Activations of GABAergic signaling, HSP70 and MAPK cascades are involved in baicalin's neuroprotection against gerbil global ischemia/reperfusion injury

GABAergic system and chloride cotransporters as potential therapeutic targets to mitigate cell death in ischemia

Gamma aminobutyric acid (GABA) is a critical inhibitory neurotransmitter in the central nervous system that plays a vital role in modulating neuronal excitability. Dysregulation of GABAergic signaling, particularly involving the cotransporters NKCC1 and KCC2, has been implicated in various pathologies, including epilepsy, schizophrenia, autism spectrum disorder, Down syndrome, and ischemia. NKCC1 facilitates chloride influx, whereas KCC2 mediates chloride efflux via potassium gradient. Altered expression and function of these cotransporters have been associated with excitotoxicity, inflammation, and cellular death in ischemic events characterized by reduced cerebral blood flow, leading to compromised tissue metabolism and subsequent cell death. NKCC1 inhibition has emerged as a potential therapeutic approach to attenuate intracellular chloride accumulation and mitigate neuronal damage during ischemic events. Similarly, targeting KCC2, which regulates chloride efflux, holds promise for improving outcomes and reducing neuronal damage under ischemic conditions. This review emphasizes the critical roles of GABA, NKCC1, and KCC2 in ischemic pathologies and their potential as therapeutic targets. Inhibiting or modulating the activity of these cotransporters represents a promising strategy for reducing neuronal damage, preventing excitotoxicity, and improving neurological outcomes following ischemic events. Furthermore, exploring the interactions between natural compounds and NKCC1/KCC2 provides additional avenues for potential therapeutic interventions for ischemic injury.

Neurotoxic and cytoprotective mechanisms in the ischemic neocortex

Neuronal damage in ischemic stroke occurs due to permanent imbalance between the metabolic needs of the brain and the ability of the blood-vascular system to maintain glucose delivery and adequate gas exchange. Oxidative stress and excitotoxicity trigger complex processes of neuroinflammation, necrosis, and apoptosis of both neurons and glial cells. This review summarizes data on the structural and chemical changes in the neocortex and main cytoprotective effects induced by focal ischemic stroke. We focus on the expression of neurotrophins (NT) and molecular and cellular changes in neurovascular units in ischemic brain. We also discuss how these factors affect the apoptosis of cortical cells. Ischemic damage involves close interaction of a wide range of signaling molecules, each acting as an efficient marker of cell state in both the ischemic core and penumbra. NTs play the main regulatory role in brain tissue recovery after ischemic injury. Heterogeneous distribution of the BDNF, NT-3, and GDNF immunoreactivity is concordant with the selective response of different types of cortical neurons and glia to ischemic injury and allows mapping the position of viable neurons. Astrocytes are the central link in neurovascular coupling in ischemic brain by providing other cells with a wide range of vasotropic factors. The NT expression coincides with the distribution of reactive astrocytes, marking the boundaries of the penumbra. The development of ischemic stroke is accompanied by a dramatic change in the distribution of GDNF reactivity. In early ischemic period, it is mainly observed in cortical neurons, while in late one, the bulk of GDNF-positive cells are various types of glia, in particular, astrocytes. The proportion of GDNF-positive astrocytes increases gradually throughout the ischemic period. Some factors that exert cytoprotective effects in early ischemic period may display neurotoxic and pro-apoptotic effects later on. The number of apoptotic cells in the ischemic brain tissue correlates with the BDNF levels, corroborating its protective effects. Cytoprotection and neuroplasticity are two lines of brain protection and recovery after ischemic stroke. NTs can be considered an important link in these processes. To develop efficient pharmacological therapy for ischemic brain injury, we have to deepen our understanding of neurochemical adaptation of brain tissue to acute stroke.

