Oroxylin A increases BDNF production by activation of MAPK–CREB pathway in rat primary cortical neuronal culture

Resveratrol-Loaded Pluronic Micelles Ameliorate Scopolamine-Induced Cognitive Dysfunction Targeting Acetylcholinesterase Activity and Programmed Cell Death

Numerous experimental studies suggest the potential for resveratrol (RVT) to be useful in the Alzheimer's disease treatment, but its low bioavailability limits its application. This study aimed to assess the potential of resveratrol-loaded micelles as a neuronal delivery platform to protect rats from scopolamine-induced memory impairment. Resveratrol was incorporated into Pluronic micelles, and the effects of micellar (mRVT) and pure resveratrol (RVT) were compared in the model of scopolamine-induced dementia in male Wistar rats. Memory performance was assessed by a T maze test. The effect of the treatment on specific neurotransmitter levels and protein expression in the cortex and the hippocampus were evaluated biochemically. Our results revealed that the polymeric micelles were in nanoscale (approximately 33 nm) and reached 79% encapsulation efficiency. The treatment with mRVT demonstrated better spatial memory protective effect. The biochemical assays showed that mRVT in a dose of 10 mg/kg enhanced the effects of the pure drug in regard to noradrenalin neurotransmission and acetylcholinesterase inhibitory activity in the hippocampus. Furthermore, micellar resveratrol increased the cAMP-response element-binding protein expression in the cortex and hippocampus of rats as well as the Bcl2/BAX ratio, which indicated an anti-apoptotic effect in the experimental dementia model. In conclusion, our results indicated the potential of a micellar system loaded with resveratrol for neurodegenerative diseases treatment.

The Neuroprotective Effects of Oroxylum indicum Extract in SHSY-5Y Neuronal Cells by Upregulating BDNF Gene Expression under LPS Induced Inflammation

The brain-derived neurotrophic factor (BDNF) plays a crucial role during neuronal development as well as during differentiation and synaptogenesis. They are important proteins present in the brain that support neuronal health and protect the neurons from detrimental signals. The results from the present study suggest BDNF expression can be increase up to ~8-fold by treating the neuroblastoma cells SHSY-5Y with an herbal extract of Oroxylum indicum (50 μg/mL) and ~5.5-fold under lipopolysaccharides (LPS)-induced inflammation conditions. The Oroxylum indicum extract (Sabroxy) was standardized to 10% oroxylin A, 6% chrysin, and 15% baicalein. In addition, Sabroxy has shown to possess antioxidant activity that could decrease the damage caused by the exacerbation of radicals during neurodegeneration. A mode of action of over expression of BDNF with and without inflammation is proposed for the Oroxylum indicum extract, where the three major hydroxyflavones exert their effects through additive or synergistic effects via five possible targets including GABA, Adenoside A2A and estrogen receptor bindings, anti-inflammatory effects, and reduced mitochondrial ROS production.

An insight into crosstalk among multiple signalling pathways contributing to the pathophysiology of PTSD and depressive disorders

Post-traumatic stress disorder (PTSD) and depressive disorders represent two significant mental health challenges with substantial global prevalence. These are debilitating conditions characterized by persistent, often comorbid, symptoms that severely impact an individual's quality of life. Both PTSD and depressive disorders are often precipitated by exposure to traumatic events or chronic stress. The profound impact of PTSD and depressive disorders on individuals and society necessitates a comprehensive exploration of their shared and distinct pathophysiological features. Although the activation of the stress system is essential for maintaining homeostasis, the ability to recover from it after diminishing the threat stimulus is also equally important. However, little is known about the main reasons for individuals' differential susceptibility to external stressful stimuli. The solution to this question can be found by delving into the interplay of stress with the cognitive and emotional processing of traumatic incidents at the molecular level. Evidence suggests that dysregulation in these signalling cascades may contribute to the persistence and severity of PTSD and depressive symptoms. The treatment strategies available for this disorder are antidepressants, which have shown good efficiency in normalizing symptom severity; however, their efficacy is limited in most individuals. This calls for the exploration and development of innovative medications to address the treatment of PTSD. This review delves into the intricate crosstalk among multiple signalling pathways implicated in the development and manifestation of these mental health conditions. By unravelling the complexities of crosstalk among multiple signalling pathways, this review aims to contribute to the broader knowledge base, providing insights that could inform the development of targeted interventions for individuals grappling with the challenges of PTSD and depressive disorders.

Potential effect of physical exercise on the downregulation of BDNF mRNA expression in rat hippocampus following intracerebral hemorrhage

OBJECTIVES

Physical exercise is known to induce expression of the neuroprotective brain derived neurotrophic factor (BDNF) in the hippocampus. This study examined the effects of physical exercise on hippocampal BDNF expression and the potential benefits for preventing remote secondary hippocampal damage and neurological impairment following intracerebral hemorrhage (ICH).

MATERIALS AND METHODS

Wistar rats were randomly assigned to sham-operated, ICH, and ICH followed by exercise (ICH/Ex) groups. The two ICH groups were injected with type IV collagenase into the left basal ganglia, while sham animals were injected with equal-volume saline. The ICH/Ex group rats ran on a treadmill at 11 m/min for 30 min/day from day 3 to 16 post-ICH. All animals were examined for neurological function on day 2 pretreatment and from day 3 to 15 posttreatment, for spontaneous motor activity in the open field on day 15, and for cognitive ability using the object location test on day 16. Animals were then euthanized and bilateral hippocampi collected for gene expression analyses.

RESULTS

Experimental ICH induced neurological deficits that were not reversed by exercise. In contrast, ICH did not alter spontaneous activity or object location ability. Expression of BDNF mRNA of the ICH group was significantly downregulated in the ipsilateral hippocampus compared to the SHAM group, but this downregulation was not shown in the ICH/Ex group. The ICH/Ex group showed the downregulation of caspase-3 mRNA expression in the contralateral hippocampus compared to the SHAM group, while neither ICH nor exercise influenced toll-like receptor 4 mRNA expression.

CONCLUSIONS

ICH induced the secondary BDNF downregulation in the hippocampus remote from the lesion, whereas physical exercise might partially mitigate the downregulation.

Redox Protein Thioredoxin Mediates Neurite Outgrowth in Primary Cultured Mouse Cerebral Cortical Neurons

Thioredoxin system plays an important role in maintaining the cellular redox balance. Recent evidence suggests that thioredoxin (Trx) system may promote cell survival and neuroprotection. In this study, we explored the role of thioredoxin system in neuronal differentiation using a primary mouse cortical neuronal cell culture. First, Trx and Trx reductase (TrxR) protein levels were analyzed in cultured neurons from 1 to 32 days in vitro (DIV). The result showed that Trx and TrxR protein levels time-dependently increased in the neuron cell culture from 1 to 18 DIV. To establish the role of Trx in neuronal differentiation, Trx gene expression was knockdown in cultured neurons using Trx sgRNA CRISPR/Cas9 technology. Treatment with CRISPR/Cas9/Trx sgRNA decreased Trx protein levels and caused a reduction in dendritic outgrowth and branching of cultured neurons. Then, primary cortical neurons were treated with the Trx inhibitor PX12 to block Trx reducing activity. Treatment with PX12 also reduced dendritic outgrowth and branching. Furthermore, PX12 treatment reduced the ratio of phosphorylated cyclic AMP response element-binding protein (CREB)/total CREB protein levels. To investigate whether CREB phosphorylation is redox regulated, SH-SY5Y cells were treated with H2O2, which reduced phosphorylated CREB protein levels and increased CREB thiol oxidation. However, treatment with CB3, a Trx-mimetic tripeptide, rescued H2O2-decreased CREB phosphorylation. Our results suggest that Trx regulates neuronal differentiation and maturation of primary mouse cortical neurons by targeting CREB neurotrophic pathway. Trx may regulate CREB activation by maintaining the cellular redox balance.

