Effects of bilobalide on anxiety, spatial learning, memory and levels of hippocampal glucocorticoid receptors in male Kunming mice

Suppressive effects of bilobalide on depression-like behaviors induced by chronic unpredictable mild stress in mice

Background: Depression is a psychiatric disorder with depressed mood and even suicide attempts as the main clinical symptoms, and its pathogenesis has not yet been fully elucidated. Brain derived neurotrophic factor (BDNF) plays an important role in the pathogenesis of depression. Purpose: The main aim of the present study was to evaluate the effectiveness and reveal the potential mechanisms of bilobalide (BB) intervention in alleviating depression-like behaviors by using chronic unpredictable mild stress (CUMS) mice via mediating the BDNF pathway. Methods: Behavioral assessments were carried out by using the sucrose preference test (SPT), tail suspension test (TST), and forced swimming test (FST). CUMS mice were randomly divided into 5 groups: CUMS + solvent, CUMS + BB low, CUMS + BB medium, CUMS + BB high and CUMS + fluoxetine. Total serum levels of tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) were measured by ELISA. Expression of TNF-α, IL-6, AKT, GSK3β, β-catenin, Trk-B and BDNF in the mouse hippocampus was assessed by western blotting. Results: BB treatment reduced the levels of pro-inflammatory cytokines (IL-6 and TNF-α) and increased the protein expression of BDNF in the hippocampus region of the CUMS mice. Moreover, BB treatment enhanced the AKT/GSK3β/β-catenin signaling pathway which is downstream of the BDNF receptor Trk-B in the hippocampus of these mice. Conclusions: Overall, the experimental results indicated that BB reverses CUMS-induced depression-like behavior. BB exerts antidepressant-like effects by inhibiting neuroinflammation and enhancing the function of neurotrophic factors.

Early-life bisphenol AP exposure impacted neurobehaviors in adulthood through microglial activation in mice

Bisphenol AP (BPAP), a structural analog of bisphenol A (BPA), has been widely detected in environment and biota. BPAP was reported to interfere with hormone and metabolism, while limited data were available about its effects on neurobehavior, especially exposure to it during early-life time. A mouse model of early-life BPAP exposure was established to evaluate the long-term neurobehaviors in offspring. Collectively, early-life BPAP exposure caused anxiety-like behaviors and impaired learning and memory in adult offspring. Through brain bulk RNA-sequencing (RNA-seq), we found differential expressed genes were enriched in pathways related to behaviors and neurodevelopment, which were consistent with the observed phenotype. Besides, single-nucleus RNA-sequencing (snRNA-seq) showed BPAP exposure altered the transcriptome of microglia in hippocampus. Mechanistically, BPAP exposure induced inflammations in hippocampus through upregulating Iba-1 and activating the microglia. In addition, we observed that BPAP exposure could activate peripheral immunity and promote proportion of macrophages and activation of dendritic cells in the offspring. In conclusion, early-life exposure to BPAP impaired neurobehaviors in adult offspring accompanied with excessive activation of hippocampal microglia. Our findings provide new clues to the underlying mechanisms of BPAP's neurotoxic effects and therefore more cautions should be taken about BPAP.

The Use of Ginkgo Biloba L. as a Neuroprotective Agent in the Alzheimer's Disease

Alzheimer's disease, a neurodegenerative disease, is one of the most common causes of dementia if elderly people worldwide. Alzheimer's disease leads to the alienation of individuals and their exclusion from social and professional life. It is characterized mainly by the degradation of memory and disorientation, which occurs as a result of the loss of neuronal structure and function in different brain areas. In recent years, more and more attention has been paid to use in the treatment of natural bioactive compounds that will be effective in neurodegenerative diseases, including Alzheimer's disease. G. biloba L. and its most frequently used standardized extract (EGb 761), have been used for many years in supportive therapy and in the prevention of cognitive disorders. The paper presents an overview of reports on the pathogenesis of Alzheimer's disease, as well as a summary of the properties of G. biloba extract and its effects on the possible pathogenesis of the disease. By exploring more about the pathogenesis of the disease and the benefits of G. biloba extract for patients with Alzheimer's disease, it will be possible to create an individualized therapeutic protocol to optimize the treatment.

Bilobalide: A review of its pharmacology, pharmacokinetics, toxicity, and safety

Bilobalide is a natural sesquiterpene trilactone from Ginkgo biloba leaves. It has good water solubility and is widely used in food and pharmaceutical fields. In the last decade, a plethora of studies on the pharmacological activities of bilobalide has been conducted and demonstrated that bilobalide possessed an extensive range of pharmacological activities such as neuroprotective, antioxidative, antiinflammatory, anti-ischemic, and cardiovascular protective activities. Pharmacokinetic studies indicated that bilobalide may have the characteristics of rapid absorption, good bioavailability, wide distribution, and slow elimination. This review aims to summarize the advances in pharmacological, pharmacokinetics, toxicity, and safety studies of bilobalide in the last decade with an emphasis on its neuroprotective and antiinflammatory activities, to provide researchers with the latest information and point out the limitations of relevant research at the current stage and the aspects that should be strengthened in future research.

Hormesis and Ginkgo biloba (GB): Numerous biological effects of GB are mediated via hormesis

Ginkgo biloba (GB) extracts have been shown to commonly induce biphasic dose responses in a range of cell types and endpoints (e.g., cochlea neural stem cells, cell viability, cell proliferation). The magnitude and width of the low dose stimulation of these biphasic dose responses are similar to those reported for hormetic dose responses. These hormetic dose responses occur within direct stimulatory responses as well as in preconditioning experimental protocols, displaying acquired resistance within an adaptive homeodynamic and temporal framework and repeated measurement protocols. The demonstrated GB dose responses further reflect the general occurrence of hormetic dose responses that consistently appear to be independent of the biological model, endpoint, inducing agent, and/or mechanism. These findings have important implications for consideration(s) of study designs involving dose selection, dose spacing, sample size, and statistical power. This illustrates and strengthens the need to characterize the low dose stimulatory response range and optimal dose in order to explore potential public health and clinical applications of plant-derived agents, such as GB.

Ginkgo biloba attenuates aluminum lactate-induced neurotoxicity in reproductive senescent female rats: behavioral, biochemical, and histopathological study

Extensive use of aluminum (Al) in industry, cooking utensils, and wrapping or freezing the food items, due to its cheapness and abundance in the environment, has become a major concern. Growing evidence supports that environmental pollutant Al promotes the aggregation of amyloid beta (Aβ) in the brain, which is the main pathological marker of Alzheimer's disease (AD). Further, AD- and Al-induced neurotoxic effects are more common among women following reproductive senescence due to decline in estrogen. Though clinically Ginkgo biloba extract (GBE) has been exploited as a memory enhancer, its role in Al-induced neurotoxicity in reproductive senescent female rats needs to be evaluated. Animals were exposed to intraperitoneal dose (10 mg/kg b.wt) of Al and oral dose (100 mg/kg b.wt.) of GBE daily for 6 weeks. A significant decline in the Al-induced Aβ aggregates was observed in hippocampal and cortical regions of the brain with GBE supplementation, as confirmed by thioflavin (ThT) and Congo red staining. GBE administration significantly decreased the reactive oxygen species, lipid peroxidation, nitric oxide, and citrulline levels in comparison to Al-treated rats. On the contrary, a significant increase in the reduced glutathione, GSH/GSSG ratio as well as in the activities of antioxidant enzymes was observed with GBE administration. Based on the above results, GBE prevented the neuronal loss in the hippocampus and cortex, hence caused significant improvement in the learning and memory of the animals in terms of AChE activity, serotonin levels, Morris water maze, and active and passive avoidance tests. In conclusion, GBE has alleviated the behavioral, biochemical, and histopathological alterations due to Al toxicity in rats. However, molecular studies are going on to better understand the mechanism of GBE protection against the environmental toxicant Al exposure. Graphical abstract .

Bilobalide alleviates depression-like behavior and cognitive deficit induced by chronic unpredictable mild stress in mice

Bilobalide (BB), a unique constituent of Ginkgo biloba, has powerful neuroprotection and stress-alleviating properties. However, whether BB exerts a positive effect on depression and cognitive deficit induced by chronic stress is not known. The present study was designed to investigate the influence of BB on depression and cognitive impairments induced by chronic unpredictable mild stress (CUMS) in mice. During daily exposure to stressors for 5 consecutive weeks, mice were administered BB at the doses of 0, 3, or 6 mg/kg/day intraperitoneally. We replicated the finding that CUMS induced depression-like behavior and cognitive deficits as the CUMS+vehicle (VEH) group showed a significant increase in immobility in the tail suspension test, a decrease in the discrimination index of the novel object recognition task, and increased latency to platform and decreased number of platform crossings in the Morris water maze compared with the control+VEH group. Chronic administration of BB effectively reversed these alterations. In addition, the CUMS+VEH group showed significantly higher levels of baseline serum corticosterone than those of the control+VEH group and BB dose-dependently inhibited this effect. Our results suggest that BB may be useful for inhibition of depression-like behavior and cognitive deficits, and this protective effect was possibly exerted partly through an action on the hypothalamic-pituitary-adrenal axis.

Metabolite-related antidepressant action of diterpene ginkgolides in the prefrontal cortex

PURPOSE

Ginkgo biloba extract (GBE) contains diterpene ginkgolides (DGs), which have been shown to have neuroprotective effects by a number of previous studies. We previously demonstrated part of the action of DG. However, the impact of DG on the prefrontal cortex (PFC) remains unclear. Here, we evaluated the effects of DG and venlafaxine (for comparison) on behavioral and metabolite changes in the PFC using mice models and gas chromatography-mass spectrometry-based metabolomics.

MATERIALS AND METHODS

Mice were randomly divided into control (saline), DG (12.18 mg/kg) and venlafaxine (16 mg/kg) groups. After 2 weeks of treatment, depression and anxiety-related behavioral tests were performed. Metabolic profiles of the PFC were detected by gas chromatography-mass spectrometry.

RESULTS

The DG group exhibited positive effects in the sucrose preference test. The differential metabolites were mainly related to amino acid metabolism, energy metabolism and lipid metabolism. The results indicated that the DG group exhibited perturbed lipid metabolism, molecular transport and small-molecule biochemistry in the PFC. Compared with the control group, pathway analysis indicated that venlafaxine and DG had similar effects on alanine, aspartate and glutamate metabolism.

CONCLUSION

These findings demonstrate that DG has antidepressant-like, but not anxiolytic-like, effects in mice, suggesting that it might have therapeutic potential for the treatment of major depressive disorder.

YY-1224, a terpene trilactone-strengthened Ginkgo biloba, attenuates neurodegenerative changes induced by β-amyloid (1-42) or double transgenic overexpression of APP and PS1 via inhibition of cyclooxygenase-2

BACKGROUND

Ginkgo biloba has been reported to possess free radical-scavenging antioxidant activity and anti-inflammatory properties. In our pilot study, YY-1224, a terpene trilactone-strengthened extract of G. biloba, showed anti-inflammatory, neurotrophic, and antioxidant effects.

RESULTS

We investigated the pharmacological potential of YY-1224 in β-amyloid (Aβ) (1-42)-induced memory impairment using cyclooxygenase-2 (COX-2) knockout (-/-) and APPswe/PS1dE9 transgenic (APP/PS1 Tg) mice. Repeated treatment with YY-1224 significantly attenuated Aβ (1-42)-induced memory impairment in COX-2 (+/+) mice, but not in COX-2 (-/-) mice. YY-1224 significantly attenuated Aβ (1-42)-induced upregulation of platelet-activating factor (PAF) receptor gene expression, reactive oxygen species, and pro-inflammatory factors. In addition, YY-1224 significantly inhibited Aβ (1-42)-induced downregulation of PAF-acetylhydrolase-1 (PAF-AH-1) and peroxisome proliferator-activated receptor γ (PPARγ) gene expression. These changes were more pronounced in COX-2 (+/+) mice than in COX-2 (-/-) mice. YY-1224 significantly attenuated learning impairment, Aβ deposition, and pro-inflammatory microglial activation in APP/PS1 Tg mice, whereas it significantly enhanced PAF-AH and PPARγ expression. A preferential COX-2 inhibitor, meloxicam, did not affect the pharmacological activity by YY-1224, suggesting that the COX-2 gene is a critical mediator of the neuroprotective effects of YY-1224. The protective activity of YY-1224 appeared to be more efficacious than a standard G. biloba extract (Gb) against Aβ insult.

