Characterization of the effect of SR48692 on inositol monophosphate, cyclic GMP and cyclic AMP responses linked to neurotensin receptor activation in neuronal and non-neuronal cells.
1. Neurotensin stimulated inositol monophosphate (IP1) formation in both human colonic carcinoma HT29 cells and in mouse neuroblastoma N1E115 cells with EC50 values of 3.5 +/- 0.5 nM (n = 4) and 0.46 +/- 0.02 nM (n = 3), respectively. Neurotensin also stimulated cyclic GMP production with an EC50 of 0.47 +/- 1.2 nM and inhibited cyclic AMP accumulation induced by forskolin (0.5 microM) with an IC50 of 1.33 +/- 1.5 nM (n = 3) on the N1E115 cell line. 2. The competitive antagonism by the non-peptide neurotensin receptor antagonist, SR48692 of neurotensin-induced IP1 formation revealed pA2 values of 8.7 +/- 0.2 (n = 3) for HT29 and 10.1 +/- 0.2 (n = 3) for N1E115 cells. SR48692 also antagonized the cyclic GMP and cyclic AMP responses induced by neurotensin in the N1E115 cell line with pA2 values of 10.7 +/- 0.7 (n = 3) and 9.8 +/- 0.3 (n = 3), respectively. 3. In CHO cells transfected with the rat neurotensin receptor, neurotensin stimulated IP1 and cyclic AMP formation with EC50 values of 3.0 +/- 0.5 nM (n = 3) and 72.2 +/- 20.7 nM (n = 3), respectively. Both effects were antagonized by SR48692, giving pA2 values of 8.4 +/- 0.1 (n = 3) for IP1 and 7.2 +/- 0.4 (n = 3) for cyclic AMP responses. 4. Radioligand binding experiments, performed with [125I]-neurotensin (0.2 nM), yielded IC50 values of 15.3 nM (n = 2) and 20.4 nM (n = 2) for SR48692 versus neurotensin receptor binding sites labelled in HT29 and N1E115 cells, respectively. 5 In conclusion, SR48692 appears to be a potent, species-independent antagonist of the signal transduction events triggered by neurotensin receptor activation in both neuronal and non-neuronal cell systems.
Sanofi Recherche, Montpellier, France.
F
F
Oury-Donat
O
O
Thurneyssen
N
N
Gonalons
P
P
Forgez
D
D
Gully
G
G
Le Fur
P
P
Soubrie
D000818:Animals; D002277:Carcinoma / Q000188:drug therapy*; D002460:Cell Line; D003106:Colon / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology*; D006152:Cyclic GMP / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D051379:Mice; D009447:Neuroblastoma / Q000188:drug therapy; D009496:Neurotensin / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology*; D011804:Quinolines / Q000494:pharmacology*; D018028:Receptors, Neurotensin / Q000037:antagonists & inhibitors*
D007295:Inositol Phosphates; D011720:Pyrazoles; D011804:Quinolines; D018028:Receptors, Neurotensin; C079087:SR 48692; D009496:Neurotensin; D000242:Cyclic AMP; D006152:Cyclic GMP