Osteoblast activity in the goldfish scale responds sensitively to mechanical stress.
The adaptive response of bone to mechanical loading in teleosts is not well understood. We recently developed a new assay system using teleost scales, which consists of osteoblasts, osteoclasts, and bone matrix protein. In this system, alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) were used as markers of osteoblasts and osteoclasts, respectively. Using this assay system, we examined the effects of mechanical loading on ALP and TRAP activity in goldfish scales. ALP activity in the scales was significantly elevated (p<0.01) by ultrasound stimuli (1 MHz, 50% duty factor, 0.5 Hz pulse repetition frequency, 60 mW/cm(2) [I(SATA)] and 6 min) after both 18 h and 24h of incubation while TRAP activity remained unchanged. In addition, mRNA expression of both insulin-like growth factor-I (IGF-I) and estrogen receptors (ER) increased significantly, as did ALP activity. After the goldfish had been swimming for 3 days (speed: 2 body lengths/second, duration: 3h/day), the scales' ALP activity increased significantly (p<0.01) but TRAP activity did not change. These in vitro and in vivo results strongly suggest that osteoblasts in the goldfish scale respond sensitively to mechanical stress and may be important in promoting bone formation.
Kitamura
Kei-ichiro
K
Department of Clinical Laboratory Science, Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, Kanazawa, Ishikawa 920-0942, Japan. kkitamur@mhs.mp.kanazawa-u.ac.jp
Suzuki
Nobuo
N
Sato
Yusuke
Y
Nemoto
Tetsu
T
Ikegame
Mika
M
Shimizu
Nobuaki
N
Kondo
Takashi
T
Furusawa
Yukihiro
Y
Wada
Shigehito
S
Hattori
Atsuhiko
A
D000135:Acid Phosphatase / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D000825:Animal Structures / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D005609:Free Radicals / Q000378:metabolism; D005786:Gene Expression Regulation; D006054:Goldfish / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D010006:Osteoblasts / Q000201:enzymology / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D013314:Stress, Mechanical; D013550:Swimming / Q000502:physiology; D000071681:Tartrate-Resistant Acid Phosphatase; D013997:Time Factors; D014465:Ultrasonics
D005609:Free Radicals; D007527:Isoenzymes; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D007334:Insulin-Like Growth Factor I; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase