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Antagonist SR (antagonist + sr)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

PRECLINICAL STUDY: FULL ARTICLE: Altered architecture and functional consequences of the mesolimbic dopamine system in cannabis dependence

ADDICTION BIOLOGY, Issue 3 2010
Saturnino Spiga
ABSTRACT Cannabinoid withdrawal produces a hypofunction of mesencephalic dopamine neurons that impinge upon medium spiny neurons (MSN) of the forebrain. After chronic treatment with two structurally different cannabinoid agonists, ,9 -tetrahydrocannabinol and CP55 940 (CP) rats were withdrawn spontaneously and pharmacologically with the CB1 antagonist SR141716A (SR). In these two conditions, evaluation of tyrosine hydroxylase (TH)-positive neurons revealed significant morphometrical reductions in the ventrotegmental area but not substantia nigra pars compacta of withdrawn rats. Similarly, confocal analysis of Golgi,Cox-stained sections of the nucleus accumbens revealed a decrease in the shell, but not the core, of the spines' density of withdrawn rats. Administration of the CB1 antagonist SR to control rats, provoked structural abnormalities reminiscent of those observed in withdrawal conditions and support the regulatory role of cannabinoids in neurogenesis, axonal growth and synaptogenesis by acting as eu-proliferative signals through the CB1 receptors. Further, these measures were incorporated into a realistic computational model that predicts a strong reduction in the excitability of morphologically altered MSN, yielding a significant reduction in action potential output. These pieces of evidence support the tenet that withdrawal from addictive compounds alters functioning of the mesolimbic system and provide direct morphological evidence for functional abnormalities associated with cannabinoid dependence at the level of dopaminergic neurons and their postsynaptic counterpart and are coherent with recent hypothesis underscoring a hypodopaminergic state as a distinctive feature of the ,addicted brain'. [source]

Neurokinin-1 receptor activation induces reactive oxygen species and epithelial damage in allergic airway inflammation

CLINICAL & EXPERIMENTAL ALLERGY, Issue 12 2007
J. Springer
Summary Background An induction of reactive oxygen species (ROS) is characteristic for inflammation but the exact pathways have not been identified for allergic airway diseases so far. Objective The aim of this study was to characterize the role of the tachykinin NK-1 receptor on ROS production during allergen challenge and subsequent inflammation and remodelling. Methods Precision-cut lung slices of ovalbumin (OVA)-sensitized mice were cultivated and ROS-generation in response to OVA challenge (10 ,g/mL) was examined by the 2,,7,-dichloroflourescein-diacetate method. Long-term ROS effects on epithelial proliferation were investigated by 5-bromo-2,-deoxyuridine incorporation (72 h). In vivo, the results were validated in OVA-sensitized animals which were treated intra-nasally with either placebo, the tachykinin neurokinin 1 (NK-1) receptor antagonist SR 140333 or the anti-oxidant N -acetylcystein (NAC) before allergen challenge. Inflammatory infiltration and remodelling were assessed 48 h after allergen challenge. Results ROS generation was increased by 3.7-fold, which was inhibited by SR 140333. [Sar9,Met11(O2)]-Substance P (5 nm) caused a tachykinin NK-1 receptor-dependent fourfold increase in ROS generation. Epithelial proliferation was decreased by 68% by incubation with [Sar9,Met11(O2)]-SP over 72 h. In-vivo, treatment with SR 140333 and NAC reduced epithelial damage (91.4% and 76.8% vs. placebo, respectively, P<0.01) and goblet cell hyperplasia (67.4% and 50.1% vs. placebo, respectively, P<0.05), and decreased inflammatory cell influx (65.3% and 45.3% vs. placebo, respectively, P<0.01). Conclusion Allergen challenge induces ROS in a tachykinin NK-1 receptor-dependent manner. Inhibition of the tachykinin NK-1 receptor reduces epithelial damage and subsequent remodelling in vivo. Therefore, patients may possibly benefit from treatment regime that includes radical scavengers or tachykinin NK-1 receptor antagonists. [source]

Interactions of tachykinin receptor antagonists with lipopolysaccharide-induced airway inflammation in mice

