title: 3, 4-Didehydroretinol kinetics differ during lactation in sows on a retinol depletion regimen and the serum:milk 3, 4-didehydroretinol:retinol ratios are correlated.
abstract: 3, 4-Didehydroretinol (DR) metabolism was previously followed in vitamin A (VA)-replete lactating sows. This study followed DR appearance and clearance after dosage in serum and milk during 2 lactation cycles in sows (n = 8) fed VA-free feed for 3 gestation-lactation cycles. During lactations 2 and 3, 35 μmol 3, 4-didehydroretinyl acetate was given orally after overnight food deprivation. Blood and milk were collected at 0, 1.5, 3, 5, 7, 9, 16, 24, 36, 48, 60, and 72 h; livers were obtained at kill. Samples were analyzed for DR, retinol (R), and 3, 4-didehydroretinyl esters. During lactations 2 and 3, the 5-h serum DR:R ratios were 0.028 ± 0.017 and 0.069 ± 0.042, respectively, and serum R concentrations were 0.75 ± 0.23 and 0.86 ± 0.37 μmol/L, respectively. The DR:R ratio and serum R were 0.018 ± 0.013 and 0.94 ± 0.12 μmol/L, respectively, in VA-replete sows from the same herd. After lactation 3, liver VA was 0.23 ± 0.05 μmol/g, indicating low-normal VA status. Serum DR area-under-the curve from 0 to 48 h increased as liver stores decreased. Thirteen to 23% of DR dose was secreted into milk, consistent with VA-replete sows. Milk DR concentrations were greater during lactation 3 than 2. Peak concentration occurred earlier and the half-life was shorter for milk DR in the more VA-depleted sows. The milk and serum DR:R were correlated from 3 to 9 h (r = 0.70; P < 0.0001) and increased as VA stores decreased regardless of serum R concentration. Milk DR:R may replace serum measurements during lactation.
authors.affiliation: Interdepartmental Graduate Program in Nutritional Sciences, School of Pharmacy, University of Wisconsin, Madison, WI 53705, USA.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Surles
authors.forename: Paul R
authors.initials: PR
authors.lastname: Hutson
authors.forename: Ashley R
authors.initials: AR
authors.lastname: Valentine
authors.forename: Jordan P
authors.initials: JP
authors.lastname: Mills
authors.forename: Sherry A
authors.initials: SA
authors.lastname: Tanumihardjo
mesh_terms: D000818:Animals; D019540:Area Under Curve; D005260:Female; D007774:Lactation / Q000378:metabolism*; D008892:Milk / Q000378:metabolism*; D012172:Retinaldehyde / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D013552:Swine; D014801:Vitamin A / Q000378:metabolism*; D014802:Vitamin A Deficiency / Q000378:metabolism*
chemical_list: D014801:Vitamin A; C017184:dehydroretinal; D012172:Retinaldehyde