Effect of vitamin K2 on cortical and cancellous bones in orchidectomized and/or sciatic neurectomized rats.
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.
Article: Effects of alendronate and alfacalcidol on the femoral bone mass and bone strength in orchidectomized rats.[show abstract] [hide abstract]
ABSTRACT: The purpose of the present study was to compare the effects of alendronate (ALN) and alfacalcidol (ALF) on the femoral bone mass and bone strength in orchidectomized rats and to clarify the skeletal benefits of combined administration of ALN and ALF. Fifty male Sprague-Dawley rats, 3 months of age, were randomized by the stratified weight method into five groups: the age-matched control (CON), orchidectomy (ORX), ORX + ALN (2.5 microg/kg, s.c., 5 times a week), ORX + ALF (0.1 microg/kg, p.o., 5 times a week), and ORX + ALN + ALF groups. After 12 weeks of feeding, the femoral distal metaphysis and mid-diaphysis were processed for peripheral quantitative tomographic analysis and biomechanical testing. In the femoral distal metaphysis, ALN prevented the ORX-induced reduction in the trabecular volumetric bone mineral density (vBMD) and breaking energy, and ALF prevented the ORX-induced reduction in the trabecular vBMD and increased the breaking energy to values above those observed in the CON group. Both ALN and ALF increased the maximum load to values above those observed in the ORX group. The improvements in parameters described above were more pronounced when ALN and ALF were administered in combination. In the femoral mid-diaphysis, on the other hand, ALN did not significantly affect the cortical bone parameters, whereas ALF increased the cortical area and maximum load to values above those observed in the ORX group. Furthermore, no apparent benefit of combined administration of ALN and ALF was observed. These findings suggest differential effects of ALN and ALF on femoral bone mass and the beneficial effects of combined administration of ALN and ALF on the trabecular bone of the femur in ORX rats.The Chinese journal of physiology 01/2009; 51(6):331-7. · 0.56 Impact Factor
Article: Effects of vitamin K(2) and risedronate on bone formation and resorption, osteocyte lacunar system, and porosity in the cortical bone of glucocorticoid-treated rats.[show abstract] [hide abstract]
ABSTRACT: The purpose of the present study was to examine the effects of vitamin K(2) and risedronate on bone formation and resorption, the osteocyte lacunar system, and porosity in the cortical bone of glucocorticoid (GC)-treated rats. Forty-nine female Sprague-Dawley rats, 3 months of age, were randomized into five groups according to the following treatment schedule: age-matched control, GC administration, and GC administration with concomitant administration of vitamin K(2), risedronate, or vitamin K(2) + risedronate. At the end of the 8-week experiment, classical bone histomorphometric analysis was performed, and the osteocyte lacunar system and porosity were evaluated on the cortical bone of the tibial diaphysis. GC administration decreased percent cortical bone area and increased percent marrow area as a result of decreased periosteal bone formation, and increased endocortical bone erosion, and increased cortical porosity. Vitamin K(2) prevented a reduction in periosteal bone formation but did not affect percent cortical bone and marrow areas. Risedronate prevented a reduction in periosteal bone formation and an increase in endocortical bone erosion, resulting in prevention of alterations in percent cortical bone and marrow areas. Both vitamin K(2) and risedronate increased osteocyte density and lacunar occupancy and prevented a GC-induced increase in cortical porosity. Vitamin K(2) and risedronate had additive effects on osteocyte density and lacunar occupancy and a synergistic effect on cortical porosity. The present study showed the efficacy of vitamin K(2) and risedronate for bone formation and resorption, the osteocyte lacunar system, and porosity in the cortical bone of GC-treated rats.Calcified Tissue International 07/2008; 83(2):121-8. · 2.38 Impact Factor
Article: Osteoarthitis of leptin-deficient ob/ob mice in response to biomechanical loading in micro-CT.[show abstract] [hide abstract]
ABSTRACT: Mechanotransduction is the mechanism that due to reacting chondrocytes on biomechanical loading of body mass. Higher biomechanical loading lead to increased degeneration of chondrocytes, whereas moderate loading is protecting. This suggests that body fat regulates bone metabolism first by means of hormonal factors and second that the effects of muscle and loading are signaling factors in mechanotransduction. Leptin, a peptide hormone produced predominantly by white fat cells, is one of these hormonal factors. The aim of this study was to investigate and measure the different effects of weight-bearing on trabecular bone formation in mice without the stimulation of leptin and with or without osteoarthritis. 40 C57BL/ 6J ob/ob-mice in the age of 20 weeks have been devided into two groups with an ad-libitum-diet and with reduced diet. The hip- and knee-joints have been examinated in micro-CT-scan and histomorphologically. Animals with an ad-libitum-diet were found to increase body weight significantly at the age of six weeks in comparison with lean mice. At the age of twenty weeks the obese mice were almost twice as heavy as the lean mice. Significant statistical differences are shown between the two groups for body weight and bone mineral density. Examination of trabecular bone in micro-CT revealed that the only statistically significant difference between the two groups was the trabecular number for the proximal femur. High weight-bearing insignificantly improved all trabecular bone parameters in the obese mice. Correlation was found between trabecular number and bone mineral density on the one hand and body weight on the other hand. The correlation between body weight and osteoarthritis shows a significant increase in grade of osteoarthritis as body weight increases in hip-joint and knee-joint but not in osteoarthritis-positive (OP) versus osteoarthritis-negative (ON) mices. The correlation of the hip-joint between micro-CT data and body weight shows an increase in these data as body weight increases in OP mices. The correlation of the hip-joint between micro-CT data and osteoarthritis shows a decrease in these data as osteoarthritis increases in OP mices. The correlation of the knee-joint between micro-CT data and body weight shows differencies between ON and OP mices. The correlation of the knee-joint between micro-CT data and osteoarthritis shows an increase in these data as osteoarthritis increases in OP mices. biomechanical loading led to decreased bone mineral density by a decrease in the number of trabeculae. Trabecular thickness was not increased by biomechanical loading in growing mice. Decreased body weight in leptin-deficient mice protects against bone loss. This finding is consistent with the principle of light-weight construction of bone. Differences in osteoarthritis-positive and osteoarthritis-negative mices show the eventual importance of diet in leptin-deficience. It is not possible to conclude that these results also apply to human beings.International journal of biological sciences 02/2009; 5(3):265-75. · 2.70 Impact Factor