An Experimental Model of Vitamin D Insufficiency and Established Osteopenia

ZENI S, MASTAGLIA SR, MANDULINIS P, DE GRANDI MC, OLIVERI B, SOMOZA J, FRIEDMAN S

Buenos Aires

Congreso; XXI Asociación Argentina de osteología y Metabolismo Mineral; 2004

Asociación Argentina de osteología y Metabolismo Mineral (AAOMM)

An Experimental Model of Vitamin D Insufficiency and Established Osteopenia.   Zeni Susana N,1,2 Mastaglia Silvina,1 Mandalunis Patricia,3 De Grandi  Maria del C,1 Oliveri Beatriz,1 Somoza Julia, Friedman Silvia.2 1Sección Osteopatías Medicas, Hospital de Clínicas, Universidad de Buenos Aires; 2Cátedra de Bioquímica Genera; 3Fisiología, Facultad de Odontología, UBA.   Vitamin D (Vit D) deficiency negatively affects bone and mineral metabolism. Normal levels of 25 OHVit D can be attained by means of exposure to UV radiation and/or adequate dietary intake. In rats,bilateral ovariectomy (OVX) accelerates bone metabolism with an increase in resorption, which results in bone loss and, in time, in generalized osteopenia. With the aims to determining whether the success of antiresorptive therapies depends on optimal levels of Vit D, the objective of our study was to design an experimental model of Vit D deficiency and established osteopenia. Adult Wistar rats (270-300 g) were OVX. After 15 days, and during 90 days, the animals received the following treatment: Group 1 (n = 8): diet containing Vit D, housed under white light; Group 2 (n = 16): diet not containing Vit D, housed under red light. At the same time 8 SHAM rats which served as controls, were fed a diet containing Vit D and housed under white light (Group 3). Eight animals in Group 2 were killed after 60 days (day 75of the study = To). At To and 90 days after the onset of treatment (day 105 of the study = Tf), densitometry of the total skeleton was performed (Lunar DPX) [BMD (LS) = lumbar spine BMD] and blood samples were obtained to determine sCTX (ELISA) and 25 HOVit D (RIA). Two and 12 days prior to sacrifice, animals were injected with tetracycline in order to perform histomorphometric determinations (Bone volume = % BV/Bs, and Eroded surface = % ES/BS) on the proximal tibia. Levels of 25 HOVit D at To in OVX animals not receiving endogenous or exogenous Vit D show established Vit D deficiency, which is greater at the end of the study. In addition, both biochemical (sCTX) and histologic (%ES/BS) resorption parameters were more elevated in Vit D deficiency; thus, bone mass was shown to be more deteriorated both by densitometric [BMD (LS)] and histologic (%BV/BS) findings. Conclusion: It can be stated that the model obtained using the experimental conditions established herein, is a model of Vit D deficiency and osteopenia, which may prove useful to evaluate antiresorptive drugs.   BMD(LS) Tf sCTX To25 OHVitD Tf25 OHVitD BV/BS% ES/BS% Group 1 _5.3 F 2.4 b 204 F 12.9 a 45.8 F 4.1 a 46.5 F 3.9 a 14.6 F 2.1 b 28.5 F 2.2 a Group 2 _7.8 F 2.0 b 231 F 11.4 b 12.6 F 1.3 b 10.8 F 0.8 b 10.7 F 3.1 c 33.5 F 1.9 b Group 3 2.5 F 1.9 a 181 F 13.2 c 50.3 F 2.1 a 52.1 F 2.9 a 28.2 F 3.4 a 17.5 F 3.4 c Different letters indicate a value of p b 0.05.