Abstract
Serum concentrations of T4, T3, and rT3 as well as liver and kidney 5'-deiodinase activity, have been examined in rats stressed by restraint. After immobilization, serum concentrations of T3 decreased significantly (6 hr, -33 ± 1%; 8 h, -42 ± 3%), while serum rT3 increased (6 h, +55 ± 3%; 8 h, +75 ± 5%). In the same or similarly treated animals, there was a time-dependent reduction in T4 5'-deiodinase activity in both liver (4 h, -23 ± 2%; 8 h, -43 ± 3%) and kidney (4 h, -18 ± 1%; 8 h, -42 ± 3%) homogenates. The reduction in hepatic and renal T3 production was due to reduced enzyme activity and not to reduced substrate availability. In spite of reductions in serum TSH (4 h, -9 ± 1%; 8 h, -51 ± 5%), the serum T4 concentration did not fall. The serum concentration of corticosterone reached 30 times the basal level after 8 h of restraint. Either adrenalectomy or metyrapone treatment, followed by replacement with nonstress doses of B, completely prevented the alterations of iodothyronine metabolism induced by restraint. These results indicate that the stress-induced elevation of plasma glucorticoids plays a key role in the pathogenesis of the low T3 syndrome in this model. The reduction in serum T3 may be accounted for by a reduction in T3 production by liver and kidney, adding support to the concept that these organs are an important source of plasma T3 in the rat.
| Original language | English |
|---|---|
| Pages (from-to) | 1033-1038 |
| Number of pages | 6 |
| Journal | Endocrinology |
| Volume | 120 |
| Issue number | 3 |
| State | Published - Jan 1 1987 |
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ASJC Scopus subject areas
- Endocrinology
- Endocrinology, Diabetes and Metabolism
Cite this
The role of glucocorticoids in the stress-induced reduction of extrathyroidal 3,5,3'-triiodothyronine generation in rats. / Bianco, A. C.; Nunes, M. T.; Hell, N. S.; Maciel, R. M B.
In: Endocrinology, Vol. 120, No. 3, 01.01.1987, p. 1033-1038.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The role of glucocorticoids in the stress-induced reduction of extrathyroidal 3,5,3'-triiodothyronine generation in rats
AU - Bianco, A. C.
AU - Nunes, M. T.
AU - Hell, N. S.
AU - Maciel, R. M B
PY - 1987/1/1
Y1 - 1987/1/1
N2 - Serum concentrations of T4, T3, and rT3 as well as liver and kidney 5'-deiodinase activity, have been examined in rats stressed by restraint. After immobilization, serum concentrations of T3 decreased significantly (6 hr, -33 ± 1%; 8 h, -42 ± 3%), while serum rT3 increased (6 h, +55 ± 3%; 8 h, +75 ± 5%). In the same or similarly treated animals, there was a time-dependent reduction in T4 5'-deiodinase activity in both liver (4 h, -23 ± 2%; 8 h, -43 ± 3%) and kidney (4 h, -18 ± 1%; 8 h, -42 ± 3%) homogenates. The reduction in hepatic and renal T3 production was due to reduced enzyme activity and not to reduced substrate availability. In spite of reductions in serum TSH (4 h, -9 ± 1%; 8 h, -51 ± 5%), the serum T4 concentration did not fall. The serum concentration of corticosterone reached 30 times the basal level after 8 h of restraint. Either adrenalectomy or metyrapone treatment, followed by replacement with nonstress doses of B, completely prevented the alterations of iodothyronine metabolism induced by restraint. These results indicate that the stress-induced elevation of plasma glucorticoids plays a key role in the pathogenesis of the low T3 syndrome in this model. The reduction in serum T3 may be accounted for by a reduction in T3 production by liver and kidney, adding support to the concept that these organs are an important source of plasma T3 in the rat.
AB - Serum concentrations of T4, T3, and rT3 as well as liver and kidney 5'-deiodinase activity, have been examined in rats stressed by restraint. After immobilization, serum concentrations of T3 decreased significantly (6 hr, -33 ± 1%; 8 h, -42 ± 3%), while serum rT3 increased (6 h, +55 ± 3%; 8 h, +75 ± 5%). In the same or similarly treated animals, there was a time-dependent reduction in T4 5'-deiodinase activity in both liver (4 h, -23 ± 2%; 8 h, -43 ± 3%) and kidney (4 h, -18 ± 1%; 8 h, -42 ± 3%) homogenates. The reduction in hepatic and renal T3 production was due to reduced enzyme activity and not to reduced substrate availability. In spite of reductions in serum TSH (4 h, -9 ± 1%; 8 h, -51 ± 5%), the serum T4 concentration did not fall. The serum concentration of corticosterone reached 30 times the basal level after 8 h of restraint. Either adrenalectomy or metyrapone treatment, followed by replacement with nonstress doses of B, completely prevented the alterations of iodothyronine metabolism induced by restraint. These results indicate that the stress-induced elevation of plasma glucorticoids plays a key role in the pathogenesis of the low T3 syndrome in this model. The reduction in serum T3 may be accounted for by a reduction in T3 production by liver and kidney, adding support to the concept that these organs are an important source of plasma T3 in the rat.
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M3 - Article
VL - 120
SP - 1033
EP - 1038
JO - Endocrinology
JF - Endocrinology
SN - 0013-7227
IS - 3
ER -