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Elizabeth Burcher - One of the best experts on this subject based on the ideXlab platform.
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Smooth muscle, neurons and interstitial cells of guinea pig ileum: are there tachykinin neurokinin 1 receptor subtypes?
Pharmacology, 2002Co-Authors: Maria A Matuszek, Elizabeth BurcherAbstract:Binding and autoradiographic studies were carried out in guinea pig ileum to examine neurokinin (NK) 1 receptor location and subtypes using the NK-1-selective radioligand [(125)I]Bolton-Hunter[Sar(9),Met(O(2))(11)]SP. Two membrane preparations were made: (1) longitudinal muscle containing the myenteric plexus and (2) circular muscle containing the interstitial cells of Cajal. In saturation binding studies, the K(D) was estimated as 1.3 and 1.0 nmol/l in each preparation, respectively. In competition binding, the rank order of potency was similar in both membrane preparations: SR140333 approximately CP99994 > or = [Sar(9),Met(O(2))(11)]SP approximately physalaemin approximately CP96345 (pIC(50) 9.5-8.7) >> Neuropeptide Gamma > or = septide (pIC(50) 7.8-7.4). Similarly, scyliorhinin I displayed equal affinity in both preparations, although binding was at two sites, of high affinity (pIC(50) 9.1, 30%) and low affinity (pIC(50) 7.2-6.6, 70%). The only competitor to bind differently in the two muscle preparations was scyliorhinin II, which bound to one site with low potency in the circular muscle (pIC(50) 6.9) but to high-affinity (pIC(50) 9.0, 17%) and low-affinity (pIC(50) 6.7, 83%) sites in the longitudinal muscle. In autoradiographic studies, dense specific binding was associated with the myenteric plexus and the inner circular muscle containing the interstitial cells of Cajal, with minimal specific binding to longitudinal and circular smooth muscle. These results suggest that the NK-1 receptor on the interstitial cells and the myenteric plexus is similar. The apparently low numbers of binding sites on intestinal smooth muscle may be due to a low expression of the NK-1 receptor. Alternatively, the radioligand may not recognize the guinea pig ileum muscle NK-1 receptors due to possible minor differences in their sequence or glycosylation.
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An investigation of tachykinin NK2 receptor subtypes in the rat.
European journal of pharmacology, 1998Co-Authors: Maria A Matuszek, Xiang-ping Zeng, John Strigas, Elizabeth BurcherAbstract:The heterogeneity of tachykinin NK2 receptor subtypes was examined in five tissues from the rat, using binding and functional techniques. Initial experiments with the selective radioligand [125I][Lys5,Tyr(I2)7,MeLeu9,Nle10]neurokinin A-(4-10) showed no specific binding to rat spinal cord membranes or sections. However, this radioligand exhibited high specific binding (80-95% of total) in membranes from the rat fundus, colon, bladder and vas deferens. Dissociation constants (KD) were lower in bladder and colon (0.4 nM) than in fundus (1.9 nM) or vas deferens (1.4 nM). Neurokinin A, Neuropeptide Gamma, [Lys5,MeLeu9,Nle10]NK(4-10), SR 48968 [(S)-N-methyl-N[4-(4-acetylamino-4-phenylpiperidino)-2-(3,4-dichlorophen yl)butyl]benzamine], GR 94800 [PhCO-Ala-Ala-DTrp-Phe-DPro-Pro-Nle-NH2] and MEN 10627 [cyclo(Met-Asp-Trp-Phe-Dap-Leu)cyclo(2beta-5beta)] displayed high affinity (pIC50 8.4-9.5) as competitors, with no significant difference in potency between these four tissues. [Lys5,MeLeu9,Nle10]neurokinin A-(4-10) contracted the isolated fundus (EC50 117 nM) and bladder (EC50 10 nM) and these responses were similarly inhibited by the tachykinin NK2 receptor antagonists, SR 48968 and MEN 10627 (pA2 values 7.6-8.2). In spite of differences in KD seen in some tissues, these results do not provide compelling evidence for tachykinin NK2 receptor heterogeneity in smooth muscle-containing tissues in the rat. The absence of detectable binding in rat spinal cord may be due to very low expression of tachykinin NK2 receptors, or to existence of a different receptor subtype.
