Thyroid function in fasting rats: variations in 131I uptake and transient decrease in peroxidase activity.
Serum thyroxine and triiodothyronine, radioiodide thyroid uptake and thyroid peroxidase (TPO) activity were studied over a 2 to 5 day period in fasting rats treated (F+) or not (F-) with TSH. In F- rats, TPO activity was transiently decreased on the 3rd day, whereas in F+ it was always higher than in controls. On the 5th day, the 2 h thyroid uptake of 131I decreased in F-, while the 24 h uptake increased in both F- and F+. Serum T3 and T4 decreased in both fasting groups. Thus, not all effects of fasting on rat thyroid function are reverted by TSH administration, suggesting intrinsic impairment of glandular function.
Moura
E G
EG
Laboratório de Fisiologia Endócrina, Universidade do Estado do Rio de Janeiro, Brasil.
Ramos
C F
CF
Nascimento
C C
CC
Rosenthal
D
D
Breitenbach
M M
MM
D000818:Animals; D005508:Food Deprivation; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013961:Thyroid Gland / Q000378:metabolism / Q000502:physiology*; D013972:Thyrotropin / Q000008:administration & dosage*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
D007457:Iodine Radioisotopes; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine