Stimulation of Inositol Phosphate Production by Neurotensin in Neuroblastoma N1E115 Cells: Implication of GTP‐Binding Proteins and Relationship with the Cyclic GMP Response

Abstract

The association of neurotensin to its receptor in differentiated neuroblastoma N1E115 cells led to a fast and transitory increase of the intracellular concentration in inositol trisphosphate and inositol bisphosphate, followed by a slower and more stable increase in inositol monophosphate. The action of inositol 1,4,5-trisphosphate on digitonin-permeabilized N1E115 cells resulted in a stimulation of cyclic GMP levels that mimicked that induced by neurotensin. Therefore, the cyclic GMP stimulation is probably a consequence of the initial inositol trisphosphate formation triggered by neurotensin. Fluoroaluminate ions and pertussis toxin had the capacity to modulate positively and negatively, respectively, the formation of inositol trisphosphate induced by neurotensin, indicating that GTP-binding proteins are involved in the regulation of inositol phosphate levels by neurotensin receptors.