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Tachykinin NK-2 Receptors in Child Urinary Bladder
The Journal of urology, 1996Co-Authors: Xiang-ping Zeng, Elizabeth BurcherAbstract:AbstractPurpose: Although NK-2 receptors mediate contractions to tachykinins in adult detrusor muscle, little is known about the functions of tachykinins in child urinary bladder. Here we have used highly selective agonists and antagonists to examine NK-2 receptors in child detrusor muscle.Materials and Methods: Specimens of urinary bladder from 23 children (0 to 10 years) were obtained at operation for vesicoureteric reflux. Strips of detrusor muscle were mounted in organ baths in Krebs solution containing phosphoramidon (10 micromolar), and isometric tension was recorded. Contractile responses were elicited by tachykinins and selective agonists in the presence and absence of autonomic inhibitors and of tachykinin NK-2 receptor antagonists.Results: The NK-2 receptor agonists neurokinin A (NKA), Neuropeptide Gamma and [Lys5, MeLeu9, Nle10]-NKA(4-10) contracted the isolated child detrusor, with pD2 values of 7.7, 7.2 and 7.3. The maximum response to NKA was greater than that to the other 2 agonists. No age...
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Radioligand binding, autoradiographic and functional studies demonstrate tachykinin NK-2 receptors in dog urinary bladder.
The Journal of pharmacology and experimental therapeutics, 1996Co-Authors: Christian J. Mussap, C Stamatakos, Elizabeth BurcherAbstract:Tachykinin receptors in the dog bladder were characterized using radioligand binding, functional and autoradiographic techniques. In detrusor muscle homogenates, specific binding of [125l]iodohistidyl neurokinin A (INKA) and [125l]Bolton Hunter eledoisin was reversible, saturable and, to a single class of sites of Kd, 3,6 and 27 nM, respectively. No specific binding of [125l]Bolton Hunter[Sar9, Met (O2)11] substance P occurred. INKA binding was reduced by the peptidase inhibitor bacitracin. The rank potency order of agonists competing for binding of both radioligands indicated interaction at NK-2 sites. NK-2-selective antagonists also competed for INKA binding, with SR 48968, GR 94800, MDL 29913 and the selective agonist [Lys5, MeLeu9, Nle10]-NKA(4-10) showing biphasic binding profiles. Autoradiographic studies revealed specific binding of INKA and [125l]Bolton Hunter eledoisin over detrusor muscle and small arteries. [125l]Bolton Hunter [Sar9, Met (O2)11] SP labeled the intima of arteries and arterioles, but not the detrusor muscle. Tachykinins contracted detrusor muscle strips, with potency order at the carbachol EC15 NKA = kassinin > [Lys5, MeLeu9, Nle10]-NKA(4-10) = Neuropeptide Gamma = Neuropeptide K = NKB > > MDL 28564, with [Sar9, Met(O2)11]-SP ineffective. Shallow concentration-response curves, variable efficacies and inhibition by atropine and mepyramine suggest that other mechanisms may influence contractile responses. Responses to [Lys5, MeLeu9, Nle10]-NKA(4-10) were inhibited competitively by MDL 29913 and MEN 10207 (pA2 values: 6.4 and 5.3, respectively). Antagonism by SR 48968 and GR 94800 was noncompetitive (both pK8 values 8.9). In summary, NK-2-preferring ligands showed superior potency as both binding competitors and contractile agonists, demonstrating that NK-2 receptors mediate detrusor muscle contraction, similar to the human detrusor. Tachykinins may play important roles in the micturition reflex and in regulating detrusor muscle blood flow in the dog.
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Characterization of Tachykinin NK sub 2 Receptors in Human Urinary Bladder
The Journal of urology, 1995Co-Authors: Xiang-ping Zeng, Kate H. Moore, Elizabeth BurcherAbstract:AbstractFunctional and radioligand binding studies with selective agonists and antagonists were used to investigate tachykinin receptors in the human bladder. Strips of detrusor muscle were contracted by the tachykinins neurokinin A and Neuropeptide Gamma, and by the NK2 receptor selective agonists [Lys5, MeLeu9, Nle10]-NKA(4-10) and [Lys5, Tyr(I sub 2)7, MeLeu9, Nle10]-NKA(4-10), with pD2 values 8.2, 8.0, 8.1 and 7.1. [Sar9, Met(O2)11]-SP and senktide were ineffective agonists, indicating an absence of NK1 and NK3 receptors. The contractile responses to [Lys5, MeLeu9, Nle10]-NKA(4-10) were inhibited competitively by the NK2 receptor selective antagonists SR 48968, GR 94800 and MDL 29913, with pA2 values 9.1, 8.6 and 7.0. Specific binding of the new NK2 receptor selective radioligand [sup 125 I]-[Lys5, Tyr(I2)7, MeLeu9, Nle10]-NKA(4-10) was saturable to a high affinity site (KD 2.3 nM.). Specific binding was inhibited by NK2 receptor agonists and antagonists, but not by NK1 and NK3 analogues, showing bind...
