Influence of type II 5' deiodinase on TSH content in diabetic rats.
The influence of hypothalamic and pituitary type II 5'deiodinase (5'D-II) activities and T3 content on pituitary TSH content was investigated in streptozotocin (STZ)-induced diabetic rats (D). The results show, first, that hypothalamic and pituitary 5'D-II activities were lower in neonatal D rats versus control (C) rats, and the normal developmental pattern was altered. Secondly, when D and C rats were thyroidectomized (Tx) at 25 days of age (D+Tx, C+Tx), pituitary and hypothalamic 5'D-II activities increased ten days later in both populations vs. intact rats, but the percentage of increase was smaller in D+Tx than in C+Tx. The hypothalamic T3 to T4 ratios were also decreased in D+Tx animals (0.38) as compared to C+Tx rats (1.64). The hypothalamic T3 content was reduced by 30% in D as compared to C rats and by 80% in D+Tx as compared to C+Tx rats, showing a defect in hypothalamic T4 deiodination. Pituitary TSH content increased after Tx in D+Tx, but not in C+Tx. These results in diabetic rats indicate that the hypothalamic and pituitary 5'D-II activity and hypothalamic T3 content are affected by diabetes and play a role in the regulation of pituitary TSH content.
Aláez
C
C
Instituto de Bioquímica, CSIC, Universidad Complutense de Madrid, Facultad de Farmacia, Ciudad Universitaria, Spain.
Calvo
R
R
Obregón
M J
MJ
Alvarez
C
C
Goya
L
L
Escrivá
F
F
Martín
M A
MA
Pascual-Leone
A M
AM
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000201:enzymology / Q000378:metabolism*; D004195:Disease Models, Animal; D007031:Hypothalamus / Q000201:enzymology / Q000378:metabolism; D007453:Iodide Peroxidase / Q000378:metabolism*; D010902:Pituitary Gland / Q000201:enzymology / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013311:Streptozocin; D013965:Thyroidectomy; D013972:Thyrotropin / Q000378:metabolism*; D014284:Triiodothyronine / Q000378:metabolism*; D000097564:Iodothyronine Deiodinase Type II
D007453:Iodide Peroxidase; D013311:Streptozocin; D013972:Thyrotropin; D014284:Triiodothyronine; D000097564:Iodothyronine Deiodinase Type II