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Uchino M, Sashide Y, Takeda M. Suppression of the Excitability of Rat Nociceptive Secondary Sensory Neurons following Local Administration of the Phytochemical, (-)-Epigallocatechin-3-gallate. Brain Res 2023:148426. [PMID: 37257804 DOI: 10.1016/j.brainres.2023.148426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 05/02/2023] [Accepted: 05/24/2023] [Indexed: 06/02/2023]
Abstract
The phytochemical, polyphenolic compound, (-)-epigallocatechin-3-gallate (EGCG), is the main catechin found in green tea. Although a modulatory effect of EGCG on voltage-gated sodium and potassium channels has been reported in excitable tissues, the in vivo effect of EGCG on the excitability of nociceptive sensory neurons remains to be determined. Our aim was to investigate whether local administration of EGCG to rats attenuates the excitability of nociceptive spinal trigeminal nucleus caudalis (SpVc) neurons in response to mechanical stimulation in vivo. Extracellular single unit recordings were made from SpVc neurons in response to orofacial mechanical stimulation of anesthetized rats. The mean firing frequency of SpVc wide-dynamic range neurons following both non-noxious and noxious mechanical stimuli was significantly inhibited by EGCG in a dose-dependent and reversible manner. The mean magnitude of inhibition by EGCG on SpVc neuronal discharge frequency was similar to that of the local anesthetic, 1% lidocaine. Local injection of half-dose of lidocaine replaced the half-dose of EGCG. These results suggest that local injection of EGCG suppresses the excitability of nociceptive SpVc neurons, possibly via the inhibition of voltage-gated sodium channels and opening of voltage-gated potassium channels in the trigeminal ganglion. Therefore, administration of EGCG as a local anesthetic may provide relief from trigeminal nociceptive pain without side effects.
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Affiliation(s)
- Mizuho Uchino
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - Yukito Sashide
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - Mamoru Takeda
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan.
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Dhage PA, Sharbidre AA, Dakua SP, Balakrishnan S. Leveraging hallmark Alzheimer's molecular targets using phytoconstituents: Current perspective and emerging trends. Biomed Pharmacother 2021; 139:111634. [PMID: 33965726 DOI: 10.1016/j.biopha.2021.111634] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 04/19/2021] [Accepted: 04/19/2021] [Indexed: 01/04/2023] Open
Abstract
Alzheimer's disease (AD), a type of dementia, severely distresses different brain regions. Characterized by various neuropathologies, it interferes with cognitive functions and neuropsychiatrical controls. This progressive deterioration has negative impacts not only on an individual's daily activity but also on social and occupational life. The pharmacological approach has always remained in the limelight for the treatment of AD. However, this approach is condemned with several side effects. Henceforth, a change in treatment approach has become crucial. Plant-based natural products are garnering special attention due to lesser side effects associated with their use. The current review emphasizes the anti-AD properties of phytoconstituents, throws light on those under clinical trials, and compiles information on their specific mode of actions against AD-related different neuropathologies. The phytoconstituents alone or in combinations will surely help discover new potent drugs for the effective treatment of AD with lesser side effects than the currently available pharmacological treatment.
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Affiliation(s)
- Prajakta A Dhage
- Department of Zoology, K.R.T. Arts, B.H. Commerce and A.M. Science College (KTHM College), Nashik 422002, MS, India
| | - Archana A Sharbidre
- Department of Zoology, Savitribai Phule Pune University, Pune 411007, MS, India.
| | - Sarada P Dakua
- Department of Surgery, Hamad Medical Corporation (HMC), 3050 Doha, Qatar
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Calabrese EJ, Tsatsakis A, Agathokleous E, Giordano J, Calabrese V. Does Green Tea Induce Hormesis? Dose Response 2020; 18:1559325820936170. [PMID: 32728352 PMCID: PMC7364811 DOI: 10.1177/1559325820936170] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 04/28/2020] [Accepted: 05/21/2020] [Indexed: 12/20/2022] Open
Abstract
Green tea, and its principal constituent (-)-epigallocatechin-3-gallate (EGCG), are commonly shown to induce biphasic concentration/dose responses in a broad range of cell types, including non-tumor cells, and tumor cell lines. The most active area of research dealt with an assessment of neural cells with application to neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease cell models, often using preconditioning experimental protocols. The general findings demonstrate EGCG-induced hormetic effects resulting in an enhanced acquired resilience within an adaptive and temporally dependent homeodynamic framework. The biphasic dose responses displayed the typical quantitative features of the hormetic dose response with respect to the amplitude and width of the stimulatory response. These findings provide further evidence for the general occurrence of hormetic dose responses with such responses being independent of the biological model, end point, inducing agent, and mechanism. The biphasic nature of these responses has important implications since it suggests optimal dose ranges for end points of public health and therapeutic applications. These findings indicate the need to assess the entire dose-response continuum in order to better define the nature of the dose response, especially in the low-dose zone where such exposures are common in human populations.
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Affiliation(s)
- Edward J Calabrese
- Department of Environmental Health Sciences, Morrill Science Center I, University of Massachusetts, Amherst, MA, USA
| | - Aristidis Tsatsakis
- Centre of Toxicology Science and Research, University of Crete, School of Medicine, Crete, Greece
| | - Evgenios Agathokleous
- Institute of Ecology, School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, China
| | - James Giordano
- Department of Neurology and Biochemistry, Georgetown University Medical Center Washington, DC, USA
| | - Vittorio Calabrese
- Department of Biomedical and Biotechnological Sciences, School of Medicine University of Catania, Catania, Italy
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Jabir NR, Khan FR, Tabrez S. Cholinesterase targeting by polyphenols: A therapeutic approach for the treatment of Alzheimer's disease. CNS Neurosci Ther 2018; 24:753-762. [PMID: 29770579 DOI: 10.1111/cns.12971] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/05/2018] [Accepted: 04/07/2018] [Indexed: 12/19/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive irreversible neurodegenerative disorder characterized by excessive deposition of β-amyloid (Aβ) oligomers, and neurofibrillary tangles (NFTs), comprising of hyperphosphorylated tau proteins. The cholinergic system has been suggested as the earliest and most affected molecular mechanism that describes AD pathophysiology. Moreover, cholinesterase inhibitors (ChEIs) are the potential class of drugs that can amplify cholinergic activity to improve cognition and global performance and reduce psychiatric and behavioral disturbances. Approximately, 60%-80% of all cases of dementia in the world are patients with AD. In view of the continuous rise of this disease especially in the aged population, there is a dire need to come up with a novel compound and/or mixture that could work against this devastating disease. In this regard, the best is to rely on natural compounds rather than synthetic ones, because natural compounds are easily available, cost-effective, and comparatively less toxic. To serve this purpose, lately, scientific community has started exploring the possibility of using different polyphenols either solitary or in combination that can serve as therapeutics against AD. In the current article, we have summarized the role of various polyphenols, namely quercetin, resveratrol, curcumin, gallocatechins, cinnamic acid, caffeine, and caffeic acid as an inhibitor of cholinesterase for the treatment of AD. We have also tried to uncover the mechanistic insight on the action of these polyphenols against AD pathogenicity.
