Ginkgo biloba abolishes aggression in mice lacking MAO A

Long-term administration of probiotics prevents gastrointestinal mucosal barrier dysfunction in septic mice partly by upregulating the 5-HT degradation pathway

Sepsis can impair gastrointestinal (GI) barrier integrity. Oral probiotics (PT) can maintain the balance of GI microflora and improve GI function. 5-Hydroxytryptamine (5-HT) is a key promoter of GI injury caused by sepsis. However, the mechanism by which PT attenuates sepsis by regulating 5-HT is not fully understood. In this study, C57BL6 mice were intragastric administrated with normal saline (NC) or PT once a day for 4 weeks before cecal ligation and puncture (CLP). Compared with NC-CLP mice, PT-CLP mice had lower clinical score, higher body temperature. The survival rate of PT-CLP mice was significantly improved. The levels of inflammatory cytokines and 5-HT were obviously decreased in PT-CLP mice, and GI peristalsis and barrier function were enhanced. Moreover, sepsis downregulated the expression of tight junction proteins, while PT pretreatment could maintain them at the level of sham operation group. Furthermore, PT pretreatment increased the expression of serotonin transporter and monoamine oxidase A. PT administration could inhibit NF-κB activity, and activate ERK activity. In conclusion, long-term supplementation of PT before CLP can prevent sepsis-induced GI mucosal barrier dysfunction in mice, which may be partially mediated by upregulating the 5-HT degradation pathway via activating ERK signaling.

Herbal Medicine for Anxiety, Depression and Insomnia

The prevalence and comorbidity of psychiatric disorders such as depression, anxiety and insomnia are very common. These well-known forms of psychiatric disorders have been affecting many people from all around the world. Herb alone, as well as herbal formula, is commonly prescribed for the therapies of mental illnesses. Since various adverse events of western medication exist, the number of people who use herbs to benefit their health is increasing. Over the past decades, the exploration in the area of herbal psychopharmacology has received much attention. Literatures showed a variety of herbal mechanisms of action used for the therapy of depression, anxiety and insomnia, involving reuptake of monoamines, affecting neuroreceptor binding and channel transporter activity, modulating neuronal communication or hypothalamic-pituitary adrenal axis (HPA) etc. Nonetheless, a systematic review on herbal pharmacology in depression, anxiety and insomnia is still lacking. This review has been performed to further identify modes of action of different herbal medicine, and thus provides useful information for the application of herbal medicine.

Ginkgo biloba leaf extract (EGb 761®) and its specific acylated flavonol constituents increase dopamine and acetylcholine levels in the rat medial prefrontal cortex: possible implications for the cognitive enhancing properties of EGb 761®

Experimental and clinical data suggest that the Ginkgo biloba standardized extract EGb 761® exerts beneficial effects in conditions which are associated with impaired cognitive function. However, the neurochemical correlates of these memory enhancing effects are not yet fully clarified. The aim of this study was to examine the effect of repeated oral administration of EGb 761® and some of its characteristic constituents on extracellular levels of dopamine (DA), noradrenaline (NA), serotonin (5-HT), acetylcholine (ACh) and the metabolites 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in the medial prefrontal cortex (mPFC) of awake rats by use of in vivo microdialysis technique. Subacute (14 days, once daily), but not acute, oral treatment with EGb 761® (100 and 300 mg/kg) or the flavonoid fraction, which represents about 24% of the whole extract caused a significant and dose-dependent increase in extracellular DA levels in the mPFC. Repeated administration of EGb 761® also caused a modest but significant increase in the NA levels, whereas the concentrations of 5-HT and those of the metabolites DOPAC, HVA and 5-HIAA were not affected. The same treatment regimen was used in a subsequent study with the aim of investigating the effects of two Ginkgo-specific acylated flavonols, 3-O-(2''-O-(6'''-O-(p-hydroxy-trans-cinnamoyl)-β-D-glucosyl)-α-L-rhamnosyl)quercetin (Q-ag) and 3-O-(2''-O-(6'''-O-(p-hydroxy-trans-cinnamoyl)-β-D-glucosyl)-α-L-rhamnosyl)kaempferol (K-ag). Both compounds together represent about 4.5% of the whole extract. Repeated oral treatment with Q-ag (10 mg/kg) for 14 days caused a significant increase in extracellular DA levels of 159% and extracellular acetylcholine (ACh) levels of 151% compared to controls. Similarly, administration of K-ag (10 mg/kg) induced a significant rise of DA levels to 142% and ACh levels to 165% of controls, whereas treatment with isorhamnetin, an O-methylated aglycon component of EGb 761® flavonol glycosides had no effect. None of the tested flavonoids had a significant effect on extracellular DOPAC and HVA levels. The present findings provide evidence that the subacute treatment with EGb 761® and its flavonol constituents increases DA and ACh release in the rat mPFC, and suggest that the two Ginkgo-specific acylated flavonol glycosides Q-ag and K-ag are active constituents contributing to these effects. As seen for isorhamnetin, the effect on neurotransmitter levels seems not to be a general effect of flavonols but rather to be a specific action of acylated flavonol glycosides which are present in EGb 761®. The direct involvement of these two flavonol derivatives in the increase of dopaminergic and cholinergic neurotransmission in the prefrontal cortex may be one of the underlying mechanisms behind the reported effects of EGb 761® on the improvement of cognitive function.

The Ginkgo biloba extract EGb 761(R) and its main constituent flavonoids and ginkgolides increase extracellular dopamine levels in the rat prefrontal cortex

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((R)) 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.

EXPERIMENTAL APPROACH

Monoamines and their metabolites were monitored by the use of microdialysis sampling and HPLC with electrochemical or fluorescence detection.

KEY RESULTS

A single oral dose of EGb 761 (100 mg.kg(-1)) 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.