title: A calcium-deficient diet caused decreased bone mineral density and secondary elevation of estrogen in aged male rats-effect of menatetrenone and elcatonin.
abstract: In view of the fact that a deficient calcium (Ca) intake results in osteoporosis in elderly males, we conducted an animal experiment on aged male Wistar rats given a Ca-deficient diet. The rats were divided into 2 groups according to diet: a Ca-deficient diet group (Ca content, 0.08% to 0.1%) and a regular diet group (Ca content, 0.8% to 1.2%). The Ca-deficient diet reduced bone mineral density (BMD) by approximately 12%. Administration of menatetrenone or elcatonin was able to reverse the reduction in BMD induced by Ca deficiency. The mean estradiol level in sera of rats fed the Ca-deficient diet was significantly increased to 4.3 times that in the regular diet group. However, the increased estradiol concentration was reduced after the administration of menatetrenone or elcatonin. The estrone concentrations in sera of menatetrenone- or elcatonin-treated rats fed the Ca-deficient diet decreased to a level lower than that of animals fed the regular diet. Testicular aromatase cytochrome P450 (P450(arom); estrogen synthetase) activity was significantly increased by 2.4-fold in the Ca-deficient diet group compared to that in the regular diet group, and the aromatase mRNA level was also significantly increased 1.45-fold. Testicular aromatase activity was strongly correlated with aromatase mRNA level and serum estradiol level. These data suggest that the change in testicular aromatase expression might be, in part, a compensatory mechanism for the bone mineral deficiency induced by the Ca-deficient diet in aged male rats.
authors.affiliation: Department of Internal Medicine and Biochemistry, Fujita Health University School of Medicine, Toyoake, Aichi, Japan.
authors.forename: Seiya
authors.initials: S
authors.lastname: Kato
authors.forename: Toshiki
authors.initials: T
authors.lastname: Mano
authors.forename: Takako
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Naho
authors.initials: N
authors.lastname: Yamazaki
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Himeno
authors.forename: Keiko
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Mitsuyasu
authors.initials: M
authors.lastname: Itoh
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Harada
authors.forename: Akio
authors.initials: A
authors.lastname: Nagasaka
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001141:Aromatase / Q000096:biosynthesis / Q000378:metabolism; D015519:Bone Density / Q000187:drug effects / Q000502:physiology*; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D002116:Calcitonin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002118:Calcium / Q000097:blood / Q000172:deficiency*; D002136:Calcium, Dietary / Q000378:metabolism*; D004032:Diet; D004967:Estrogens / Q000097:blood*; D008297:Male; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D013737:Testis / Q000201:enzymology; D024482:Vitamin K 2 / Q000031:analogs & derivatives* / Q000494:pharmacology*
chemical_list: D002136:Calcium, Dietary; D004967:Estrogens; D012333:RNA, Messenger; D024482:Vitamin K 2; C030814:menatetrenone; D002116:Calcitonin; D001141:Aromatase; D002118:Calcium; C012755:elcatonin