Dhawan Davinder, Singh Baweja Mandeep, Dani Vijayta
Department of Biophysics, Panjab University, Sector, 14, Chandigarh-160 014, India.
Hell J Nucl Med. 2007 Sep-Dec;10(3):167-71.
Hyperthyroidism in men is often treated with high doses of iodine-131 ((131)I), which may induce radiation side effects to patients and their environment. These therapeutic doses of (131)I could be decreased, if the (131)I uptake of the thyroid gland of the patients could be increased. Zinc sulphate has been considered to exercise a protective role by maintaining the cellular integrity of the thyroid under various pathological states. The aim of our study was to study in Wistar rats whether zinc sulphate can after treatment of the thyroid gland with (131)I: a) increase the uptake of (131)I in the thyroid and b) stabilize the function of the follicular cells. If such a stabilization finally exists in men we could have favorable results like fewer cases of hypothyroidism after (131)I treatment of hyperthyroidism. To carry out these investigations, rats were divided into four groups comprising of eight animals each. Group I animals served as normal controls. Group II animals received a dose of 3.7 MBq of (131)I. Group III animals were supplemented with zinc (227 mg/L of drinking water) and animals in Group IV were given (131)I together with zinc sulphate as above. Our results showed that in Group II, serum levels of tetra-iodo-thyronine (T(4)) and tri-iodo-thyronine (T(3)) decreased significantly as a function of time following (131)I treatment. An increase in the levels of serum thyroid stimulating hormone (TSH) was noticed one week after (131)I treatment, becoming less pronounced with time. In Group II, thyroid uptake at 2h and at 24h was significantly decreased. In the same Group biological half life (T(biol)) of (131)I in the thyroid gland, was significantly elevated four weeks after the administration of (131)I and decreased eight weeks after. In Group IV animals, zinc sulfate after four weeks, induced normalization of elevated serum TSH levels and a further increase in the T(biol) of (131)I. After eight weeks in these animals, serum T(3) became normal and TSH remained at normal levels. Thyroid (131)I uptake at 2 and 24 h was increased as compared to Group II. Group III animals showed some increase in the levels of Na(+)K(+)ATPase and type 1,5'-deiodinase (5'-DI) as compared to normal rats of Group I. In conclusion, this study suggests the protective potential of zinc sulphate in the disturbed after (131)I treatment, thyroid function, thyroid hormones and TSH while the (131)I uptake was reduced. Thus, if this result is further confirmed, zinc sulphate may show to be a promising radioprotective agent for the thyroid gland.
男性甲状腺功能亢进症通常采用大剂量碘 - 131（¹³¹I）进行治疗，这可能会给患者及其周围环境带来辐射副作用。如果能够提高患者甲状腺对¹³¹I的摄取量，那么这些治疗剂量的¹³¹I就可以降低。硫酸锌被认为在各种病理状态下通过维持甲状腺细胞的完整性发挥保护作用。我们研究的目的是在Wistar大鼠中研究硫酸锌在¹³¹I治疗甲状腺后是否能够：a）增加甲状腺对¹³¹I的摄取；b）稳定滤泡细胞的功能。如果男性患者最终确实存在这种稳定作用，那么在¹³¹I治疗甲状腺功能亢进症后，我们可能会得到更好的结果，比如甲状腺功能减退症的病例减少。为了进行这些研究，将大鼠分为四组，每组八只动物。第一组动物作为正常对照。第二组动物接受3.7 MBq的¹³¹I剂量。第三组动物补充锌（饮用水中含227 mg/L），第四组动物像上述那样同时给予¹³¹I和硫酸锌。我们的结果表明，在第二组中，四碘甲状腺原氨酸（T₄）和三碘甲状腺原氨酸（T₃）的血清水平在¹³¹I治疗后随时间显著下降。在¹³¹I治疗一周后，血清促甲状腺激素（TSH）水平升高，随着时间推移这种升高变得不那么明显。在第二组中，2小时和24小时时甲状腺摄取量显著降低。在同一组中，¹³¹I在甲状腺中的生物半衰期（T₍biol₎）在给予¹³¹I后四周显著升高，八周后降低。在第四组动物中，四周后硫酸锌使升高的血清TSH水平恢复正常，并使¹³¹I的T₍biol₎进一步增加。八周后，这些动物的血清T₃恢复正常，TSH保持在正常水平。与第二组相比，2小时和24小时时甲状腺¹³¹I摄取量增加。与第一组的正常大鼠相比，第三组动物的Na⁺K⁺ATP酶和1型5'-脱碘酶（5'-DI）水平有所升高。总之，本研究表明硫酸锌对¹³¹I治疗后紊乱的甲状腺功能、甲状腺激素和TSH具有保护潜力，同时¹³¹I摄取量减少。因此，如果这一结果得到进一步证实，硫酸锌可能会成为一种有前景的甲状腺辐射防护剂。