Andrzej Bartke - One of the best experts on this subject based on the ideXlab platform.
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In vivo and in vitro effects of Neuropeptide K and Neuropeptide Gamma on the release of growth hormone.
Neuroreport, 1995Co-Authors: Luciano Debeljuk, Andrzej Bartke, Valeria Rettori, Samuel M. MccannAbstract:There is anatomical and experimental evidence suggesting that tachykinins have a role in the regulation of secretion of anterior pituitary hormones. In this investigation, the effects of Neuropeptide K and Neuropeptide Gamma on the secretion of GH were studied in vivo and in vitro. Injections of Neuropeptide K into the third ventricle of freely moving, ovariectomized rats resulted in a significant increase of plasma GH, but Neuropeptide Gamma induced no significant changes in these levels, although it did induce a significant increase in GH pulse height. In vitro, neither Neuropeptide K nor Neuropeptide Gamma had any apparent effect on GH release from hemipituitaries incubated for 2 h. These results suggest that Neuropeptide K may have a modulatory function in the regulation of GH secretion from the anterior pituitary, through an action exerted at the hypothalamic level, and the effects of Neuropeptide Gamma seem to be more marginal.
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tachykinins and their gene expression in the anterior pituitary of the siberian hamster effects of photoperiod thyroid hormones and analogs of hypothalamic hormones
Endocrine, 1995Co-Authors: Luciano Debeljuk, Andrzej BartkeAbstract:The anterior pituitary gland of the Siberian hamster contains high concentrations of tachykinins compared to other laboratory rodents. In this investigation we studied the relative quantities of neurokinin A (NKA), Neuropeptide Gamma (NPG), and Neuropeptide K (NPK) present in extracts of anterior pituitaries from this species. The anterior pituitary extracts, purified by HPLC, contained similar quantities of NKA and NPG, and lower quantities of NPK. The anterior pituitary gland of the Siberian hamster contained mRNA encoding β-preprotachykinin A, which is a precursor of substance P, NKA, and NPK. This fact proves that the anterior pituitary gland of the Siberian hamster has the ability to synthesize tachykinins. Animals exposed to short photoperiods had higher concentrations of tachykinins in the pituitary gland, and triiodothyronine markedly depressed the stores of these peptides in the anterior pituitary. In some groups of animals, the somatostatin analog octreotide induced a small, but significant decrease of the levels of NKA in the pituitary. The present results, together with previously published findings, indicate that thyroid hormones and estrogens are the most active endogenous substances to suppress the levels of anterior pituitary tachykinins in the Siberian hamster.
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Tachykinins and their gene expression in the anterior pituitary of the siberian hamster—Effects of photoperiod, thyroid hormones, and analogs of hypothalamic hormones
Endocrine, 1995Co-Authors: Luciano Debeljuk, J. N. Rao, Andrzej BartkeAbstract:The anterior pituitary gland of the Siberian hamster contains high concentrations of tachykinins compared to other laboratory rodents. In this investigation we studied the relative quantities of neurokinin A (NKA), Neuropeptide Gamma (NPG), and Neuropeptide K (NPK) present in extracts of anterior pituitaries from this species. The anterior pituitary extracts, purified by HPLC, contained similar quantities of NKA and NPG, and lower quantities of NPK. The anterior pituitary gland of the Siberian hamster contained mRNA encoding β-preprotachykinin A, which is a precursor of substance P, NKA, and NPK. This fact proves that the anterior pituitary gland of the Siberian hamster has the ability to synthesize tachykinins. Animals exposed to short photoperiods had higher concentrations of tachykinins in the pituitary gland, and triiodothyronine markedly depressed the stores of these peptides in the anterior pituitary. In some groups of animals, the somatostatin analog octreotide induced a small, but significant decrease of the levels of NKA in the pituitary. The present results, together with previously published findings, indicate that thyroid hormones and estrogens are the most active endogenous substances to suppress the levels of anterior pituitary tachykinins in the Siberian hamster.
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Effects of tachykinins on the secretory activity of rat Sertoli cells in vitro.
Endocrinology, 1995Co-Authors: J. N. Rao, L Debeljuk, Andrzej BartkeAbstract:In the present study we investigated the effects of various tachykinins on the secretory activity of rat Sertoli cells in vitro. Sertoli cells were isolated from testes of immature Sprague Dawley rats, cultured for 4 days and thereafter incubated with three concentrations (0.1 pM, 1 pM or 100 pM) of substance P (SP), neurokinin A (NKA), Neuropeptide K (NPK) or Neuropeptide Gamma (NPG) for 24 h. Levels of transferrin and lactic acid were determined in the culture media and expressed per micrograms of cellular DNA. Among all the peptides studied, NPG exhibited the greatest stimulatory effect on the release of transferrin and lactate, with NKA and NPK being less potent and SP being the least potent. Also, the effects of tachykinins on the aromatase activity of cultured Sertoli cells, as reflected by their ability to metabolize testosterone to estradiol (E2), were studied. No stimulatory effect was observed at lower concentrations (1 pM), while at 100 pM both NPG and NKA increased estradiol levels in the medium. SP and NPK had no significant effect on estradiol levels in the medium. This study reveals that tachykinins are able to influence the secretory activity of Sertoli cells, and that some of these peptides can also enhance the aromatase activity. Thus there is a possibility that tachykinins may have a physiological role as modulators of the function of Sertoli cells.
Xiang-ping Zeng - One of the best experts on this subject based on the ideXlab platform.
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An investigation of tachykinin NK2 receptor subtypes in the rat.
European journal of pharmacology, 1998Co-Authors: Maria A Matuszek, Xiang-ping Zeng, John Strigas, Elizabeth BurcherAbstract:The heterogeneity of tachykinin NK2 receptor subtypes was examined in five tissues from the rat, using binding and functional techniques. Initial experiments with the selective radioligand [125I][Lys5,Tyr(I2)7,MeLeu9,Nle10]neurokinin A-(4-10) showed no specific binding to rat spinal cord membranes or sections. However, this radioligand exhibited high specific binding (80-95% of total) in membranes from the rat fundus, colon, bladder and vas deferens. Dissociation constants (KD) were lower in bladder and colon (0.4 nM) than in fundus (1.9 nM) or vas deferens (1.4 nM). Neurokinin A, Neuropeptide Gamma, [Lys5,MeLeu9,Nle10]NK(4-10), SR 48968 [(S)-N-methyl-N[4-(4-acetylamino-4-phenylpiperidino)-2-(3,4-dichlorophen yl)butyl]benzamine], GR 94800 [PhCO-Ala-Ala-DTrp-Phe-DPro-Pro-Nle-NH2] and MEN 10627 [cyclo(Met-Asp-Trp-Phe-Dap-Leu)cyclo(2beta-5beta)] displayed high affinity (pIC50 8.4-9.5) as competitors, with no significant difference in potency between these four tissues. [Lys5,MeLeu9,Nle10]neurokinin A-(4-10) contracted the isolated fundus (EC50 117 nM) and bladder (EC50 10 nM) and these responses were similarly inhibited by the tachykinin NK2 receptor antagonists, SR 48968 and MEN 10627 (pA2 values 7.6-8.2). In spite of differences in KD seen in some tissues, these results do not provide compelling evidence for tachykinin NK2 receptor heterogeneity in smooth muscle-containing tissues in the rat. The absence of detectable binding in rat spinal cord may be due to very low expression of tachykinin NK2 receptors, or to existence of a different receptor subtype.
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Tachykinin NK-2 Receptors in Child Urinary Bladder
The Journal of urology, 1996Co-Authors: Xiang-ping Zeng, Elizabeth BurcherAbstract:AbstractPurpose: Although NK-2 receptors mediate contractions to tachykinins in adult detrusor muscle, little is known about the functions of tachykinins in child urinary bladder. Here we have used highly selective agonists and antagonists to examine NK-2 receptors in child detrusor muscle.Materials and Methods: Specimens of urinary bladder from 23 children (0 to 10 years) were obtained at operation for vesicoureteric reflux. Strips of detrusor muscle were mounted in organ baths in Krebs solution containing phosphoramidon (10 micromolar), and isometric tension was recorded. Contractile responses were elicited by tachykinins and selective agonists in the presence and absence of autonomic inhibitors and of tachykinin NK-2 receptor antagonists.Results: The NK-2 receptor agonists neurokinin A (NKA), Neuropeptide Gamma and [Lys5, MeLeu9, Nle10]-NKA(4-10) contracted the isolated child detrusor, with pD2 values of 7.7, 7.2 and 7.3. The maximum response to NKA was greater than that to the other 2 agonists. No age...
