title: Comparison of vitamin C deficiency with food restriction on collagen cross-link ratios in bone, urine and skin of weanling guinea-pigs.
abstract: Mild-to-moderate vitamin C depletion in weanling guinea-pigs affects pyridinoline:deoxypyridinoline (collagen cross-link) ratios in femur shaft and urine, attributed to impairment of hydroxylation of collagen lysine. We investigated: (1). whether the picture at two time points is compatible with progressive accumulation of abnormal collagen; (2). whether any changes are seen in skin, where little deoxypyridinoline occurs; (3). whether total food restriction has similar effects. Male weanling Dunkin-Hartley guinea-pigs were fed diets containing either 0.5 (vitamin C-restricted) or 160.0-320.0 (vitamin C-adequate) mg vitamin C/d. Two groups receiving the vitamin C-adequate diet received it ad libitum. Two other groups received the vitamin C-adequate diet in a restricted amount, limited to that which permitted nearly the same growth rate as in the vitamin C-restricted groups. Animals were fed for 4 or 8 weeks; urine was collected, and vitamin C and collagen indices were measured. In the femur shaft, the hydroxyproline content per unit weight was unaffected by vitamin C restriction or by total food restriction. Deoxypyridinoline was increased and the pyridinoline:deoxypyridinoline ratio was decreased in vitamin C-restricted groups, but not in food-restricted groups. Changes in the value of the ratio were greater after 8 than after 4 weeks. Urine indices mirrored bone indices. In skin, the main effect of vitamin C restriction was to reduce hydroxyproline. Here, the cross-link ratios changed less markedly than in bone, and there was less deoxypyridinoline. We conclude that the picture at two time points is compatible with a progressive accumulation of pyridinoline-enriched collagen in vitamin C-deprived animals, that the picture in skin differs from that of bone and urine, and that cross-link changes are not produced by total food restriction.
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, CB1 9NL, UK. Chris.Bates@mrc-hnr.cam.ac.uk
authors.forename: C J
authors.initials: CJ
authors.lastname: Bates
authors.forename: Harumi
authors.initials: H
authors.lastname: Tsuchiya
mesh_terms: D000596:Amino Acids / Q000378:metabolism / Q000652:urine; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D001206:Ascorbic Acid Deficiency / Q000378:metabolism* / Q000652:urine; D001835:Body Weight; D001842:Bone and Bones / Q000378:metabolism*; D003094:Collagen / Q000378:metabolism*; D004435:Eating; D005508:Food Deprivation; D006168:Guinea Pigs; D008297:Male; D012867:Skin / Q000378:metabolism*
chemical_list: D000596:Amino Acids; C015484:pyridinoline; C036020:deoxypyridinoline; D003094:Collagen; D001205:Ascorbic Acid