title: The generation of C-3α epimer of 25-hydroxyvitamin D and its biological effects on bone mineral density in adult rodents.
abstract: The source and function of C-3α epimer of 25(OH)D (C-3 epimer) is unknown. The objectives were to (1) establish if increasing doses of vitamin D (VD) results in a proportionate dose-response in C-3 epimer; and (2) determine the biological response of bone to C-3 epimer treatment. Sprague Dawley rats (12 weeks, n = 36 female, n = 36 male) were randomized to control AIN93-M diet (1 IU VD3/g diet) or an experimental diet for 8 weeks containing VD3 at 2 or 4 IU/g diet, C-3 epimer at 0.5 or 1 IU/g diet or 25(OH)D (0.5 IU/g diet). BW and food consumption were measured weekly. Blood was sampled at week 0, 4, and 8 for assessment of VD metabolites and bone metabolism biomarkers. DXA (week 0, 4, and 8) and in vivo micro CT (μCT) (week 0 and 8) were performed in vivo plus ex vivo μCT imaging and bone biomechanics. Dietary intake and anthropometry did not differ among diet groups. The dose-response of VD generated significantly elevated C-3 epimer only in females with concentrations of 4 IU VD diet group [mean 84.6 (62.5) nmol/L] exceeding control [mean 21.4 (18.5) nmol/L, p = 0.005]. Both sexes in the 25(OH)D group did not show significant increases in C-3 epimer, whereas 0.5 and 1 IU epimer groups exceeded 100 nmol/L of C-3 epimer by 8 weeks. These data suggest C-3 epimer is endogenously generated with higher intakes of VD. Endogenous and exogenous C-3 epimer accumulates in serum without impact upon bone health outcomes in a healthy young adult model over 8 weeks.
authors.affiliation: Dietetics and Human Nutrition, McGill University, Macdonald-Stewart Building, Macdonald Campus, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, Montréal, QC, H9X 3V9, Canada.
authors.forename: Christina
authors.initials: C
authors.lastname: Bianchini
authors.forename: Paula
authors.initials: P
authors.lastname: Lavery
authors.forename: Sherry
authors.initials: S
authors.lastname: Agellon
authors.forename: Hope A
authors.initials: HA
authors.lastname: Weiler
mesh_terms: D015502:Absorptiometry, Photon; D000818:Animals; D015519:Bone Density / Q000187:drug effects*; D019587:Dietary Supplements; D005260:Female; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000494:pharmacology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D