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Characterization of Tachykinin NK sub 2 Receptors in Human Urinary Bladder
The Journal of urology, 1995Co-Authors: Xiang-ping Zeng, Kate H. Moore, Elizabeth BurcherAbstract:AbstractFunctional and radioligand binding studies with selective agonists and antagonists were used to investigate tachykinin receptors in the human bladder. Strips of detrusor muscle were contracted by the tachykinins neurokinin A and Neuropeptide Gamma, and by the NK2 receptor selective agonists [Lys5, MeLeu9, Nle10]-NKA(4-10) and [Lys5, Tyr(I sub 2)7, MeLeu9, Nle10]-NKA(4-10), with pD2 values 8.2, 8.0, 8.1 and 7.1. [Sar9, Met(O2)11]-SP and senktide were ineffective agonists, indicating an absence of NK1 and NK3 receptors. The contractile responses to [Lys5, MeLeu9, Nle10]-NKA(4-10) were inhibited competitively by the NK2 receptor selective antagonists SR 48968, GR 94800 and MDL 29913, with pA2 values 9.1, 8.6 and 7.0. Specific binding of the new NK2 receptor selective radioligand [sup 125 I]-[Lys5, Tyr(I2)7, MeLeu9, Nle10]-NKA(4-10) was saturable to a high affinity site (KD 2.3 nM.). Specific binding was inhibited by NK2 receptor agonists and antagonists, but not by NK1 and NK3 analogues, showing bind...
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Evidence for tachykinin NK-2 receptors in guinea-pig airways from binding and functional studies, using [125I]-[Lys5,Tyr(I2)7,MeLeu9,Nle10]-NKA(4-10).
Neuropeptides, 1994Co-Authors: Xiang-ping Zeng, Solange Lavielle, Elizabeth BurcherAbstract:The potent contractile responses of guinea-pig airways to neurokinin A (NKA) and Neuropeptide Gamma (NP Gamma) are thought to be mediated by NK-2 receptors. However, NK-2 binding sites are not detectable using the radioligand [125I]-iodohistidyl-NKA. Here, a novel, highly selective iodinated radioligand, [125I]-[Lys5,Tyr(I2)7,MeLeu9,Nle10]-NKA(4-10), and a number of related peptides have been used to characterize NK-2 receptors on guinea-pig airways, using binding and functional studies. Specific binding of [125I]-[Lys5,Tyr(I2)7,MeLeu9,Nle10]-NKA(4-10), was saturable and to a single high affinity site, with KD 1.29 +/- 0.36 nM (n = 4). The rank order of potency for tachykinins and analogues as competitors for the binding was: [Lys5,Tyr(I2)7,MeLeu9,Nle10]-NKA(4-10) > or = NP Gamma > or = [Lys5,MeLeu9,Nle10]-NKA(4-10) > NKA > or = SR 48968 >> MDL 29913 > or = substance P (SP) = [127I]-Bolton-Hunter NKA (BHNKA) > or = MEN 10207 > neurokinin B (NKB). Septide, [DPro9,Pro10,Trp11]-SP, the NK-1 selective ligands [Sar9,Met(O2)11]-SP, [Pro9]-SP and CP 96345, the NK-3 selective senktide, and calcitonin gene-related peptide (CGRP) were weak or ineffective. On guinea-pig isolated bronchi, the potency order of contractile agonists was: [Lys5,MeLeu9,Nle10]-NKA(4-10) > NKA > or = NP Gamma > or = [Lys5,Tyr7,MeLeu9, Nle10]-NKA(4-10) > or = septide = BHNKA > or = [Lys5,Tyr(I2)7,MeLeu9,Nle10]-NKA(4-10) > or = [Sar9,Met(O2)11]-SP > or = NKB = [Pro9]-SP > or = SP >> senktide.(ABSTRACT TRUNCATED AT 250 WORDS)
Christian J. Mussap - One of the best experts on this subject based on the ideXlab platform.
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Radioligand binding, autoradiographic and functional studies demonstrate tachykinin NK-2 receptors in dog urinary bladder.
