Melatonin (N-acetyl-5-methoxytryptamine) is produced in the pineal gland and is a major component of the regulation of the circadian rhythm. Melatonin is produced from tryptophan through a number of hydroxylation and methylation steps. It is metabolized in the liver, and excreted in urine as 6-hydroxymelatonin and 6-sulfatoxymelatonin. Melatonin and metabolites of melatonin, have demonstrated antioxidant and free radical scavenging potential. There is also evidence that they play a role in the regulation of reactive oxygen protein pathways. Published research shows a possible correlation to melatonin levels and the prevalence of certain cancers. Saliva can be used to measure melatonin levels. Saliva, compared to serum or plasma, is relatively easy to obtain and does not contain many of the interfering substances present in serum and plasma. Melatonin in saliva is representative of the levels circulating throughout the body, although the exact proportion is still not fully quantified with published values ranging from 20-50 % of serum values. New areas of research have grown around studying melatonin and the effect on libido, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and other hormone pathways. The role in cancer, sleep cycle, aging, and other areas are also growing in interest, with particular focus on melatonin receptors and the bioavailability of circulating melatonin with the increased use of melatonin as a dietary supplement.
Administration of melatonin improves testicular blood flow, circulating hormones, and semen quality in Shiba goats: H. Samir, et al.; Theriogenology 146, 111 (2020), Application(s): Goat plasma, Abstract;
Melatonin activates cell death programs for the suppression of uterine leiomyoma cell proliferation: P.H. Lin, et al.; J. Pineal Res. 68, e12620 (2020), Application(s): Mouse serum, Abstract;
Melatonin decreases cocaine-induced locomotor activity in pinealectomized rats: S. Barbosa-Méndez & A. Salzar-Juárez; Braz. J. Psychiatry 42, 295 (2020), Application(s): Rat plasma, Abstract; Full Text
Changes in clock gene expression in esophagus in rat reflux esophagitis: A. Hashimoto, et al.; Dig. Dis. Sci. 64, 2132 (2019), Application(s): Melatonin levels in rat serum, Abstract; Full Text
Melatonin suppression of heat-induced leaf senescence involves changes in abscisic acid and cytokinin biosynthesis and signaling pathways in perennial ryegrass (Lolium perenne L.): J. Zhang, et al.; Env. Exp. Bot. 138, 36 (2017), Application(s): Melatonin levels in leaves,
Melatonin systemically ameliorates drought stress-induced damage in Medicago sativa plants by modulating nitro-oxidative homeostasis and proline metabolism: C. Antoniou, et al.; J. Pineal Res. 62, e12401 (2017), Application(s): Melatonin levels in leaves, Abstract;
Exogenous melatonin suppresses dark-induced leaf senescence by activating the superoxide dismutase-catalase antioxidant pathway and down-regulating chlorophyll degradation in excised leaves of perennial ryegrass (Lolium perenne L.): J. Zhang, et al.; Front. Plant Sci. 7, 1500 (2016), Application(s): Melatonin levels in leaves, Abstract; Full Text
Partially defective store operated calcium entry and Hem(ITAM) signaling in platelets of serotonin transporter deficient mice: K. Wolf, et al.; PLoS One 11, e0147664 (2016), Application(s): Melatonin levels in mouse plasma, Abstract; Full Text