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 9 2004
M Veron
Summary 1.,Several observations suggest that tachykinins are involved in the pathogenesis of bronchopulmonary alterations. We have investigated the effect of antagonists for tachykinin NK1 (SR 140333), NK2 (SR 48968) or NK3 (SR 142801) receptors on inflammatory cell recruitment, tumour necrosis factor (TNF)-, and interleukin (IL)-6 release and matrix metalloproteinase (MMP)-9 activity in the bronchoalveolar lavage fluid (BALF) of mice exposed to lipopolysaccharide (LPS; 100 µg/mL aerosol for 30 min). 2.,Treatment of mice with a combination of SR 140333 and SR 48968 (10,6 mol/L, aerosol) significantly reduced the increase in the number of total cells and neutrophils and MMP-9 activity in the BALF of mice 2.5 h after LPS exposure. Treatment with the NK3 antagonist SR 142801 (10,6 mol/L, aerosol) did not inhibit the influx of neutrophils, but markedly reduced the increase in TNF-, and IL-6 levels at 2.5 h and MMP-9 activity at 20 h. 3.,These results show that the three tachykinin receptor antagonists may interfere with the development of airway inflammation, namely neutrophilia, TNF-, release or MMP-9 activity in the BALF of mice exposed to LPS and suggest that not only NK1 and NK2 receptors, but also NK3 receptors are involved in the modulation of the inflammatory response and airway remodelling. [source]

Vasopressin-induced facilitation of adrenergic responses in the rat mesenteric artery is V1 -receptor dependent

AUTONOMIC & AUTACOID PHARMACOLOGY, Issue 1 2003
J. O. Streefkerk
Summary 1 The present study was designed to analyse the possible involvement of V1 - and V2 -receptors in vasopressin (AVP)-induced facilitation of the sympathetic nervous system. Furthermore, we aimed to determine whether the site of facilitation by AVP is located pre- or postsynaptically. 2 Electrical field stimulation (EFS) was applied on the rat mesteric artery to activate the sympathetic nervous system. In addition, we evaluated the direct vascular effects of AVP. The postsynaptic effect of AVP on the sympathetic nervous system was investigated by exposing the vessels to exogenous noradrenaline. These experiments were performed in the absence or presence of selective V1 and V2 receptor antagonists SR 49059 and SR 121463, respectively. Desmopressin was applied as a selective V2 agonist. 3 The direct vasoconstrictor effect of AVP was antagonized by SR 49059 and not by SR 121463. Desmopressin neither showed any direct vasoconstrictor effect nor produced vasodilatation after a precontraction induced by noradrenaline (10 ,m). The EFS-induced rise in vascular tone could be increased by a sub-pressor concentration of AVP. This fascilitation could be antagonized by SR 49059, but not by SR 121463. Desmopressin did not influence the increase in vascular tone during EFS. Vasoconstriction induced by exogenous noradrenaline could be facilitated by a sub-pressor concentration of AVP and this selective postsynaptic effect could be antagonized by V1 -receptor blockade. 4 In conclusion, the AVP-induced facilitation of the sympathetic nervous system is completely V1 -receptor dependent and at least partly postsynaptically mediated. [source]

Virodhamine relaxes the human pulmonary artery through the endothelial cannabinoid receptor and indirectly through a COX product

BRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2008
H Koz, owska
Background and purpose: The endocannabinoid virodhamine is a partial agonist at the cannabinoid CB1 receptor and a full agonist at the CB2 receptor, and relaxes rat mesenteric arteries through endothelial cannabinoid receptors. Its concentration in the periphery exceeds that of the endocannabinoid anandamide. Here, we examined the influence of virodhamine on the human pulmonary artery. Experimental approach: Isolated human pulmonary arteries were obtained during resections for lung carcinoma. Vasorelaxant effects of virodhamine were examined on endothelium-intact vessels precontracted with 5-HT or KCl. Key results: Virodhamine, unlike WIN 55,212-2, relaxed 5-HT-precontracted vessels concentration dependently. The effect of virodhamine was reduced by endothelium denudation, two antagonists of the endothelial cannabinoid receptor, cannabidiol and O-1918, and a high concentration of the CB1 receptor antagonist rimonabant (5 ,M), but only slightly attenuated by the NOS inhibitor L -NAME and not affected by a lower concentration of rimonabant (100 nM) or by the CB2 and vanilloid receptor antagonists SR 144528 and capsazepine, respectively. The COX inhibitor indomethacin and the fatty acid amide hydrolase inhibitor URB597 and combined administration of selective blockers of small (apamin) and intermediate and large (charybdotoxin) conductance Ca2+ -activated K+ channels attenuated virodhamine-induced relaxation. The vasorelaxant potency of virodhamine was lower in KCl- than in 5-HT-precontracted preparations. Conclusions and implications: Virodhamine relaxes the human pulmonary artery through the putative endothelial cannabinoid receptor and indirectly through a COX-derived vasorelaxant prostanoid formed from the virodhamine metabolite, arachidonic acid. One or both of these mechanisms may stimulate vasorelaxant Ca2+ -activated K+ channels. British Journal of Pharmacology (2008) 155, 1034,1042; doi:10.1038/bjp.2008.371; published online 22 September 2008 [source]