The Journal of pharmacology and experimental therapeutics, 1996Co-Authors: Christian J. Mussap, C Stamatakos, Elizabeth BurcherAbstract:Tachykinin receptors in the dog bladder were characterized using radioligand binding, functional and autoradiographic techniques. In detrusor muscle homogenates, specific binding of [125l]iodohistidyl neurokinin A (INKA) and [125l]Bolton Hunter eledoisin was reversible, saturable and, to a single class of sites of Kd, 3,6 and 27 nM, respectively. No specific binding of [125l]Bolton Hunter[Sar9, Met (O2)11] substance P occurred. INKA binding was reduced by the peptidase inhibitor bacitracin. The rank potency order of agonists competing for binding of both radioligands indicated interaction at NK-2 sites. NK-2-selective antagonists also competed for INKA binding, with SR 48968, GR 94800, MDL 29913 and the selective agonist [Lys5, MeLeu9, Nle10]-NKA(4-10) showing biphasic binding profiles. Autoradiographic studies revealed specific binding of INKA and [125l]Bolton Hunter eledoisin over detrusor muscle and small arteries. [125l]Bolton Hunter [Sar9, Met (O2)11] SP labeled the intima of arteries and arterioles, but not the detrusor muscle. Tachykinins contracted detrusor muscle strips, with potency order at the carbachol EC15 NKA = kassinin > [Lys5, MeLeu9, Nle10]-NKA(4-10) = Neuropeptide Gamma = Neuropeptide K = NKB > > MDL 28564, with [Sar9, Met(O2)11]-SP ineffective. Shallow concentration-response curves, variable efficacies and inhibition by atropine and mepyramine suggest that other mechanisms may influence contractile responses. Responses to [Lys5, MeLeu9, Nle10]-NKA(4-10) were inhibited competitively by MDL 29913 and MEN 10207 (pA2 values: 6.4 and 5.3, respectively). Antagonism by SR 48968 and GR 94800 was noncompetitive (both pK8 values 8.9). In summary, NK-2-preferring ligands showed superior potency as both binding competitors and contractile agonists, demonstrating that NK-2 receptors mediate detrusor muscle contraction, similar to the human detrusor. Tachykinins may play important roles in the micturition reflex and in regulating detrusor muscle blood flow in the dog.
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Characterization and autoradiographic localization of tachykinin receptors in rat gastric fundus.
The Journal of pharmacology and experimental therapeutics, 1993Co-Authors: Christian J. Mussap, Elizabeth BurcherAbstract:Tachykinin receptors in rat gastric fundus were characterized using radioligand binding, functional and autoradiographic techniques. In crude homogenates of fundus, the specific binding of 125I-iodohistidyl-neurokinin A (INKA), 125I-Bolton-Hunter eledoisin (BHELE) and 125I-Bolton-Hunter [Sar9,Met(O2)11]-SP (BHSar-SP) was reversible and saturable. INKA and, in particular, BHSar-SP showed high affinity binding (Kds, 2.2 and 0.6 nM, respectively), with lower affinity for BHELE (Kd, 17 nM). The binding capacity was higher for INKA and BHELE than for BHSar-SP. The superior potency of neurokinin (NK)-2-preferring agonists (Neuropeptide Gamma > or = [Lys5,MeLeu9,Nle10]-NKA(4-10) > or = Neuropeptide K > neurokinin A [NKA] > [Sar9,Met(O2)11]-SP > senktide) and antagonists (SR 48,968 > GR 94,800 > MDL 29,913 > L-659,877 > MEN 10,207) as competitors for INKA and BHELE binding suggests interaction at mainly NK-2 sites. Additional competition studies showed that BHSar-SP was binding to NK-1 sites. Autoradiographic studies revealed very dense INKA and BHELE specific binding over the circular muscle and muscularis mucosae, while BHSar-SP binding was observed only to the circular muscle. The weak specific binding for 125I-Bolton-Hunter scyliorhinin II localized to the muscularis mucosae may indicate NK-3 sites. This was consistent with functional studies showing concentration-dependent contractions of fundus strips by NK-2-preferring tachykinin agonists (potency, pD2s, 7.1 to 8.1) and [Sar9, Met(O2)11]-SP (pD2, 7.1). The NK-2 selective antagonist MDL 29,913 inhibited INKA binding (Kd, 14 nM) with more than tenfold greater affinity than did MEN 10,207. The antagonism by MDL 29,913 was noncompetitive, with a nonparallel rightward shift of the concentration-response curves to the agonists Neuropeptide Gamma, Neuropeptide K, NKA and [Lys5,MeLeu9,Nle10]-NKA(4-10) (dose ratios at 400 nM MDL 29,913 were 230, 62, 40 and 23, respectively). These data indicate that classic NK-2 receptors predominate in the rat fundus and that NK-1 and perhaps NK-3 receptors also exist.
