Gaitán E, Merino H
Acta Endocrinol (Copenh). 1976 Dec;83(4):763-71. doi: 10.1530/acta.0.0830763.
Epidemiological findings from the city of Cali, Colombia, support the hypothesis that water supply and iodine intake are not the only dietary factors which influence the magnitude of the goitre endemia. Experiments were conducted in rats to determine whether casein has a counteracting effect on the goitrogenic and antithyroid activities of methimazole (MMI) and goitrogenic water extracts (GWE) from the endemic area of the Cauca Valley. Female albino rats (Charles River, DC strain) 100-110 g initial weight, receiving 12 mug of iodine daily, were divided into three groups annd put on special diets: protein-free, 8 % casein, or 60 % casein, respectively. Each group (24 rats) was then divided into three subgroups. Subgroup one received goitrogen-free water and was used as a control. Subgroup two was administered MMI, 50 mug/day/rat. Subgroup three was given per animal a daily amount of GWE equivalent in antithyroid potency to 50 mug of MMI. At 77 days, the thyroid glands were studied for weight, 131I uptake, and 127I concentration. Animals on the protein-free diet showed significantly (P less than 0.05 - less than 0.01) larger thyroid glands per 100 g body weight and lower thyroidal 4 h 131I uptake and 127I-concentrations than rats on casein diets. These differences were significantly increased (P less than 0.01) by the administration of MMI and GWE. All the effects were completely reversed by the 60 % casein diet showing no differences between control rats and those on MMI or GWE. Rats on 8 % casein showed intermediate values between those of animals on protein-free and 60 % casein diets; differences were still present between the control as against the MMI or GWE groups, The results indicate that under these experimental conditions, a poor-protein diet impairs the thyroidal transport of iodine, decreases its concentration in the thyroid and is accompanied by an enlargement of the gland. Under these circumstances, the action of thiourea-like antithyroid agents is enhanced. The administration of protein reverses these alterations and decreases the action of such antithyroid agents. Whether the changes observed are due to a direct action of casein on the thyroid and/or to effects of malnutrition on the metabolism of antithyroid compounds remains to be determined.
供水和碘摄入量并非影响甲状腺肿地方病严重程度的唯一饮食因素。在大鼠身上进行了实验，以确定酪蛋白是否对甲巯咪唑（MMI）的致甲状腺肿和抗甲状腺活性以及考卡山谷地方病流行区的致甲状腺肿水提取物（GWE）具有抵消作用。初始体重为100 - 110克、每日摄入12微克碘的雌性白化大鼠（查尔斯河DC品系）被分为三组，并给予特殊饮食：分别为无蛋白饮食、8%酪蛋白饮食或60%酪蛋白饮食。然后将每组（24只大鼠）再分为三个亚组。第一亚组饮用无致甲状腺肿物质的水，作为对照。第二亚组每只大鼠每天给予50微克MMI。第三亚组每只动物每天给予与50微克MMI抗甲状腺效力相当的GWE量。在77天时，对甲状腺进行重量、131I摄取和127I浓度的研究。与食用酪蛋白饮食的大鼠相比，食用无蛋白饮食的动物每100克体重的甲状腺明显更大（P小于0.05 - 小于0.01），甲状腺4小时131I摄取和127I浓度更低。给予MMI和GWE后，这些差异显著增加（P小于0.01）。60%酪蛋白饮食完全逆转了所有这些影响，显示对照大鼠与接受MMI或GWE的大鼠之间没有差异。食用8%酪蛋白的大鼠的值介于食用无蛋白饮食和60%酪蛋白饮食的动物之间；对照与MMI或GWE组之间仍存在差异。结果表明，在这些实验条件下，低蛋白饮食会损害甲状腺对碘的转运，降低其在甲状腺中的浓度，并伴有甲状腺肿大。在这种情况下，硫脲类抗甲状腺药物的作用会增强。给予蛋白质可逆转这些改变，并降低此类抗甲状腺药物的作用。观察到的这些变化是由于酪蛋白对甲状腺的直接作用和/或营养不良对抗甲状腺化合物代谢的影响，仍有待确定。
