Dietary Calcium Levels and Treatment Interval Determine the Effects of Lead Ingestion on Plasma 1,25-Dihydroxyvitamin D Concentration in Chicks

• Published in: The Journal of nutrition Vol. 125; no. 5; pp. 1328 - 1333
• Main Author: Fullmer, Curtis S.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.1995; American Institute of Nutrition
• Subjects: ABSORCION; ABSORCION DIGESTIVA; ABSORPTION; ABSORPTION DIGESTIVE; ANIMAL MODELS; Animals; ARN; Birds; BLOOD PLASMA; CALBINDIN; Calbindins; CALCIO; CALCITRIOL; Calcitriol - blood; CALCIUM; Calcium - deficiency; CALCIUM BINDING PROTEINS; Calcium, Dietary - administration & dosage; Calcium, Dietary - pharmacology; Chickens; CHICKS; DIET; DIETA; DIGESTIVE ABSORPTION; DOSAGE EFFECTS; Dose-Response Relationship, Drug; Drug Interactions; ESTEROLES; EXPERIMENTACION; EXPERIMENTATION; FOOD INTAKE; HUESOS DE LOS MIEMBROS; INGESTION DE ALIMENTOS; INGESTION DE NUTRIENTES; INGESTION DE SUBSTANCES NUTRITIVES; INTESTINAL ABSORPTION; Kidney - metabolism; KIDNEYS; LEAD; Lead - pharmacokinetics; Lead - toxicity; LIMB BONES; Male; MINERAL NUTRIENTS; MODELE ANIMAL; MODELOS ANIMALES; NUTRIENT INTAKE; NUTRIENTES MINERALES; Nutrition; OS DES MEMBRES; PLASMA SANGUIN; PLASMA SANGUINEO; PLOMB; PLOMO; POLLITO; POUSSIN; PRISE ALIMENTAIRE (HOMME); PROTEINAS QUE LIGAN CALCIO; PROTEINE DE LIAISON CALCIUM; REGIME ALIMENTAIRE; REIN; RINONES; RNA; RNA, Messenger - analysis; RNA, Messenger - genetics; S100 Calcium Binding Protein G - blood; S100 Calcium Binding Protein G - genetics; STEROL; STEROLS; SUBSTANCE NUTRITIVE MINERALE; TIBIA; Tibia - metabolism; Time Factors; TOXICIDAD; TOXICITE; TOXICITY; Vitamin D; toxicity; calcium; chicks; vitamin D; lead
• ISSN: 0022-3166; 1541-6100
• DOI: 10.1093/jn/125.5.1328

The combined effects of dietary calcium level and lead level on several indices of vitamin D endocrine function were examined in young, growing chicks. Day-old animals fed a nutritionally adequate diet for 2 wk were fed diets either adequate (1.2%) or low (0.1%) in calcium, and containing 0, 0.2 or 0.8% lead for an additional 1 or 2 wk. In the calcium-adequate group, lead ingestion significantly elevated intestinal calbindin-D28k protein and mRNA levels as well as plasma 1,25-dihydroxyvitamin D concentration compared with the control animals fed a lead-free diet. The effect was apparent after 1 wk of treatment and continued through wk 2. In the calcium-deficient group, the early (1 wk) increases in plasma 1,25-dihydroxyvitamin D and calbindin-D28k protein and mRNA were significantly reversed by lead ingestion over the 2-wk trial period in a dose-dependent fashion. In these circumstances, vitamin D endocrine function is severely compromised. Therefore, lead ingestion may result in either enhanced or diminished circulating 1,25-dihydroxyvitamin D concentrations and ensuing intestinal responses, depending of dietary calcium level and the duration of lead intake. These results provide possible explanations for several apparently conflicting sets of observations regarding lead-calcium interactions.