Article

Effect of vitamin K2 on cortical and cancellous bones in orchidectomized and/or sciatic neurectomized rats.

Department of Sports Medicine, Keio University School of Medicine, Tokyo, Japan.
Journal of Bone and Mineral Research (impact factor: 6.37). 05/2003; 18(4):776-83. DOI:10.1359/jbmr.2003.18.4.776 pp.776-83
Source: PubMed

ABSTRACT We examined the effect of vitamin K2 on cortical and cancellous bones in orchidectomized and/or sciatic neurectomized rats. Ninety male Sprague-Dawley rats, 3 months of age, were randomized by stratified weight method into nine groups with 10 rats in each group: baseline control (BLC), age-matched intact control (IN), IN+vitamin K2 administration (K), orchidectomy (ORX), ORX+K, unilateral sciatic neurectomy (NX), NX+K, ORX+NX (ONX), and ONX+K. Vitamin K2 (menatetrenone) was administered orally twice a week at a dose of 30 mg/kg each. After 10 weeks of feeding, the tibial shaft and proximal tibia were processed for cortical and cancellous bone histomorphometric analyses, respectively. An ORX-induced reduction in maturation-related cortical bone gain and ORX-induced cancellous bone loss were attributable to increased endocortical and trabecular bone turnover, respectively. NX- and ONX-induced reductions in maturation-related cortical bone gain were attributable to decreased periosteal bone formation and increased endocortical bone turnover, while NX- and ONX-induced cancellous bone loss was attributable to increased bone resorption and decreased bone formation. ORX-induced cancellous bone loss was more pronounced when combined with immobilization. Vitamin K2 administration did not significantly alter any parameters in IN rats. Vitamin K2 administration in ORX rats suppressed endocortical bone resorption and trabecular bone turnover, retarding a reduction in maturation-related cortical bone gain and cancellous bone loss. This effect on cancellous bone loss was primarily because of prevention of a reduction of trabecular thickness. Vitamin K2 administration in NX and ONX rats suppressed bone resorption and stimulated bone formation (mineralization), with retardation of a reduction of trabecular thickness without any significant effect on cancellous bone mass, and suppressed endocortical bone resorption, retarding a reduction in maturation-related cortical bone gain. The present study provides evidence indicating that vitamin K2 has the potential to suppress bone resorption or bone turnover and/or stimulate bone formation in vivo in ORX and/or NX rats.

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    Jun Iwamoto, Hideo Matsumoto, Tsuyoshi Takeda, Yoshihiro Sato, Edward Xu, James K Yeh
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Keywords

3 months
 
bone formation
 
bone resorption
 
bone turnover
 
cancellous bones
 
endocortical bone turnover
 
IN+vitamin K2 administration
 
male Sprague-Dawley rats
 
ONX rats suppressed bone resorption
 
periosteal bone formation
 
proximal tibia
 
sciatic neurectomized rats
 
significant effect
 
stimulate bone formation
 
suppressed endocortical bone resorption
 
tibial shaft
 
trabecular bone turnover
 
unilateral sciatic neurectomy
 
vitamin K2
 
Vitamin K2 administration
 

Jun Iwamoto