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Neuropharmacological profile of SR 140333, a non-peptide antagonist of substance-P (NK1) receptor
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NEUROPEFTIDES: FUNCTION AND PHARMA COLOGY
Consistent progress has been made in the discovery, evaluation and pharmacological use of new neurokinin-receptor antagonists. Compounds can be classified in 3 categories as peptides, peptidoids and non-peptides. Prototypes of each category have been evaluated in vitro by measuring binding and biological activities in reliable pharmacological preparations and in vivo, after applications of antagonists intravenously, intrathecally or intacerebroventricularly. Antagonists have been characterized in vitro by estimating their affinities in terms of pAz and by determining the type of antagonism (competitive, non-equilibrium, non-competitive) that they exert. Schild plots have been obtained for the prototype compound of each category. The present comparative study indicates that peptide antagonists, such as CP-96,345, CP-99,994, RP-67,580, SR-48,968 are very potent antagonists, competitive and selective for NK- 1 or NK-2 receptors, specific for the neurokinins when compared to other peptides (angiotensin, bradykinin, bombesin, endothelin). Similar results have been obtained with peptidoids, such as FK 888, FK 224, R-454 and R-455, which show high affinity, selectivity for the NK- 1 receptor and act as competitive antagonists specific for the neurokinin functional sites. Other peptidoids, R-396, GR 100679 and congeners and new compounds obtained recently in our laboratory show fairly high affinities and selectivity for NK-2 receptors. These compounds have been carefully evaluated in human NK2 receptors. Among the peptides, the most interesting compound, R-487, has been shown to antagonize NK-3 receptors in the central nervous system and in peripheral organs. Analogues of R-487 have been recently designed and prepared in order to improve the NK-3 receptor antagonist. Supported by the Medical Research Council of Canada
P106 SR 140333, a Novel and Potent Antagonist of the NKl Receptor: Chsracterisation on the U373MG Ceii Line F. Omy-Donat, I. A. Lefevre, X. Emonds-Alt, G. Le Fur and P. Soubrie Sanofi Recherche, F 34184 Montpellier, France In this study, we have evaluated the activitv of the nonpeptide Ml receptor antagonist, SR 140333 on the human astrocytoma cell line U3 73MG which has provided a convenient tool for the study of receptors of the NKl subtype. In this cell line, NKl receptors are functionally linked to phospholipase C, leading to an accumulation of inositol phosphates (IF), an increase in intracellular free calcium [Ca’+]i and a stimulation of taurine release. Radioligand binding conducted with [1251]-BHSP (Kd = 0.15 nM)revealedacompetitiveinhibitionbySR 140333 with a Ki of 0.5 nM. The NKl selective agonist [Sar?MetOJ1]-SP stimulated IPl formation with an ECJo of 5 nM, the maximal stimulation being reached at the
concentration of 100 nM. SR140333 blocked the stimulatoryeffectofthisagonist(100nM)withanICnof2nM. The 3H-taurine release which is regulated by protein kinase C activation was also stimulate&y [W,MeW1]SP (EC50= 7.1 nM) while SR 140333 inhibited the 3H-taurine release induced by the agonist ( 100 nM) with an I& of2.5nM.TheNKl induced[Ca*+]~mobilisati~hasbeen suggested to evoke an increase in outward current. Using patch-clamp technique, we found that SR 140333 concentration-dependently (1C50= 5 nM) inhibited the current induced by [S~I@,M~~CV’]-SP(50 nM). Thus, SR 140333 is a potent functional antagonist of NKl receptors on a human cell line.
P107 Neuropharmacological Pro& of SR 140333, a Non-peptide Antagonist of Substance-P (NKl) Receptor M. Jung, M. Poncelet, X. Emonds-Alt, G. Le Fur and Ph. Soubrie Sanofi Recherche, F-34 184 Montpellier, France SR 140333 a potent, non-peptide antagonist of the substance P NKl receptor subtype with high affinity for NK1 receptors from both rat cortical membranes and human IM9 cells (Ki = 0.02 nM and 0.01 nM, respectively) was studied on various effects induced by NKl agonists in rats and mice. SR 140333 given intmperitoneally antagonized dose-dependently and in a stereoselective manner septide (i.c.v.Finduced scratching (EDSO= 0.05 mg/kg), septide (intrastriatal)-induced turning (ED50 = 0.06 mg/kg) and septide (i.v.)-induced salivation (ED50 = 0.2 mgkg). SR 140333 was also found to inhibit apomorphine (intrastriatal)--induced turning (EDSO= 0.09 mg!kg). A structurally related compound which exhibited low and high affinity for rat cortical (Ki > 500 nM) and IM9 cells (Ki = 0.2 r&f) NKl receptors respectively, was only effective in antagonizing the turning induced by apomorphine. On the other hand, SR 140333 was unable to prevent the central effects (i.e. scratching and turning) induced by [Sarq,Met(02)‘*]SP whereas it strongly inhibited the [Sarq,Met(02)11]-SP -induced salivation (EDJO = 0.18 mg/kg). These results indicate that SR 140333 behaves as a centrally active NKI receptor antagonist, and might suggest the existence of NKl receptor subtypes in rodents.
