Department of Anatomy and Embryology, Faculty of Medicine, Ain Shams University, Cairo, Egypt.
Folia Morphol (Warsz). 2020;79(3):476-488. doi: 10.5603/FM.a2019.0100. Epub 2019 Sep 6.
Obesity is known to induce a state of lipotoxicity that affects the different organs of the body. Metformin is an antidiabetic drug commonly used in obesity treatment. It was known to improve thyroid function and its regulating hormones. Structural changes in the thyroid gland associated with obesity have not been well investigated. So, the aim of the present study is to detect structural changes in thyroid gland induced by obesity and to investigate the possible protective role of metformin therapy.
Thirty adult female albino rats were divided into three groups (10 rats each). Group I (control group), group II (rats fed with a high-fat diet), and group III (rats fed with a high-fat diet and treated with metformin therapy). After 12 weeks, rats from all groups were sacrificed. Blood samples were taken for measurement of lipid profile, thyroid stimulating hormone (TSH), free T3 and free T4. Thyroid glands were extracted and processed for histological and ultrastructural study. Morphometric measurements for the colloid area of thyroid follicles and height of the follicular cells were done.
Group I displayed normal biochemical parameters and architecture of the thyroid gland. Group II revealed disordered lipid profile, high TSH, free T3 and T4. Microscopically, large thyroid follicles with excessive colloid accumulation and decreased follicular cells height were seen. Some follicular cells showed pyknotic nuclei, vacuolated cytoplasm and disrupted basement membrane with mast cell infiltration of the thyroid tissue. Ultrastructurally, group II follicular cells showed loss of apical microvilli, dense shrunken nuclei, dilated endoplasmic reticulum, swollen damaged mitochondria with large intracellular vacuoles and colloid droplets. In group III, the biochemical parameters and structure of thyroid follicles were improved, and they had a near-normal appearance.
Obesity induced by high-fat diet in female rats structurally and functionally changed the thyroid gland in a way that may explain hypothyroidism associated with obesity. These changes were improved by metformin therapy.
肥胖已知会引起脂肪毒性状态，影响身体的不同器官。二甲双胍是一种常用于肥胖症治疗的抗糖尿病药物。它被认为可以改善甲状腺功能及其调节激素。与肥胖相关的甲状腺结构变化尚未得到很好的研究。因此，本研究旨在检测肥胖引起的甲状腺结构变化，并研究二甲双胍治疗的可能保护作用。
将 30 只成年雌性白化大鼠分为三组（每组 10 只）。第 I 组（对照组）、第 II 组（喂食高脂肪饮食的大鼠）和第 III 组（喂食高脂肪饮食并接受二甲双胍治疗的大鼠）。12 周后，所有组的大鼠均被处死。采集血液样本测量血脂谱、促甲状腺激素（TSH）、游离 T3 和游离 T4。提取甲状腺并进行组织学和超微结构研究。对甲状腺滤泡的胶体面积和滤泡细胞高度进行形态计量测量。
第 I 组显示正常的生化参数和甲状腺结构。第 II 组显示紊乱的血脂谱、高 TSH、游离 T3 和 T4。显微镜下，可见大的甲状腺滤泡，胶体堆积过多，滤泡细胞高度降低。一些滤泡细胞显示出固缩核、空泡化细胞质和破坏的基底膜，甲状腺组织中有肥大细胞浸润。超微结构上，第 II 组的滤泡细胞显示出顶端微绒毛丧失、致密皱缩的核、扩张的内质网、肿胀受损的线粒体，伴有大的细胞内空泡和胶体滴。第 III 组的生化参数和甲状腺滤泡结构得到改善，外观接近正常。
高脂肪饮食诱导的肥胖症以一种可能解释与肥胖相关的甲状腺功能减退的方式在结构和功能上改变了雌性大鼠的甲状腺。这些变化通过二甲双胍治疗得到改善。
