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Shimizu T, Tanaka K, Shimizu S, Higashi Y, Yawata T, Nakamura K, Taniuchi K, Ueba T, Yuri K, Saito M. Possible inhibitory role of endogenous 2-arachidonoylglycerol as an endocannabinoid in (±)-epibatidine-induced activation of central adrenomedullary outflow in the rat. Neuropharmacology 2015; 95:278-89. [PMID: 25882827 DOI: 10.1016/j.neuropharm.2015.03.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 03/30/2015] [Accepted: 03/31/2015] [Indexed: 10/23/2022]
Abstract
We previously reported that intracerebroventricularly (i.c.v.) administered (±)-epibatidine (1, 5 or 10 nmol/animal), a nicotinic acetylcholine receptor agonist, dose-dependently induced secretion of noradrenaline and adrenaline (catecholamines) from the rat adrenal medulla by brain diacylglycerol lipase- (DGL), monoacylglycerol lipase- (MGL) and cyclooxygenase-mediated mechanisms. Diacylglycerol is hydrolyzed by DGL into 2-arachidonoylglycerol (2-AG), which is further hydrolyzed by MGL to arachidonic acid (AA), a cyclooxygenase substrate. These findings suggest that brain 2-AG-derived AA is involved in the (±)-epibatidine-induced response. This AA precursor 2-AG is also a major brain endocannabinoid, which inhibits synaptic transmission through presynaptic cannabinoid CB1 receptors. Released 2-AG into the synaptic cleft is rapidly inactivated by cellular uptake. Here, we examined a role of brain 2-AG as an endocannabinoid in the (±)-epibatidine-induced activation of central adrenomedullary outflow using anesthetized male Wistar rats. In central presence of AM251 (CB1 antagonist) (90 and 180 nmol/animal, i.c.v.), (±)-epibatidine elevated plasma catecholamines even at an ineffective dose (1 nmol/animal, i.c.v.). Central pretreatment with ACEA (CB1 agonist) (0.7 and 1.4 μmol/animal, i.c.v.), 2-AG ether (stable 2-AG analog for MGL) (0.5 and 1.0 μmol/animal, i.c.v.) or AM404 (endocannabinoid uptake inhibitor) (80 and 250 nmol/animal, i.c.v.) significantly reduced an effective dose of (±)-epibatidine- (5 nmol/animal, i.c.v.) induced elevation of plasma catecholamines, and AM251 (90 and 180 nmol/animal, i.c.v.) centrally abolished the reduction induced by 2-AG ether (1.0 μmol/animal, i.c.v.) or AM404 (250 nmol/animal, i.c.v.). Immunohistochemical studies demonstrated that (±)-epibatidine (10 nmol/animal, i.c.v.) activated DGLα-positive spinally projecting neurons in the hypothalamic paraventricular nucleus, a control center of central adrenomedullary system. These results suggest a possibility that a brain endocannabinoid, probably 2-AG, plays an inhibitory role in (±)-epibatidine-induced activation of central adrenomedullary outflow through brain CB1 receptors in the rat.
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Affiliation(s)
- Takahiro Shimizu
- Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan.
| | - Kenjiro Tanaka
- Department of Neurobiology and Anatomy, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan
| | - Shogo Shimizu
- Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan
| | - Youichirou Higashi
- Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan
| | - Toshio Yawata
- Department of Neurosurgery, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan
| | - Kumiko Nakamura
- Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan
| | - Keisuke Taniuchi
- Department of Gastroenterology and Hepatology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan
| | - Tetsuya Ueba
- Department of Neurosurgery, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan
| | - Kazunari Yuri
- Department of Neurobiology and Anatomy, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan
| | - Motoaki Saito
- Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan
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Rowe DL, Hermens DF. Attention-deficit/hyperactivity disorder: neurophysiology, information processing, arousal and drug development. Expert Rev Neurother 2014; 6:1721-34. [PMID: 17144785 DOI: 10.1586/14737175.6.11.1721] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this review, we draw on literature from both animal and human neurophysiological studies to consider the neurochemical mechanisms underlying attention-deficit/ hyperactivity disorder (ADHD). Psychophysiological and neuropsychological research is used to propose possible etiological endophenotypes of ADHD. These are conceptualized as patients with distinct cortical-arousal, information-processing or maturational abnormalities, or a combination thereof, and how the endophenotypes can be used to help drug development and optimize treatment and management. To illustrate, the paper focuses on neuro- and psychophysiological evidence that suggests cholinergic mechanisms may underlie specific information-processing abnormalities that occur in ADHD. The clinical implications for a cholinergic hypothesis of ADHD are considered, along with its possible implications for treatment and pharmacological development.
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Affiliation(s)
- Donald L Rowe
- The Brain Dynamics Centre and Department of Psychological Medicine, Westmead Hospital and University of Sydney, NSW, Australia.
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Shimizu T, Tanaka K, Nakamura K, Taniuchi K, Yokotani K. Brain phospholipase C, diacylglycerol lipase and monoacylglycerol lipase are involved in (±)-epibatidine-induced activation of central adrenomedullary outflow in rats. Eur J Pharmacol 2012; 691:93-102. [PMID: 22796670 DOI: 10.1016/j.ejphar.2012.07.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 06/27/2012] [Accepted: 07/02/2012] [Indexed: 02/02/2023]
Abstract
We previously reported that intracerebroventricularly (i.c.v.) administered (±)-epibatidine (a potent agonist of nicotinic acetylcholine receptors) (1, 5 and 10 nmol/animal) dose-dependently elevated plasma levels of noradrenaline and adrenaline and that this response was reduced by i.c.v. administered indomethacin (cyclooxygenase inhibitor) and abolished by bilateral adrenalectomy, indicating the involvement of brain arachidonic acid, as a substrate of cyclooxygenase, in this alkaloid-induced secretion of both catecholamines from the adrenal medulla in rats. Arachidonic acid is mainly released by the action of phospholipase A(2), but is also released by a phospholipase C-, diacylglycerol lipase- and monoacylglycerol lipase-mediated pathway. In the present study, (±)-epibatidine (5 nmol/animal, i.c.v.)-induced elevation of plasma catecholamines was not influenced by pretreatment with mepacrine (phospholipase A(2) inhibitor) (1.1 and 2.2 μmol/animal, i.c.v.), but was effectively reduced by pretreatment with U-73122 (1-[6-[[(17 β)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione) (phospholipase C inhibitor) (10 and 30 nmol/animal, i.c.v.), RHC-80267 [1,6-bis(cyclohexyloximinocarbonylamino)hexane] (diacylglycerol lipase inhibitor) (1.3 and 2.6 μmol/animal, i.c.v.), MAFP (methyl arachidonoyl fluorophosphonate) (monoacylglycerol lipase inhibitor) (0.7 and 1.4 μmol/animal, i.c.v.) or JZL184 [4-nitrophenyl 4-(dibenzo[d][1,3]dioxol-5-yl(hydroxy)methyl)piperidine-1-carboxylate] (selective monoacylglycerol lipase inhibitor) (0.7 and 1.4 μmol/animal, i.c.v.). Immunohistochemical studies demonstrated that (±)-epibatidine (10 nmol/animal, i.c.v.) activates spinally projecting neurons expressing monoacylglycerol lipase in the rat hypothalamic paraventricular nucleus, a control center of central sympatho-adrenomedullary outflow. Taken together, the brain phospholipase C-, diacylglycerol lipase- and monoacylglycerol lipase-mediated pathway seems to be involved in the centrally administered (±)-epibatidine-induced activation of central adrenomedullary outflow in rats.
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Affiliation(s)
- Takahiro Shimizu
- Department of Pharmacology, School of Medicine, Kochi University, Nankoku, Kochi 783-8505, Japan.
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Berthoud HR, Shin AC, Zheng H. Obesity surgery and gut-brain communication. Physiol Behav 2011; 105:106-19. [PMID: 21315095 PMCID: PMC3118403 DOI: 10.1016/j.physbeh.2011.01.023] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 01/25/2011] [Accepted: 01/26/2011] [Indexed: 12/15/2022]
Abstract
The prevalence of obesity, and the cluster of serious metabolic diseases it is associated with, continues to rise globally, and hopes for effective treatment with drugs have been considerably set back. Thus, success with bariatric surgeries to induce sustained body weight loss and effectively cure most of the associated co-morbidities appears almost "miraculous" and systematic investigation of the mechanisms at work has gained momentum. Here, we will discuss the basic organization of gut-brain communication and review clinical and pre-clinical investigations on the potential mechanisms by which gastric bypass surgery leads to its beneficial effects on energy balance and glucose homeostasis. Although a lot has been learned regarding changes in energy intake and expenditure, secretion of gut hormones, and improvement in glucose homeostasis, there has not yet been the "breakthrough observation" of identifying a key signaling component common to the beneficial effects of the surgery. However, given the complexity and redundancy of gut-brain signaling and gut signaling to other relevant organs, it is perhaps more realistic to expect a number of key signaling changes that act in concert to bring about the "miracle".
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Affiliation(s)
- Hans-Rudolf Berthoud
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA.
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Nicotinic receptor agonist-induced salivation and its cellular mechanism in parotid acini of rats. Auton Neurosci 2011; 161:81-6. [DOI: 10.1016/j.autneu.2011.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 12/13/2010] [Accepted: 01/12/2011] [Indexed: 11/20/2022]
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Shimizu T, Tanaka K, Hasegawa T, Yokotani K. Brain α4β2 nicotinic acetylcholine receptors are involved in the secretion of noradrenaline and adrenaline from adrenal medulla in rats. Eur J Pharmacol 2011; 654:241-8. [DOI: 10.1016/j.ejphar.2010.12.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 11/30/2010] [Accepted: 12/15/2010] [Indexed: 10/18/2022]
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Ozturk Fincan GS, Vural IM, Ercan ZS, Sarioglu Y. Enhancement effects of nicotine on neurogenic relaxation responses in the corpus cavernosum in rabbits: The role of nicotinic acetylcholine receptor subtypes. Eur J Pharmacol 2010; 627:281-4. [DOI: 10.1016/j.ejphar.2009.10.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2009] [Revised: 09/26/2009] [Accepted: 10/14/2009] [Indexed: 11/30/2022]
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Vural IM, Ozturk Fincan GS, Burul Bozkurt N, Ercan ZS, Sarioglu Y. Role of nicotinic acetylcholine receptor subtypes on nicotine-induced neurogenic contractile response alternation in the rabbit gastric fundus. Eur J Pharmacol 2009; 602:395-8. [DOI: 10.1016/j.ejphar.2008.11.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 10/30/2008] [Accepted: 11/17/2008] [Indexed: 11/28/2022]
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Hydrogen peroxide and antioxidizing enzymes involved in modulation of transient facilitatory effects of nicotine on neurogenic contractile responses in rat gastric fundus. Eur J Pharmacol 2008; 587:267-72. [DOI: 10.1016/j.ejphar.2008.03.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 03/03/2008] [Accepted: 03/14/2008] [Indexed: 11/22/2022]
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Chen FN, Zhang YX, Zhang ZJ. Simultaneous Determination of Epinephrine, Noradrenaline and Dopamine in Human Serum Samples by High Performance Liquid Chromatography with Chemiluminescence Detection. CHINESE J CHEM 2007. [DOI: 10.1002/cjoc.200790183] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Eguchi S, Miyashita S, Kitamura Y, Kawasaki H. Alpha3beta4-nicotinic receptors mediate adrenergic nerve- and peptidergic (CGRP) nerve-dependent vasodilation induced by nicotine in rat mesenteric arteries. Br J Pharmacol 2007; 151:1216-23. [PMID: 17572697 PMCID: PMC2189836 DOI: 10.1038/sj.bjp.0707331] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND AND PURPOSE Previous studies demonstrated that nicotine-induced endothelium-independent vasodilation is mediated by perivascular adrenergic nerves and nerves releasing calcitonin gene-related peptide (CGRPergic nerves). We characterized the nicotinic acetylcholine (ACh) receptor subtype underlying the vasodilation in response to nicotine in rat mesenteric arteries. EXPERIMENTAL APPROACH Rat mesenteric vascular beds without endothelium were contracted by perfusion with Krebs solution containing methoxamine and the perfusion pressure was measured with a pressure transducer. KEY RESULTS Perfusion of nicotine (1-100 microM) for 1 min caused a concentration-dependent decrease in perfusion pressure due to vasodilation. Perfusion of (+/-)-epibatidine (1-100 nM) (non-selective agonist) or (-)-cytisine (1-100 microM) (partial agonist for nicotinic beta2 subtype and full agonist for nicotinic beta4 subtype) induced vasodilation in a concentration-dependent manner. Vasodilation induced by nicotine, (-)-cytisine- and (+/-)-epibatidine was markedly attenuated by guanethidine (5 microM) and pretreatment with capsaicin (1 microM). Mecamylamine (relatively selective antagonist for alpha3beta4 subtype), but not dihydro-beta-erythroidine (selective antagonist for alpha4beta2 subtype) or alpha-bungarotoxin (selective antagonist for alpha7 subtype), markedly inhibited nicotine-induced vasodilation. Nicotine-induced vasodilation was inhibited by methyllycaconitine at high concentrations (>1 microM), which non-selectively antagonize nicotinic receptors, while a low concentration of 10 nM, which selectively antagonizes alpha7 subtype, had no effect. (-)-Cytisine and (+/-)-epibatidine-induced vasodilation were abolished by mecamylamine. CONCLUSION AND IMPLICATIONS These results suggest that the nicotinic alpha3beta4 receptor subtype, but not the alpha7 and alpha4beta2 subtypes, is responsible for the vasodilation in rat mesenteric arteries induced by nicotine- and nicotinic ACh receptor agonists through stimulation of adrenergic and CGRPergic perivascular nerves.
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Affiliation(s)
- S Eguchi
- Department of Clinical Pharmaceutical Science, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Okayama, Japan
| | - S Miyashita
- Department of Clinical Pharmaceutical Science, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Okayama, Japan
| | - Y Kitamura
- Department of Pharmaceutical Care and Health Science, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Okayama, Japan
| | - H Kawasaki
- Department of Clinical Pharmaceutical Science, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Okayama, Japan
- Author for correspondence:
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Ilhan SO, Vural IM, Dileköz E, Oztürk GS, Sarioglu Y. Enhancement effects of nicotine on neurogenic contractile responses in rabbit gastric fundus. Eur J Pharmacol 2007; 561:182-8. [PMID: 17292347 DOI: 10.1016/j.ejphar.2006.12.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Revised: 12/15/2006] [Accepted: 12/21/2006] [Indexed: 10/23/2022]
Abstract
Nicotine, a nicotinic acetylcholine receptor agonist, plays a role in the modulation of neurotransmitter release following nerve stimulation in both the central and the peripheral nervous system. Nitric oxide and prostaglandins modulate the release of various neurotransmitters in different tissues. We aimed to investigate the effects of nicotine on neurogenic contractile responses via nicotinic acetylcholine receptors and, if a change occurred, to investigate the effects of N(W)-nitro-L-arginine methyl ester (L-NAME) and indomethacin on this change in rabbit gastric fundus. Electrical field stimulation (EFS)-evoked contractile responses were recorded from gastric fundus strips obtained from rabbits with an isometric force displacement transducer. Nicotine was applied to preparations at varying concentrations. Then, the effects of hexamethonium, cadmium (Cd(2+)), indomethacin, and L-NAME were tested on the EFS-evoked contractions in the presence of nicotine. Nicotine-induced transient neurogenic contractions in a dose-dependent manner. Cd(2+) and hexamethonium inhibited nicotine-induced transient neurogenic contractions, but indomethacin and L-NAME produced no effect. In conclusion, nicotine increased EFS-evoked contractile responses, possibly by facilitating neurotransmitter release from nerve terminals by a mechanism dependent on the influx of Ca(2+) from voltage-gated Ca(2+) channels via activation of nicotinic acetylcholine receptors in isolated rabbit gastric fundus. Endogenous nitric oxide and prostaglandins do not play a physiological role in the regulation of this neurotransmitter release.
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Affiliation(s)
- Sevil Ozger Ilhan
- Refik Saydam Hygiene Center Presidency, School of Public Health, Ankara, Turkey
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Bozkurt NB, Vural IM, Sarioglu Y, Pekiner C. Nicotine potentiates the nitrergic relaxation responses of rabbit corpus cavernosum tissue via nicotinic acetylcholine receptors. Eur J Pharmacol 2007; 558:172-8. [PMID: 17208220 DOI: 10.1016/j.ejphar.2006.11.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 11/23/2006] [Accepted: 11/24/2006] [Indexed: 10/23/2022]
Abstract
The presence of neuronal nicotinic acetylcholine receptors in rabbit corpus cavernosum tissue and possible mechanisms underlying the potentiation of electrical field stimulation induced relaxation by nicotine were analyzed. In corpus cavernosum tissue strips nicotine (3 x 10(-5) M) and acetylcholine (10(-3) M) produced potentiation on electrical field stimulation (amplitude 50 V; frequency 4 Hz; width 0.8 ms) induced relaxation responses. This nicotine-induced potentiation was not altered by atropine (10(-6) M), guanethidine (5 x 10(-6) M) and indomethacin (10(-5) M), but abolished by hexamethonium chloride (10(-5) M) and L-nitro arginine methyl ester (10(-5) M). Nicotine did not cause any alteration on a single dose of carbachol (3 x 10(-5) M) and sodium nitroprusside (10(-5) M) induced relaxation responses. The results suggest that, nicotine-induced potentiation is NO and nicotinic acetylcholine receptor dependent but independent from prostaglandin synthesis, activation of muscarinic receptors and does not require intact adrenergic neurons. Nicotine did not affect smooth muscle and endothelium directly. In conclusion, in this study we showed for the first time that, nicotine acts on the nicotinic acetylcholine receptors located on the nitrergic nerves, thereby evoking the release of NO from these nerve terminals inducing relaxation response in rabbit corpus cavernosum tissue.
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Affiliation(s)
- Nihan Burul Bozkurt
- Hacettepe University, Faculty of Pharmacy, Department of Pharmacology, 06100, Sihhiye, Ankara, Turkey
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Abstract
Experiments were performed on nembutal-narcotized rabbits. To study motor activity of the large intestine stimulation was applied to the right vagus nerve and left sympathetic trunk, as well as to the right pelvic nerve and left sympathetic trunk. We found a decreasing gradient of serotoninergic innervation from the ascending colon to the transverse colon and rectum (45-50, 30-35, and 25-30%, respectively) during simultaneous stimulation of the sympathetic trunk and vagus nerve and an increasing gradient of serotoninergic innervation in the large intestine during simultaneous stimulation of the sympathetic trunk and pelvic nerve. Stimulation of serotoninergic fibers was accompanied by arterial spasm in the microcirculatory bed and venous congestion.
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Affiliation(s)
- A E Lychkova
- Central Research Institute of Gastroenterology, Moscow
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Amtage F, Neughebauer B, McIntosh JM, Freiman T, Zentner J, Feuerstein TJ, Jackisch R. Characterization of nicotinic receptors inducing noradrenaline release and absence of nicotinic autoreceptors in human neocortex. Brain Res Bull 2004; 62:413-23. [PMID: 15168907 DOI: 10.1016/j.brainresbull.2003.11.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2003] [Revised: 10/30/2003] [Accepted: 11/03/2003] [Indexed: 11/24/2022]
Abstract
UNLABELLED Presynaptic facilitatory nicotinic receptors (nAChRs) on noradrenergic axon terminals were studied in slices of human or rat neocortex and of rat hippocampus preincubated with [3H]noradrenaline ([3H]NA). During superfusion of the slices, stimulation by nicotinic agonists for 2 min only slightly increased [3H]NA outflow in the rat neocortex, but caused a tetrodotoxin-sensitive. Ca(2+)-dependent release of [3H]NA in rat hippocampus and human neocortex. In both tissues a similar rank order of potency of nicotinic agonists was found: epibatidine >> DMPP > nicotine approximately cytisine > or = acetylcholine; choline was ineffective. In human neocortex, the effects of nicotine (100 microM) were reduced by mecamylamine, methyllycaconitine, di-hydro-beta-erythroidine (10 microM, each) and the alpha3beta2/alpha6betax-selective alpha-conotoxin MII (100/200 nM). The alpha3beta4 selective alpha-conotoxin AuIB (1 microM), and the alpha7 selective alpha-conotoxin ImI (200 nM) as well as alpha-bungarotoxin (125 nM) were ineffective. Glutamate receptor antagonists (300 microM AP-5, 100 microM DNQX) acted inhibitory, suggesting the participation of nAChRs on glutamatergic neurons. On the other hand, nAChR agonists were unable to evoke exocytotic release of [3H]acetylcholine from human and rat neocortical slices preincubated with [3H]choline. IN CONCLUSION (1) alpha3beta2 and/or alpha6 containing nAChRs are at least partially responsible for presynaptic cholinergic facilitation of noradrenergic transmission in human neocortex; (2) nicotinic autoreceptors were not detectable in rat and human neocortex.
