| 1. |
- Bautista, D M, et al.
(författare)
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Pungent products from garlic activate the sensory ion channel TRPA1
- 2005
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 102:34, s. 12248-12252
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Tidskriftsartikel (refereegranskat)abstract
- Garlic belongs to the Allium family of plants that produce organosulfur compounds, such as allicin and diallyl disulfide (DADS), which account for their pungency and spicy aroma. Many health benefits have been ascribed to Allium extracts, including hypotensive and vasorelaxant activities. However, the molecular mechanisms underlying these effects remain unknown. Intriguingly, allicin and DADS share structural similarities with allyl isothiocyanate, the pungent ingredient in wasabi and other mustard plants that induces pain and inflammation by activating TRPA1, an excitatory ion channel on primary sensory neurons of the pain pathway. Here we show that allicin and DADS excite an allyl isothiocyanate-sensitive subpopulation of sensory neurons and induce vasodilation by activating capsaicin-sensitive perivascular sensory nerve endings. Moreover, allicin and DADS activate the cloned TRPA1 channel when expressed in heterologous systems. These and other results suggest that garlic excites sensory neurons primarily through activation of TRPA1. Thus different plant genera, including Allium and Brassica, have developed evolutionary convergent strategies that target TRPA1 channels on sensory nerve endings to achieve chemical deterrence.
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| 2. |
- Movahed Rad, Pouya
(författare)
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Endogenous activators of the pain receptor TRPV1 From cell to man
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- N-acylethanolamines (NAEs) belong to a growing family of endogenous signalling molecules acting on a variety of receptors and ion channels. In 1992, it was reported that the N-acylethanolamine anandamide is present in the brain and activates the central cannabinoid (CB) receptor. Anandamide and other NAEs are considered to be generated on demand following receptor activation or cell stress. The tissue level of anandamide increases during ischemic tissue injury and inflammation. Hydrolytic cleavage of the amide bond by fatty acid amide hydrolase is responsible for the elimination of anandamide and other N-acylethanolamines. Studies on whole animals or isolated tissues have shown that anandamide induces a variety of effects in the cardiovascular system, including vasodilatation, bradycardia and hypotension. Macrophages and monocytes, endothelial cells and sensory nerves are possible cellular sources of anandamide in the vascular system. The mechanisms behind the cardiovascular effects of anandamide are not fully understood, but seem to depend on the bioassay and the mode of administration of anandamide. In isolated arterial segments, anandamide produces vasorelaxation via activation of transient receptor potential vanilloid 1 (TRPV1) on perivascular sensory nerves and the subsequent release of the potent vasodilator calcitonin gene-related peptide. TRPV1 is a nonselective cation channel, belonging to the transient receptor potential ion channel superfamily, and the receptor for the pungent ingredient in hot chilli peppers. In this work, we show that anandamide and its metabolically stable analogue methanandamide are able to cause vasodilatation in intact vascular beds by a similar TRPV1-dependent mechanism. The vasodilator response to methanandamide in rat isolated perfused mesenteric arterial bed is inhibited by the TRPV1 antagonist ruthenium red. More importantly, anandamide together with well known plant-derived or synthetic TRPV1 agonists are able to cause vasodilatation in vivo in human skin, an effect inhibited by the selective TRPV1 antagonist capsazepine. The endogenous C18 NAEs N-linolenoylethanolamine (18:3 NAE), N-linoleoylethanolamine (18:2 NAE), N-oleoylethanolamine (18:1 NAE) and N-stearoylethanolamine (18:0 NAE) are structurally related to anandamide, but these lipids are poor ligands at cannabinoid CB1 receptors. Here we show that these lipids are present in rat sensory ganglia and vascular tissue in levels that may substantially exceed those of anandamide. 18:3 NAE, 18:2 NAE and 18:1 NAE, but not 18:0 NAE and oleic acid, activate rat TRPV1 on perivascular sensory nerves and human TRPV1 expressed in eukaryotic cells. In conclusion, this study clearly show that, in the rat isolated mesenteric arterial bed, the vasodilator response to methanandamide is mediated predominantly via activation of TRPV1 on sensory nerves. We also demonstrate for the first time that anandamide has biological activity in man, causing vasodilatation in human skin microcirculation via activation of TRPV1. We also identify novel endogenous TRPV1 ligands, belonging to the C18 NAE family of lipids. These unsaturated C18 NAEs, which are poor ligands at the cannabinoid CB1 receptor, may act in concert with anandamide as endogenous TRPV1 modulators in conditions associated with activation of capsaicin-sensitive sensory nerves, including pain, inflammation, ischemia and bladder instability.
