Interleukin 6 Effects on the Pituitary-Thyroid Axis in the Rat

Eur J Endocrinol. 1994 Sep;131(3):302-6. doi: 10.1530/eje.0.1310302.

Abstract

It has been postulated recently that cytokines, and in particular interleukin 1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha), may have a role in the pathogenesis of the changes of serum thyroid hormone concentrations that are encountered in patients with non-thyroidal illness (NTI). Many of the IL-1 and TNF-alpha effects are believed to be mediated by the induction of IL-6 synthesis, which might, therefore, represent an important mediator of thyroid hormone changes in NTI. To address this problem, male Wistar rats were injected subcutaneously with 2.5 micrograms of recombinant human IL-6 (rhIL-6, in 500 microliters of saline solution), with 2.5 micrograms of rhIL-6 preincubated with 100 microliters of anti-IL-6 neutralizing antibody or with saline solution alone (control group). Administration of rhIL-6 resulted in a significant decrease of thyroxine (T4) from 82 +/- 4 nmol/l (mean +/- SEM) to a nadir of 33 +/- 3 nmol/l (p < 0.0001) after 48 h, and of triiodothyronine (T3) from 1.6 +/- 0.1 to 0.8 +/- 0.1 nmol/l after 48 h (p < 0.0001). A slight decrease in serum T4 and T3 concentrations also was observed in the control group, but the lowest values (T4, 66 +/- 3 nmol/l; T3, 1.2 +/- 0.1 nmol/l) were significantly higher (p < 0.0001) than in IL-6-treated rats. The IL-6-induced changes could be prevented by preincubation of rhIL-6 with its neutralizing antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Hypothyroidism / blood
  • Hypothyroidism / chemically induced
  • Injections, Subcutaneous
  • Interleukin-6 / pharmacology*
  • Male
  • Methimazole
  • Pituitary Gland / drug effects*
  • Rats
  • Rats, Wistar
  • Recombinant Proteins
  • Thyroid Gland / drug effects*
  • Thyrotropin / blood
  • Thyroxine / blood
  • Triiodothyronine / blood
  • Triiodothyronine, Reverse / blood

Substances

  • Interleukin-6
  • Recombinant Proteins
  • Triiodothyronine
  • Methimazole
  • Triiodothyronine, Reverse
  • Thyrotropin
  • Thyroxine