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Affiliation(s)
- Nasimudeen R Jabir
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Fayaz Rahman Khan
- Department of Physical Therapy, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Shams Tabrez
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
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Wightman EL, Haskell CF, Forster JS, Veasey RC, Kennedy DO. Epigallocatechin gallate, cerebral blood flow parameters, cognitive performance and mood in healthy humans: a double-blind, placebo-controlled, crossover investigation. Hum Psychopharmacol 2012; 27:177-86. [PMID: 22389082 DOI: 10.1002/hup.1263] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE The aim of the study was to assess the effects of oral ingestion of the 'green tea' polyphenol epigallocatechin gallate (EGCG) on cognitive performance, mood and localised cerebral blood flow (CBF) parameters in healthy human adults. METHOD In this double-blind, placebo-controlled, crossover study, 27 healthy adults received placebo and two doses (135 and 270 mg) of EGCG in counterbalanced order on separate days. Following a 45-min resting absorption period, participants performed a selection of computerised cognitive tasks that activate the frontal cortex for a further 42 min. CBF and haemodynamics, as indexed by concentration changes in oxygenated and deoxygenated haemoglobin, were assessed in the frontal cortex throughout the post-treatment period using Near-infrared spectroscopy (NIRS). RESULTS During the post-dose task performance period, the administration of 135 mg EGCG resulted in reduced CBF in the frontal cortex, as indexed by significantly lower concentrations of both oxygenated and total haemoglobin, in comparison with placebo. Heart rate was significantly reduced from pre dose to post dose across all treatments. No significant differences were observed for the level of deoxygenated haemoglobin or on any of the cognitive performance/mood measures. CONCLUSIONS These results demonstrate that a single dose of orally administered EGCG can modulate CBF parameters in healthy humans but that this is not associated with changes in cognitive performance or mood.
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Affiliation(s)
- Emma L Wightman
- Brain, Performance and Nutrition Research Centre, Northumbria University, Newcastle upon Tyne, United Kingdom
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Kennedy DO, Wightman EL. Herbal extracts and phytochemicals: plant secondary metabolites and the enhancement of human brain function. Adv Nutr 2011; 2:32-50. [PMID: 22211188 PMCID: PMC3042794 DOI: 10.3945/an.110.000117] [Citation(s) in RCA: 289] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Humans consume a wide range of foods, drugs, and dietary supplements that are derived from plants and which modify the functioning of the central nervous sytem (CNS). The psychoactive properties of these substances are attributable to the presence of plant secondary metabolites, chemicals that are not required for the immediate survival of the plant but which are synthesized to increase the fitness of the plant to survive by allowing it to interact with its environment, including pathogens and herbivorous and symbiotic insects. In many cases, the effects of these phytochemicals on the human CNS might be linked either to their ecological roles in the life of the plant or to molecular and biochemical similarities in the biology of plants and higher animals. This review assesses the current evidence for the efficacy of a range of readily available plant-based extracts and chemicals that may improve brain function and which have attracted sufficient research in this regard to reach a conclusion as to their potential effectiveness as nootropics. Many of these candidate phytochemicals/extracts can be grouped by the chemical nature of their potentially active secondary metabolite constituents into alkaloids (caffeine, nicotine), terpenes (ginkgo, ginseng, valerian, Melissa officinalis, sage), and phenolic compounds (curcumin, resveratrol, epigallocatechin-3-gallate, Hypericum perforatum, soy isoflavones). They are discussed in terms of how an increased understanding of the relationship between their ecological roles and CNS effects might further the field of natural, phytochemical drug discovery.
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Affiliation(s)
- David O Kennedy
- Brain, Performance and Nutrition Research Centre, School of Life Sciences, Northumbria University, Newcastle, UK.
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Yoo KY, Choi JH, Hwang IK, Lee CH, Lee SO, Han SM, Shin HC, Kang IJ, Won MH. (-)-Epigallocatechin-3-gallate increases cell proliferation and neuroblasts in the subgranular zone of the dentate gyrus in adult mice. Phytother Res 2010; 24:1065-70. [PMID: 20013823 DOI: 10.1002/ptr.3083] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Neurogenesis is regulated by several factors such as age, stress and pharmacological agents. We observed the effects of (-)-epigallocatechin-3-gallate (EGCG), a major catechin of green tea, on neurogenesis in mice. The animals were orally administered EGCG for 4 weeks. Brain sections were stained using a marker for cell proliferation (Ki67 and BrdU) and neuroblasts (doublecortin, DCX). In all groups, Ki67, BrdU and DCX immunoreaction were observed in the subgranular zone of the dentate gyrus. Oral administration of EGCG significantly increased the number of Ki67-, BrdU- and DCX-immunoreactive cells as well as BrdU/DCX-colabled cells in the subgranular zone when compared to those in the vehicle-treated group. These results indicate that oral administration of EGCG can enhance cell proliferation and increase the number of neuroblasts in mice hippocampal dentate gyrus.
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Affiliation(s)
- Ki-Yeon Yoo
- Department of Anatomy and Neurobiology, and Institute of Neurodegeneration and Neuroregeneration, College of Medicine, Hallym University, Chuncheon 200-702, South Korea
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Kim TH, Lim JM, Kim SS, Kim J, Park M, Song JH. Effects of (-) epigallocatechin-3-gallate on Na(+) currents in rat dorsal root ganglion neurons. Eur J Pharmacol 2008; 604:20-6. [PMID: 19111536 DOI: 10.1016/j.ejphar.2008.12.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 11/20/2008] [Accepted: 12/09/2008] [Indexed: 11/24/2022]
Abstract
The natural product (-) epigallocatechin-3-gallate (EGCG) is the major polyphenolic constituent found in green tea. Dorsal root ganglion neurons are primary sensory neurons, and express tetrodotoxin-sensitive and tetrodotoxin-resistant Na(+) currents, which are both actively involved in the generation and propagation of nociceptive signals. Effects of EGCG on tetrodotoxin-sensitive and tetrodotoxin-resistant Na(+) currents in rat dorsal root ganglion neurons were investigated using the whole-cell variation of the patch-clamp techniques. EGCG inhibited both types of Na(+) currents potently and in a concentration-dependent manner. The apparent dissociation constant, K(d), was estimated to be 0.74 and 0.80 microM for tetrodotoxin-sensitive and tetrodotoxin-resistant Na(+) currents, respectively. (-) Epigallocatechin (EGC) was far less potent to inhibit Na(+) currents than EGCG, suggesting that gallate moiety of EGCG is an important functional group to modulate Na(+) currents. EGCG had little or no effect on the activation or steady-state inactivation voltage of either type of Na(+) current. EGCG simply reduced the availability of Na(+) channels for activation. Thus, EGCG appears to bind to resting Na(+) channels to inhibit them. EGCG slowed the recovery of tetrodotoxin-sensitive Na(+) current from inactivation. The property of EGCG to inhibit sensory Na(+) currents can be utilized to develop an analgesic agent.
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Affiliation(s)
- Tae Hoon Kim
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul 156-756, Republic of Korea
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9
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Kim KY, Choi SJ, Jang HJ, Zuo DC, Shahi PK, Parajuli SP, Yeum CH, Yoon PJ, Choi S, Jun JY. (-)-epigallocatechin gallate inhibits the pacemaker activity of interstitial cells of cajal of mouse small intestine. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2008; 12:111-5. [PMID: 20157403 DOI: 10.4196/kjpp.2008.12.3.111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effects of (-)-epigallocatechin gallate (EGCG) on pacemaker activities of cultured interstitial cells of Cajal (ICC) from murine small intestine were investigated using whole-cell patch-clamp technique at 30 and Ca(2+) image analysis. ICC generated spontaneous pacemaker currents at a holding potential of -70 mV. The treatment of ICC with EGCG resulted in a dose-dependent decrease in the frequency and amplitude of pacemaker currents. SQ-22536, an adenylate cyclase inhibitor, and ODQ, a guanylate cyclase inhibitor, did not inhibit the effects of EGCG. EGCG-induced effects on pacemaker currents were not inhibited by glibenclamide, an ATP-sensitive K(+) channel blocker and TEA, a Ca(2+)-activated K(+) channel blocker. Also, we found that EGCG inhibited the spontaneous [Ca(2+)](i) oscillations in cultured ICC. In conclusion, EGCG inhibited the pacemaker activity of ICC and reduced [Ca(2+)](i) oscillations by cAMP-, cGMP-, ATP-sensitive K+ channel-independent manner.
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Affiliation(s)
- Kweon Young Kim
- Department of Rehabilitation, College of Medicine, Chosun University, Gwangju 501-759, Korea
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Ghayur MN, Khan H, Gilani AH. Antispasmodic, bronchodilator and vasodilator activities of (+)-catechin, a naturally occurring flavonoid. Arch Pharm Res 2007; 30:970-5. [PMID: 17879750 DOI: 10.1007/bf02993965] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Catechin is a well-known flavonoid found in many food plants and often utilized by naturopaths for the symptomatic treatment of several gastrointestinal, respiratory and vascular diseases. Our aim was to explore the biological basis for the medicinal use of this flavonoid by investigating whether catechin exhibits any pharmacological activity on smooth muscle preparations. We found that catechin dose-dependently relaxes both spontaneous and high K(+) (80 mM)-induced contraction in rabbit jejunum, showing specificity for the latter by causing a right-ward shift in the Ca(2+) dose-response curve. Similar results were observed with verapamil, a standard Ca(2+) channel blocker (CCB). Catechin also inhibited high K(+)-induced contraction in intact smooth muscle preparations from rat stomach fundus, guinea-pig ileum and guinea-pig trachea. In rat aorta, catechin inhibited phenylephrine (PE, 1 microM) and K(+)-induced contractions in a similar fashion. In PE-contracted, endothelium-intact aorta, this vasodilator effect was partially blocked by Nomega-nitro-L-arginine methyl ester and atropine, indicating activity at cholinergic receptors and possibly a CCB effect at higher doses of catechin. In guinea-pig atria catechin was found inactive. These data suggest that catechin may possess Ca(2+) antagonist activity--in addition to an endothelium-dependent relaxant component in blood vessels--thus providing a pharmacological basis for the efficacy of catechin in hyperexcitability disorders of gastrointestinal, respiratory and vascular smooth muscle.
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Affiliation(s)
- Muhammad Nabeel Ghayur
- Natural Product Research Lab, Department of Biological and Biomedical Sciences, Aga Khan University Medical College, Karachi, Pakistan
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Vignes M, Maurice T, Lanté F, Nedjar M, Thethi K, Guiramand J, Récasens M. Anxiolytic properties of green tea polyphenol (−)-epigallocatechin gallate (EGCG). Brain Res 2006; 1110:102-15. [PMID: 16859659 DOI: 10.1016/j.brainres.2006.06.062] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2006] [Revised: 06/14/2006] [Accepted: 06/19/2006] [Indexed: 11/29/2022]
Abstract
Naturally occurring polyphenols are potent antioxidants. Some of these compounds are also ligands for the GABA(A) receptor benzodiazepine site. This feature endows them with sedative properties. Here, the anxiolytic activity of the green tea polyphenol (-)-epigallocatechin gallate (EGCG) was investigated after acute administration in mice, using behavioral tests (elevated plus-maze and passive avoidance tests) and by electrophysiology on cultured hippocampal neurons. Patch-clamp experiments revealed that EGCG (1-10 muM) had no effect on GABA currents. However, EGCG reversed GABA(A) receptor negative modulator methyl beta-carboline-3-carboxylate (beta-CCM) inhibition on GABA currents in a concentration dependent manner. This was also observed at the level of synaptic GABA(A) receptors by recording spontaneous inhibitory synaptic transmission. In addition, EGCG consistently inhibited spontaneous excitatory synaptic transmission. Behavioral tests indicated that EGCG exerted both anxiolytic and amnesic effects just like the benzodiazepine drug, chlordiazepoxide. Indeed, EGCG in a dose-dependent manner both increased the time spent in open arms of the plus-maze and decreased the step-down latency in the passive avoidance test. GABA(A) negative modulator beta-CCM antagonized EGCG-induced amnesia. Finally, state-dependent learning was observable after chlordiazepoxide and EGCG administration using a modified passive avoidance procedure. Optimal retention was observed only when animals were trained and tested in the same state (veh-veh or drug-drug) and significant retrieval alteration was observed in different states (veh-drug or drug-veh). Moreover, EGCG and chlordiazepoxide fully generalized in substitution studies, indicating that they induced indistinguishable chemical states for the brain. Therefore, our data support that EGCG can induce anxiolytic activity which could result from an interaction with GABA(A) receptors.
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Affiliation(s)
- Michel Vignes
- Laboratory Oxidative Stress and Neuroprotection, University of Montpellier II, Montpellier, France.
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12
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Jeong HS, Kim YS, Park JS. Modulation of neuronal activity by EGCG. Brain Res 2005; 1047:267-70. [PMID: 15904899 DOI: 10.1016/j.brainres.2005.04.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Revised: 04/06/2005] [Accepted: 04/15/2005] [Indexed: 11/17/2022]
Abstract
This study aims to investigate whether (-)-epigallocatechin-3-gallate (EGCG) affects neuronal activity of acutely isolated rat medial vestibular nuclear neurons in whole-cell configuration patch-clamp experiments. EGCG (0.5 and 1 muM) lowered the spontaneous firing rate and hyperpolarized the membrane potential of medial vestibular nuclear neurons. However, it did not change the amplitude of afterhyperpolarization or the spike width of the action potential. A second application of EGCG with the same concentration elicited lesser responses. These results suggest that EGCG decreases neuronal activity by affecting potassium currents which are responsible for membrane potentials.
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Affiliation(s)
- Han-Seong Jeong
- Department of Physiology, Chonnam National University Medical School, Gwangju 501-190, Republic of Korea
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Lim DY. Comparison of green tea extract and epigallocatechin gallate on secretion of catecholamines from the rabbit adrenal medulla. Arch Pharm Res 2005; 28:914-22. [PMID: 16178417 DOI: 10.1007/bf02973877] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The present study was designed to examine the effects of green tea extract (CUMC6335) and epigallocatechin gallate (EGCG) on secretion of catecholamines (CA) in the isolated perfused rabbit adrenal gland. In the presence of CUMC6335 (200 microg/mL) into an adrenal vein for 60 min, CA secretory responses evoked by ACh (5.32 mM), high K+ (56 mM), DMPP (100 microM for 2 min), and Bay-K-8644 (10 microM for 4 min) from the isolated perfused rabbit adrenal glands were greatly inhibited in a time-dependent fashion. However, EGCG (10 microg/mL) did not affect CA release evoked by ACh, high K+, and Bay-K-8644. CUMC6335 itself failed to affect basal catecholamine output. Taken together, these results demonstrate that CUMC6335 inhibits CA secretion evoked by stimulation of cholinergic nicotinic receptors, as well as the direct membrane depolarization from the isolated perfused rabbit adrenal gland. It is thought that this inhibitory effect of CUMC6335 may be due at least in part to the blocking action of the L-type dihydropyridine calcium channels in the rabbit adrenomedullary chromaffin cells, which is relevant to the cholinergic nicotinic blockade. It seems that there is a big difference in mode of action between CUMC6335 and EGCG.
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Affiliation(s)
- Dong-Yoon Lim
- Department of Pharmacology, College of Medicine, Chosun University, Gwangju 501-759, Korea.
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Williamson C. Tea drinking prevents memory loss? NUTR BULL 2005. [DOI: 10.1111/j.1467-3010.2005.00482.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Katayama Y, Ooishi K, Hirai K, Homma T, Noda Y. Excitatory actions of motilin on myenteric neurons of the guinea-pig small intestine. Auton Neurosci 2005; 118:88-92. [PMID: 15795181 DOI: 10.1016/j.autneu.2005.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Revised: 01/20/2005] [Accepted: 01/24/2005] [Indexed: 11/24/2022]
Abstract
Motilin is considered as a key factor in controlling interdigestive migrating contractions. The present electrophysiological experiments were performed in vitro to examine actions of motilin on myenteric neurons of guinea-pigs after 18-h fasting period. Superfusion of motilin depolarized both S and AH neurons; the lowest effective concentration was 10 nM, and motilin depolarization was observed in 9 of 23 S neurons and in 5 of 25 AH neurons. The motilin depolarizations were associated with an increase in neuronal input resistance. The motilin responses were preserved in Ca2+ free/high Mg2+ solution in which no Ca2+ dependent synaptic transmission occurred. The reversal potential of the motilin responses was estimated about -95 mV, close to the equilibrium potential for K+. Furthermore, muscarinic depolarizations were blocked during the motilin responses. All of these indicated that motilin directly excited myenteric neurons mainly by inactivating K+ channels. It is concluded that motilin might modulate neuronal excitability of the myenteric plexus, leading to the control of interdigestive migrating contractions.
