Melatonin suppresses osteoclastic and osteoblastic activities in the scales of goldfish.
The effects of melatonin on osteoclastic and osteoblastic cells were examined using a culture system of the goldfish scale. Tartrate-resistant acid phosphatase (TRACP) and alkaline phosphatase (ALP) were used as markers of osteoclastic and osteoblastic cells, respectively. In Earle's minimum essential medium containing melatonin (10(-9) to 10(-5) m), activities of both enzymes in scales were significantly suppressed at 6 hr after incubation (TRACP: 10(-8), 10(-6), 10(-5) m; ALP: 10(-7) to 10(-5) m), but at 18 hr only ALP activity was significantly lowered (10(-8), 10(-7) m). Estradiol-17beta (E(2)) enhanced both activities, which were significantly inhibited and brought down to the level of the controls when co-incubated with E(2) and melatonin (TRACP at 6 hr: 10(-9) to 10(-5) m; ALP at 6 hr: 10(-7) m; ALP at 18 hr: 10(-8) m). Moreover, using reverse-transcription polymerase chain reaction, the mRNA expression of the estrogen receptor (ER) and insulin-like growth factor (IGF)-1, which are related to osteoblastic growth and differentiation, was decreased in the melatonin-treated scales. These results suggest that melatonin acts directly on the scale osteoclastic and osteoblastic cells where it suppresses the ALP activity via down-regulation of ER and IGF-1 mRNAs expression. This is the first report on the function of melatonin in osteoclasts and on the suppressive effect of melatonin in osteoblasts among vertebrates.
Suzuki
Nobuo
N
Noto Marine Laboratory, Institute of Nature and Environmental Technology, Kanazawa University, Uchiura, Ishikawa 927-0553, Japan. nobuo@kenroku.kanazawa-u.ac.jp
Hattori
Atsuhiko
A
D000135:Acid Phosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D003238:Connective Tissue / Q000187:drug effects / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006054:Goldfish; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D023421:Models, Animal; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D010010:Osteoclasts / Q000187:drug effects* / Q000378:metabolism; D000071681:Tartrate-Resistant Acid Phosphatase
D007527:Isoenzymes; D004958:Estradiol; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D008550:Melatonin