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Effects of sex and exercise training on bone volume and density in Nrf2‐deficient rats
Author(s) -
Wahl John Andrew,
Park Hyerim,
Barsoum MinaMichael,
Restrepo Alexis,
Dewell Isabella,
Wahl Jake,
Maraj Joshua,
Peterson William,
ReidFoley Emily,
Ballehr Kelsey,
Bedwell Kristin,
Medarev Steven,
Schartz Kaley,
Sadowsky Dylan,
Delp Michael,
Geurts Aron,
MullerDelp Judy
Publication year - 2019
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.2019.33.1_supplement.702.2
Subject(s) - sed , treadmill , bone resorption , endocrinology , femur , medicine , bone density , aerobic exercise , chemistry , osteoporosis , surgery
Nuclear factor (erythroid‐derived 2)‐like 2 (Nrf2) is a transcription factor that is crucial in maintaining cellular redox homeostasis. In female mice, Nrf2 deficiency has been shown to increase bone resorption in the femur. In contrast, treadmill exercise training has been shown to increase bone density in the femur of aged rats. We tested the hypothesis that the absence of Nrf2 would reduce or negate increases in bone density induced by exercise training. We exercise trained male and female wild type Sprague‐Dawley (WT) rats, and their littermates lacking the Nrf2 gene (Nrf2KO). Rats were either exercise trained (EX) on a motor‐driven treadmill 5 days/wk or remained sedentary (SED) in their cages for 10–12 weeks. A mixed moderate aerobic and high‐intensity interval training protocol was utilized. At the end of the training period, femurs were cleaned, then scanned and analyzed using a Scanco Medical uCT35 micro‐CT with a resolution of 12 micron‐voxels. Total volume, bone volume, bone volume/total volume (BV/TV), connectivity and number of trabeculae were evaluated in trabecular bone. In both WT and Nrf2KO male rats, exercise training increased trabecular number (EX: 2.8 ± 0.1 vs. SED: 2.4 ± 0.1; P<0.05) and BV/TV (EX: 0.17± 0.01 vs. SED: 0.13 ± 0.01; P=0.06), and tended to increase connectivity (EX: 31.9 ± 2.5 vs. SED: 24.7 ± 2.5; P=0.09). Surprisingly, total volume, bone volume, BV/TV, connectivity and number of trabeculae were all more than 100% higher in femurs from females as compared to males (female vs. male; P<0.1 for all parameters). There were no significant effects of training or Nrf2KO genotype on bone parameters in females. These data suggest that female hormones are powerful regulators of bone growth and remodeling, masking the effects of either deletion of the Nrf2 gene or treadmill exercise. Support or Funding Information NIH Grant Number R15AG055029 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .