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Involuntary wheel running decreases adiposity, improves but does not fully protect against negative skeletal effects of obesity induced by a high-fat diet in rats

Jay J. Cao, Matthew J. Picklo Sr.
Calcified tissues international 2015 v.97 no.2 pp. 145-155
acid phosphatase, adiposity, alpha-tocopherol, antioxidants, ascorbic acid, blood serum, bone density, bone metabolism, exercise, femur, high fat diet, insulin-like growth factor I, lard, leptin, obesity, osteocalcin, rats, vitamin supplements
This study investigated whether exercise or antioxidant supplementation with vitamin C and E during exercise affects bone structure and markers of bone metabolism in obese rat. Sprague–Dawley rats, 6-week old, were fed a normal-fat diet (NF, 10 % kcal as fat) and a high-fat diet (HF, 45 % with extra fat from lard) ad libitum for 14 weeks. Then, rats on the high-fat diet were assigned randomly to three treatment groups for additional 12 weeks with forced exercise: HF; HF + exercise (HF + Ex); and HF with vitamin C (0.5 g ascorbate/kg diet) and vitamin E (0.4 g a-tocopherol acetate/kg diet) supplementation + exercise (HF + Ex + VCE). At the end of the study, body weight and fat (%) were similar among NF, HF + Ex, and HF + Ex + VCE, whereas HF had greater body weight and fat (%) than other groups. Compared to NF, HF had elevated serum leptin, tartrate-resistant acid phosphatase (TRAP), and IGF-1; increased trabecular separation and structural model index; and lowered bone mineral density, trabecular connectivity density, and trabecular number in distal femur, while HF ? Ex and HF ? Ex ? VCE had elevated serum TRAP and decreased bone volume/total volume and trabecular number of distal femurs. Compared to HF, HF + Ex and HF + Ex + VCE had decreased serum TRAP and osteocalcin and improved bone structural properties of the distal femur. These findings suggest that exercise, while decreasing body fat, does not fully protect against the negative skeletal effects of existing obesity induced by a high-fat diet. Furthermore, vitamin C and E supplementation has no additional benefits on bone structural properties during exercise.