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Effects of a High‐Fat, High‐Cholesterol Diet or Hyperphagia on Bone Mass, Bone Strength and Serum Turnover Markers in Male Rats
Author(s) -
Ortinau Laura Christine,
Richard Matthew,
Dirkes Rebecca,
Linden Melissa,
Rector R. Scott,
Hinton Pamela
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.678.9
Subject(s) - medicine , endocrinology , osteocalcin , bone remodeling , bone resorption , bone mineral , chemistry , cholesterol , osteoporosis , alkaline phosphatase , biochemistry , enzyme
Individuals with obesity and type 2 diabetes (T2D) have increased risk for fracture, despite normal or elevated bone mineral density (BMD). Here, we tested the hypothesis that bone outcomes would be negatively impacted by hyperphagia or a high‐fat, high‐cholesterol diet (HFC) versus a control diet (CON) using hyperphagic Ostuka Long‐Evans Tokushima Fatty (OLETF) rats, which spontaneously develop obesity and T2D, and normophagic Long‐Evans Tokushima (LETO) rats. Eight‐week old male OLETF and LETO rats were randomly assigned to either the CON (10% kcal fat from soybean oil and lard) or HFC (45% kcal fat from soybean oil and lard with 1% cholesterol) diet for 24 weeks. At 32 weeks of age, body composition, total body bone mineral content (BMC) and BMD were measured by DXA. Bone strength was measured by torsional loading of the femur to failure. Serum markers of bone formation (amino‐terminal propeptide of type I collagen, P1NP; osteocalcin, OC) and resorption (tartrate‐resistant acid phosphatase, TRAP5b; C‐terminal peptide of type I collagen, CTx) were measured using ELISA. Fasting glucose was measured using glucose oxidase. Main and interactive effects of diet (HFC vs. CON) and hyperphagia (hyperphagic OLETF vs. normophagic LETO) were evaluated using two‐factor analysis of variance with peak body weight as a covariate. The HFC diet or hyperphagia significantly increased body weight and fat mass (HFC vs. CON: p<0.05; hyperphagic OLETF vs. normophagic LETO: p<0.05); and hyperphagic OLETF rats had significantly increased blood glucose (p<0.001). Hyperphagia reduced total body BMC and, high‐fat‐feeding decreased BMC and BMD (p<0.05). Hyperphagic OLETF rats had reduced serum P1NP and TRAP5b, and increased CTx vs. normophagic LETO rats (p<0.001, all). The HFC diet increased TRAP5b compared to the CON diet (p<0.05). There were significant interactions for the bone strength outcomes, such that maximal torque (Tmax), stiffness (Ks), ultimate tensile strength (Su), were increased only in normophagic LETO rats fed the HFC diet (Tmax p=0.061; Ks p=0.058; and Su p<0.05) vs L‐CON; the HFC diet had no effect on these measures in hyperphagic OLETF rats. Overall, hyperphagia reduced total body BMC, and increased bone resorption and decreased formation. Consumption of a HFC diet reduced total body BMC and BMD, and increased cortical bone strength in normophagic rats. Support or Funding Information This work was supported by NIH, a VA Career Development Award, a University of Missouri Research Council Grant, and the Department of Nutrition & Exercise Physiology.