Changes in serum 1,25-dihydroxyvitamin D3 and mRNAs for osteocalcin and alkaline phosphatase in femur unloaded by tail suspension in rats.
To elucidate the mechanism involved in the development of disuse atrophy of bone by skeletal unloading, changes in osteocalcin and alkaline phosphatase mRNAs, markers for bone formation, were studied in the hind limb bones of tail-suspended rats. Tail suspension for 8 and 14 days resulted in a significant decrease in osteocalcin mRNA in the femur when compared with age-matched non-suspended controls. Serum 1,25-dihydroxyvitamin D3 decreased to 60% of the control level after 8 days of skeletal unloading but regained almost normal levels over the next 7 days. Since it is known that vitamin D3 up regulates and glucocorticoid down regulates transcription of the osteocalcin gene, the endocrine response evoked by tail suspension may have aggravated the disuse atrophy caused by skeletal unloading in this study.
Ito
T
T
Department of Endocrinology and Metabolism, Division of Molecular and Cellular Adaptation, Research Institute of Environmental Medicine, Nagoya University, Nagoya.
Ohmori
S
S
Kanda
K
K
Kawano
S
S
Murata
Y
Y
Seo
H
H
D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D018488:Bone Demineralization, Pathologic / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D002117:Calcitriol / Q000097:blood / Q000378:metabolism*; D005269:Femur / Q000201:enzymology* / Q000378:metabolism; D015870:Gene Expression; D019417:Hindlimb Suspension; D008297:Male; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D018474:Weightlessness Simulation / Q000009:adverse effects*
D012333:RNA, Messenger; D015675:Osteocalcin; D000469:Alkaline Phosphatase; D002117:Calcitriol