated further to 7V, -dimethylserotonin (= bufotenine). The iV-methylation is catalysed by a relatively unspecific iV-methyltransferase. By acetylation of 5-hydroxytryptamine 7V-acetyl-serotonin is produced, which is an intermediary product in the course of the melatonin synthesis (= 5-methoxy-AT-acetylserotonin). The production of 5-methoxytryptamine, which we were able to demonstrate in normal human blood and urine, seems to occur fairly easily by deacetylation of melatonin, whereas a direct 0-methylation of serotonin to 5-methoxy-tryptamine, at least in vitro, takes place to a substantially smaller extent. ... 

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