Prolonged Effects of Recombinant Human Interleukin-1 α on Mouse Thyroid Function

Rapid and prolonged effects of recombinant human interleukin-1 α (IL-1 α) on mouse thyroid were studied. After daily administration of 15 μg or 1 μ IL-1 for 7 consecutive days, serum T4 concentrations rapidly fell to undetectable levels but returned to near control level after the cessation of IL-1. On the 3lst day, 3 weeks after the drug cessation, a significant depression of serum T4 was observed again. In addition, the IL-1-treated mouse thyroid showed an in vitro unresponsiveness to TSH, with an increase of pituitary TSH (2.24-fold by 15 μg IL-1). To understand underlying mechanisms further, serial observations were performed. Thyroidal T4 contents increased initially, decreased to a low level at day 14, and returned to approximately the control level. IL-1 administration induced an increase in the basal thyroidal cAMP level for a prolonged period. Its response to TSH showed a gradual decline to a level approximately 30% of the control by the 31st day. Pituitary TSH contents on the 22nd and 31st days ...