Effect of starvation on hypothalamic-pituitary-thyroid function in the rat.
Total starvation in the rat for 2 days did not alter the hypothalamic content of thyrotropin-releasing hormone (TRH), but did decrease both pituitary TSH content and serum TSH concentration. Five days starvation resulted in a significant decrease in serum TSH and a slightly enhanced serum TSH response to exogenous TRH, suggesting that the pituitary retains its sensitivity to TRH. Fasting for 5 days resulted in a decreased 1 and 4th, but an increased 24th thyroid 131I uptake. Other starvation-induced abnormalities of intrathyroid 131I metabolism were a consistent increase in the percent of organified 131I present as MIT and DIT and a decreased percent 131I labeled T4 AND T3. These alterations in the intrathyroid metabolism of 131I in the starved rat probably reflect both a decrease in serum TSH concentration and a decrease in urinary and fecal loss of administered 131I. The serum total and free T4 and total and free T3 concentrations were decreased following 2 and 5 days of starvation.
D000818:Animals; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology*; D007457:Iodine Radioisotopes; D008297:Male; D011485:Protein Binding; D051381:Rats; D013217:Starvation / Q000503:physiopathology*; D013961:Thyroid Gland / Q000503:physiopathology*; D013972:Thyrotropin / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D007457:Iodine Radioisotopes; D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D013974:Thyroxine