High dose vitamin D supplementation does not rescue bone loss following Roux-en-Y gastric bypass in female rats.

Autor: Niu A; Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, United States of America., Carpenter TO; Department of Pediatrics, Endocrine Section, Yale University School of Medicine, New Haven, CT, United States of America., Grams JM; Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, United States of America; Department of Surgery, Birmingham VA Medical Center, Birmingham, AL, United States of America., Bozorgmehri S; Department of Urology, North Florida/South Georgia Veterans Affairs Medical Center and University of Florida, Gainesville, FL, United States of America., Tommasini SM; Department of Orthopaedics and Rehabilitation, Yale University, New Haven, CT 06520, United States of America., Schafer AL; Endocrine Research Unit, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, CA, United States of America., Canales BK; Department of Urology, North Florida/South Georgia Veterans Affairs Medical Center and University of Florida, Gainesville, FL, United States of America. Electronic address: benjamin.canales@urology.ufl.edu.
Jazyk: angličtina
Zdroj: Bone [Bone] 2019 Oct; Vol. 127, pp. 172-180. Date of Electronic Publication: 2019 Jun 19.
DOI: 10.1016/j.bone.2019.06.015
Abstrakt: Postoperative bone loss and increased fracture risk associated with Roux-en-Y gastric bypass (RYGB) have been attributed to vitamin D/calcium malabsorption and resultant secondary hyperparathyroidism (HPT). Adequate vitamin D supplementation (VDS), particularly in an older female population, reduces incidence of secondary HPT but the effect on bone loss and fracture risk remains unclear. To investigate whether VDS corrects the RYGB bone phenotype, 41 obese adult female rats were randomized to RYGB with 1000 IU (R1000) or 5000 IU (R5000) vitamin D/kg food or a sham surgical procedure with either paired (PF) or ad libitum (AL) feeding. Bone turnover markers, urinary calcium/creatinine ratio (CCR), and serum calciotropic and gut hormones were assessed throughout a 14-week postoperative period. Femurs were analyzed by micro-computed tomography (μCT), three-point bending test, and histomorphometry. 1000 IU animals had low 25‑hydroxyvitamin D (25(OH)D), high serum parathyroid hormone (PTH), and very low urine CCR levels. 5000 IU corrected the 25(OH)D and secondary HPT but did not increase urine CCR or serum levels of 1,25‑dihydroxyvitamin D (1,25(OH)D) significantly between RYGB groups. Compared to sham animals at 14 weeks, RYGB animals had significantly higher serum osteocalcin (OCN) and C-terminal telopeptide (CTX) levels. The gut hormone peptide tyrosine tyrosine hormone (PYY) was higher in the RYGB groups, and leptin was lower. μCT and biomechanical testing revealed RYGB females had decreased cortical and trabecular bone volume and weaker, stiffer bone than controls. Histomorphometry showed decreased bone volume and increased osteoid volume with increased mineral apposition rate in RYGB compared to controls. No differences in bone phenotype were identified between 1000 IU and 5000 IU groups, and osteoclast numbers were comparable across all four groups. Thus, in our model, 5000 IU VDS corrected vitamin D deficiency and secondary HPT but did not rescue RYGB mineralization rate nor the osteomalacia phenotype. Longer studies in this model are required to evaluate durability of these detrimental effects. Our findings not only underscore the importance of lifelong repletion of both calcium and vitamin D but also suggest that additional factors affect skeletal health in this population.
(Copyright © 2019 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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