title: Effects of subacute hypothyroidism on metabolism and growth-related molecules.
abstract: Thyroid hormones are crucial hormones that primarily regulate the metabolism of entire body cells. In this study, Sprague-Dawley rats were grouped into sham thyroidectomy (Sham Tx), thyroidectomy (Tx), Tx with thyroxine replacement (Tx + T4), and PTU injection (PTU) groups. Metabolic parameters were measured by means of metabolic cages for 14 days. After 14 days, the rats were sacrificed while the levels of plasma or serum TSH and growth-related molecules, such as active and total ghrelin, GH, and IGF-1, were assayed. The results revealed that hypothyroid rats tended to eat less food and experienced substantial body weight gain, whereas the rats with T4 replacement tended to eat more food while continuing to lose weight. In hypothyroid rats, the growth-related molecules, such as active ghrelin and total ghrelin secretion, were enhanced, and the ghrelin receptors were also up-regulated. However, circulating GH levels were not elevated and IGF-1 secretion was inhibited in hypothyroid rats. In the Tx + T4 group, the changes of active ghrelin, total ghrelin, GHS-R expression, and IGF-1 were reversed, whereas the GH secretion was higher than that of the Sham Tx group and hypothyroid groups. This study resulted in the novel finding that the ghrelin/GHS-R axis and GH/IGF-1 axis are interrupted in hypothyroid rats.
authors: Department of Physiology, School of Medicine, National Yang-Ming University, Taipei 11221, Taiwan.
authors: Yen-Jui
authors: YJ
authors: Chang
authors: Departments of Internal Medicine and Medical Research and Education, Taipei Veterans General Hospital, Taipei 11217, Taiwan.
authors: Chii-Min
authors: CM
authors: Hwu
authors: Department of Internal Medicine, Yangming Branch, Taipei City Hospital, Taipei 11146, Taiwan.
authors: Chii-Chang
authors: CC
authors: Yeh
authors: Department of Physiology, School of Medicine, National Yang-Ming University, Taipei 11221, Taiwan. pswang3879@gmail.com.
authors: Paulus S
authors: PS
authors: Wang
authors: Department of Physiology and Pharmacology, Chang Gung University, Taoyuan 33333, Taiwan. swwang@mail.cgu.edu.tw.
authors: Shyi-Wu
authors: SW
authors: Wang
mesh_terms: D000818:Animals; D001835:Body Weight; D004435:Eating; D054439:Ghrelin / Q000378:metabolism; D013006:Growth Hormone / Q000097:blood; D007037:Hypothyroidism / Q000097:blood / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D010903:Pituitary Gland, Anterior / Q000378:metabolism; D051381:Rats; D054440:Receptors, Ghrelin / Q000378:metabolism; D013972:Thyrotropin / Q000097:blood / Q000378:metabolism
chemical_list: D054439:Ghrelin; D054440:Receptors, Ghrelin; D007334:Insulin-Like Growth Factor I; D013972:Thyrotropin; D013006:Growth Hormone