Block of neurotensin receptor down-regulation by an aminosteroid in N1E-115 cells.

We have demonstrated that the aminosteroid, U-73122 (1-(6-([17 beta-3-methoxyestra-1,3,5(10)-trien-17-yl]amino)hexyl)-1H-pyrrole- 2,5-dione) blocks agonist induced down-regulation of neurotensin receptors in murine neuroblastoma clone N1E-115 cells. U-73122 is known to inhibit polyphosphoinositide hydrolysis by affecting the coupling of GTP-binding proteins. Our results may indicate that GTP-binding proteins play a role in the mechanism of down-regulation of the neurotensin receptor.