title: Iodide and T4 kinetics in plasma, thyroid gland and skin of 10-day-old rats: effects of iodine deficiency.
abstract: The effects of iodine deficiency on the peripheral metabolism of thyroid hormone in immature rat were evaluated by measuring the kinetics of iodide and thyroxine (T4) in control and iodine-deficient 10-day-old rats. Iodine-deficient pups were obtained by giving the mother drinking water containing perchlorate; this anion is not transferred but prevents iodine transfer in the mother's milk. Labelled iodocompounds were measured in plasma, thyroid and skin for 48 h following intravenous injection of Na131I plus [125I]T4. Data were interpreted by compartmental analysis. The iodide plasma clearance rate, plasma equivalent distribution volume, plasma concentration, production and iodine thyroid content of iodine-deficient rats were significantly lower (-29%, -31%, -84%, -89% and -87% respectively) than in control 10-day-old rats. The iodide thyroid uptake was reduced (-47%) but remained higher than the release of iodine as T4. Cutaneous iodine was lost much more quickly by iodine-deficient pups than by control pups, explaining the decreased iodide distribution volume. The parameters of T4 metabolism were not changed by iodine deficiency, except for a slight but significant reduction of the thyroxinemia and T4 pools (-13%). Thence, T4 production was not significantly changed (about 8 pmol/h in control and iodine-deficient rats). The labelled T4 curves in iodine-deficient and control skin were superimposed and the patterns of labelled T3 derived from [125I]T4 were identical. Thus, the skin of immature rats converts T4 to T3; this process was not disturbed by iodine deficiency. The thyroid function of immature rats is particularly resistant to iodine deficiency, but the mechanisms remain unknown.
authors: Laboratoire de Physiologie Comparée II, UA 1197 du CNRS, Université de Montpellier II, France.
authors: N
authors: N
authors: Zeghal
authors: F
authors: F
authors: Gondran
authors: M
authors: M
authors: Redjem
authors: M D
authors: MD
authors: Giudicelli
authors: Y
authors: Y
authors: Aissouni
authors: E
authors: E
authors: Vigouroux
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000097:blood / Q000378:metabolism*; D000833:Animals, Suckling; D007454:Iodides / Q000097:blood / Q000493:pharmacokinetics*; D007455:Iodine / Q000172:deficiency*; D008954:Models, Biological; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D012867:Skin / Q000378:metabolism*; D013961:Thyroid Gland / Q000378:metabolism*; D013974:Thyroxine / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D007454:Iodides; D007455:Iodine; D013974:Thyroxine