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Characterization of the tachykinin NK2 receptor subtype in the rabbit pulmonary artery
Peptides, 1992Co-Authors: Xiao-hui Xiao, Christian J. Mussap, Elizabeth BurcherAbstract:Contractile responses to neurokinin A (NKA), Neuropeptide Gamma(NP Gamma), and the NK2 receptor-selective analogs [Lys5,MeLeu9,Nle10]NKA(4-10) and MDL 28,564 were determined in the endothelium-denuded rabbit pulmonary artery. Responses to NKA, NP Gamma, and [Lys5,MeLeu9,Nle10]NKA(4-10) were antagonized by the NK2 receptor antagonist MDL 29,913, with pA2 values of 6.67, 6.46, and 7.32, respectively. Autoradiographic studies failed to demonstrate any specific binding sites for [125I]-iodohistidyl NKA (INKA) over the pulmonary artery. These data suggest the presence in rabbit pulmonary artery of an unusual "nonclassical" NK2 receptor subtype, which appears to lack affinity for INKA.
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Radioiodinated substance P, neurokinin A, and eledoisin bind predominantly in NK1 receptors in guinea pig lung.
Molecular pharmacology, 1992Co-Authors: Dominic P. Geraghty, Christian J. Mussap, Elizabeth BurcherAbstract:In homogenates of guinea pig lung, binding of 125I-Bolton-Hunter-labeled substance P (BHSP), Bolton-Hunter-labeled eledoisin (BHELE), and [125I]iodohistidyl neurokinin A (INKA) was investigated. Equilibrium dissociation constants (derived from "cold" saturation experiments) for BHSP, INKA, and BHELE were 0.96 +/- 0.15, 1.61 +/- 0.26, and 1.98 +/- 0.12 nM, respectively. Specific binding of all three radioligands was increased 2-3-fold by 10 microM phosphoramidon. The rank order of potency of unlabeled tachykinins in competing against BHSP was substance P (SP) greater than [Sar9,Met(O2)11]-SP greater than SP methyl ester greater than Neuropeptide Gamma greater than neurokinin A greater than or equal to neurokinin B = kassinin greater than or equal to eledoisin greater than or equal to scyliorhinin II much greater than Neuropeptide K, indicating binding to sites with the general characteristics of NK1 receptors. Similar rank potency orders were observed for INKA and BHELE, showing binding to NK1 sites, rather than to NK2 or NK3 sites, which are labeled with high affinity by these radioligands in other tissues. For all radioligands, competition curves for SP and the NK1-selective agonist [Sar9,Met(O2)11]-SP could be resolved into two components, representing high and low affinity binding sites. These were present in the approximate ratios 2:3 (for BHSP), 1:1 (for INKA), and 8:1 (for BHELE). Other agonist competition curves also yielded high and low affinity components. The data suggest that BHSP and INKA bind partly and BHELE predominantly to high affinity NK1 receptors. The nature of the low affinity site(s) could be another tachykinin receptor or a low affinity state of the NK1 receptor. Binding to a "classical" NK2 receptor is unlikely, because selective NK2 receptor antagonists and analogs were very weak competitors. Our data suggest that, in addition to the NK1 receptor, another type of tachykinin receptor may exist in this tissue. The inability to detect NK2 binding sites is strikingly at variance with functional studies.
J C Beaujouan - One of the best experts on this subject based on the ideXlab platform.
