Neve P, Starling J R, Golstein J, Krupp P P
Laboratory of Pathology and Electron Microscopy, Brussels, Belgium.
Endocrinology. 1988 Jul;123(1):478-86. doi: 10.1210/endo-123-1-478.
This study tested the effects of different iodine intakes on thyroid ultrastructure and function in thyroid remnants after subtotal thyroidectomy (sub-tx). Removal of most of the thyroid gland causes an elevation of endogenous TSH, which chronically stimulates the residual tissue. Male Sprague-Dawley rats were divided into three groups; Low Iodine Group (LIG), Moderate Iodine Group (MIG), and High Iodine Group (HIG). There was no significant difference among total thyroid weights removed by sub-tx, but thyroid remnant weights and TSH levels were higher at death (6 weeks after sub-tx) in LIG than in MIG and HIG. Total specific activities of cathepsin D and of arylsulfatase A in the sedimentable and nonsedimentable subcellular fractions were at least 38% lower in LIG than in MIG and HIG. The ratio between relative follicular volume and colloid volume determined by morphometry was higher in LIG than in MIG and lower in HIG than in MIG. Ultrastructurally, the relative volume occupied by secondary lysosomes was higher in HIG than in MIG, whereas the number of secondary lysosomes was not higher in LIG than in controls. Autoradiographic studies with 125I revealed that a large part of the radioactivity was in thyroid cell secondary lysosomes in MIG and HIG when radioiodine was injected 3 weeks before death. It is concluded that after sub-tx, iodine 1) regulates the weight of thyroid remnants, perhaps only indirectly through TSH, 2) modulates the number of secondary lysosomes in thyroid cells, and 3) slows down the turnover of secondary lysosomes. An iodine-deficient regimen impedes the secondary lysosomes to increase. Because of these findings, we postulate that chronic TSH stimulation along with a possible toxic role of iodine after sub-tx could induce an accumulation of lysosomal bodies.
本研究检测了不同碘摄入量对甲状腺次全切除术后甲状腺残余组织的超微结构及功能的影响。大部分甲状腺组织切除后会导致内源性促甲状腺激素（TSH）升高，从而长期刺激残余组织。将雄性斯普拉格 - 道利大鼠分为三组：低碘组（LIG）、中碘组（MIG）和高碘组（HIG）。甲状腺次全切除术后切除的甲状腺总重量在三组间无显著差异，但低碘组在处死时（甲状腺次全切除术后6周）的甲状腺残余重量和TSH水平高于中碘组和高碘组。低碘组中可沉降和不可沉降亚细胞组分中的组织蛋白酶D和芳基硫酸酯酶A的总比活性至少比中碘组和高碘组低38%。通过形态测量法测定的相对滤泡体积与胶体体积之比在低碘组高于中碘组，在高碘组低于中碘组。超微结构上，高碘组中次级溶酶体所占的相对体积高于中碘组，而低碘组中次级溶酶体的数量并不高于对照组。用125I进行的放射自显影研究显示，在处死前3周注射放射性碘时，中碘组和高碘组中大部分放射性位于甲状腺细胞的次级溶酶体中。研究得出结论，甲状腺次全切除术后，碘1）调节甲状腺残余组织的重量，可能仅通过TSH间接调节；2）调节甲状腺细胞中次级溶酶体的数量；3）减缓次级溶酶体的周转。缺碘方案会阻碍次级溶酶体数量增加。基于这些发现，我们推测甲状腺次全切除术后慢性TSH刺激以及碘可能的毒性作用可导致溶酶体的积累。