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Affiliation(s)
- Yoshifumi Katayama
- Department of Autonomic Physiology, Medical Research Institute, Tokyo Medical and Dental University, 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo, 101-0062, Japan.
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Pu F, Mishima K, Irie K, Egashira N, Ishibashi D, Matsumoto Y, Ikeda T, Iwasaki K, Fujii H, Kosuna K, Fujiwara M. Differential Effects of Buckwheat and Kudingcha Extract on Neuronal Damage in Cultured Hippocampal Neurons and Spatial Memory Impairment Induced by Scopolamine in an Eight-Arm Radial Maze. ACTA ACUST UNITED AC 2005. [DOI: 10.1248/jhs.51.636] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Fengling Pu
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University
| | - Kenichi Mishima
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University
| | - Keiichi Irie
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University
| | - Nobuaki Egashira
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University
| | - Daisuke Ishibashi
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University
| | - Yoshiaki Matsumoto
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University
| | - Tomoaki Ikeda
- Department of Obstetrics and Gynecology, Miyazaki Medical College, University of Miyazaki
| | - Katsunori Iwasaki
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University
| | | | | | - Michihiro Fujiwara
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University
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17
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Okello EJ, Savelev SU, Perry EK. In vitro anti-?-secretase and dual anti-cholinesterase activities ofCamellia sinensis L. (tea) relevant to treatment of dementia. Phytother Res 2004; 18:624-7. [PMID: 15476306 DOI: 10.1002/ptr.1519] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The primary target of licensed drugs for the treatment of Alzheimer's disease is the inhibition of the enzyme acetylcholinesterase, although preventing beta-amyloidosis is a prime target for drugs in development. The in vitro dual anti-cholinesterase and beta-secretase activities of Camellia sinensis L. extract (tea) is reported. Green and black tea inhibited human acetylcholinesterase (AChE) with IC(50) values of 0.03 mg/mL and 0.06 mg/mL respectively, and human butyrylcholinesterase (BuChE) with IC(50) values 0.05 mg/mL. Green tea at a final assay concentration of 0.03 mg/mL inhibited beta-secretase by 38%. These novel findings suggest that tea infusions contain biologically active principles, perhaps acting synergistically, that may be used to retard the progression of the disease assuming that these principles, yet to be identified, reach the brain.
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Affiliation(s)
- Edward J Okello
- School of Biology, Ridley Building, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK.
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18
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CEREGRZYN M, KUWAHARA A. The effect of epigallocatechin gallate on intestinal motility in normal and endotoxemic mice. Biomed Res 2004. [DOI: 10.2220/biomedres.25.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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19
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Katayama Y, Homma T, Honda K, Hirai K. Actions of orexin-A in the myenteric plexus of the guinea-pig small intestine. Neuroreport 2003; 14:1515-8. [PMID: 12960776 DOI: 10.1097/00001756-200308060-00023] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Orexins and orexin-receptors are localized by displaying their immunoreactivity in the enteric nervous system. Intracellular recordings were made from isolated myenteric neurons to investigate actions of orexin-A in the myenteric plexus of the guinea-pig ileum. Superfusion of orexin-A caused membrane depolarizations in a subset of S and AH neurons. Orexin-A responses were preserved in Ca2+ free/high Mg2+ solution and associated with an increase in input membrane resistance; their reversal potential was about -90 mV. Orexin-A augmented nicotinic fast EPSPs, whereas it did not affect the postsynaptic sensitivity to acetylcholine; this indicates that orexin-A increased the presynaptic release of acetylcholine. In conclusion, orexin-A contributes in the regulation of gut motility via its pre- and postsynaptic actions in the myenteric plexus.
