α2-Adrenoceptor Changes During Cerebral Ageing. The Effect of <i>Ginkgo biloba</i> Extract

Huguet, François; Tarrade, T

doi:10.1111/j.2042-7158.1992.tb14357.x

Cited by 51 publications

(17 citation statements)

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“…, 2000). Chronic treatment with EGb 761 increased binding (B max values) to muscarinic acetylcholine receptors (Taylor, 1986) and α 2 ‐adrenoceptors (Huguet and Tarrade, 1992) in the hippocampal membranes, and 5‐HT 1A receptors (Huguet et al. , 1994) in cortical membranes of aged, but not young, rats.…”

Section: Discussionmentioning

confidence: 99%

TheGinkgo bilobaextract EGb 761^®and its main constituent flavonoids and ginkgolides increase extracellular dopamine levels in the rat prefrontal cortex

Yoshitake

Kehr

2010

British J Pharmacology

113

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Background and purpose:Experimental and clinical data suggest that extracts of Ginkgo biloba improve cognitive function. However, the neurochemical correlates of these effects are not yet fully clarified. The purpose of this study was to examine the effects of acute and repeated oral administration of the standardized extract EGb 761 ® on extracellular levels of dopamine, noradrenaline and serotonin (5-HT), and the dopamine metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the prefrontal cortex (PFC) and striatum of conscious rats. ) had no effect on monoamine levels. However, following chronic (100 mg·kg -1 /14 days/once daily) treatment, the same dose significantly increased extracellular dopamine and noradrenaline levels, while 5-HT levels were unaffected. Chronic treatment with EGb 761 showed dose-dependent increases in frontocortical dopamine levels and, to a lesser extent, in the striatum. The extracellular levels of HVA and DOPAC were not affected by either acute or repeated doses. Treatment with the main constituents of EGb 761 revealed that the increase in dopamine levels was mostly caused by the flavonol glycosides and ginkgolide fractions, whereas bilobalide treatment was without effect. Conclusions and implications:The present results demonstrate that chronic but not acute treatment with EGb 761 increased dopaminergic transmission in the PFC. This finding may be one of the mechanisms underlying the reported effects of G. biloba in improving cognitive function. Pharmacology (2010) 159, 659-668; doi:10.1111/j.1476-5381.2009.00580.x; published online 25 January 2010 British Journal ofKeywords: Ginkgo biloba; microdialysis; monoamines; dopamine; noradrenaline; serotonin; prefrontal cortex; cognitive function Abbreviations: CMC, carboxymethylcellulose; DOPAC, 3,4-dihydroxyphenylacetic acid; HPLC, high-performance liquid chromatography; HVA, homovanillic acid; MAO, monoamine oxidase; PFC, prefrontal cortex IntroductionExtracts of Ginkgo biloba (EGb 761 ® ) have been shown to exert beneficial effects as cognitive enhancers in ageing, anti-stress agents and in therapy of age-related neurological disorders such as Alzheimer's disease (see DeFeudis and Drieu, 2000;DeFeudis, 2003;DeKosky and Furberg, 2008). A number of clinical studies have demonstrated that extracts of G. biloba, and particularly the standardized extract EGb 761, could ameliorate cognitive defects associated with mild to moderate Alzheimer's disease (Andrieu et al., 2003;Kanowski and Hoerr, 2003;Mazza et al., 2006;Napryeyenko et al., 2007;Scripnikov et al., 2007;Dodge et al., 2008). However, a recent Cochrane review on published randomized, double-blind, clinical trials has found that the use of G. biloba extracts was safe but the evidence for a significant benefit in people with dementia or cognitive impairment was inconsistent and unconvincing (Birks and Grimley Evans, 2007). In addition, a randomized, double-blind, placebo-controlled clinical study on 3069 volunteers aged 75 years or older receiving EGb 761 a...

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Section: Discussionmentioning

confidence: 99%

TheGinkgo bilobaextract EGb 761^®and its main constituent flavonoids and ginkgolides increase extracellular dopamine levels in the rat prefrontal cortex

Yoshitake

Kehr

2010

British J Pharmacology

113

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“…Indeed, in the United States and particularly in Europe, G biloba is perhaps the most widely used herbal treatment consumed specifically to prevent age-related cognitive decline 2. Putative mechanisms of action on brain functioning include vascular effects such as cerebral vasorelaxation and reduction of blood viscosity,3,4 reduction of oxygen free radicals,5 and neurotransmitter system effects 6,7. Moreover, some in vitro studies indicate that G biloba may inhibit amyloid aggregation, suggesting another mechanism of preventing or delaying cognitive decline associated with Alzheimer disease 8…”