Baicalein prevents stress-induced anxiety behaviors in zebrafish model

Baicalein is a flavonoid mainly obtained from plants with wide range of biological activities, including neuroprotection. An acute and unexpected chronic stress (UCS) protocol has recently been adapted to zebrafish, a popular vertebrate model in brain research. The present study was aimed to evaluate baicalein's anti-anxiety potential in a zebrafish model by induction, which included neuropharmacological evaluation to determine behavioural parameters in the novel tank diving test (NTDT) and light-dark preference test (LDPT). The toxicity was also assessed using the brine shrimp lethality assay, and the 50% lethal concentration (LC50) was determined. The animals were then stressed for 7 days before being treated with different doses of baicalein (1 and 2 mg/L) for another 7 days in UCS condition. Due to acute stress and UCS, the frequency of entries and time spent in the 1) top region and 2) light area of the novel tank reduced significantly, indicating the existence of elevated anxiety levels. The biological activity of baicalein was demonstrated by its high LC50 values (1,000 μg/ml). Additionally, baicalein administration increased the frequency of entries and duration spent in the light region, indicating a significant decrease in anxiety levels. Overall, the present results showed that baicalein has a therapeutic advantage in reversing the detrimental consequences of UCS and acute stress, making it is a promising lead molecule for new drug design, development, and therapy for stress.

Phenolics as GABAA Receptor Ligands: An Updated Review

Natural products can act as potential GABA modulators, avoiding the undesirable effects of traditional pharmacology used for the inhibition of the central nervous system such as benzodiazepines (BZD). Phenolics, especially flavonoids and phlorotannins, have been considered as modulators of the BZD-site of GABA_A receptors (GABA_ARs), with sedative, anxiolytic or anticonvulsant effects. However, the wide chemical structural variability of flavonoids shows their potential action at more than one additional binding site on GABA_ARs, which may act either negatively, positively, by neutralizing GABA_ARs, or directly as allosteric agonists. Therefore, the aim of the present review is to compile and discuss an update of the role of phenolics, namely as pharmacological targets involving dysfunctions of the GABA system, analyzing both their different compounds and their mechanism as GABAergic modulators. We focus this review on articles written in English since the year 2010 until the present. Of course, although more research would be necessary to fully establish the type specificity of phenolics and their pharmacological activity, the evidence supports their potential as GABA_AR modulators, thereby favoring their inclusion in the development of new therapeutic targets based on natural products. Specifically, the data compiled in this review allows for the directing of future research towards ortho-dihydroxy diterpene galdosol, the flavonoids isoliquiritigenin (chalcone), rhusflavone and agathisflavone (biflavonoids), as well as the phlorotannins, dieckol and triphlorethol A. Clinically, flavonoids are the most interesting phenolics due to their potential as anticonvulsant and anxiolytic drugs, and phlorotannins are also of interest as sedative agents.

Evaluation of botanicals as potential COVID-19 symptoms terminator

Information about the coronavirus disease 2019 (COVID-19) pandemic is still evolving since its appearance in December 2019 and has affected the whole world. Particularly, a search for an effective and safe treatment for COVID-19 continues. Botanical mixtures contain secondary metabolites (such as flavonoids, phenolics, alkaloids, essential oils etc.) with many therapeutic effects. In this study, the use of herbal treatments against COVID-19 was evaluated. Medical synthetic drugs focus mainly on respiratory symptoms, however herbal therapy with plant extracts may be useful to relieve overall symptoms of COVID-19 due to the variety of bioactive ingredients. Since COVID-19 is a virus that affects the respiratory tract, the antiviral effects of botanicals/plants against respiratory viruses have been examined through clinical studies. Data about COVID-19 patients revealed that the virus not only affects the respiratory system but different organs including the gastrointestinal (GI) system. As GI symptoms seriously affect quality of life, herbal options that might eliminate these problems were also evaluated. Finally, computer modeling studies of plants and their active compounds on COVID-19 were included. In summary, herbal therapies were identified as potential options for both antiviral effects and control of COVID-19 symptoms. Further data will be needed to enlighten all aspects of COVID-19 pathogenesis, before determining the effects of plants on severe acute respiratory syndrome coronavirus 2.

Unusual Bioactive Compounds with Antioxidant Properties in Adjuvant Therapy Supporting Cognition Impairment in Age-Related Neurodegenerative Disorders

Cognitive function decline is strictly related to age, resulting in the loss of the ability to perform daily behaviors and is a fundamental clinical neurodegeneration symptom. It has been proven that an adequate diet, comprehensive nutrition, and a healthy lifestyle may significantly inhibit neurodegenerative processes, improving cognitive functions. Therefore, intensive research has been conducted on cognitive-enhancing treatment for many years, especially with substances of natural origin. There are several intervention programs aimed at improving cognitive functions in elderly adults. Cognitive functions depend on body weight, food consumed daily, the quality of the intestinal microflora, and the supplements used. The effectiveness in the prevention of dementia is particularly high before the onset of the first symptoms. The impact of diet and nutrition on age-associated cognitive decline is becoming a growing field as a vital factor that may be easily modified, and the effects may be observed on an ongoing basis. The paper presents a review of the latest preclinical and clinical studies on the influence of natural antioxidants on cognitive functions, with particular emphasis on neurodegenerative diseases. Nevertheless, despite the promising research results in animal models, the clinical application of natural compounds will only be possible after solving a few challenges.

Baicalein, Baicalin, and Wogonin: Protective Effects against Ischemia-Induced Neurodegeneration in the Brain and Retina

Ischemia is a common pathological condition present in many neurodegenerative diseases, including ischemic stroke, retinal vascular occlusion, diabetic retinopathy, and glaucoma, threatening the sight and lives of millions of people globally. Ischemia can trigger excessive oxidative stress, inflammation, and vascular dysfunction, leading to the disruption of tissue homeostasis and, ultimately, cell death. Current therapies are very limited and have a narrow time window for effective treatment. Thus, there is an urgent need to develop more effective therapeutic options for ischemia-induced neural injuries. With emerging reports on the pharmacological properties of natural flavonoids, these compounds present potent antioxidative, anti-inflammatory, and antiapoptotic agents for the treatment of ischemic insults. Three major active flavonoids, baicalein, baicalin, and wogonin, have been extracted from Scutellaria baicalensis Georgi (S. baicalensis); all of which are reported to have low cytotoxicity. They have been demonstrated to exert promising pharmacological capabilities in preventing cell and tissue damage. This review focuses on the therapeutic potentials of these flavonoids against ischemia-induced neurotoxicity and damage in the brain and retina. The bioactivity and bioavailability of baicalein, baicalin, and wogonin are also discussed. It is with hope that the therapeutic potential of these flavonoids can be utilized and developed as natural treatments for ischemia-induced injuries of the central nervous system (CNS).

Natural Products for Neurodegeneration: Regulating Neurotrophic Signals

Neurodegenerative disorders (NDs) are heterogeneous groups of ailments typically characterized by progressive damage of the nervous system. Several drugs are used to treat NDs but they have only symptomatic benefits with various side effects. Numerous researches have been performed to prove the advantages of phytochemicals for the treatment of NDs. Furthermore, phytochemicals such as polyphenols might play a pivotal role in rescue from neurodegeneration due to their various effects as anti-inflammatory, antioxidative, and antiamyloidogenic agents by controlling apoptotic factors, neurotrophic factors (NTFs), free radical scavenging system, and mitochondrial stress. On the other hand, neurotrophins (NTs) including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT4/5, and NT3 might have a crucial neuroprotective role, and their diminution triggers the development of the NDs. Polyphenols can interfere directly with intracellular signaling molecules to alter brain activity. Several natural products also improve the biosynthesis of endogenous genes encoding antiapoptotic Bcl-2 as well as NTFs such as glial cell and brain-derived NTFs. Various epidemiological studies have demonstrated that the initiation of these genes could play an essential role in the neuroprotective function of dietary compounds. Hence, targeting NTs might represent a promising approach for the management of NDs. In this review, we focus on the natural product-mediated neurotrophic signal-modulating cascades, which are involved in the neuroprotective effects.

Anti-inflammatory and immunomodulatory effects of baicalin in cerebrovascular and neurological disorders

Inflammatory responses play an extraordinary role in the pathogenesis of cerebrovascular and neurological disorders. Baicalin is one of the important flavonoids, which is extracted from Scutellaria baicalensis Georgi. Recently, numerous in vivo and in vitro studies have shown that baicalin has salutary effects for anti-inflammatory and immunomodulatory and has been demonstrated to exert beneficial therapeutic properties in cerebrovascular and neurological diseases. In this review, we aim to discuss that baicalin exerts anti-inflammatory effects through multiple pathways and targets, thus affecting the production of a variety of inflammatory cytokines and neuroprotective process of neurological diseases; furthermore, the related targets of the anti-inflammatory effects of baicalin were analyzed via using the tools of network pharmacology, to provide theoretical basis and innovative ideas for the future clinical application of baicalin.

