Effect of calmodulin inhibitors on thyroid hormone secretion

Endocrinology. 1986 Nov;119(5):2279-83. doi: 10.1210/endo-119-5-2279.


The effect of calmodulin inhibitors, N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide (W-7) and trifluoperazine, on TSH-induced thyroid hormone secretion from rat thyroid was examined in vivo and in vitro. The ip administration of 5 mg W-7 to the rat inhibited T4 and T3 secretion from rat thyroids at 2, 3, and 4 h after the ip injection of 2 IU TSH, and so did the ip injection of trifluoperazine at 3 and 4 h. However, the ip injection of N-(6-aminohexyl)-1-naphthalene sulfonamide as a control substance did not show any significant inhibition of T4 and T3 release. To identify the site of action of calmodulin, the effect of W-7 on (Bu)2cAMP-induced thyroid hormone secretion was tested in vitro. One hundred micromolar W-7 completely inhibited T4 release from the rat thyroid when it was enhanced by TSH or (Bu)2cAMP, suggesting that the inhibitory effect of W-7 is subsequent to cAMP formation. These results suggest that calmodulin may play a role in thyroid hormone secretion from the thyroid, acting beyond cAMP formation.

MeSH terms

  • Animals
  • Bucladesine / pharmacology
  • Calmodulin / antagonists & inhibitors*
  • Cyclic AMP / biosynthesis
  • Male
  • Rats
  • Rats, Inbred Strains
  • Sulfonamides / pharmacology
  • Thyroid Gland / drug effects
  • Thyroid Gland / metabolism
  • Thyroid Hormones / metabolism*
  • Thyroxine / metabolism
  • Time Factors
  • Trifluoperazine / pharmacology
  • Triiodothyronine / metabolism


  • Calmodulin
  • Sulfonamides
  • Thyroid Hormones
  • Triiodothyronine
  • Trifluoperazine
  • Bucladesine
  • W 7
  • Cyclic AMP
  • Thyroxine