title: Effects of vitamin K on the morphometric and material properties of bone in the tibiae of growing rats.
abstract: Suboptimal vitamin K nutriture is evident during rapid growth. We aimed to determine whether vitamin K(2) (menaquinone-4 [MK-4]) supplementation is beneficial to bone structure and intrinsic bone tissue properties in growing rats. Male Wistar rats (5 weeks old) were assigned to either a control diet (n = 8) or an MK-4-supplemented diet (22 mg d(-1) kg(-1) body weight, n = 8). After a 9-week feeding period, we determined the serum concentration ratio of undercarboxylated osteocalcin to γ-carboxylated osteocalcin and the urinary deoxypyridinoline level. All rats were then euthanized, and their tibiae were analyzed by micro-computed tomography for trabecular architecture and synchrotron radiation micro-computed tomography for cortical pore structure and mineralization. Fourier transform infrared microspectroscopy and a nanoindentation test were performed on the cortical midlayers of the anterior and posterior cortices to assess bone tissue properties. Neither body weight nor tibia length differed significantly between the 2 groups. Dietary MK-4 supplementation decreased the ratio of undercarboxylated osteocalcin to γ-carboxylated osteocalcin but did not affect deoxypyridinoline, indicating a positive effect on bone formation but not bone resorption. Trabecular volume fraction and thickness were increased by MK-4 (P < .05). Neither the cortical pore structure nor mineralization was affected by MK-4. On the other hand, MK-4 increased mineral crystallinity, collagen maturity, and hardness in both the anterior and posterior cortices (P < .05). These data indicate the potential benefit of MK-4 supplementation during growth in terms of enhancing bone quality.
authors.affiliation: Bioengineering Division, Osaka University Graduate School of Engineering Science, Machikaneyama-cho 1-3, Toyonaka 560-8531, Japan. matsu@me.es.osaka-u.ac.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Takushi
authors.initials: T
authors.lastname: Miyakawa
authors.forename: Daiki
authors.initials: D
authors.lastname: Yamamoto
mesh_terms: D000465:Algorithms; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D015415:Biomarkers; D001835:Body Weight / Q000187:drug effects; D001846:Bone Development / Q000187:drug effects* / Q000528:radiation effects; D001862:Bone Resorption / Q000517:prevention & control; D002113:Calcification, Physiologic / Q000187:drug effects; D004032:Diet; D008297:Male; D055595:Mechanical Phenomena; D009929:Organ Size / Q000187:drug effects; D015675:Osteocalcin / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017550:Spectroscopy, Fourier Transform Infrared; D013977:Tibia / Q000033:anatomy & histology / Q000187:drug effects* / Q000254:growth & development*; D014057:Tomography, X-Ray Computed; D014129:Trabecular Meshwork / Q000033:anatomy & histology / Q000254:growth & development; D014812:Vitamin K / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D015415:Biomarkers; D014815:Vitamins; D015675:Osteocalcin; D014812:Vitamin K; C036020:deoxypyridinoline