Preparation, Characterization and in vivo Study of Borneol-Baicalin-Liposomes for Treatment of Cerebral Ischemia-Reperfusion Injury

Purpose

Baicalin (BA) has a good neuroprotective effect, but it is eliminated quickly in the body and does not easily reach the brain. In this experiment, borneol (BO) was used as an auxiliary drug to prepare borneol-baicalin-liposomes (BO-BA-LP) to prolong the efficacy time of BA, synergistically synergize, introduce drugs into the brain, and better exert the therapeutic effect on cerebral ischemia-reperfusion (I/R) injury.

Methods

Through single-factor inspection and response surface optimization analysis, obtained the best preparation process of BO-BA-LP and characterized by various analytical techniques. Validated the long-term effectiveness of BA-BO-LP through pharmacokinetic studies and conducted pharmacodynamic studies on the middle cerebral artery occlusion (MCAO) rat model to verify the therapeutic effect of BO-BA-LP on cerebral I/R injury.

Results

The optimum preparation conditions of BO-BA-LP were as follows: the dosage of BO was 9.55 mg, the ratio of phospholipid to drug was 4.02:1, the ratio of phospholipid to cholesterol was 7.25:1, the entrapment efficiency (EE) was 41.49%, and the drug loading (DL) was 4.29%. The particle size range of the liposomes was 167.1 nm, and the polydispersity index (PDI) range was 0.113. The results of pharmacokinetic experiments showed that the combination of BA and BO liposomes effectively improved the pharmacokinetic parameters of BA and prolonged the half-life of BA. Pharmacodynamic studies have found that, compared with BA-LP, BO-BA-LP can significantly improve neurological deficits, cerebral infarction volume, and brain pathological states on MCAO rats.

Conclusion

These results demonstrated that BO-BA-LP can improve the circulation of drugs in the blood, and the addition of BO can enhance the therapeutic effect of BA and effectively improve cerebral I/R.

Curcumin Effects on Memory Impairment and Restoration of Irregular Neuronal Distribution in the Hippocampal CA1 Region After Global Cerebral Ischemia in Male Rats

Introduction:

Global Cerebral Ischemia (GCI) causes neuronal damage with subsequent neurological and cognitive impairments. Curcumin has anti-inflammatory, antioxidant, and neuroprotective properties, which makes it a potential candidate for improving GCI-induced impairments. This study aimed to investigate the effects of curcumin on the neurological and memory deficits, as well as spatial neuronal distribution in the Cornu Ammonis 1 region after GCI in rats.

Methods:

56 Sprague-Dawley male rats were randomly assigned into 4 groups of sham (n=14), control (n=14), curcumin 50 mg/kg (n=14), and curcumin 100 mg/kg (n=14). Each group was divided into the two subgroups of short-term (7 days) and long-term (28 days) treatment periods. The Neurological Severity Score (NSS), passive avoidance task, and the traction test were performed at postoperative days of 0, 1, 2, 3, 7, 14, 21, and 28. The novel object recognition test and Voronoi tessellation were carried out on days 7 and 28 after GCI.

Results:

Curcumin 100 mg/kg significantly decreased neurological severity score on postoperative days of 7 and 28 compared with the control (P<0.001) and curcumin 50 mg/kg groups (P<0.05–P<0.001), respectively. Also, curcumin 100 mg/kg significantly increased step-through latency times on postoperative days of 3–28 and 14–28 compared with the control (P<0.05–P<0.001) and curcumin 50 mg/kg groups (P<0.01–P<0.001). Moreover, it increased the novelty preference index during the novel object recognition test in the 28-day treatment subgroup after GCI. Curcumin (100 mg/kg) could maintain the neuronal aggregation in the CA1 region after GCI at a level near to what is generally observed in normal rats.

Conclusion:

Curcumin could improve memory and neurological deficits and restore irregular neuronal distribution in the CA1 region after GCI in a time-dependent manner, and its higher dose was more effective than its lower dose. Curcumin may have beneficial effects on reducing brain complications after ischemia.

Neuroprotection of multifunctional phytochemicals as novel therapeutic strategy for neurodegenerative disorders: antiapoptotic and antiamyloidogenic activities by modulation of cellular signal pathways

In neurodegenerative disorders, including Alzheimer's and Parkinson's disease, neuroprotection by diet and natural bioactive compounds has been proposed to prevent the onset and progress of neurodegeneration by modification of pathogenic factors. Plant food-derived phytochemicals protect neurons via targeting oxidative stress, mitochondrial dysfunction, neurotrophic factor deficit, apoptosis and abnormal protein accumulation. This review presents the molecular mechanism of neuroprotection by phytochemicals: direct regulation of mitochondrial apoptotic machinery, modification of cellular signal pathways, induction of antiapoptotic Bcl-2 protein family and prosurvival neurotrophic factors, such as brain- and glial cell line-derived neurotrophic factor, and prevention of protein aggregation. Multitargeted neuroprotective agents are under development based on the structure of blood–brain barrier-permeable phytochemicals to ameliorate brain dysfunction and prevent neurodegeneration.