Therapeutic targeting of Ras/Raf/MAPK pathway by natural products: A systematic and mechanistic approach for neurodegeneration

BACKGROUND

Multiple dysregulated pathways are behind the pathogenesis of neurodegenerative diseases (NDDs); however, the crucial targets are still unknown. Oxidative stress, apoptosis, autophagy, and inflammation are the most dominant pathways that strongly influence neurodegeneration. In this way, targeting the Ras/Raf/mitogen-activated protein kinases (MAPKs) pathway appears to be a developing strategy for combating NDDs like Parkinson's disease, Alzheimer's disease, stroke, aging, and other NDDs. Accordingly, plant secondary metabolites have shown promising potentials for the simultaneous modulation of the Ras/Raf/MAPKs pathway and play an essential role in NDDs. MAPKs include p38 MAPK, extracellular signal-regulated kinase 1/2 (ERK 1/2), and c-Jun N-terminal kinase (JNK), which are important molecular players in neurodegeneration. Ras/Raf, which is located the upstream of MAPK pathway influences the initiation and progression of neurodegeneration and is regulated by natural products.

PURPOSE

Thus, the present study aimed to investigate the neuroprotective roles of plant- and marine-derived secondary metabolites against several NDDs through the modulation of the Ras/Raf/MAPK signaling pathway.

STUDY DESIGN AND METHODS

A systematic and comprehensive review was performed to highlight the modulatory roles of natural products on the Ras/Raf/MAPK signaling pathway in NDDs, according to the PRISMA guideline, using scholarly electronic databases, including PubMed, Scopus, and Web of Sciences. Associated reference lists were also searched for the literature review.

RESULTS

From a total of 1495 results, finally 107 articles were included in the present study. The results show that several natural compounds such as alkaloid, phenolic, terpenoids, and nanoformulation were shown to have modulatory effects on the Ras/Raf/MAPKs pathway.

CONCLUSION

Natural products are promising multi-targeted agents with on NDDs through Ras/Raf/MAPKs pathway. Nevertheless, additional and complementary studies are necessary to check its efficacy and potential side effects.

Danhong injection improves neurological function in rats with ischemic stroke by enhancing neurogenesis and activating BDNF/AKT/CREB signaling pathway

Danhong injection (DHI) is a traditional Chinese medicine injection that promotes blood circulation and removes blood stasis and has been widely used in the treatment of stroke. Many studies have focused on the mechanism of DHI in acute ischemic stroke (IS); however, few studies have thoroughly explored its role during recovery. In this study, we aimed to determine the effect of DHI on long-term neurological function recovery after cerebral ischemia and explored the related mechanisms. Middle cerebral artery occlusion (MCAO) was used to establish an IS model in rats. The efficacy of DHI was assessed using neurological severity scores, behaviors, cerebral infarction volume and histopathology. Immunofluorescence staining was performed to assess hippocampal neurogenesis. An in vitro oxygen-glucose deprivation/reoxygenation (OGD/R) cell model was constructed and western-blot analyses were performed to verify the underlying mechanisms. Our results showed that DHI treatment greatly reduced the infarct volume, promoted neurological recovery and reversed brain pathological changes. Furthermore, DHI promoted neurogenesis by increasing the migration and proliferation of neural stem cells, and enhancing synaptic plasticity. Moreover, we found that the pro-neurogenic effects of DHI were related to an increase in brain-derived neurotrophic factor (BDNF) expression and the activation of AKT/CREB, which were attenuated by ANA-12 and LY294002, the inhibitors of the BDNF receptor and PI3K. These results suggest that DHI improves neurological function by enhancing neurogenesis and activating the BDNF/AKT/CREB signaling pathways.

Anticancer potential of oroxylin A: from mechanistic insight to synergistic perspectives

Oroxylin A (OA), a well-known constituent of the root of Scutellariae plants, has been used in ethnomedicine already for centuries in treating various neoplastic disorders. However, only recent molecular studies have revealed the different mechanisms behind its action, demonstrating antiproliferative, anti-inflammatory, and proapoptotic effects, restricting also the spread of cancer cells to distant organs. A variety of cellular targets and modulated signal transduction pathways regulated by OA have been determined in diverse cells derived from different malignant tissues. In this review article, these anticancer activities are thoroughly described, representing OA as a potential lead structure for the design of novel more potent anticancer medicines. In addition, co-effects of this natural compound with conventional anticancer agents are analyzed and the advantages provided by nanotechnological methods for more efficient application of OA are discussed. In this way, OA might represent an excellent example of using ethnopharmacological knowledge for designing modern medicines.

Saffron essential oil ameliorates CUMS-induced depression-like behavior in mice via the MAPK-CREB1-BDNF signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Saffron, the dried stigma of Crocus sativus L., has a long history of use in the treatment of depression in traditional Chinese medicine and Islamic medicine. The unique aroma of saffron, primarily derived from its volatile oil, has been widely used by folk to mitigate anxiety and depression via sniffing because the aroma of saffron has a pleasant and invigorating effect.

AIM OF THE STUDY

This study aimed to investigate the antidepressant effect and the underlying mechanism of saffron essential oil (SEO) in mice exposed to chronic unpredictable mild stress (CUMS).

MATERIALS AND METHODS

In this study, compounds of SEO were identified using gas chromatography-mass spectrometry analysis, while network pharmacology was used to predict potential active compounds, antidepressant targets, and related signaling pathways of SEO. The CUMS depression model was further used to explore the therapeutic effect and possible mechanism of SEO. During the modeling period, mice were regularly administered fluoxetine (3.6 mg/kg, i.g.) or diluted SEO (2%, 4%, and 6% SEO, inhalation). The antidepressant and neuroprotective effects of SEO were evaluated by behavior tests (the open field test, the sucrose preference test, the tail suspension test, and the forced swimming test), hematoxylin-eosin staining, and Nissl staining. The enzyme-linked immunosorbent assay kits were used to measure dopamine (DA), 5-serotonin (5-HT), brain-derived neurotrophic factor (BDNF), and γ-aminobutyric acid (GABA) levels in serum. The relative abundance of Raf1, MEK1, P-ERK1/2/ERK1/2, P-CREB1/CREB1, BDNF, and P-Trk B/Trk B in the hippocampus was determined using western blot (WB).

RESULTS

According to the network pharmacology analysis, seven active SEO compounds mediated 113 targets related to depression treatment, most of which were enriched in the 5-HT synapse, calcium signaling pathway, and cAMP signaling pathway. In vivo experiments indicated that fluoxetine and SEO improved depression-like behaviors in depressed mice. The levels of 5-HT, DA, BDNF, and GABA in serum increased significantly. Histopathological examinations revealed that fluoxetine and SEO ameliorated neuronal damage in the hippocampus. WB analysis showed that the relative expressions of Raf1, MEK1, P-ERK1/2/ERK1/2, P-CREB1/CREB1, BDNF, and P-Trk B/Trk B were significantly higher in the fluoxetine and SEO groups than in the CUMS group.

CONCLUSION

Overall, these findings suggest that SEO significantly alleviates the depressive symptoms in CUMS exposed mice and partially restores hippocampal neuronal damage. Meanwhile, the best efficacy was observed in 4% SEO. Furthermore, the antidepressant mechanism of SEO is primarily dependent on the regulation of the MAPK-CREB1-BDNF signaling pathway.

Yuk-Gunja-Tang attenuates neuronal death and memory impairment via ERK/CREB/BDNF signaling in the hippocampi of experimental Alzheimer’s disease model

Yuk-Gunja-Tang (YG) is the Korean traditional medicine in East Asia for gastrointestinal disorders. In the present study, we determined the protective effects of YG on glutamate-induced cytotoxicity in HT22 hippocampal neuronal cells and mice with scopolamine-induced memory impairment. In vitro assessments were performed using a cell viability assay, flow cytometry, and Western blotting, while in vivo assessments were performed in C57BL/6 mice administered with YG for 7 days and injected with scopolamine (1 mg/kg) for 7 days. We assessed the memory function using the Y-maze, novel object recognition, and passive avoidance tests. Protein expression analyses and histological analyses were performed using hippocampal tissues. YG treatment significantly restored cell viability against glutamate-induced apoptosis. It significantly suppressed glutamate-induced reactive oxygen species accumulation and mitochondrial dysfunction. It also increased Bcl-2 protein expression and decreased HO-1 protein expression. It activated the extracellular signal-regulated kinase/cAMP response element binding protein (ERK/CREB) signaling pathway and increased the expression of brain-derived neurotrophic factor (BDNF) under excitotoxic conditions. In the scopolamine-injected mice, YG ameliorated memory impairment in the Y-maze, novel object recognition, and passive avoidance tests; restored dysfunction in the acetylcholine, acetylcholinesterase expression levels; reduced neuronal damage in Nissl staining; and increased BDNF and phosphorylated ERK and CREB levels in Western blotting and immunofluorescence staining. Thus, YG exerted neuroprotective effects by activating ERK/CREB/BDNF signaling in the hippocampus, indicating its potential cognition-enhancing effects, especially in Alzheimer’s disease.

Microbiota-Gut-Brain Axis Regulation of Adult Hippocampal Neurogenesis

The birth, maturation, and integration of new neurons in the adult hippocampus regulates specific learning and memory processes, responses to stress, and antidepressant treatment efficacy. This process of adult hippocampal neurogenesis is sensitive to environmental stimuli, including peripheral signals from certain cytokines, hormones, and metabolites, which can promote or hinder the production and survival of new hippocampal neurons. The trillions of microorganisms resident to the gastrointestinal tract, collectively known as the gut microbiota, also demonstrate the ability to modulate adult hippocampal neurogenesis. In doing so, the microbiota-gut-brain axis can influence brain functions regulated by adult hippocampal neurogenesis. Unlike the hippocampus, the gut microbiota is highly accessible to direct interventions, such as prebiotics, probiotics, and antibiotics, and can be manipulated by lifestyle choices including diet. Therefore, understanding the pathways by which the gut microbiota shapes hippocampal neurogenesis may reveal novel targets for non-invasive therapeutics to treat disorders in which alterations in hippocampal neurogenesis have been implicated. This review first outlines the factors which influence both the gut microbiome and adult hippocampal neurogenesis, with cognizance that these effects might happen either independently or due to microbiota-driven mechanisms. We then highlight approaches for investigating the regulation of adult hippocampal neurogenesis by the microbiota-gut-brain axis. Finally, we summarize the current evidence demonstrating the gut microbiota's ability to influence adult hippocampal neurogenesis, including mechanisms driven through immune pathways, microbial metabolites, endocrine signalling, and the nervous system, and postulate implications for these effects in disease onset and treatment.

Antidepressant-like activity of oroxylin A in mice models of depression: A behavioral and neurobiological characterization

Depression is a mood disorder which causes a huge economic burden to both families and societies. However, those monoamine-based antidepressants used in clinical practice have been found to have various limitations. Therefore, currently it is very necessary to explore novel antidepressant targets and medications. As a main active component extracted from Scutellariae radix, oroxylin A possesses many pharmacological functions such as anti-cancer, anti-inflammation and neuroprotection. Here, the present study aims to investigate whether oroxylin A possess antidepressant-like actions using the chronic unpredictable mild stress (CUMS) and chronic restraint stress (CRS) models of depression, forced swim test, tail suspension test, open field test, sucrose preference test, western blotting, immunofluorescence and viral-mediated gene interference. Our results revealed that treatment of oroxylin A fully prevented both the CUMS-induced and CRS-induced depressive-like behaviors in mice. Moreover, the protecting effects of oroxylin A against CUMS and CRS on mice behaviors were accompanied with a significant enhancement on the levels of brain-derived neurotrophic factor (BDNF), phosphorylated tyrosine kinase B (pTrkB), phosphorylated cAMP-response element binding protein (pCREB) and neurogenesis in the hippocampus. Furthermore, genetic knockdown of BDNF and TrkB in the hippocampus remarkably abolished the antidepressant-like efficacy of oroxylin A in both the CUMS and CRS models of depression, proving that the hippocampal BDNF-TrkB system participates in the antidepressant mechanism of oroxylin A. In summary, our findings are the first evidence showing that oroxylin A possesses potential of being an antidepressant candidate.

Cancer Chemotherapy via Natural Bioactive Compounds

BACKGROUND

Cancer-induced mortality is increasingly prevalent globally which skyrocketed the necessity to discover new/novel safe and effective anticancer drugs. Cancer is characterized by the continuous multiplication of cells in the human which is unable to control. Scientific research is drawing its attention towards naturally-derived bioactive compounds as they have fewer side effects compared to the current synthetic drugs used for chemotherapy.

OBJECTIVE

Drugs isolated from natural sources and their role in the manipulation of epigenetic markers in cancer are discussed briefly in this review article.

METHODS

With advancing medicinal plant biotechnology and microbiology in the past century, several anticancer phytomedicines were developed. Modern pharmacopeia contains at least 25% herbal-based remedy including clinically used anticancer drugs. These drugs mainly include the podophyllotoxin derivatives vinca alkaloids, curcumin, mistletoe plant extracts, taxanes, camptothecin, combretastatin, and others including colchicine, artesunate, homoharringtonine, ellipticine, roscovitine, maytanasin, tapsigargin,andbruceantin.

RESULTS

Compounds (psammaplin, didemnin, dolastin, ecteinascidin,and halichondrin) isolated from marine sources and animals such as microalgae, cyanobacteria, heterotrophic bacteria, invertebrates. They have been evaluated for their anticancer activity on cells and experimental animal models and used chemotherapy.Drug induced manipulation of epigenetic markers plays an important role in the treatment of cancer.

CONCLUSION

The development of a new drug from isolated bioactive compounds of plant sources has been a feasible way to lower the toxicity and increase their effectiveness against cancer. Potential anticancer therapeutic leads obtained from various ethnomedicinal plants, foods, marine, and microorganisms are showing effective yet realistically safe pharmacological activity. This review will highlight important plant-based bioactive compounds like curcumin, stilbenes, terpenes, other polyphenolic phyto-compounds, and structurally related families that are used to prevent/ ameliorate cancer. However, a contribution from all possible fields of science is still a prerequisite for discovering safe and effective anticancer drugs.

The effect of propofol on hypoxia- and TNF-α-mediated BDNF/TrkB pathway dysregulation in primary rat hippocampal neurons

AIMS

Hypoxia and inflammation may lead to BDNF/TrkB dysregulation and neurological disorders. Propofol is an anesthetic with neuroprotective properties. We wondered whether and how propofol affected BDNF/TrkB pathway in hippocampal neurons and astrocytes.

METHODS

Primary rat hippocampal neurons and astrocytes were cultured and exposed to propofol followed by hypoxia or TNF-α treatment. The expression of BDNF and the expression/truncation/phosphorylation of TrkB were measured. The underlying mechanisms were investigated.

RESULTS

Hypoxia and TNF-α reduced the expression of BDNF, which was reversed by pretreatment of 25 μM propofol in hippocampal neurons. Furthermore, hypoxia and TNF-α increased the phosphorylation of ERK and phosphorylation of CREB at Ser142, while reduced the phosphorylation of CREB at Ser133, which were all reversed by 25 μM propofol and 10 μM ERK inhibitor. In addition, hypoxia or TNF-α did not affect TrkB expression, truncation, or phosphorylation in hippocampal neurons and astrocytes. However, in hippocampal neurons, 50 μM propofol induced TrkB phosphorylation, which may be mediated by p35 expression and Cdk5 activation, as suggested by the data showing that blockade of p35 or Cdk5 expression mitigated propofol-induced TrkB phosphorylation.

CONCLUSIONS

Propofol modulated BDNF/TrkB pathway in hippocampal neurons via ERK/CREB and p35/Cdk5 under the condition of hypoxia or TNF-α exposure.

Metabolite profiling reveals organ-specific flavone accumulation in Scutellaria and identifies a scutellarin isomer isoscutellarein 8-O-β-glucuronopyranoside

Scutellaria is a genus of plants containing multiple species with well-documented medicinal effects. S. baicalensis and S. barbata are among the best-studied Scutellaria species, and previous works have established flavones to be the primary source of their bioactivity. Recent genomic and biochemical studies with S. baicalensis and S. barbata have advanced our understanding of flavone biosynthesis in Scutellaria. However, as over several hundreds of Scutellaria species occur throughout the world, flavone biosynthesis in most species remains poorly understood. In this study, we analyzed organ-specific flavone profiles of seven Scutellaria species, including S. baicalensis, S. barbata, and two species native to the Americas (S. wrightii to Texas and S. racemosa to Central and South America). We found that the roots of almost all these species produce only 4'-deoxyflavones, while 4'-hydroxyflavones are accumulated exclusively in their aerial parts. On the other hand, S. racemosa and S. wrightii also accumulated high levels of 4'-deoxyflavones in their aerial parts, different with the flavone profiles of S. baicalensis and S. barbata. Furthermore, our metabolomics and NMR study identified the accumulation of isoscutellarein 8-O-β-glucuronopyranoside, a rare 4'-hydroxyflavone, in the stems and leaves of several Scutellaria species including S. baicalensis and S. barbata, but not in S. racemosa and S. wrightii. Distinctive organ-specific metabolite profiles among Scutellaria species indicate the selectivity and diverse physiological roles of flavones.

Neuroregenerative Potential of Prenyl- and Pyranochalcones: A Structure-Activity Study

Loss of neuronal tissue is a hallmark of age-related neurodegenerative diseases. Since adult neurogenesis has been confirmed in the human brain, great interest has arisen in substances stimulating the endogenous neuronal regeneration mechanism based on adult neural stem cells. Medicinal plants are a valuable source of neuroactive small molecules. In the structure-activity study presented here, the activities of prenyl- and pyranochalcones were compared to each other, using a differentiation assay based on the doublecortin promoter sequences. The latter revealed that the pyrano ring is a crucial structural element for the induction of neuronal differentiation of adult neural stem cells, while compounds with a prenyl group show significantly lower activities. Furthermore, a decrease of pro-differentiation activity was observed following structural modifications, such as substitutions on the pyrano ring and on the B-ring of the chalcone. We also initiated the elucidation of the structural characteristics of the newly discovered lead substance xanthohumol C, which correlated with the activation of the doublecortin promoter during neuronal differentiation.

Effects of an Oroxylum indicum Extract (Sabroxy®) on Cognitive Function in Adults With Self-reported Mild Cognitive Impairment: A Randomized, Double-Blind, Placebo-Controlled Study

Background: Oroxylum indicum has been used in traditional Ayurvedic medicine for the prevention and treatment of several diseases and may have neuroprotective effects.

Purpose: Examine the effects of Oroxylum indicum on cognitive function in older adults with self-reported cognitive complaints.

Study Design: Two-arm, parallel-group, 12-week, randomized, double-blind, placebo-controlled trial.

Methods: Eighty-two volunteers received either 500 mg, twice daily of a standardized Oroxylum indicum extract or placebo. Outcome measures included several computer-based cognitive tasks, the Control, Autonomy, Self-Realization, and Pleasure scale (CASP-19), Cognitive Failures Questionnaire (CFQ), and the Montreal Cognitive Assessment (MoCA). Changes in the concentration of brain-derived neurotrophic factor (BDNF) were also examined.

Results: Compared to the placebo, Oroxylum indicum was associated with greater improvements in episodic memory, and on several computer-based cognitive tasks such as immediate word recall and numeric working memory, and a faster rate of learning on the location learning task. However, there were no other significant differences in performance on the other assessed cognitive tests, the MoCA total score, or other self-report questionnaires. BDNF concentrations increased significantly in both groups, with no statistically-significant between-group differences. Oroxylum indicum was well tolerated except for an increased tendency for mild digestive complaints and headaches.

Conclusion: The results of this first human trial on the cognitive-enhancing effects of Oroxylum indicum suggest that it is a promising herbal candidate for the improvement of cognitive function in older adults with self-reported cognitive complaints.

Learning, Neurogenesis, and Effects of Flavonoids on Learning

Learning and memory are two of our mind's most magical abilities. Different brain regions have roles in processing and storing different types of memories. The hippocampus is the part of the brain responsible for receiving information and storing it in the neocortex. One of the most impressive characteristics of the hippocampus is its capacity for neurogenesis, which is a process in which new neurons are produced and then transformed into mature neurons and finally integrated into neural circuits. The neurogenesis process in the hippocampus, an example of neuroplasticity in the adult brain, is believed to aid hippocampal-dependent learning and memory. New neurons are constantly produced in the hippocampus and integrated into the pre-existing neuronal network; this allows old memories already stored in the neocortex to be removed from the hippocampus and replaced with new ones. Factors affecting neurogenesis in the hippocampus may also affect hippocampal-dependent learning and memory. The flavonoids can particularly exert powerful actions in mammalian cognition and improve hippocampal-dependent learning and memory by positively affecting hippocampal neurogenesis.

Low-intensity pulsed ultrasound for regenerating peripheral nerves: potential for penile nerve

Peripheral nerve damage, such as that found after surgery or trauma, is a substantial clinical challenge. Much research continues in attempts to improve outcomes after peripheral nerve damage and to promote nerve repair after injury. In recent years, low-intensity pulsed ultrasound (LIPUS) has been studied as a potential method of stimulating peripheral nerve regeneration. In this review, the physiology of peripheral nerve regeneration is reviewed, and the experiments employing LIPUS to improve peripheral nerve regeneration are discussed. Application of LIPUS following nerve surgery may promote nerve regeneration and improve functional outcomes through a variety of proposed mechanisms. These include an increase of neurotrophic factors, Schwann cell (SC) activation, cellular signaling activations, and induction of mitosis. We searched PubMed for articles related to these topics in both in vitro and in vivo animal research models. We found numerous studies, suggesting that LIPUS following nerve surgery promotes nerve regeneration and improves functional outcomes. Based on these findings, LIPUS could be a novel and valuable treatment for nerve injury-induced erectile dysfunction.

Neuroprotective Effect of Cudrania tricuspidata Fruit Extracts on Scopolamine-Induced Learning and Memory Impairment

Cudrania tricuspidata has diverse biological activities, such as antioxidant, anti-inflammatory, anticancer, and neuroprotective effects. This study investigated the protective effects of C. tricuspidata fruit extracts (CTFE) against scopolamine (SCO)-induced neuron impairment. The neuroprotective effects of CTFE on SCO-induced memory dysfunction were confirmed in mice using the Barnes maze test. The results showed that co-treatment of SCO and CTFE increased the stay time in the target zone compared with SCO treatment alone. Similarly, the results obtained by the fear conditioning test revealed that SCO-CTFE co-treatment induced the freezing action time under both the contextual fear condition and the cued fear condition compared with SCO treatment alone. Moreover, we showed that CTFE reduced the SCO-induced acetylcholinesterase (AChE) activity, thereby increasing the acetylcholine concentration in mice hippocampal tissues. Consistent with the improvement of memory and recognition function in vivo, our in vitro results showed that CTFE induced cAMP response element binding protein (CREB) and extracellular regulated kinase 1/2 (ERK1/2) activity in PC12 cells and reduced SCO-induced AChE activity. In addition, the microarray results of the hippocampal tissue support our data showing that CTFE affects gene expressions associated with neurogenesis and neuronal cell differentiation markers such as spp1 and klk6. Overall, CTFE exerts a neuroprotective effect via regulation of the CREB and ERK1/2 signaling pathways and could be a therapeutic candidate for neurodegenerative diseases.

Potential role of TrkB agonist in neuronal survival by promoting CREB/BDNF and PI3K/Akt signaling in vitro and in vivo model of 3-nitropropionic acid (3-NP)-induced neuronal death

Striatal neurons depends on an afferent supply of brain-derived neurotrophic factor-(BDNF) that explicitly interacts with tropomyosin receptor kinase B (TrkB) receptor and performs sundry functions including synaptic plasticity, neuronal differentiation and growth. Therefore, we aimed to scrutinize an active molecule that functions identical to BDNF in activating TrkB receptor and it's downstream targets for restoring neuronal survival in Huntington disease (HD). Data from in vitro Neuro-2a cell line showed that treatment with 7,8-dihydroxyflavone (7,8-DHF), improved 3-nitropropionic acid (3-NP) induced neuronal death by stabilizing the loss of mitochondrial membrane potential and transiently increased the activity of cAMP-response element-binding protein (CREB) and BDNF via TrkB receptor activation. Consistent with in vitro findings, our in vivo results stated that treatment with 7,8-DHF at a dose of 10 mg/kg body weight ameliorated various behavior alterations caused by 3-NP intoxication. Further histopathological and electron microscopy evidences from striatal region of 3-NP mice brain treated with 7,8-DHF showed more improved neurons with intact mitochondria and less autophagic vacuoles. Protein expression analysis of both in vitro and in vivo study showed that 7,8-DHF promotes neuronal survival through upregulation and phosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt at serine-473/threonine-308). Akt phosphorylation additionally phosphorylates Bad at serine-136 and inhibits its translocation to mitochondria thereby promoting mitochondrial biogenesis, enhanced ATP production and inhibit apoptosis mediated neuronal death. These aforementioned findings help in strengthening our hypothesis and has come up with a novel neuroprotective mechanism of 7,8-DHF against 3-NP induced neuronal death.

Exercise Plus Pharmacological Neuromodulation of Synaptic Inhibition Enhance Motor Function Recovery After Ischemic Stroke

The objective of this study was to examine the interactive effects of exercise and low-level inhibition of GABA_A receptors on the recovery of motor function and BDNF expression in the primary motor cortex (M1) of a stroke rat model. Male Sprague-Dawley rats were divided into five groups: sham (SHAM), control (CON), exercise (EX), bicuculline (BIC), and bicuculline plus exercise (BICEX) groups. All rats, except those in the SHAM group, underwent middle cerebral artery occlusion (MCAO) surgery to induce an ischemic stroke. GABA_A receptor antagonist, bicuculline (0.25 mg/kg, i.p.), was administered to the BIC and BICEX groups. The EX and BICEX groups exercised on a treadmill (11 m/min for 30 min). Each intervention started 3 days after the MCAO surgery and was carried out every day for 2 weeks. Following the intervention, bilateral M1 BDNF mRNA and protein expression levels were assessed using qRT-PCR and ELISA. Marginal recovery was found in the EX and BIC groups, whereas motor function recovery was enhanced with exercise in the presence of BIC administration specifically in the BICEX group. Furthermore, BDNF protein level in the ipsilateral M1 was significantly higher in the BICEX group than in other groups. This study indicated that exercise combined with low-level inhibition of GABA_A receptors after stroke could facilitate the recovery of motor function accompanied by BDNF upregulation in the ipsilateral M1. Therefore, this study provides a novel insight of pharmacological neuromodulation into stroke rehabilitation.

Painful neurotrophins and their role in visceral pain

Beyond their well-known role in embryonic development of the central and peripheral nervous system, neurotrophins, particularly nerve growth factor and brain-derived neurotrophic factor, exert an essential role in pain production and sensitization. This has mainly been studied within the framework of somatic pain, and even antibodies (tanezumab and fasinumab) have recently been developed for their use in chronic somatic painful conditions, such as osteoarthritis or low back pain. However, data suggest that neurotrophins also exert an important role in the occurrence of visceral pain and visceral sensitization. Visceral pain is a distressing symptom that prompts many consultations and is typically encountered in both 'organic' (generally inflammatory) and 'functional' (displaying no obvious structural changes in routine clinical evaluations) disorders of the gut, such as inflammatory bowel disease and irritable bowel syndrome, respectively. The present review provides a summary of neurotrophins as a molecular family and their role in pain in general and addresses recent investigations of the involvement of nerve growth factor and brain-derived neurotrophic factor in visceral pain, particularly that associated with inflammatory bowel disease and irritable bowel syndrome.

The pharmacogenetics of natural products: A pharmacokinetic and pharmacodynamic perspective

Natural products have represented attractive alternatives for disease prevention and treatment over the course of human history and have contributed to the development of modern drugs. These natural products possess beneficial efficacies as well as adverse efffects, which vary largely among individuals because of genetic variations in their pharmacokinetics and pharmacodynamics. As with other synthetic chemical drugs, the dosing of natural products can be optimized to improve efficacy and reduce toxicity according to the pharmacogenetic properties. With the emergence and development of pharmacogenomics, it is possible to discover and identify the targets/mechanisms of pharmacological effects and therapeutic responses of natural products effectively and efficiently on the whole genome level. This review covers the effects of genetic variations in drug metabolizing enzymes, drug transporters, and direct and indirect interactions with the pharmacological targets/pathways on the individual response to natural products, and provides suggestions on dosing regimen adjustments of natural products based on their pharmacokinetic and pharmacogenetic paratmeters. Finally, we provide our viewpoints on the importance and necessity of pharmacogenetic and pharmacogenomic research of natural products in natural medicine's rational development and clinical application of precision medicine.

The MEK/ERK/CREB signaling pathway is involved in atrazine induced hippocampal neurotoxicity in Sprague Dawley rats

Atrazine (ATR) is a commonly used artificial synthetic herbicide world-wide, which has been implicated as a potential threat to human health. Previous studies have demonstrated that exposure to ATR affects hippocampus-dependent learning and memory in rodents, but the exact molecular mechanism remains to be elucidated. In this study, we investigated the effect of ATR on the hippocampus of postnatal day 35 male Sprague Dawley (SD) rats administered doses of either 10 or 100 mg/kg body weight (BW)/day of ATR for a period of 30 days. A Morris water maze (MWM) test revealed that ATR treatment impaired memory performance in the spatial probe test, especially amongst the high-dose group. Moreover, analysis by electron microscopy showed that hippocampal neuron ultrastructure in the dentate gyrus (DG) and cornu ammonis 1 (CA1) sub-regions was impaired in the ATR-treated groups. Finally, a downregulation in the mRNA and protein expression levels of members of the MEK/ERK/CREB pathway and downstream factors brain-derived neurotrophic factor (BDNF) and Zif268 was observed in hippocampal tissue following ATR treatment. Taken together, these results suggest that developmental exposure to ATR is able to induce functional and morphological lesions in the hippocampus of SD rats, and that the MEK/ERK/CREB signaling pathway may be involved in this process.

Transcranial ultrasound stimulation promotes brain-derived neurotrophic factor and reduces apoptosis in a mouse model of traumatic brain injury

BACKGROUND

The protein expressions of brain-derived neurotrophic factor (BDNF) can be elevated by transcranial ultrasound stimulation in the rat brain.

OBJECTIVE

The purpose of this study was to investigate the effects and underlying mechanisms of BDNF enhancement by low-intensity pulsed ultrasound (LIPUS) on traumatic brain injury (TBI).

METHODS

Mice subjected to controlled cortical impact injury were treated with LIPUS in the injured region daily for a period of 4 days. Western blot analysis and immunohistochemistry were performed to assess the effects of LIPUS.

RESULTS

The results showed that the LIPUS treatment significantly promoted the neurotrophic factors BDNF and vascular endothelial growth factor (VEGF) at day 4 after TBI. Meanwhile, LIPUS also enhanced the phosphorylation of Tropomyosin-related kinase B (TrkB), Akt, and cAMP-response element binding protein (CREB). Furthermore, treatment with LIPUS significantly decreased the level of cleaved caspase-3. The reduction of apoptotic process was inhibited by the anti-BDNF antibody.

CONCLUSIONS

In short, post-injury LIPUS treatment increased BDNF protein levels and inhibited the progression of apoptosis following TBI. The neuroprotective effects of LIPUS may be associated with enhancements of the protein levels of neurotrophic factors, at least partially via the TrkB/Akt-CREB signaling pathway.

Colonic N-methyl-d-aspartate receptor contributes to visceral hypersensitivity in irritable bowel syndrome

BACKGROUND AND AIMS

N-methyl-d-aspartate receptor (NMDAR) in brain, spinal cord, and enteric nervous system is involved in visceral hypersensitivity. This study aimed to reveal the functional expression of NMDAR on mucosal cells in colon and to investigate the downstream signal pathway from colonic NMDAR activation to visceral hypersensitivity in irritable bowel syndrome (IBS).

METHODS

The expression of mucosal NMDAR in IBS patients and healthy controls was assessed by immunohistochemistry and Western blot and correlated with abdominal pain/discomfort scores quantified by a validated questionnaire. Electromyography recording in response to colorectal distension was recorded to measure the colonic sensitivity of mice receiving NMDA administration intracolonically. Brain-derived neurotrophic factor (BDNF) expression and extracellular signal-regulated kinase (ERK) pathway activation were examined in human colonic epithelial HT29 cells after NMDA stimulation, with or without MK801 or U0126 pretreatment.

RESULTS

A significant upregulation of mucosal NMDAR was observed in IBS patients compared with controls, which was significantly correlated with abdominal pain/discomfort scores. Intracolonic administration of NMDA in normal mice produced increased colonic sensitivity to colorectal distension and elevated expression of BDNF and activation of ERK. Activation of NMDAR in colonic epithelial HT29 cells in vitro induced increased BDNF secretion in cell supernatants and higher BDNF expression in cells, as well as elevated phosphorylated ERK.

CONCLUSIONS

This study demonstrated that the activation of mucosal NMDAR in colon may contribute to the visceral hypersensitivity in IBS, by increasing production of BDNF in an ERK-dependent pathway.

Low-level laser irradiation modulates brain-derived neurotrophic factor mRNA transcription through calcium-dependent activation of the ERK/CREB pathway

Low-level laser (LLL) irradiation has been reported to promote neuronal differentiation, but the mechanism remains unclear. Brain-derived neurotrophic factor (BDNF) has been confirmed to be one of the most important neurotrophic factors because it is critical for the differentiation and survival of neurons during development. Thus, this study aimed to investigate the effects of LLL irradiation on Bdnf messenger RNA (mRNA) transcription and the molecular pathway involved in LLL-induced Bdnf mRNA transcription in cultured dorsal root ganglion neurons (DRGNs) using Ca²⁺ imaging, pharmacological detections, RNA interference, immunocytochemistry assay, Western blot, and qPCR analysis. We show here that LLL induced increases in the [Ca²⁺] _i level, Bdnf mRNA transcription, cAMP-response element-binding protein (CREB) phosphorylation, and extracellular signal-regulated kinase (ERK) phosphorylation, mediated by Ca²⁺ release via inositol triphosphate receptor (IP3R)-sensitive calcium (Ca²⁺) stores. Blockade of Ca²⁺ increase suppressed Bdnf mRNA transcription, CREB phosphorylation, and ERK phosphorylation. Downregulation of phosphorylated (p)-CREB reduced Bdnf mRNA transcription triggered by LLL. Furthermore, blockade of ERK using PD98059 inhibitor reduced p-CREB and Bdnf mRNA transcription induced by LLL. Taken together, these findings establish the Ca²⁺-ERK-CREB cascade as a potential signaling pathway involved in LLL-induced Bdnf mRNA transcription. To our knowledge, this is the first report of the mechanisms of Ca²⁺-dependent Bdnf mRNA transcription triggered by LLL. These findings may help further explore the complex molecular signaling networks in LLL-triggered nerve regeneration in vivo and may also provide experimental evidence for the development of LLL for clinical applications.

Fast-acting antidepressants rapidly stimulate ERK signaling and BDNF release in primary neuronal cultures

Recent preclinical and clinical studies demonstrate that three functionally different compounds, the NMDA receptor channel blocker ketamine, mGlu_2/3 receptor antagonist LY341495, and NMDA receptor glycine site agent GLYX-13 produce rapid and long lasting antidepressant effects. Furthermore, these agents are reported to stimulate ERK and mTORC1 signaling in brain. Here we used rat primary cortical culture neurons to further examine the cellular actions of these agents. The results demonstrate that low concentrations of all three compounds rapidly increase levels of the phosphorylated and activated forms of ERK and a downstream target of mTORC1, p70S6 kinase, in a concentration and time dependent manner. In addition, each compound rapidly increases BDNF release into the culture media. Further studies demonstrate that induction of BDNF release, as well as stimulation of phospho-ERK is blocked by incubation with an AMPA receptor antagonist. The requirement for AMPA receptor stimulation suggests that the effects of these rapid agents are activity dependent. This possibility is supported by studies demonstrating that neuronal silencing, via incubation with the GABA_A receptor agonist muscimol, completely blocks phospho-ERK and BDNF release by each agent. Finally, incubation with each drug for 24 h increases the number and length of neuronal branches. Together, the results demonstrate that these three different rapid acting antidepressant agents increase ERK signaling and BDNF release in an activity dependent manner that leads to increased neuronal complexity. Further studies will be required to determine the exact mechanisms underlying these effects in cultured neurons and in rodent models.

Overview of Oroxylin A: A Promising Flavonoid Compound

Oroxylin A is one of the main active components extracted from Scutellariae radix. It has been proved that oroxylin A possesses a broad spectrum of pharmacological functions, including anti-cancer, antiinflammation, neuroprotective, anti-coagulation and so on. The pharmacological activity of oroxylin A has been studied in vitro and on animal models, which reflected its promising potency in disease treatment. This review aims to recapitulate the pharmacological function and the molecular mechanisms of oroxylin A, as well as its sources, extraction, synthesis and toxicity study. These data confirmed the therapeutic potential of oroxylin A and provided reference for further development. Copyright © 2016 John Wiley & Sons, Ltd.

Modulating adult neurogenesis through dietary interventions

Three areas in the brain continuously generate new neurons throughout life: the subventricular zone lining the lateral ventricles, the dentate gyrus in the hippocampus and the median eminence in the hypothalamus. These areas harbour neural stem cells, which contribute to neural repair by generating daughter cells that then become functional neurons or glia. Impaired neurogenesis leads to detrimental consequences, such as depression, decline of cognitive abilities and obesity. Adult neurogenesis is a versatile process that can be modulated either positively or negatively by many effectors, external or endogenous. Diet can modify neurogenesis both ways, either directly by ways of food-borne molecules, or possibly by the modifications induced on gut microbiota composition. It is therefore critical to define dietary strategies optimal for the maintenance of the stem cell pools.

Plant Natural Product Puerarin Ameliorates Depressive Behaviors and Chronic Pain in Mice with Spared Nerve Injury (SNI)

Simultaneous relief of the pain from body and brain remains an ongoing challenge. The aim of the present study was to clarify whether plant-derived isoflavone puerarin could ameliorate comorbid depression and pain. We investigated the effects of puerarin on depressive-like behaviors and neuropathic pain in C57BL/6 N mice with spared nerve injury (SNI). After SNI surgery, mice were allowed to recover spontaneously for 7 days and subsequently treated with puerarin, anti-depressant citalopram, and analgesic ibuprofen, alone or in combination, for 8 or 14 days. Forced swim test and tail suspension test were used to assess depressive-like behaviors, whereas von Frey filament test was used to estimate the sensitivity to the mechanical stimulation. Our results suggested that puerarin effectively ameliorated depression and pain in SNI mice although citalopram exhibited anti-depressant activity. In contrast, ibuprofen showed lesser activities against SNI-induced depression and pain. Further mechanistic studies revealed the uniqueness of puerarin as follows: (1) puerarin did not recover SNI-induced depletion of reduced glutathione and loss of superoxide dismutase (SOD), whereas citalopram and ibuprofen showed somewhat antioxidant activities; (2) puerarin markedly promoted the activation of CREB pathway although puerarin and citalopram activated ERK pathway to the same extent; (3) puerarin rapidly and persistently induced brain-derived neurotrophic factor (BDNF) expression whereas citalopram only induced BDNF expression after a prolonged stimulation. Collectively, these results suggest that puerarin may ameliorate the SNI-induced depression and pain via activating ERK, CREB, and BDNF pathways. Puerarin may serve as new lead compound for the development of novel therapeutics for depression and pain comorbidity.

Regulation mechanism of peptides derived from sea cucumber (Apostichopus japonicas) for modulation of learning and memory

Peptides derived from the sea cucumber Apostichopus japonicas have immunomodulatory and antioxidant activities. Three dosage levels of peptide hydrolysates were fed to Institute of Cancer Research (ICR) mice. Standardized Y and Morris water mazes were used to determine the effects of A. japonicas peptides on learning and memory. All 3 mouse test groups showed reductions in the latency period (LP), the number of times that a mouse swam over the location of a platform (NCP), the ratio of the distance from a target quadrant to the total swimming distance (DTQ), and the time spent in the target quadrant (TTQ). Microarray analysis was then carried out and 308 genes were differentially expressed between groups, of which 235 were up and 73 were down regulated in the brains of test group animals, compared with control group animals. Expressions of genes identified in microarrays were then analyzed using qRT-PCR.

Citalopram Ameliorates Synaptic Plasticity Deficits in Different Cognition-Associated Brain Regions Induced by Social Isolation in Middle-Aged Rats

Our previous experiments demonstrated that social isolation (SI) caused AD-like tau hyperphosphorylation and spatial memory deficits in middle-aged rats. However, the underlying mechanisms of SI-induced spatial memory deficits remain elusive. Middle-aged rats (10 months) were group or isolation reared for 8 weeks. Following the initial 4-week period of rearing, citalopram (10 mg/kg i.p.) was administered for 28 days. Then, pathophysiological changes were assessed by performing behavioral, biochemical, and pathological analyses. We found that SI could cause cognitive dysfunction and decrease synaptic protein (synaptophysin or PSD93) expression in different brain regions associated with cognition, such as the prefrontal cortex, dorsal hippocampus, ventral hippocampus, amygdala, and caudal putamen, but not in the entorhinal cortex or posterior cingulate. Citalopram could significantly improve learning and memory and partially restore synaptophysin or PSD93 expression in the prefrontal cortex, hippocampus, and amygdala in SI rats. Moreover, SI decreased the number of dendritic spines in the prefrontal cortex, dorsal hippocampus, and ventral hippocampus, which could be reversed by citalopram. Furthermore, SI reduced the levels of BDNF, serine-473-phosphorylated Akt (active form), and serine-9-phosphorylated GSK-3β (inactive form) with no significant changes in the levels of total GSK-3β and Akt in the dorsal hippocampus, but not in the posterior cingulate. Our results suggest that decreased synaptic plasticity in cognition-associated regions might contribute to SI-induced cognitive deficits, and citalopram could ameliorate these deficits by promoting synaptic plasticity mainly in the prefrontal cortex, dorsal hippocampus, and ventral hippocampus. The BDNF/Akt/GSK-3β pathway plays an important role in regulating synaptic plasticity in SI rats.

Danggui-Jakyak-San enhances hippocampal long-term potentiation through the ERK/CREB/BDNF cascade

ETHNOPHARMACOLOGICAL RELEVANCE

Danggui-Jakyak-San (DJS), a traditional herbal prescription, has long been used to treat gerontological disorders due to insufficient blood supply.

AIM OF THE STUDY

Previously, we reported that DJS increased hippocampal neurogenesis and enhanced learning and memory. However, the precise mechanism of DJS and its effects on learning and memory are still not well understood. In this study, we investigated the effect of DJS on hippocampal long-term potentiation (LTP), a cellular mechanism thought to underlie learning and memory.

MATERIALS AND METHODS

To understand the effect of DJS on LTP, we used acute mouse hippocampal slices and delivered one train of high frequency stimulation (100 Hz, 100 pulses). Western blots were used to analyze the changes in protein levels induced by DJS. Morris water maze test was used to evaluate the effect of DJS on spatial long-term memory.

RESULTS

DJS enhanced LTP in the Schaffer-collateral pathway of the hippocampus in a concentration-dependent manner. Extracellular signal-regulated kinase 1/2 (ERK1/2) and cAMP response element-binding protein (CREB) were activated by DJS. Moreover, brain-derived neurotropic factor (BDNF) was also increased by DJS. Blockade of ERK1/2 activation with PD198306 blocked the DJS-induced activation of the ERK1/2/CREB/BDNF cascade and LTP enhancement. In vivo, DJS improved spatial long-term memory and upregulated the hippocampal CREB/BDNF cascade.

CONCLUSION

These results suggest that DJS enhances hippocampal LTP and spatial memory through the ERK/CREB/BDNF cascade.

Cognitive effects following acute wild blueberry supplementation in 7- to 10-year-old children

PURPOSE

Previously, anthocyanin-rich blueberry treatments have shown positive effects on cognition in both animals and human adults. However, little research has considered whether these benefits transfer to children. Here we describe an acute time-course and dose-response investigation considering whether these cognitive benefits extend to children.

METHODS

Using a double-blind cross-over design, on three occasions children (n = 21; 7-10 years) consumed placebo (vehicle) or blueberry drinks containing 15 or 30 g freeze-dried wild blueberry (WBB) powder. A cognitive battery including tests of verbal memory, word recognition, response interference, response inhibition and levels of processing was performed at baseline, and 1.15, 3 and 6 h following treatment.

RESULTS

Significant WBB-related improvements included final immediate recall at 1.15 h, delayed word recognition sustained over each period, and accuracy on cognitively demanding incongruent trials in the interference task at 3 h. Importantly, across all measures, cognitive performance improved, consistent with a dose-response model, with the best performance following 30 g WBB and the worst following vehicle.

CONCLUSION

Findings demonstrate WBB-related cognitive improvements in 7- to 10-year-old children. These effects would seem to be particularly sensitive to the cognitive demand of task.

Liraglutide Promotes Cortical Neurite Outgrowth via the MEK-ERK Pathway

Liraglutide is the glucagon-like peptide-1 (GLP-1) synthetic form which has been approved by the US Food and Drug Administration to be released onto the market. The metabolic benefits of incretin hormone as an anti-diabetic agent are widely recognized, but its potential extra-pancreatic effects of GLP-1 analog (liraglutide) in the central nerve system are less well known. To this purpose, we used immunofluorescence method to examine the effect of liraglutide on neurite outgrowth in primary cortical neuron culture by measuring neurite length and confirmed the promotion effect. Then, we investigated the potential mechanisms and found that liraglutide promoted neurite outgrowth in a dose-dependant manner, and this effect could be partially inhibited by MEK-ERK inhibitor U0126. Besides, liraglutide induced an increase of p-ERK/ERK expression, which could be blocked in the presence of U0126. Similarly, phosphorylated transcription factor (p-CREB) level shared the same trend with p-ERK/ERK ratio after liraglutide treatment. Collectively, our data illustrated that that liraglutide exerts neurotrophin-like activity partly via MEK-ERK pathway, which might offer a novel idea for treatment of axon-associated neurological diseases.

cAMP-mediated secretion of brain-derived neurotrophic factor in developing airway smooth muscle

Moderate hyperoxic exposure in preterm infants contributes to subsequent airway dysfunction and to risk of developing recurrent wheeze and asthma. The regulatory mechanisms that can contribute to hyperoxia-induced airway dysfunction are still under investigation. Recent studies in mice show that hyperoxia increases brain-derived neurotrophic factor (BDNF), a growth factor that increases airway smooth muscle (ASM) proliferation and contractility. We assessed the mechanisms underlying effects of moderate hyperoxia (50% O2) on BDNF expression and secretion in developing human ASM. Hyperoxia increased BDNF secretion, but did not alter endogenous BDNF mRNA or intracellular protein levels. Exposure to hyperoxia significantly increased [Ca2+]i responses to histamine, an effect blunted by the BDNF chelator TrkB-Fc. Hyperoxia also increased ASM cAMP levels, associated with reduced PDE4 activity, but did not alter protein kinase A (PKA) activity or adenylyl cyclase mRNA levels. However, 50% O2 increased expression of Epac2, which is activated by cAMP and can regulate protein secretion. Silencing RNA studies indicated that Epac2, but not Epac1, is important for hyperoxia-induced BDNF secretion, while PKA inhibition did not influence BDNF secretion. In turn, BDNF had autocrine effects of enhancing ASM cAMP levels, an effect inhibited by TrkB and BDNF siRNAs. Together, these novel studies suggest that hyperoxia can modulate BDNF secretion, via cAMP-mediated Epac2 activation in ASM, resulting in a positive feedback effect of BDNF-mediated elevation in cAMP levels. The potential functional role of this pathway is to sustain BDNF secretion following hyperoxic stimulus, leading to enhanced ASM contractility and proliferation.

