VITAMIN-A-DEFICIENCY AND THYROTROPIN SECRETION IN THE RAT

  • 1 January 1979
    • journal article
    • research article
    • Vol. 75  (8) , 887-890
Abstract
Basal serum TSH [thyrotropin] concentrations and TRH[thyroliberin]-induced TSH response were studied in control and in vitamin A-deficient rats, at different times between the 5th wk on diet (when growth of deficient animals was still normal) and the beginning of the weight plateau (as soon as growth of deficient animals had stopped). In deficient rats the TSH values were always lower than in the control rats. TRH injections (50 ng/100 g b.w. [body weight]) in anesthetized animals (amobarbital 1 mg/100 g b.w.) resulted in an .apprx. 12-fold increase in serum TSH levels within 6 min. The TSH levels remained elevated for at least 15 min and were similar in control and deficient rats. The lower basal serum TSH concentrations apparently are the result of a feedback mechanism triggered by an increase of serum free thyroxine and free triiodothyronine.