The flavonoid baicalin improves glucose metabolism by targeting the PH domain of AKT and activating AKT/GSK3β phosphorylation

Baicalin is one of the main flavonoids of the dried root of Scutellaria baicalensis Georgi and is reported to exert beneficial effects on the regulation of glucose/lipid metabolism. However, understanding its specific target and unique mechanism for improving glucose utilization is a challenge. In this paper, target fishing with a baicalin probe reveals that baicalin interacts with AKT. An immunofluorescence assay further demonstrates the colocalization of baicalin with AKT in the cytoplasm. A competitive test and virtual docking show that baicalin might bind to the pleckstrin homology domain of AKT. This specific binding hampers AKT membrane translocation, activates the phosphorylation of AKT on Ser473, induces the downstream glycogen synthase kinase 3β activation, and affects glycogen synthesis.

A comprehensive review on phytochemistry, pharmacology, and flavonoid biosynthesis of Scutellaria baicalensis

CONTEXT

Scutellaria baicalensis Georgi (Lamiaceae) is a popular medicinal plant. Its roots are used as the famous traditional Chinese medicine Huang-Qin, which is recorded in Chinese Pharmacopoeia, European Pharmacopoeia, and British Pharmacopoeia.

OBJECTIVE

This review comprehensively summarizes research progress in phytochemistry, pharmacology, and flavonoid biosynthesis of S. baicalensis.

METHODS

English and Chinese literature from 1973 to March 2018 was collected from databases including Web of Science, SciFinder, PubMed, Elsevier, Baidu Scholar (Chinese), and CNKI (Chinese). Scutellaria baicalensis, chemical constituents, phytochemistry, biological activities, and biosynthesis were used as the key words.

RESULTS

A total of 126 small molecules (1-126) and 6 polysaccharides have been isolated from S. baicalensis. The small molecules can be classified into four structural types, namely, free flavonoids, flavonoid glycosides, phenylethanoid glycosides, and other small molecules. Extracts of S. baicalensis and its major chemical constituents have been reported to possess anti-viral, anti-tumor, anti-bacterial, antioxidant, anti-inflammatory, hepatoprotective, and neuroprotective activities. Key steps in the biosynthetic pathways of Scutellaria flavonoids have also been summarized.

CONCLUSIONS

This article could be helpful for researchers who are interested in the chemical constituents, bioactivities, biosynthesis, and clinical applications of S. baicalensis.

Neuroprotective and Cognitive Enhancement Potentials of Baicalin: A Review

Neurodegenerative diseases are a heterogeneous group of disorders that are characterized by the gradual loss of neurons. The development of effective neuroprotective agents to prevent and control neurodegenerative diseases is specifically important. Recently, there has been an increasing interest in selecting flavonoid compounds as potential neuroprotective agents, owing to their high effectiveness with low side effects. Baicalin is one of the important flavonoid compounds, which is mainly isolated from the root of Scutellaria baicalensis Georgi (an important Chinese medicinal herb). In recent years, a number of studies have shown that baicalin has a potent neuroprotective effect in various in vitro and in vivo models of neuronal injury. In particular, baicalin effectively prevents neurodegenerative diseases through various pharmacological mechanisms, including antioxidative stress, anti-excitotoxicity, anti-apoptotic, anti-inflammatory, stimulating neurogenesis, promoting the expression of neuronal protective factors, etc. This review mainly focuses on the neuroprotective and cognitive enhancement effects of baicalin. The aim of the present review is to compile all information in relation to the neuroprotective and cognitive enhancement effects of baicalin and its molecular mechanisms of action in various in vitro and in vivo experimental models.

