Methods: Retired breeder female Wistar rats were ovariectomyzed and fed either with or without 100μg/kg/day MK-4. Half of the rats (inactive groups) were kept in small cages, which prevent rats from walking2). After 21 weeks, all the rats were returned to regular cages and treated with 1.76 mg/Kg risedronate orally once a week for 18weeks.
Results: Compared to those of femoral cortical bone of the sham-operated rats, values by nano-indentation and confocal laser Raman microspectroscopy parameters such as mineral/matrix showed significant improvement from that of inactive group by the prior MK-4 treatment.
Conclusions: Bed rest patients, if treated with MK-4 during hospitalization, may react better to later risedronate administration, which results in more resilient bone of better quality.
1)Y Matsumoto, Y Mikuni-Takagaki, Y Kozai, K Miyagawa, K Naruse, H Wakao, R Kawamata, I Kashima, T Sakurai Prior treatment with vitamin K2significantly improves the efficacy of risedronate. Osteoporos Int. 20:1863, 2009
2) K Miyagawa,Y Kozai, Y Ito, T Furuhama,K Naruse,K Nonaka, Y Nagai, H Yamato, IKashima, K Ohya,K Aoki, and Y Mikuni-TakagakiA novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats. J.Bone Miner. Metab. 29:422, 2011