INSULIN BINDING AND FLUID-PHASE ENDOCYTOSIS STIMULATION IN THE MOUSE NEUROBLASTOMA CELL-LINE 41A3

As well as many other hormones and growth factors, insulin is known to influence several processes in the CNS; its specific effects, however , are still poorly understood. Neuroblastoma cell lines represent a us eful experimental system for the analysis of the insulin-specific effe ct on neurons, in the absence of possible regulatory mechanisms elicit ed by other neuronal/glial cells and/or soluble factors. The expressio n and the binding properties of insulin receptors, as well as the insu lin effects on both membrane fluidity and cell surface architecture, h ave been investigated in 41A3 mouse neuroblastoma cells, by radioligan d-binding fluorescence spectroscopy and scanning electron microscopy, respectively the same cells, insulin-induced modifications on cytoskel etal organisation also have been studied. Binding studies were perform ed using I-125-insulin, while the cationic fluorescent probe trimethyl ammonium 1,6-diphenyl-1,3,5-hexatriene was used for biophysical invest igations. The results presented in this paper provide evidence that in sulin interacts with 41A3 neuroblastoma cells through a receptor-media ted mechanism and that, in these cells, insulin binding modifies the c ell surface morphology and stimulates endocytosis. Copyright (C) 1996 ISDN.