Endocrinology, Vol 124, 598-604, Copyright © 1989 by Endocrine Society

ARTICLES

Requirement of insulin growth factor I plus hydrocortisone for the regeneration of thyrotropin (TSH)-dependent mechanism of I-efflux and Ca2+ mobilization in FRTL-5 cells during TSH depletion

K Sho, F Okajima, H Akiyama, Y Shoda, I Kobayashi and Y Kondo
Department of Physical Biochemistry, School of Medicine, Gunma University, Maebashi, Japan.

FRTL-5 rat thyroid cells grown in culture medium supplemented with serum and 6H (TSH, insulin, hydrocortisone, transferrin, glycylhistidyllysine, and somatostatin) showed a significant increase in TSH-dependent cAMP accumulation and I- efflux after prolonged incubation (5 to 10 days) of the cells in culture medium containing 5H (6H - TSH) or serum. The induction of the cAMP response was at least partly reproduced when both serum and 5H were omitted from the medium. However the I- efflux response was completely abolished under such conditions and regenerated when serum or 5H was present. The serum or 5H effect on I- efflux response was mimicked by 2H (insulin + hydrocortisone). Insulin was replaced by 1/1000 less insulin-like growth factor-I than insulin. TSH-dependent Ca2+ mobilization of the cells was similarly affected by the presence of serum or 2H. However, the I- efflux and Ca2+ responses to an agonist other than TSH (extracellular ATP) were not substantially influenced by serum and/or 2H as well as TSH in the medium. The results indicate that serum or insulin-like growth factor-I plus hydrocortisone are required rather specifically for the regeneration of the TSH-receptor mechanism coupled with I- efflux and/or Ca2+ mobilization mechanism.

This article has been cited by other articles:

				D. P. QING, H. DING, J. VADGAMA, Y. Y. WU, and J. D. KOPPLE Elevated Myocardial Cytosolic Calcium Impairs Insulin-Like Growth Factor-1-Stimulated Protein Synthesis in Chronic Renal Failure J. Am. Soc. Nephrol., January 1, 1999; 10(1): 84 - 92. [Abstract] [Full Text]