title: Effects of vitamin K2 (menatetrenone) on calcium balance in ovariectomized rats.
abstract: Vitamin K2 (menatetrenone) has been used for the treatment of osteoporosis in Japan. We investigated the effects of ovariectomy (OVX) and vitamin K2 on the calcium (Ca) balance in 20-week-old female Fischer rats. Vitamin K2 (31 mg/kg per day) was given to animals as a dietary supplement. At weeks 4 and 8 after OVX, a Ca balance study was performed for 5 days. The intestinal Ca transport was determined using the everted gut-sac technique at week 9. The Ca balance was poorer in the OVX-control group than in the sham-control group at weeks 4 and 8 after OVX. The Ca balance improved significantly in the vitamin K2 groups as compared with the sham- and OVX-control groups. The intestinal Ca transport decreased due to OVX and was higher in the vitamin K2 administration groups than in the sham- and OVX-control groups, but not to a significant extent. The bone mineral density in the femoral metaphysis as well as the cortical area and cortical thickness in the femoral diaphysis in the OVX-control group were lower than in the sham-control group. The administration of vitamin K2 significantly inhibited an OVX-induced decrease in cortical area and cortical thickness in the femur. These findings suggest that the poor Ca balance observed in ovariectomized rats may be improved by vitamin K2; vitamin K2 may be involved in preventing bone loss in vivo.
authors.affiliation: Department of Applied Drug Research, Eisai Co., Ltd., Tokyo, Japan. m-kobayashi@hhc.eisai.co.jp
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Kuniko
authors.initials: K
authors.lastname: Hara
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Akiyama
mesh_terms: D000818:Animals; D001692:Biological Transport; D001835:Body Weight / Q000187:drug effects; D015519:Bone Density / Q000187:drug effects; D002118:Calcium / Q000378:metabolism* / Q000652:urine; D005243:Feces / Q000737:chemistry; D005260:Female; D005269:Femur / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects; D009929:Organ Size / Q000187:drug effects; D010024:Osteoporosis / Q000378:metabolism; D010052:Ovariectomy; D051381:Rats; D011916:Rats, Inbred F344; D014599:Uterus / Q000187:drug effects / Q000378:metabolism; D024482:Vitamin K 2 / Q000031:analogs & derivatives* / Q000494:pharmacology*
chemical_list: D024482:Vitamin K 2; C030814:menatetrenone; D002118:Calcium