Adaptive cellular stress pathways as therapeutic targets of dietary phytochemicals: focus on the nervous system

During the past 5 decades, it has been widely promulgated that the chemicals in plants that are good for health act as direct scavengers of free radicals. Here we review evidence that favors a different hypothesis for the health benefits of plant consumption, namely, that some phytochemicals exert disease-preventive and therapeutic actions by engaging one or more adaptive cellular response pathways in cells. The evolutionary basis for the latter mechanism is grounded in the fact that plants produce natural antifeedant/noxious chemicals that discourage insects and other organisms from eating them. However, in the amounts typically consumed by humans, the phytochemicals activate one or more conserved adaptive cellular stress response pathways and thereby enhance the ability of cells to resist injury and disease. Examplesof such pathways include those involving the transcription factors nuclear factor erythroid 2-related factor 2, nuclear factor-κB, hypoxia-inducible factor 1α, peroxisome proliferator-activated receptor γ, and forkhead box subgroup O, as well as the production and action of trophic factors and hormones. Translational research to develop interventions that target these pathways may lead to new classes of therapeutic agents that act by stimulating adaptive stress response pathways to bolster endogenous defenses against tissue injury and disease. Because neurons are particularly sensitive to potentially noxious phytochemicals, we focus on the nervous system but also include findings from other cell types in which actions of phytochemicals on specific signal transduction pathways have been more thoroughly studied.

Post-injury treatment with 7,8-dihydroxyflavone, a TrkB receptor agonist, protects against experimental traumatic brain injury via PI3K/Akt signaling

Tropomyosin-related kinase B (TrkB) signaling is critical for promoting neuronal survival following brain damage. The present study investigated the effects and underlying mechanisms of TrkB activation by the TrkB agonist 7,8-dihydroxyflavone (7,8-DHF) on traumatic brain injury (TBI). Mice subjected to controlled cortical impact received intraperitoneal 7,8-DHF or vehicle injection 10 min post-injury and subsequently daily for 3 days. Behavioral studies, histology analysis and brain water content assessment were performed. Levels of TrkB signaling-related molecules and apoptosis-related proteins were analyzed. The protective effect of 7,8-DHF was also investigated in primary neurons subjected to stretch injury. Treatment with 20 mg/kg 7,8-DHF attenuated functional deficits and brain damage up to post-injury day 28. 7,8-DHF also reduced brain edema, neuronal death, and apoptosis at day 4. These changes were accompanied by a significant decrease in cleaved caspase-3 and increase in Bcl-2/Bax ratio. 7,8-DHF enhanced phosphorylation of TrkB, Akt (Ser473/Thr308), and Bad at day 4, but had no effect on Erk 1/2 phosphorylation. Moreover, 7,8-DHF increased brain-derived neurotrophic factor levels and promoted cAMP response element-binding protein (CREB) activation. This beneficial effect was attenuated by inhibition of TrkB or PI3K/Akt. 7,8-DHF also promoted survival and reduced apoptosis in cortical neurons subjected to stretch injury. Remarkably, delayed administration of 7,8-DHF at 3 h post-injury reduced brain tissue damage. Our study demonstrates that activation of TrkB signaling by 7,8-DHF protects against TBI via the PI3K/Akt but not Erk pathway, and this protective effect may be amplified via the PI3K/Akt-CREB cascades.

A new bis-seco-abietane diterpenoid from Hyptis crenata Pohl ex Benth

A new, highly oxidized, bis-seco-abietane diterpenoid named hyptisolide A (1) was isolated from Hyptis crenata Pohl ex Benth. Its structure and stereochemistry were elucidated on the basis of data obtained by HRESIMS, NMR, and X-ray diffraction analyses, and its absolute configuration was determined with vibrational circular dichroism spectroscopy. By reporter gene assay, 1 was demonstrated to induce cAMP-responsive element-dependent transcription in Neuro2A cells.

Oroxylin A enhances memory consolidation through the brain-derived neurotrophic factor in mice

Memory consolidation is a process by which acquired information is transformed from a labile into a more stable state that can be retrieved at a later time. In the present study, we investigated the role of oroxylin A on the memory consolidation process in mice. Oroxylin A improved the memory retention administered at 0 h, 1 h and 3 h after training in a passive avoidance task, suggesting that oroxylin A facilitates memory consolidation. Oroxylin A increased mature brain-derived neurotrophic factor (mBDNF) levels in the hippocampus from 6h to 24h after administration. Moreover, 3h post-training administration of oroxylin A enhanced the mBDNF level at 9h after the acquisition trial compared to the level at 6h after the acquisition trial. However, 6h post-training administration of oroxylin A did not increase the mBDNF level at 9h after the acquisition trial. Blocking mBDNF signaling with recombinant tropomyosin receptor kinase B (TrkB)-Fc or k252a at 9h after the acquisition trial obstructed the effect of oroxylin A on memory consolidation. Taken together, our data suggest that oroxylin A facilitates memory consolidation through BDNF-TrkB signaling and confirms that the increase of BDNF in a specific time window plays a crucial role in memory consolidation.

Systems pharmacology dissection of multi-scale mechanisms of action for herbal medicines in stroke treatment and prevention

Annually, tens of millions of first-ever strokes occur in the world; however, currently there is lack of effective and widely applicable pharmacological treatments for stroke patients. Herbal medicines, characterized as multi-constituent, multi-target and multi-effect, have been acknowledged with conspicuous effects in treating stroke, and attract extensive interest of researchers although the mechanism of action is yet unclear. In this work, we introduce an innovative systems-pharmacology method that combines pharmacokinetic prescreening, target fishing and network analysis to decipher the mechanisms of action of 10 herbal medicines like Salvia miltiorrhizae, Ginkgo biloba and Ephedrae herba which are efficient in stroke treatment and prevention. Our systematic analysis results display that, in these anti-stroke herbal medicines, 168 out of 1285 constituents with the favorable pharmacokinetic profiles might be implicated in stroke therapy, and the systematic use of these compounds probably acts through multiple mechanisms to synergistically benefit patients with stroke, which can roughly be classified as preventing ischemic inflammatory response, scavenging free radicals and inhibiting neuronal apoptosis against ischemic cerebral damage, as well as exhibiting lipid-lowering, anti-diabetic, anti-thrombotic and antiplatelet effects to decrease recurrent strokes. Relying on systems biology-based analysis, we speculate that herbal medicines, being characterized as the classical combination therapies, might be not only engaged in multiple mechanisms of action to synergistically improve the stroke outcomes, but also might be participated in reducing the risk factors for recurrent strokes.

Induction of GDNF and BDNF by hRheb(S16H) transduction of SNpc neurons: neuroprotective mechanisms of hRheb(S16H) in a model of Parkinson's disease

The transduction of dopaminergic (DA) neurons with human ras homolog enriched in brain, which has a S16H mutation [hRheb(S16H)] protects the nigrostriatal DA projection in the 6-hydroxydopamine (6-OHDA)-treated animal model of Parkinson's disease (PD). However, it is still unclear whether the expression of active hRheb induces the production of neurotrophic factors such as glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF), which are involved in neuroprotection, in mature neurons. Here, we show that transduction of nigral DA neurons with hRheb(S16H) significantly increases the levels of phospho-cyclic adenosine monophosphate (cAMP) response element-binding protein (p-CREB), GDNF, and BDNF in neurons, which are attenuated by rapamycin, a specific inhibitor of mammalian target of rapamycin complex 1 (mTORC1). Moreover, treatment with specific neutralizing antibodies for GDNF and BDNF reduced the protective effects of hRheb(S16H) against 1-methyl-4-phenylpyridinium (MPP(+))-induced neurotoxicity. These results show that activation of hRheb/mTORC1 signaling pathway could impart to DA neurons the important ability to continuously produce GDNF and BDNF as therapeutic agents against PD.