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| 3. |
- Movahed Rad, Pouya, et al.
(författare)
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Endogenous unsaturated C18 N-acylethanolamines are vanilloid receptor (TRPV1) agonists.
- 2005
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Ingår i: Journal of Biological Chemistry. - 1083-351X .- 0021-9258. ; 280:46, s. 38496-38504
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Tidskriftsartikel (refereegranskat)abstract
- The endogenous C18 N-acylethanolamines (NAEs) N-linolenoylethanolamine (18:3 NAE), N-linoleoylethanolamine (18:2 NAE), N-oleoylethanolamine (18:1 NAE), and N-stearoylethanolamine (18:0 NAE) are structurally related to the endocannabinoid anandamide (20:4 NAE), but these lipids are poor ligands at cannabinoid CB1 receptors. Anandamide is also an activator of the transient receptor potential (TRP) vanilloid 1 (TRPV1) on primary sensory neurons. Here we show that C18 NAEs are present in rat sensory ganglia and vascular tissue. With the exception of 18:3 NAE in rat sensory ganglia, the levels of C18 NAEs are equal to or substantially exceed those of anandamide. At submicromolar concentrations, 18:3 NAE, 18:2 NAE, and 18:1 NAE, but not 18:0 NAE and oleic acid, activate native rTRPV1 on perivascular sensory nerves. 18:1 NAE does not activate these nerves in TRPV1 gene knock-out mice. Only the unsaturated C18 NAEs elicit whole cell currents and fluorometric calcium responses in HEK293 cells expressing hTRPV1. Molecular modeling revealed a low energy cluster of U-shaped unsaturated NAE conformers, sharing several pharmacophoric elements with capsaicin. Furthermore, one of the two major low energy conformational families of anandamide also overlaps with the cannabinoid CB1 receptor ligand HU210, which is in line with anandamide being a dual activator of TRPV1 and the cannabinoid CB1 receptor. This study shows that several endogenous non-cannabinoid NAEs, many of which are more abundant than anandamide in rat tissues, activate TRPV1 and thus may play a role as endogenous TRPV1 modulators.
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| 4. |
- Movahed Rad, Pouya, et al.
(författare)
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Vascular effects of anandamide and N-acylvanillylamines in the human forearm and skin microcirculation.
- 2005
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Ingår i: British Journal of Pharmacology. - : Wiley. - 1476-5381 .- 0007-1188. ; 146:2, s. 171-179
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Tidskriftsartikel (refereegranskat)abstract
- 1 The endocannabinoid anandamide is an emerging potential signalling molecule in the cardiovascular system. Anandamide causes vasodilatation, bradycardia and hypotension in animals and has been implicated in the pathophysiology of endotoxic, haemorrhagic and cardiogenic shock, but its vascular effects have not been studied in man. 2 Human forearm blood flow and skin microcirculatory flow were recorded using venous occlusion plethysmography and laser-Doppler perfusion imaging ( LDPI), respectively. Each test drug was infused into the brachial artery or applied topically on the skin followed by a standardized pin-prick to disrupt the epidermal barrier. 3 Anandamide failed to affect forearm blood flow when administered intra-arterially at infusion rates of 0.3-300 nmol min(-1). The highest infusion rate led to an anandamide concentration of approximately 1 mu M in venous blood as measured by mass spectrometry. 4 Dermal application of anandamide significantly increased skin microcirculatory flow and coapplication of the transient receptor potential vanilloid 1 ( TRPV1) antagonist capsazepine inhibited this effect. The TRPV1 agonists capsaicin, olvanil and arvanil all induced concentration-dependent increases in skin blood flow and burning pain when administered dermally. Coapplication of capsazepine inhibited blood flow and pain responses to all three TRPV1 agonists. 5 This study shows that locally applied anandamide is a vasodilator in the human skin microcirculation. The results are consistent with this lipid being an activator of TRPV1 on primary sensory nerves, but do not support a role for anandamide as a circulating vasoactive hormone in the human forearm vascular bed.
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