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Affiliation(s)
- Florian Amtage
- Neuropharmakologisches Labor Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Universität Freiburg, Hansastr 9A, D-79104 Freiburg, Germany
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Toda N, Okamura T. The pharmacology of nitric oxide in the peripheral nervous system of blood vessels. Pharmacol Rev 2003; 55:271-324. [PMID: 12773630 DOI: 10.1124/pr.55.2.3] [Citation(s) in RCA: 221] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Unanticipated, novel hypothesis on nitric oxide (NO) radical, an inorganic, labile, gaseous molecule, as a neurotransmitter first appeared in late 1989 and into the early 1990s, and solid evidences supporting this idea have been accumulated during the last decade of the 20th century. The discovery of nitrergic innervation of vascular smooth muscle has led to a new understanding of the neurogenic control of vascular function. Physiological roles of the nitrergic nerve in vascular smooth muscle include the dominant vasodilator control of cerebral and ocular arteries, the reciprocal regulation with the adrenergic vasoconstrictor nerve in other arteries and veins, and in the initiation and maintenance of penile erection in association with smooth muscle relaxation of the corpus cavernosum. The discovery of autonomic efferent nerves in which NO plays key roles as a neurotransmitter in blood vessels, the physiological roles of this nerve in the control of smooth muscle tone of the artery, vein, and corpus cavernosum, and pharmacological and pathological implications of neurogenic NO have been reviewed. This nerve is a postganglionic parasympathetic nerve. Mechanical responses to stimulation of the nerve, mainly mediated by NO, clearly differ from those to cholinergic nerve stimulation. The naming "nitrergic or nitroxidergic" is therefore proposed to avoid confusion of the term "cholinergic nerve", from which acetylcholine is released as a major neurotransmitter. By establishing functional roles of nitrergic, cholinergic, adrenergic, and other autonomic efferent nerves in the regulation of vascular tone and the interactions of these nerves in vivo, especially in humans, progress in the understanding of cardiovascular dysfunctions and the development of pharmacotherapeutic strategies would be expected in the future.
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Affiliation(s)
- Noboru Toda
- Toyama Institute for Cardiovascular Pharmacology Research, Toyama Bldg., 7-13, 1-Chome, Azuchi-machi, Chuo-ku, Osaka 541-0052, Japan.
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Raasch W, Jungbluth B, Schäfer U, Häuser W, Dominiak P. Modification of noradrenaline release in pithed spontaneously hypertensive rats by I1-binding sites in addition to alpha2-adrenoceptors. J Pharmacol Exp Ther 2003; 304:1063-71. [PMID: 12604683 DOI: 10.1124/jpet.102.044966] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is known that moxonidine acts as an agonist at presynaptic alpha(2)-adrenoceptors of the postganglionic sympathetic nerve terminals and leads to a reduction in noradrenaline release. In addition, it is conceivable that I(1)-binding sites located in other regions of the pre- and postganglionic sympathetic neurons are involved in this effect. Our aim was to investigate whether and to what extent activation of the I(1)-binding sites contributes to the moxonidine-induced inhibition of noradrenaline release. Noradrenaline release was induced in pithed spontaneously hypertensive rats (pretreated with phenoxybenzamine/desipramine at 10/0.5 mg/kg) by stimulation of sympathetic overflow from the spinal cord. Noradrenaline overflow was reduced using moxonidine (0.18, 0.6, and 1.8 mg/kg) by 39.4, 70.4, or 78.7%, respectively, even when all alpha(1)-/alpha(2)-adrenoceptors were blocked effectively by phenoxybenzamine. In contrast, the I(1)-antagonist efaroxan (0.1, 1, and 3 mg/kg) increased noradrenaline overflow from 453 (control) to 1710, 1999, or 2754 pg/ml, suggesting an autoreceptor-like function of I(1)-binding sites. In consequence, moxonidine (0.18, 0.6, and 1.8 mg/kg) reduced the increase in noradrenaline overflow in efaroxan-treated animals (1 mg/kg) by 22.7, 41.7, and 50.5%, respectively. Agmatine (6 and 60 mg/kg), an endogenous agonist at I(1)-binding sites, reduced noradrenaline overflow (-36 or 53%), even under alpha(2)-adrenoceptor blockade. When 2-endo-amino-3-exo-isopropylbicyclo[2.2.1]heptane (AGN192403) (10 mg/kg) was injected, a selective blocker of I(1)-binding sites, noradrenaline overflow was not influenced by agmatine. It is concluded that moxonidine reduces noradrenaline overflow by acting at I(1)-binding sites in addition to its agonistic property at alpha(2)-adrenoceptors. The exact location of the I(1)-binding sites on the pre- or postsynaptic sympathetic neurons is unknown, but the location in the pre- or postsynaptic membrane of the sympathetic ganglion is the most plausible explanation.