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Affiliation(s)
- Yoshifumi Katayama
- Department of Autonomic Physiology, Medical Research Institute, Tokyo Medical and Dental University, 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
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20
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Ceregrzyn M, Kuwahara A. The effect of epigallocatechin gallate on intestinal motility in mice. Environ Health Prev Med 2003; 8:47-51. [PMID: 21432088 DOI: 10.1007/bf02897926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2002] [Accepted: 01/31/2003] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVES The epigallocatechin-3-gallate (EGCg) that is present in human diet originates mainly from tea leaves. Catechins have a number of possible application as medicines, however, there is no consistent evidence showing their influence on the gastrointestinal tract. Thus, the aim of the present study was to investigate the effect of EGCg on the motility of the murine isolated intestine. METHODS Segments of jejunum submerged in Krebs buffer were exposed to EGCg and the response was recorded under isometric conditions. RESULTS EGCg induced a dose-dependent inhibition of spontaneous activity in the jejunum. EGCg induced a decrease in the amplitude and frequency of jejunal contractions. moreover, the rythmicity of spontaneous, activity was altered in the presence of EGCg. A significant effect of EGCg was observed in the presence of 10(-4) M. The effect of EGCg was in part inhibited by pretreatment with methylene blue (guanylate cyclase inhibitor), while tetrodotoxin, (sodium channel blocker), L-nitro arginine methyl ester (nitric oxide synthase inhibitor), and N-ethylmaleimide (adenylate cyclase inhibitor) showed no effect. CONCLUSIONS The results of the present study suggest that EGCg inhibits the motility of the jejunum by direct action on smooth muscle cells where a guanylate cyclase-dependent mechanism may be partly involved.
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Affiliation(s)
- Michal Ceregrzyn
- Laboratory of Physiology, Institute for Environmental Sciences, University of Shizuoka, 52-1 Yada, 422-8526, Shizuoka, Shizuoka, Japan,
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21
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Lim DY, Lee ES, Park HG, Kim BC, Hong SP, Lee EB. Comparison of green tea extract and epigallocatechin gallate on blood pressure and contractile responses of vascular smooth muscle of rats. Arch Pharm Res 2003; 26:214-23. [PMID: 12723935 DOI: 10.1007/bf02976833] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The present study was conducted to investigate the effects of green tea extract (GTE) on arteral blood pressure and contractile responses of isolated aortic strips of the normotensive rats and to establish the mechanism of action. The phenylephrine (10(-8) approximately 10(-5) M)-induced contractile responses were greatly inhibited in the presence of GTE (0.3 approximately 1.2 mg/mL) in a dose-dependent fashion. Also, high potassium (3.5 x 10(-2) approximately 5.6 x 10(-2) M)-induced contractile responses were depressed in the presence of 0.6 approximately 1.2 mg/mL of GTE, but not affected in low concentration of GTE (0.3 mg/mL). However, epigallocatechin gallate (EGCG, 4 approximately 12 microg/mL) did not affect the contractile responses evoked by phenylephrine and high K+. GTE (5 approximately 20 mg/kg) given into a femoral vein of the normotensive rat produced a dose-dependent depressor response, which is transient. Interestingly, the infusion of a moderate dose of GTE (10 mg/kg/30 min) made a significant reduction in pressor responses induced by intravenous norepinephrine. However, EGCG (1 mg/kg/30 min) did not affect them. Collectively, these results obtained from the present study demonstrate that intravenous GTE causes a dose-dependent depressor action in the anesthetized rat at least partly through the blockade of adrenergic alpha1-receptors. GTE also causes the relaxation in the isolated aortic strips of the rat via the blockade of adrenergic alpha1-receptors, in addition to the unknown direct mechanism. It seems that there is a big difference in the vascular effect between GTE and EGCG.
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Affiliation(s)
- Dong-Yoon Lim
- Department of Pharmacology, College of Medicine, Chosun University, Gwangju 501-759, Korea.
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