P108 Comparison of the Effects of (k)CP96,345 and L-66&169 at Neuroidnin Receptors in Rat and Guinea-pig Isoiated Tissues Z. Razzaque, J. Longmore and R. G. Hill Merck Sharp and Dohme Research Laboratories, Eastwick Road, Harlow, Essex CM20 2QR, UK Tissues from different species are usually used to assess the effects of drugs at the three neurokinin-receptor subtypes.’ We compared(f)CP-96,345 andL-668,169 effects (selective NKI-receptor antagonists) on NKI-, NIG- and
NEUROPEFTIDES: FUNCTION AND PHARMA COLOGY
Consistent progress has been made in the discovery, evaluation and pharmacological use of new neurokinin-receptor antagonists. Compounds can be classified in 3 categories as peptides, peptidoids and non-peptides. Prototypes of each category have been evaluated in vitro by measuring binding and biological activities in reliable pharmacological preparations and in vivo, after applications of antagonists intravenously, intrathecally or intacerebroventricularly. Antagonists have been characterized in vitro by estimating their affinities in terms of pAz and by determining the type of antagonism (competitive, non-equilibrium, non-competitive) that they exert. Schild plots have been obtained for the prototype compound of each category. The present comparative study indicates that peptide antagonists, such as CP-96,345, CP-99,994, RP-67,580, SR-48,968 are very potent antagonists, competitive and selective for NK- 1 or NK-2 receptors, specific for the neurokinins when compared to other peptides (angiotensin, bradykinin, bombesin, endothelin). Similar results have been obtained with peptidoids, such as FK 888, FK 224, R-454 and R-455, which show high affinity, selectivity for the NK- 1 receptor and act as competitive antagonists specific for the neurokinin functional sites. Other peptidoids, R-396, GR 100679 and congeners and new compounds obtained recently in our laboratory show fairly high affinities and selectivity for NK-2 receptors. These compounds have been carefully evaluated in human NK2 receptors. Among the peptides, the most interesting compound, R-487, has been shown to antagonize NK-3 receptors in the central nervous system and in peripheral organs. Analogues of R-487 have been recently designed and prepared in order to improve the NK-3 receptor antagonist. Supported by the Medical Research Council of Canada
P106 SR 140333, a Novel and Potent Antagonist of the NKl Receptor: Chsracterisation on the U373MG Ceii Line F. Omy-Donat, I. A. Lefevre, X. Emonds-Alt, G. Le Fur and P. Soubrie Sanofi Recherche, F 34184 Montpellier, France In this study, we have evaluated the activitv of the nonpeptide Ml receptor antagonist, SR 140333 on the human astrocytoma cell line U3 73MG which has provided a convenient tool for the study of receptors of the NKl subtype. In this cell line, NKl receptors are functionally linked to phospholipase C, leading to an accumulation of inositol phosphates (IF), an increase in intracellular free calcium [Ca’+]i and a stimulation of taurine release. Radioligand binding conducted with [1251]-BHSP (Kd = 0.15 nM)revealedacompetitiveinhibitionbySR 140333 with a Ki of 0.5 nM. The NKl selective agonist [Sar?MetOJ1]-SP stimulated IPl formation with an ECJo of 5 nM, the maximal stimulation being reached at the
concentration of 100 nM. SR140333 blocked the stimulatoryeffectofthisagonist(100nM)withanICnof2nM. The 3H-taurine release which is regulated by protein kinase C activation was also stimulate&y [W,MeW1]SP (EC50= 7.1 nM) while SR 140333 inhibited the 3H-taurine release induced by the agonist ( 100 nM) with an I& of2.5nM.TheNKl induced[Ca*+]~mobilisati~hasbeen suggested to evoke an increase in outward current. Using patch-clamp technique, we found that SR 140333 concentration-dependently (1C50= 5 nM) inhibited the current induced by [S~I@,M~~CV’]-SP(50 nM). Thus, SR 140333 is a potent functional antagonist of NKl receptors on a human cell line.
P107 Neuropharmacological Pro& of SR 140333, a Non-peptide Antagonist of Substance-P (NKl) Receptor M. Jung, M. Poncelet, X. Emonds-Alt, G. Le Fur and Ph. Soubrie Sanofi Recherche, F-34 184 Montpellier, France SR 140333 a potent, non-peptide antagonist of the substance P NKl receptor subtype with high affinity for NK1 receptors from both rat cortical membranes and human IM9 cells (Ki = 0.02 nM and 0.01 nM, respectively) was studied on various effects induced by NKl agonists in rats and mice. SR 140333 given intmperitoneally antagonized dose-dependently and in a stereoselective manner septide (i.c.v.Finduced scratching (EDSO= 0.05 mg/kg), septide (intrastriatal)-induced turning (ED50 = 0.06 mg/kg) and septide (i.v.)-induced salivation (ED50 = 0.2 mgkg). SR 140333 was also found to inhibit apomorphine (intrastriatal)--induced turning (EDSO= 0.09 mg!kg). A structurally related compound which exhibited low and high affinity for rat cortical (Ki > 500 nM) and IM9 cells (Ki = 0.2 r&f) NKl receptors respectively, was only effective in antagonizing the turning induced by apomorphine. On the other hand, SR 140333 was unable to prevent the central effects (i.e. scratching and turning) induced by [Sarq,Met(02)‘*]SP whereas it strongly inhibited the [Sarq,Met(02)11]-SP -induced salivation (EDJO = 0.18 mg/kg). These results indicate that SR 140333 behaves as a centrally active NKI receptor antagonist, and might suggest the existence of NKl receptor subtypes in rodents.
P108 Comparison of the Effects of (k)CP96,345 and L-66&169 at Neuroidnin Receptors in Rat and Guinea-pig Isoiated Tissues Z. Razzaque, J. Longmore and R. G. Hill Merck Sharp and Dohme Research Laboratories, Eastwick Road, Harlow, Essex CM20 2QR, UK Tissues from different species are usually used to assess the effects of drugs at the three neurokinin-receptor subtypes.’ We compared(f)CP-96,345 andL-668,169 effects (selective NKI-receptor antagonists) on NKI-, NIG- and