Diabetes, Vol 34, Issue 9 931-937, Copyright © 1985 by American Diabetes Association

ARTICLES

Insulin-induced desensitization at the receptor and postreceptor level in mitogen-activated human T-lymphocytes

L Ercolani, HL Lin and BH Ginsberg

Human T-lymphocytes activated by phytohemagglutin acquire insulin receptors in culture. Saturation analysis of insulin-binding activity in the presence of competing ligand revealed curvilinear Scatchard plots. Insulin receptors were not regulated by insulin before mitogen activation and culture of T-lymphocytes. However, insulin-induced downregulation of insulin receptors was: (1) demonstrable in receptor-positive cells, (2) dependent on insulin concentration, (3) temporally unrelated to insulin internalization, and (4) prevented by culture at 4 degrees C but not by cycloheximide at 37 degrees C. Recovery of insulin receptors required further culture of cells in media depleted of insulin for 24 h. Scatchard analysis revealed loss of receptor number without changes in receptor affinity. Insulin-induced increases in glucose transport and oxidation were demonstrable in receptor-positive cells but not in receptor-negative cells. However, these effects were extremely time-dependent. After a 2-h exposure of cells to 10(-8) M insulin, increases in glucose transport were no longer demonstrable. Elution of bound insulin from these cells followed by re-exposure to insulin depressed glucose transport in them. Recovery from this hyporesponsive, desensitized state required a 6-h culture in insulin-depleted media. Glucose oxidation of desensitized cells could be stimulated by spermine but not by insulin. These studies demonstrate the activated human T-lymphocyte is an insulin-sensitive tissue that is capable of limiting its physiologic response to insulin by receptor- and postreceptor-mediated mechanisms.
CiteULike    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				E. D. Schriock, C. K. Buffington, J. R. Givens, and J. E. Buster Enhanced Post-Receptor Insulin Effects in Women Following Dehydroepiandrosterone Infusion Reproductive Sciences, January 1, 1994; 1(1): 74 - 78. [Abstract] [PDF]