Vitamin K2 administration and bone mineral density in Senescence Accelerated Mice P‐6 (SAMP6)

Abstract

The P6 strain of senescence‐accelerated mice (SAMP6) exhibit features of skeletal aging including reduced bone mineral density (BMD), so that various physiological active agents affecting BMD could be examined. In the present study, SAMP6 were used in order to clarify the effect of vitamin K2 on BMD.We developed the further bone resorption model using water‐immersion restraint stress (WRS). Male SAMP6 were divided into three groups, i.e., control group, WRS (6 h/day, 5 times/wk) group, and WRS + vitamin K2 (30 mg/kg s.c.) group. SAMP6 were suffered from this stress between 6 to 10 weeks old. BMD was measured using computed tomography (CT) system for small animals, and bone turnover markers were also examined.BMD of trabecular bone for WRS groups was significantly lower than that of control group, suggesting that WRS was effective to reduce BMD. However, no significant difference of BMD was observed between WRS group and WRS + vitamin K2 group. On the other hand, urinary excretion of CTX, bone resorption marker, was significantly higher in WRS + vitamin K2 group than in other groups. And total osteocalcin in serum was significantly higher in WRS group than in other groups. These results indicated that vitamin K2 could affect bone turnover. This study was supported in part by a Kakenhi (22500684), and a Research Project Grant (No. 22‐A‐59) from Kawasaki Medical School.