Cultured rat cortical astrocytes synthesize melatonin: absence of a diurnal rhythm.
Melatonin not only plays a major role in the regulation of circadian rhythms, but is also involved in antioxidative defense and immunomodulation. Circulating melatonin levels are derived primarily from the pineal gland while other sources of melatonin have also been reported. Here, we show for the first time that astrocytes from the rat cortex and glioma C6 cell line synthesize melatonin in vitro. In addition, we show the presence of serotonin, the precursor of melatonin and the two key enzymes in the pathway of melatonin synthesis, i.e. N-acetyltransferase and hydroxyndole-O-methyltransferase in the cultured rat cortical astrocytes. Release of melatonin into the culture medium showed no diurnal changes. These point to astrocytes as a local source of melatonin in the rat brain. Its exact physiological function remains a topic for future studies.
Liu
Ya-Jing
YJ
Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China (USTC), Hefei, Anhui, China.
Zhuang
Jun
J
Zhu
Hong-Yan
HY
Shen
Yu-Xian
YX
Tan
Zhong-Lin
ZL
Zhou
Jiang-Ning
JN
D000121:Acetylserotonin O-Methyltransferase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001191:Arylamine N-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D001253:Astrocytes / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002478:Cells, Cultured; D002940:Circadian Rhythm / Q000502:physiology; D008550:Melatonin / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000096:biosynthesis