title: Dietary high-fat lard intake induces thyroid dysfunction and abnormal morphology in rats.
abstract: OBJECTIVE
  Excess dietary fat intake can induce lipotoxicity in non-adipose tissues. The aim of this study was to observe the effects of dietary high-fat lard intake on thyroid in rats.
  
  
  METHODS
  Male Sprague-Dawley rats were fed a high-fat lard diet for 24 weeks, and then the rats were fed a normal control diet (acute dietary modification) or the high-fat lard diet for another 6 weeks. The serum lipid profile, total thyroxine (TT4), free thyroxine (FT4) and thyrotropin (TSH) levels were determined at the 12, 18, 24 and 30 weeks. High-frequency ultrasound scanning of the thyroid glands was performed at the 24 or 30 weeks. After the rats were sacrificed, the thyroid glands were collected for histological and immunohistochemical analyses.
  
  
  RESULTS
  The high-fat lard diet significantly increased triglyceride levels in both the serum and thyroid, and decreased serum TT4 and FT4 levels in parallel with elevated serum TSH levels. Ultrasonic imaging revealed enlarged thyroid glands with lowered echotexture and relatively heterogeneous features in the high-fat lard fed rats. The thyroid glands from the high-fat lard fed rats exhibited enlarged follicle cavities and flattened follicular epithelial cells under light microscopy, and dilated endoplasmic reticulum cisternae, twisted nuclei, fewer microvilli and secretory vesicles under transmission electron microscopy. Furthermore, the thyroid glands from the high-fat lard fed rats showed markedly low levels of thyroid hormone synthesis-related proteins TTF-1 and NIS. Acute dietary modification by withdrawal of the high-fat lard diet for 6 weeks failed to ameliorate the high-fat lard diet-induced thyroid changes.
  
  
  CONCLUSIONS
  Dietary high-fat lard intake induces significant thyroid dysfunction and abnormal morphology in rats, which can not be corrected by short-term dietary modification.
authors.affiliation: 1] Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Ji-nan 250021, China [2] Institute of Endocrinology and Metabolic Diseases, Shandong Academy of Clinical Medicine, Ji-nan 250021, China.
authors.forename: Shan-shan
authors.initials: SS
authors.lastname: Shao
authors.affiliation: Shandong Provincial Hospital affiliated to Shandong University, Ji-nan 250021, China.
authors.forename: Yuan-fei
authors.initials: YF
authors.lastname: Zhao
authors.affiliation: Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Ji-nan 250021, China.
authors.forename: Yong-feng
authors.initials: YF
authors.lastname: Song
authors.affiliation: Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Ji-nan 250021, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Xu
authors.affiliation: 1] Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Ji-nan 250021, China [2] Institute of Endocrinology and Metabolic Diseases, Shandong Academy of Clinical Medicine, Ji-nan 250021, China.
authors.forename: Jian-mei
authors.initials: JM
authors.lastname: Yang
authors.affiliation: Institute of Endocrinology and Metabolic Diseases, Shandong Academy of Clinical Medicine, Ji-nan 250021, China.
authors.forename: Shi-meng
authors.initials: SM
authors.lastname: Xuan
authors.affiliation: Institute of Endocrinology and Metabolic Diseases, Shandong Academy of Clinical Medicine, Ji-nan 250021, China.
authors.forename: Hui-li
authors.initials: HL
authors.lastname: Yan
authors.affiliation: Institute of Endocrinology and Metabolic Diseases, Shandong Academy of Clinical Medicine, Ji-nan 250021, China.
authors.forename: Chun-xiao
authors.initials: CX
authors.lastname: Yu
authors.affiliation: 1] Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Ji-nan 250021, China [2] Institute of Endocrinology and Metabolic Diseases, Shandong Academy of Clinical Medicine, Ji-nan 250021, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhao
authors.affiliation: 1] Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Ji-nan 250021, China [2] Institute of Endocrinology and Metabolic Diseases, Shandong Academy of Clinical Medicine, Ji-nan 250021, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Xu
authors.affiliation: 1] Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Ji-nan 250021, China [2] Institute of Endocrinology and Metabolic Diseases, Shandong Academy of Clinical Medicine, Ji-nan 250021, China.
authors.forename: Jia-jun
authors.initials: JJ
authors.lastname: Zhao
mesh_terms: D000818:Animals; D018752:Diet, Fat-Restricted; D059305:Diet, High-Fat / Q000009:adverse effects*; D004041:Dietary Fats / Q000009:adverse effects* / Q000097:blood; D007037:Hypothyroidism / Q000097:blood / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D009687:Nuclear Proteins / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D027981:Symporters / Q000378:metabolism; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology* / Q000648:ultrastructure; D000074482:Thyroid Nuclear Factor 1; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014280:Triglycerides / Q000097:blood; D014463:Ultrasonography; D015430:Weight Gain; D000099209:Sodium-Iodide Symporters
chemical_list: D004041:Dietary Fats; D009687:Nuclear Proteins; D027981:Symporters; D000074482:Thyroid Nuclear Factor 1; D013972:Thyrotropin; D013974:Thyroxine; D014157:Transcription Factors; D014280:Triglycerides; D000099209:Sodium-Iodide Symporters; C000614416:Nkx2-1 protein, rat; C029310:lard