Ascorbic acid effects on vitamin D hormone metabolism and binding in guinea pigs

J Nutr. 1990 Oct;120(10):1185-90. doi: 10.1093/jn/120.10.1185.

Abstract

Ascorbic acid deficiency in guinea pigs fed a vitamin D-replete diet caused a moderate reduction of Ca level in serum and bone; 25-hydroxy-cholecalciferol or 25-hydroxyergocalciferol (25-OHD) serum concentration tended to decline; renal 25-hydroxycholecalciferol-1-hydroxylase (1-OHase) activity decreased 50%; and 25-hydroxycholecalciferol-24-hydroxylase activity increased 1.6-fold. Chromatin 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] receptor concentration in the intestinal mucosa decreased 20-30%, and the percentage of occupied receptors decreased from 12-15% to 6-8%. Receptor affinity for 1,25-(OH)2D3 did not change (Kd = 0.24-0.26 nmol/L, Kd2 = 0.06-0.10 nmol/L), but the cooperativity coefficient decreased from 1.7 to 1.4. Vitamin C deficiency potentiated effects of vitamin D deprivation and impaired a restorative action of vitamin D. It was accompanied by a marked delay in the elevation of 25-OHD concentration in serum as well as decreased 1-OHase activity in kidneys and a lower concentration of occupied 1,25-(OH)2D3 receptors in the intestinal mucosa. The data demonstrate a critical role for ascorbic acid in vitamin D metabolism and binding.

MeSH terms

  • 25-Hydroxyvitamin D 2 / metabolism
  • 25-Hydroxyvitamin D3 1-alpha-Hydroxylase / metabolism
  • Animals
  • Ascorbic Acid Deficiency / metabolism*
  • Bone and Bones / chemistry
  • Bone and Bones / metabolism
  • Calcifediol / metabolism
  • Calcium / analysis
  • Calcium / blood
  • Guinea Pigs
  • Intestinal Mucosa / metabolism
  • Kidney / metabolism
  • Male
  • Receptors, Calcitriol
  • Receptors, Steroid / metabolism
  • Vitamin D / administration & dosage
  • Vitamin D / metabolism*
  • Vitamin D Deficiency / metabolism*

Substances

  • Receptors, Calcitriol
  • Receptors, Steroid
  • Vitamin D
  • 25-Hydroxyvitamin D 2
  • 25-Hydroxyvitamin D3 1-alpha-Hydroxylase
  • Calcifediol
  • Calcium