Effect of 1α-vitamin D3 on bone strength and composition in growing rats with and without corticosteroid treatment

Abstract

The effects of 1 alpha-vitamin D3 were studied for 6 months in 2-month-old male and female rats on a moderately low calcium diet with or without low-dose prednisolone treatment. Both cortical bone mechanical and biochemical properties were examined. Femoral bone specimens were subjected to torsional loading tests. With age, bone strength and stiffness increased in both sexes, accompanied by an increased degree of mineralization (bone ash and calcium concentrations). During growth, strength and stiffness increased more in male than in female rats. When 1 alpha-vitamin D3 (0.5 micrograms/kg/day) was given alone, bone mechanical competence improved significantly whereas insulin-like growth factor-I (IGF-I) and calcium concentrations in the bone matrix were significantly reduced. Treatment with low-dose prednisolone (0.5 mg/kg/day) alone did not influence bone mechanical properties compared with intact control rats (without prednisolone) although a significant reduction in calcium concentration and an increased phosphorus concentration were measured. A combined therapy with prednisolone and 1 alpha-vitamin D3 significantly increased bone strength, toughness, and stiffness compared with control bones. Both mineralization degree (ash and calcium concentration) and IGF-I concentration were decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Variations in trabecular bone composition with anatomical site and age: potential implications for bone quality assessment

“…Before analysis of the biochemical composition, the bone samples were treated as described earlier (Dequeker et al 1993, Aerssens et al 1994. Briefly, the trabecular bone parts were separated from the cortical bone parts, and soft tissue and blood remnants were removed.…”

“…Bone powder samples were ashed at 700 C for 6 h as described previously (Raymaekers et al 1992, Aerssens et al 1994, and the weight of the ashed material was expressed as percentage of dry bone weight. Calcium was determined colorimetrically by a Hitachi 717 apparatus after dissolving the ashed samples in 2·5 ml 1  HCl and tenfold dilution with milli-Q water.…”

“…The total amount of proteins present in the extracts was determined as described earlier (Aerssens et al 1994) by spectrophotometry at a wavelength of 280 nm, using BSA as a standard. Osteocalcin and IGF-I concentrations in the Table 1 Distribution by age, sex and cause of death in the subjects of the study population.…”

Whole Bone Mechanics and Bone Quality

“…In rodent models, low-calcium diets have been associated with reduced BV/TV in the proximal ulna [130] and ash content, breaking strength, and elastic modulus in the femur [46]. Calcium and vitamin D supplementation increased whole bone stiffness, strength, and toughness in the femur [2] and increased stiffness but decreased maximum load and energy to maximum load in the lumbar spine [92].…”

“…(2) How do the intrinsic characteristics of bone tissue contribute to the mechanical properties of a whole bone? (3) What are the effects of extrinsic characteristics on whole bone mechanical behavior?…”