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Affiliation(s)
- Walter Raasch
- Institute of Experimental and Clinical Pharmacology, Lübeck, Germany.
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Si ML, Lee TJF. Alpha7-nicotinic acetylcholine receptors on cerebral perivascular sympathetic nerves mediate choline-induced nitrergic neurogenic vasodilation. Circ Res 2002; 91:62-9. [PMID: 12114323 DOI: 10.1161/01.res.0000024417.79275.23] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
It has been suggested in isolated porcine cerebral arteries that stimulation by nicotine of alpha7-nicotinic acetylcholine receptors (alpha7-nAChRs) on sympathetic nerves, but not direct stimulation of parasympathetic nitrergic nerves, caused nitrergic neurogenic dilation. Direct evidence supporting this hypothesis has not been presented. The present study, which used in vitro tissue bath and confocal microscopy techniques, was designed to determine whether choline, a selective agonist for alpha7-nAChRs, induced sympathetic-dependent nitrergic dilation of porcine basilar arterial rings. Choline and several nAChR agonists induced exclusive relaxation of basilar arterial rings without endothelium. The relaxation was blocked by tetrodotoxin, nitro-L-arginine, guanethidine, and beta2-adrenoceptor antagonists. Furthermore, the relaxation was blocked by methyllycaconitine and alpha-bungarotoxin (preferential alpha7-nAChR antagonists) and mecamylamine but was not affected by dihydro-beta-erythroidine (a preferential alpha4-nAChR antagonist). Confocal microscopic study demonstrated that choline and nicotine induced significant calcium influx in cultured porcine superior cervical ganglionic cells but failed to affect calcium influx in cultured sphenopalatine ganglionic cells, providing direct evidence that choline and nicotine did not act directly on the parasympathetic nitrergic neurons. The increased calcium influx in superior cervical ganglionic cells was attenuated by alpha-bungarotoxin and methyllycaconitine but not by dihydro-beta-erythroidine. These results support our hypothesis that activation of alpha7-nAChRs on cerebral perivascular sympathetic nerves causes calcium influx and the release of norepinephrine, which then act on presynaptic beta2-adrenoceptors located on the neighboring nitrergic nerve terminals, resulting in NO release and vasodilation. Endogenous choline may play an important role in regulating cerebral sympathetic activity and vascular tone.
