Characterisation of the effects of SR146131, a novel non-peptide CCK(1) receptor agonist, on IMR-32 human neuroblastoma cells.
The effect of ¿2-[4-(4-chloro-2, 5-dimethoxy-phenyl)-5-[2-cyclohexyl-ethyl)-thiazol-2-ylcarbamoy l]-5, 7-dimethyl-indol-1-yl¿-acetic acid (SR146131), a novel non-peptide agonist of cholecystokinin (CCK) CCK(1) receptors, was compared to the effect of sulphated cholecystokinin octapeptide (CCK-8-S) on CCK(1) receptors of the human neuroblastoma cell line IMR-32. SR146131 inhibited [125I]CCK-8-S binding to IMR-32 cells at nanomolar concentrations. SR146131 and CCK-8-S increased intracellular free Ca(2+) levels ([Ca(2+)](i)) in the same concentration range (EC(50)=6+/-2.3 and 1.3+/-0.14 nM, respectively). Although the shape of the [Ca(2+)](i) increase induced by CCK-8-S and SR146131 was slightly different, extracellular Ca(2+) removal affected the response of both compounds to a similar degree, and the response of both compounds was essentially due to Ca(2+) release from intracellular stores. This was also confirmed by measuring the [Ca(2+)](i) response of single cells: both compounds induced [Ca(2+)](i) oscillations at subnanomolar concentrations and elicited a large peak increase in [Ca(2+)](i) at higher concentrations (EC(50)=0.5+/-0.04 and 5.7+/-1.9 nM for CCK-8-S and SR146131, respectively). Both CCK-8-S and SR146131 induced a sustained increase of phosphoinositide turnover in these cells, and acted at similar concentrations (EC(50)=2.7+/-0.7 and 6+/-3.1 nM, respectively), although the maximal effect of SR146131 was somewhat lower than the effect of CCK-8-S. These data show that SR146131 activates human CCK(1) receptors on IMR-32 cells in a manner and with a potency similar to that of CCK-8-S.
Schaeffer
P
P
Cardiovascular/Thrombosis Research Department, Sanofi Recherche, 195 Route d'Espagne, 31036, Toulouse, France.
Nestor
A L
AL
Prabonnaud
V
V
Bachy
A
A
Laplace
M C
MC
Keane
P E
PE
Bignon
E
E
Herbert
J M
JM
D001570:Benzodiazepinones / Q000494:pharmacology; D001667:Binding, Competitive / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D020109:Devazepide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D007457:Iodine Radioisotopes; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D010671:Phenylurea Compounds / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism; D011869:Radioligand Assay; D011949:Receptors, Cholecystokinin / Q000819:agonists* / Q000037:antagonists & inhibitors; D012844:Sincalide / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
C090019:8-sulfocholecystokinin octapeptide; D001570:Benzodiazepinones; D007211:Indoles; D007457:Iodine Radioisotopes; D010671:Phenylurea Compounds; D010716:Phosphatidylinositols; D011949:Receptors, Cholecystokinin; C118846:SR 146131; D013844:Thiazoles; C058121:L 365260; D020109:Devazepide; D012844:Sincalide; D002118:Calcium