Thyroid Function in Male Zucker Rats Exposed to Cold

Abstract

SUMMARYNon-obese and obese Zucker rats were exposed to 6 OC for 20 days. At the end of the experiment thyroid stimulating hormone (TSH), circulating thyroid hormones, and the weights of the thyroid gland and a brown adipose tissue pad were measured. TSH and 3,5,3'-triiodothyronine concentrations and brown adipose tissue weights increased in response to cold in both phenotypes but by larger amounts in obese rats. Free thyroxine was lower in obese rats. There appears to be no defect in thyroid function in congenitally obese rats exposed to cold, or in their ability to develop brown adipose tissue.

The leptin receptor mutation of the obese Zucker rat causes sciatic nerve demyelination with a centripetal pattern defect

“…Central signals to periphery changes include PNS and adrenal maintenance along with inadequate reproductive activities and metabolism. 244,[262][263][264] These changes have impact on myelin maintenance due to thyroid 14,15,[19][20][21][22][23][24][25]43,265 , growth hormone/prolactin [40][41][42]266,267 deficiencies in addition to gonadotropic 41,42,58,266,267 , corticotropic [264][265][266][267][268][269] , and POMC signaling defects 60,264,266 , A diminished external and SC's neurosteroid progesterone activity, along with that of adrenal secretion, can contribute to restrain the expressions of P0 and PMP22 plasmalogens. [160][161][162]165,167,[171][172][173][174][175][176][...…”

“…11,12 This report encompasses the fine structure of sciatic nerve demyelination injuries in the young male Zucker rats. A preliminary study of this topic 13 followed investigations that have dealt with other endocrinopathies, such as thyroid gland dysfunctions (hypothyroidism [14][15][16][17][18][19][20][21][22][23][24][25][26][27] and hypercalcemia [14][15][16] ), motricity 27 along with a non-insulin-dependent diabetes mellitus (NIDDM) or diabetes type 2 [14][15][16][17] In this rat strain, these defects have been linked to a leptin receptor mutation [28][29][30][31][32][33][34][35][36] , comforted by pancreatic changes. [37][38][39] Additionally, this leptin receptor defect provokes other hypothalamo-pituitary axis failures.…”