Maintenance of trabecular structure and bone volume by vitamin K(2) in mature rats with long-term tail suspension.
Bone volume loss is one of the major health problems during long-term spaceflight. We examined the effects of vitamin K(2) on bone abnormalities in tail-suspended mature male Sprague-Dawley rats (13 weeks old). In this model, increased bone resorption and sustained suppression of bone formation resulted in progressive bone loss in 4 weeks, which simulates bone changes in humans during spaceflight. A significant decrease in bone mineral density (BMD), as well as a decreased mineral apposition rate (MAR), increased number of osteoclasts per bone perimeter (N.Oc/B.Pm), and increased osteoclast surface per bone surface (Oc.S/BS) in the suspended group was effectively prevented by vitamin K(2), given orally (menatetrenone, 22 mg/kg body weight). Microfocus computed tomography (CT) and node-strut analyses revealed that the volume and structure of trabecular bone were maintained near normal by the vitamin K(2) treatment. A recent report has suggested the abnormal metabolism or action of vitamin K in a microgravity environment, and our data therefore suggest that vitamin K(2) may be useful for the prevention of bone loss and for the maintenance of normal trabecular structure during spaceflight.
Division of Nephrology and Endocrinology, University of Tokyo School of Medicine, Japan.
Yoshiko
Y
Iwasaki
Hideyuki
H
Yamato
Hisashi
H
Murayama
Masami
M
Sato
Takeshi
T
Takahashi
Ikuko
I
Ezawa
Kiyoshi
K
Kurokawa
Masafumi
M
Fukagawa
D015502:Absorptiometry, Photon; D000596:Amino Acids / Q000652:urine; D000818:Animals; D015519:Bone Density; D001842:Bone and Bones / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005269:Femur / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D019417:Hindlimb Suspension / Q000009:adverse effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013977:Tibia / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods; D024482:Vitamin K 2 / Q000008:administration & dosage / Q000494:pharmacology*; D014893:Weightlessness / Q000009:adverse effects*
D000596:Amino Acids; D024482:Vitamin K 2; C036020:deoxypyridinoline