Fat and Sucrose Intake Induces Obesity-Related Bone Metabolism Disturbances: Kinetic and Reversibility Studies in Growing and Adult Rats

Abstract

Metabolic and bone effects were investigated in growing (G, n ¼ 45) and mature (M, n ¼ 45) rats fed a high-fat/high-sucrose diet (HFS) isocaloric to the chow diet of controls (C, n ¼ 30 per group). At week 19, a subset of 15 rats in each group (HFS or C, at both ages) was analyzed. Then one-half of the remaining 30 HFS rats in each groups continued HFS and one-half were shifted to C until week 27. Although no serum or bone marrow inflammation was seen, HFS increased visceral fat, serum leptin and insulin at week 19 and induced further alterations in lipid profile, serum adiponectin, and TGFb1, TIMP1, MMP2, and MMP9, suggesting a prediabetic phenotype and cardiovascular dysfunction at week 27 more pronounced in M than G. These events were associated with dramatic reduction of osteoclastic and osteoid surfaces with accelerated mineralizing surfaces in both HFS age groups. Mineral metabolism and its major regulators were disturbed, leading to hyperphosphatemia and hypocalcemia. These changes were associated with bone alterations in the weight-bearing tibia, not in the non-weight-bearing vertebra. Indeed in fat rats, tibia trabecular bone accrual increased in G whereas loss of trabecular bone in M was alleviated. At diaphysis cortical porosity increased in G and even more in M at week 27. After the diet switch, metabolic and bone cellular disturbances fully reversed in G, but not in M. Trabecular benefit of the obese was preserved in both age groups and in M the age-related bone loss was even lighter after the diet switch than in prolonged HFS. At the diaphysis, cortical porosity normalized in G but not in M. Hypocalcemia in G and M was irreversible. Thus, the mild metabolic syndrome induced by isocaloric HFS is able to alter bone cellular activities and mineral metabolism, reinforce trabecular bone, and affect cortical bone porosity in an irreversible manner in older rats.

Early Subchondral Bone Loss at Arthritis Onset Predicted Late Arthritis Severity in a Rat Arthritis Model

“…As in long bones, bone microarchitecture analysis is relevant in ankle bones. Parameter values were comparable with studies in femur or lumbar vertebrae (Lavet et al, ). Then we demonstrated that navicular bone was the most reproducible for measurement and the most sensitive to arthritis, as previously suggested by histological analysis performed only on navicular bones after arthritis onset (Schett et al, ), for two reasons suggested by our results.…”

“…Trabecular changes were also described and more significant in quantification compared to cortical changes. They may be related to fast trabecular remodeling compared to cortical remodeling (Lavet et al, ).…”

Fat, Sugar, and Bone Health: A Complex Relationship

“…Growing and mature rats ingested an isocaloric HFS diet for 19 and 27 weeks to induce obesity-related bone metabolism disorder [21], and it was observed that the HFS diet seemed to favor trabecular bone mass, while cortical thickness, along with density, did not obviously change.…”

Exercise Decreases Marrow Adipose Tissue Through ß-Oxidation in Obese Running Mice

“…(7,8) Similarly, in rodents, we and others have demonstrated that short-term high-fat feeding is associated with preserved or increased bone density. (9)(10)(11) There are studies that support a negative impact of obesity on bone quantity (12)(13)(14) or its biomechanical properties, (15,16) leading to the thinking that, despite increased bone quantity in the setting of obesity, bone quality and composition may not be commensurate to body weight, even representing relative bone fragility and increased fracture risk. (17,18) Further, obesity has been associated with increased fractures, albeit not classic osteoporotic fragility fractures.…”