Modelos experimentales en ratas adultas de deficiencias: nutricionales (vitamina D y/o proteína) y hormonales (estrógenos) que influyen en los cambios en masa ósea.

MAROTTE C,; GONZALES CHAVES MMS,; PELLEGRINI GG,; MANDALUNIS P,; FRIEDMAN SM,; ZENI SN

Buenos Aires

Congreso; Asociación Argentina de Osteología y Metabolismo Mineral Óseo; 2009

Asociación Argentina de Osteología y Metabolismo Mineral Óseo

The aged population often presents a low food intake toghether with a low sun exposure, which could contribute to the high prevalecence of osteopenia and fracture risk observed in this population. To evaluate the influence of the low protein intake and/or vitamin D (vit. D) contribution in the patogénesis of osteoporosis we developed the present experimental model in adult female rats. From a total of 40 adult Wistar rats (300±50 g), bilateral ovariectomy (OVX) was performed to 20 of them and a simulated surgery to the rest (SHAM). During 15 days post-surgery all the animals were fed a commercial diet (Granave SA, Bs.As.) with a 15% protein content and 200UI% of vit. D. Afterwards, the animals were divided into 5 groups, fed the specified diet during an additional period of 45 days:  G1: control (15% casein and 200UI% vit. D)  G2: 2.5% casein and 200UI% vit. D G3: 2.5%  casein and 0UI% vit. D  G4: 2.5%  casein and 200UI% vit. D  G5: 2.5%  casein and 0UI% vit. D At the baseline (Tb) and at the end ofd the study (Tf) bone mineral density and bone mineral content of total body (BMDet and BMCet, respectively) were measured by DXA (special Software for small animals, Lunar DPX). BMD of proximal tibia (BMDtp) was evaluated on the screen using a window (ROI). The difference between Tf y Tb was calculated. At Tb and at Tf were determinated in serum: Calcium (Ca), phosphorus (P), 25hydroxyvitamin D (25OHD), alkaline bone phosphatase (bALP), osteocalcin (BGP). At Tf tibias were extracted to meassure total bone volume (BV/TV %) histologicaly. The principles of lab animal care were applied (National Institute of Health 85-23,1985). Results (mean±standard error), G1 to G5, respectively: 25OHD(ng/dl): 29,4±6,1a; 50,0±0,2b; 29,4±1,5a; 8,6±2,5c; 10,3±4,5c. Cas(mg/dl): 10,00±0,2a; 10,0±0,1a; 9,9±0,6a; 9,3±0,1b; 9,8±0,1a. BALP(IU/l): 39,7±5,4a; 39,7±4,6a; 58,0±4,9b; 57,0±4,0b; 66,4±6,5b. BMDet(mg): 2,3±0,3a; 2,0±0,3a; 0,4±0,4b; 0,5±0,1b; 0,2±0,2c. CMOtp(mg/cm2): 55,0±16,2ªa; 23,0±10,1b; -325,8±11,7c; -3,0±0,4d; -40,7±13,7e. BV/TV(%):25,0±4,0a; 9,4±1,4b; 3,1±1,5c, 5,3±2,6c; 1,0±0,4d. Different letters correspond to p<0.05. The levels of 25(OH)D were significantly diminished in animals fed without vit. D. BALP was elevated in G3 and both OVX groups (G4 and G5), compared to control and G2. BMDtp and BV/TV were significantly lower in all defficient groups compared to control in a parallel way to the increment of defficiencies