Neurotensin stimulates cyclic AMP formation in CHO-rNTR-10 cells expressing the cloned rat neurotensin receptor.

Recently, we reported that the rat neurotensin receptor expressed in transfected Chinese hamster ovary cells (CHO-rNTR-10) mediates the hydrolysis of polyphosphoinositides. In this study, we show that neurotensin stimulated cyclic AMP formation in CHO-rNTR-10 cells in a dose-dependent manner (EC50 = 34 nM). Neurotensin also stimulated cyclic AMP formation in membranal preparations under Ca(2+)-free conditions. These results suggest that this cyclic AMP formation occurs from direct coupling of the neurotensin receptor to a type of GTP binding protein, mediating synthesis of cyclic AMP, and not from an increase in intracellular Ca2+ concentration from polyphosphoinositide hydrolysis.