CONCLUSIONS

Our results suggest that the protective effects of YY-1224 against Aβ toxicity may be associated with its PAF antagonistic- and PPARγ agonistic-potential as well as inhibition of the Aβ-mediated pro-inflammatory switch of microglia phenotypes through suppression of COX-2 expression.

GC-MS-based metabolomic study on the antidepressant-like effects of diterpene ginkgolides in mouse hippocampus

Ginkgo biloba extract (GBE), including EGb-761, have been suggested to have antidepressant activity based on previous behavioral and biochemical analyses. However, because GBE contain many constituents, the mechanisms underlying this suggested antidepressant activity are unclear. Here, we investigated the antidepressant-like effects of diterpene ginkgolides (DG), an important class of constituents in GBE, and studied their effects in the mouse hippocampus using a GC-MS-based metabolomics approach. Mice were randomly divided into five groups and injected daily until testing with 0.9% NaCl solution, one of three doses of DG (4.06, 12.18, and 36.54mg/kg), or venlafaxine. Sucrose preference (SPT) and tail suspension (TST) tests were then performed to evaluate depressive-like behaviors in mice. DG (12.18 and 36.54mg/kg) and venlafaxine (VLX) administration significantly increased hedonic behavior in mice in the SPT. DG (12.18mg/kg) treatment also shortened immobility time in the TST, suggestive of antidepressant-like effects. Significant differences in the metabolic profile in the DG (12.18mg/kg) compared with the control or VLX group indicative of an antidepressant-like effect were observed using multivariate analysis. Eighteen differential hippocampal metabolites were identified that discriminated the DG (12.18mg/kg) and control groups. These biochemical changes involved neurotransmitter metabolism, oxidative stress, glutathione metabolism, lipid metabolism, energy metabolism, and kynurenic acid, providing clues to the therapeutic mechanisms of DG. Thus, this study showed that DG has antidepressant-like activities in mice and shed light on the biological mechanisms underlying the effects of diterpene ginkgolides on behavior, providing an important drug candidate for the treatment of depression.

Food-derived hydrophilic antioxidant ergothioneine is distributed to the brain and exerts antidepressant effect in mice

BACKGROUND

Clinically used antidepressants suffer from various side effects. Therefore, we searched for a safe antidepressant with minimal side effects among food ingredients that are distributed to the brain. Here, we focused on ERGO (ergothioneine), which is a hydrophilic antioxidant and contained at high levels in edible golden oyster mushrooms. ERGO is a typical substrate of carnitine/organic cation transporter OCTN1/SLC22A4, which is expressed in the brain and neuronal stem cells, although little is known about its permeation through the BBB (blood-brain barrier) or its neurological activity.

METHODS

To clarify the exposure of ERGO to brain and the possible antidepressant-like effect after oral ingestion, ERGO or GOME (golden oyster mushroom extract) which contains 1.2% (w/w) ERGO was mixed with feed and provided to mice for 2 weeks, and then ERGO concentration and antidepressant-like effect were evaluated by LC-MS/MS and FST (forced swimming test) or TST (tail suspension test), respectively.

RESULTS

Diet containing ERGO or GOME greatly increased the ERGO concentrations in plasma and brain, and significantly decreased the immobility time in both FST and TST. The required amount of GOME (~37 mg/day) to show the antidepressant-like effect corresponds to at most 8 g/day in humans. In mice receiving GOME-containing diet, doublecortin-positive cells showed a significant increase from the basal level, suggesting promotion of neuronal differentiation.

CONCLUSION

Thus, orally ingested ERGO is transported across the BBB into the brain, where it may promote neuronal differentiation and alleviate symptoms of depression at plausibly achieved level of daily ingestion.

Plant-derived flavanol (-)epicatechin mitigates anxiety in association with elevated hippocampal monoamine and BDNF levels, but does not influence pattern separation in mice

Flavanols found in natural products such as cocoa and green tea elicit structural and biochemical changes in the hippocampus, a brain area important for mood and cognition. Here, we evaluated the outcome of daily consumption of the flavanol (-)epicatechin (4 mg per day in water) by adult male C57BL/6 mice on measures of anxiety in the elevated plus maze (EPM) and open field (OF). Furthermore, pattern separation, the ability to distinguish between closely spaced identical stimuli, considered to be mediated by the hippocampal dentate gyrus (DG), was tested using the touchscreen. To investigate mechanisms through which (-)epicatechin may exert its effects, mice were injected with bromodeoxyuridine (50 mg kg(-1)) to evaluate adult hippocampal neurogenesis. In addition, monoaminergic and neurotrophin signaling pathway proteins were measured in tissue derived from subject cortices and hippocampi. Flavanol consumption reduced anxiety in the OF and EPM. Elevated hippocampal and cortical tyrosine hydroxylase, downregulated cortical monoamine oxidase-A levels, as well as increased hippocampal brain-derived neurotrophic factor (BDNF) and pro-BDNF support the flavanol's anxiolytic effects. In addition, elevated pAkt in hippocampus and cortex was observed. (-)Epicatechin ingestion did not facilitate touchscreen performance or DG neurogenesis, suggesting a non-neurogenic mechanism. The concurrent modulation of complementary neurotrophic and monoaminergic signaling pathways may contribute to beneficial mood-modulating effects of this flavanol.

The effects of Ginkgo biloba extract on cognitive functions in aged female rats: the role of oxidative stress and brain-derived neurotrophic factor

The aim of this study was to investigate the effects of Ginkgo biloba extract (GBE) on cognitive functions as well as oxidative stress and brain-derived neurotrophic factor (BDNF) levels in aged female rats. Rats were divided into 4 groups according to age (young vs. aged) and treatment (GBE vs. vehicle). GBE or vehicle was given for 30 d, and a series of behavioral tests were performed. Following behavioral testing, blood samples and brain tissues were obtained for analysis of BDNF, malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and glutathione levels, and superoxide dismutase activity. Locomotor activity and anxiety levels were lower in the aged rats. Based on Morris water maze probe trial findings, GBE supplementation increased the number of platform crossings in the aged rats. MDA and 8-OHdG levels were lower in the brain tissue, and BDNF levels were higher in plasma in the rates treated with GBE. Based on these findings, we concluded that GBE supplementation improved cognitive functions by decreasing oxidative damage and increasing the BDNF level in aged female rats.

EGB1212 Post-treatment Ameliorates Hippocampal CA1 Neuronal Death and Memory Impairment Induced by Transient Global Cerebral Ischemia/Reperfusion

Extracts of Ginkgo biloba have been used in traditional medicines for centuries, and have potential for clinical applications in cerebral ischemia/reperfusion injury. However, standardized extracts have proven protective only as pre-treatments, and the major mechanisms of action remain unclear. We explored the potential of the novel extract EGB1212, which meets the United States Pharmacopeia (USP) 31 standardization criteria for pharmaceutical use, as a post-treatment after global cerebral ischemia/reperfusion (GCI/R) injury in a rat model. The pre-treated group was administered EGB1212 for 7 d prior to common carotid artery occlusion (i.e., ischemia, for 20 min). Post-treated rats received the same but starting 2 h after ischemia and continuing for 7 d. Seven days after GCI/R, brains of each group were processed for H&E staining of hippocampal CA1 neurons. Remaining rats underwent the Morris water maze and Y-maze tests of spatial learning and memory, beginning eight days after reperfusion. To assess hippocampal autophagy, light chain (LC)-3-I/LC3-II and Akt/pAkt were determined via a Western blot of rat hippocampi harvested 12, 24, or 72 h after reperfusion. EGB1212 pre- and post-treatments both improved neuronal survival and spatial learning and memory functions. Pre-treatment effectively reduced LC3-II levels and post-treatment resulted in significantly elevated pAkt levels. We conclude that EGB1212 exerted significant neuroprotection in GCI/R in both preventative and post-treatment settings. This extract shows great potential for clinical applications.