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confidence: 99%

<emph type="ital">Ginkgo biloba</emph> for Preventing Cognitive Decline in Older Adults<subtitle>A Randomized Trial</subtitle>

Snitz

O’Meara

Carlson

et al. 2009

JAMA

290

148

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“…However, Petkov et aL (30) have found a decrease in noradrenaline level by EGb 761, especially in the rat hippocampus, and Taylor (31) did not find any change in 6-receptor density, even after a 28-day treatment with EGb 761 (100 mg/kg, p.o.). Furthermore, an age-related decrease in hippocampal a 2 -receptors could be prevented by treatment with EGb 761 (32). Thus, the effect of EGb 761 on the noradrenaline level and on the density of adrenergic receptors in the brain needs further investigation.…”

Section: Effects On the Adrenergic Systemmentioning

confidence: 94%

Neuroprotective Effects of Ginkgo biloba Extract

Ahlemeyer

Krieglstein

1998

ACS Symposium Series

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Extracts of the leaves of Ginkgo biloba (such as EGb 761 and LI 1370) are widely used for the treatment of dementia and cerebral insufficiency. This review will summarize experimental results concerning the protective effects of EGb 761 and its constituents in different models of cerebral ischemia. Furthermore, we present the supposed mechanisms of action and the current status of clinical trials.For more than 40 years, the extract of the leaves of Ginkgo biloba (EGb 761) has been widely used therapeutically to increase peripheral and cerebral blood flow, as well as for the treatment of cerebral ischemia, brain disorders caused by old age, and of dementia due to neuronal degeneration or to vascular deficiency. In these age-related disorders, EGb 761 should enhance the intellectual capacity of the patients, that is, improve the learning, memory and cognitive faculties. Although it has been shown that organ systems other than the brain, e.g. the lung (1, 2) and the heart (3, 4), could also benefit from the effects of EGb 761, this review will focus only on the effects of Ginkgo biloba extract on the brain function. First, we would like to present the neuroprotective effects of EGb 761 in different in vivo and in vitro models of cerebral ischemia and relate them to the different constituents of EGb 761. Thereafter, we would like to discuss in detail the effects of EGb 761 under normoxic as well as under ischemic conditions of the brain, including the effects of EGb 761 on cerebral blood flow, on cerebral glucose and lipid metabolism, and on the neurotransmitter systems. The last part of this review will summarize the present status of clinical trials on the commercial extracts of Ginkgo biloba (EGb 761 and LI 1370). The Constituents of Ginkgo Biloba Extract (EGb 761)This extract of Ginkgo biloba is prepared by highly extracting the leaves and removing the constituents ginkgole acid and the biflavones. The purified extract, EGb 761, is standardized to 24 % flavonoids. In addition, it contains approximately 6% terpene 210

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α2-Adrenoceptor Changes During Cerebral Ageing. The Effect of Ginkgo biloba Extract

Cited by 51 publications

References 19 publications

TheGinkgo bilobaextract EGb 761^®and its main constituent flavonoids and ginkgolides increase extracellular dopamine levels in the rat prefrontal cortex

TheGinkgo bilobaextract EGb 761^®and its main constituent flavonoids and ginkgolides increase extracellular dopamine levels in the rat prefrontal cortex

<emph type="ital">Ginkgo biloba</emph> for Preventing Cognitive Decline in Older Adults<subtitle>A Randomized Trial</subtitle>

Neuroprotective Effects of Ginkgo biloba Extract

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α2-Adrenoceptor Changes During Cerebral Ageing. The Effect of Ginkgo biloba Extract

Cited by 51 publications

References 19 publications

TheGinkgo bilobaextract EGb 761®and its main constituent flavonoids and ginkgolides increase extracellular dopamine levels in the rat prefrontal cortex

TheGinkgo bilobaextract EGb 761®and its main constituent flavonoids and ginkgolides increase extracellular dopamine levels in the rat prefrontal cortex

<emph type="ital">Ginkgo biloba</emph> for Preventing Cognitive Decline in Older Adults<subtitle>A Randomized Trial</subtitle>

Neuroprotective Effects of Ginkgo biloba Extract

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TheGinkgo bilobaextract EGb 761^®and its main constituent flavonoids and ginkgolides increase extracellular dopamine levels in the rat prefrontal cortex

TheGinkgo bilobaextract EGb 761^®and its main constituent flavonoids and ginkgolides increase extracellular dopamine levels in the rat prefrontal cortex