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Affiliation(s)
- Min-Liang Si
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Ill 62794-9629, USA
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19
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Yokotani K, Okada S, Nakamura K. Characterization of functional nicotinic acetylcholine receptors involved in catecholamine release from the isolated rat adrenal gland. Eur J Pharmacol 2002; 446:83-7. [PMID: 12098588 DOI: 10.1016/s0014-2999(02)01819-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We tried to characterize nicotinic acetylcholine receptors involved in the release of catecholamines from the rat adrenal gland. The isolated adrenal gland was retrogradely perfused via the adrenal vein with Krebs-Ringer solution at a flow rate of 0.5 ml/min. Endogenous catecholamines, adrenaline and noradrenaline, released into the perfusate were electrochemically measured using high-performance liquid chromatography. (-)-Nicotine (3 x 10(-6)-3 x 10(-5) M) evoked the release of catecholamines (adrenaline >> noradrenaline) in a concentration-dependent manner. The (-)-nicotine (10(-5) M)-induced release of catecholamines was effectively attenuated by mecamylamine (10(-7) and 10(-6) M) (a relatively selective antagonist of alpha3beta4 nicotinic receptors), but not influenced by alpha-bungarotoxin (3 x 10(-7) M) (an antagonist of alpha7 nicotinic receptors) and dihydro-beta-erythroidine (10(-5) M) (a relatively selective antagonist of alpha4beta2 nicotinic receptors). (+/-)-Epibatidine (3 x 10(-7) and 10(-6) M) (a non-selective nicotinic receptor agonist), (-)-cytisine (10(-5) and 10(-4) M) (an agonist of beta4 nicotinic receptors) and (+/-)-2-(3-pyridinyl)-1-azabicyclo(2.2.2)octane (RJR-2429) (10(-5) M) (a putative agonist of alpha3beta4 nicotinic receptors) effectively evoked the release of catecholamines (adrenaline >> noradrenaline), while (E)-N-methyl-4-(3-pyridinyl)-3-butene-1-amine (RJR-2403) (up to 10(-4) M) (a selective agonist of alpha4beta2 nicotinic receptors) had no effect. The efficacies of these agonists are as follows: (+/-) epibatidine >> RJR-2429>(-)-cytisine>(-)-nicotine >> RJR-2403. These results suggest that alpha3beta4 nicotinic receptors are involved in the release of catecholamines from the rat adrenal gland.
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Affiliation(s)
- Kunihiko Yokotani
- Department of Pharmacology, Kochi Medical School, Nankoku, Kochi, 783-8505, Japan
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Yokotani K, Okada S, Murakami Y, Nakamura K. Nicotinic receptors involved in gastric noradrenaline release evoked by electrical stimulation of the splanchnic nerve in rats. Eur J Pharmacol 2001; 423:149-55. [PMID: 11448479 DOI: 10.1016/s0014-2999(01)01114-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the present experiment, we tried to compare the functional nicotinic receptors activated by electrical stimulation of the greater splanchnic nerve (containing preganglionic sympathetic nerves) to those activated by (-)-nicotine, using the isolated rat stomach. The stomach was perfused with Krebs-Ringer solution and endogenous noradrenaline released into the perfusate was electrochemically measured using high-performance liquid chromatography. The release of noradrenaline evoked by repeated application of 30 mM (-)-nicotine rapidly declined. However, the release of noradrenaline evoked by electrical stimulation of the splanchnic nerve at 2.5 Hz was not disturbed by the appearance of tachyphylaxis for (-)-nicotine. The (-)-nicotine-induced release of noradrenaline was abolished by diltiazem, but this reagent had no effect on the electrically evoked release of noradrenaline. The electrically evoked release of noradrenaline was not influenced by atropine, but was reduced to approximately 50% by hexamethonium. This electrically evoked release of noradrenaline was not influenced by alpha-bungarotoxin, alpha-conotoxin ImI (blockers of alpha 7 nicotinic receptors) or dihydro-beta-erythroidine (a blocker of alpha 4 beta 2 nicotinic receptors), but was reduced to about 50% by mecamylamine (a blocker of alpha 3 beta 4 nicotinic receptors). The (-)-nicotine-induced release of noradrenaline has already been shown to be partially blocked by dihydro-beta-erythroidine and to be abolished by mecamylamine as shown by Yokotani et al. [Eur. J. Pharmacol. 402 (2000) 223.]. These results suggest that the gastric release of noradrenaline in response to electrical stimulation of the greater splanchnic nerve is mediated by cholinergic (probably ganglionic alpha 3 beta 4 nicotinic receptor-mediated) and non-cholinergic mechanisms in rats. However, the functional nicotinic receptor activated by electrical stimulation of the splanchnic nerve seems to be different in character from that activated by (-)-nicotine.
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Affiliation(s)
- K Yokotani
- Department of Pharmacology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan.
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