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Presence of NK2 binding sites in the rat brain
Journal of neurochemistry, 2008Co-Authors: M Saffroy, Y Torrens, J Glowinski, J C BeaujouanAbstract:Attempts were made to label tachykinin NK2 binding sites in the adult rat brain using [125I]neurokinin A (NKA) as ligand in the presence of NK1 and NK3 agonist or antagonist to avoid labelling of NK1 and NK3 binding sites, respectively. A high-affinity, specifically NK2-sensitive, [125I]NKA-binding, temperature-dependent, reversible, sensitive to GTPGammaS and correspondence to a single population of binding sites (K(D) and B(max) values: 2.2 nM and 7.3 fmol/mg protein) was demonstrated on hippocampal membranes. Competition studies performed with tachykinins and tachykinin-related compounds indicated that the pharmacological properties of these NK2-sensitive [125I]NKA binding sites were identical to those identified in the rat urinary bladder and duodenum. NKA, Neuropeptide K, and Neuropeptide Gamma, as well as the potent and selective NK2 antagonists SR 144190, SR 48968 and MEN 10627, presented a nanomolar affinity for these sites. The regional distribution of these NK2-sensitive [125I]NKA binding sites differs markedly from those of NK1 and NK3 binding sites, with the largest labeling being found in the hippocampus, the thalamus and the septum. Binding in other brain structures was low or negligible. A preliminary autoradiographic analysis confirmed [125I]NKA selective binding in hippocampal CA1 and CA3 areas, particularly, and in several thalamic nuclei.
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autoradiographic distribution of tachykinin nk2 binding sites in the rat brain comparison with nk1 and nk3 binding sites
Neuroscience, 2003Co-Authors: M Saffroy, Y Torrens, J Glowinski, J C BeaujouanAbstract:The autoradiographic distribution of tachykinin NK(2) binding sites was determined in the adult rat brain using [(125)I]neurokinin A in the presence of either senktide (NK(3) agonist) and [Pro(9)]substance P (NK(1) agonist) or senktide and SR 140333 (NK(1) antagonist). Indeed, this radioligand labels two subtypes of NK(1) binding sites (which present a high affinity not only for SP but also for neurokinin A, Neuropeptide K and Neuropeptide Gamma) as well as NK(3) binding sites. The distribution of NK(2) binding sites was also compared with those of NK(1) and NK(3) binding sites, these sites being labeled with [(125)I]Bolton and Hunter substance P and [(125)I]Bolton and Hunter eledoisin, respectively. In agreement with our results obtained with membranes from various brain structures, NK(2)-sensitive [(125)I]neurokinin A labeling was mainly observed in few structures including the dorsal and ventral hippocampus, the septum, the thalamus and the prefrontal cortex. The density of NK(2) binding sites was weak when compared with those of NK(1) and NK(3) binding sites. Marked differences were observed in the distributions of NK(1), NK(2) and NK(3) binding sites. These results are discussed taking into consideration differences or similarities between the distributions of NK(2)-sensitive [(125)I]neurokinin A binding sites and of their endogenous ligands (neurokinin A, Neuropeptide K and Neuropeptide Gamma) but also local NK(2) agonist responses blocked by NK(2) antagonists. Insights on the roles of endogenous tachykinins in several brain functions are also discussed on the basis of the respective distributions of different neurokinin binding sites.
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Different Subtypes of Tachykinin NK1 Receptor Binding Sites Are Present in the Rat Brain
Journal of neurochemistry, 2002Co-Authors: J C Beaujouan, M Saffroy, Y Torrens, J GlowinskiAbstract:(2-[(125)I]iodohistidyl(1))Neurokinin A ([(125)I]NKA), which labels "septide-sensitive" but not classic NK(1) binding sites in peripheral tissues, was used to determine whether septide-sensitive binding sites are also present in the rat brain. Binding studies were performed in the presence of SR 48968 (NK(2) antagonist) and senktide (NK(3) agonist) because [(125)I]NKA also labels peripheral NK(2) binding sites and, as shown in this study, central NK(3) binding sites. [(125)I]NKA was found to label not only septide-sensitive binding sites but also a new subtype of NK(1) binding site distinct from classic NK(1) binding sites. Both subtypes of [(125)I]NKA binding sites were sensitive to tachykinin NK(1) antagonists and agonists but also to the endogenous tachykinins NKA, Neuropeptide K (NPK), and Neuropeptide Gamma (NPGamma). However, compounds of the septide family such as substance P(6-11) [SP(6-11)] and propionyl-[Met(O(2))(11)]SP(7-11) and some NK(1) antagonists, GR 82334, RP 67580, and CP 96345, had a much lower affinity for the new NK(1)-sensitive sites than for the septide-sensitive sites. The hypothalamus and colliculi possess only this new subtype of NK(1) site, whereas both types of [(125)I]NKA binding sites were found in the amygdala and some other brain structures. These results not only explain the central effects of septide or SP(6-11), but also those of NKA, NPK, and NPGamma, which can be selectively blocked by NK(1) receptor antagonists.