NKCC1 Inhibition Attenuates Chronic Cerebral Hypoperfusion-Induced White Matter Lesions by Enhancing Progenitor Cells of Oligodendrocyte Proliferation

Cerebral white matter is vulnerable to ischemic condition. However, no effective treatment to alleviate or restore the myelin damage caused by chronic cerebral hypoperfusion has been found. Na⁺-K⁺-Cl^- cotransporter 1 (NKCC1), a Na⁺-K⁺-Cl^- cotransporter widely expressed in the central nervous system (CNS), involves in regulation of cell swelling, EAA release, cell apoptosis, and proliferation. Nevertheless, the role of NKCC1 in chronic hypoperfusion-induced white matter lesions (WMLs) has not been explored. Here, mice subjected to bilateral common carotid artery stenosis (BCAS) were used as model of chronic cerebral hypoperfusion; density of progenitor cells of oligodendrocyte (OPCs), oligodendrocytes (OLs), astrocytes, and microglia was assessed by immunofluorescent staining and Western blot analysis; working memory was examined by eight-arm radial maze test; expression of MAPK signaling pathway was determined by Western blot analysis. After BCAS, white matter integrity disruption and working memory impairment were observed. NKCC1 inhibition by bumetanide administration enhanced OPC proliferation, attenuated chronic hypoperfusion-induced white matter damage, and promoted recovery of neurological function. However, NKCC1 inhibition caused no significant change in the densities of GFAP- and Iba-1-positive cells in the corpus callosum. Bumetanide administration significantly increased the expression of p-ERK and decreased the expression of p-JNK and p-p38 in comparison to vehicle-BCAS groups. In conclusion, NKCC1 inhibition might significantly ameliorate chronic cerebral hypoperfusion-induced WMLs and cognitive impairment by enhancing progenitor cells of oligodendrocyte proliferation, and this protective function of bumetanide might be mediated by modulation of the MAPK signaling pathway.

Extracellular elevation of adrenomedullin, a gene associated with schizophrenia, suppresses heat shock protein 1A/1B mRNA

Several recent gene expression studies on schizophrenia, including one using monozygotic twins discordant for the disease, have reported the upregulation of adrenomedullin (ADM), which was initially identified as a vasodilator hormone. It has been hypothesized that upregulation of ADM may be a susceptibility factor for schizophrenia, although the exact role of ADM in the central nervous system remains unclear. In this study, we used a microarray analysis to investigate the changes in global gene expression induced by the administration of exogenous ADM in SK-N-SH cells, which allowed us to evaluate the effects of elevated ADM on the central nervous system. A quantitative reverse-transcription PCR study showed that the levels of HSPA1A/1B mRNA, another gene that has been associated with schizophrenia, were significantly suppressed after exogenous ADM treatment. These results indicate that elevated ADM may be involved in the etiology of schizophrenia through the regulation of heat shock protein signaling.

Effect of baicalin on oxygen-glucose deprivation-induced endothelial cell damage

Baicalin, a plant-derived flavonoid, has been reported to exert neuroprotective effects on ischemia-like or excitotoxic injury. To confirm this function and explore the possible mechanism, we investigated the protective effect of baicalin on an in-vitro model of ischemia (oxygen-glucose deprivation-treated endothelial cell). In the present study, we found that baicalin (100 μM) inhibited cell death, reduced cell membrane damage, and maintained the integrity of the nucleus. Flow cytometric analysis and Hoechst 33258/propidium iodide double staining results showed that the necroptosis ratio decreased with baicalin treatment. Western blot analysis showed that baicalin regulated the expression of RIP-1 and RIP-3 in bEnd.3 cells and the use of detection kits showed that baicalin inhibited the production of reactive oxygen species and malondialdehyde, and increased the activity of superoxide dismutase in oxygen-glucose deprivation-treated bEnd.3 cells. These results indicated that baicalin effectively alleviated the oxidative stress, decreased the proportion of cells undergoing necrosis, and reduced cell damage.

Systematic Understanding of the Mechanism of Baicalin against Ischemic Stroke through a Network Pharmacology Approach

Ischemic stroke is accompanied by high mortality and morbidity rates. At present, there is no effective clinical treatment. Alternatively, traditional Chinese medicine has been widely used in China and Japan for the treatment of ischemic stroke. Baicalin is a flavonoid extracted from Scutellaria baicalensis that has been shown to be effective against ischemic stroke; however, its mechanism has not been fully elucidated. Based on network pharmacology, we explored the potential mechanism of baicalin on a system level. After obtaining baicalin structural information from the PubChem database, an approach combined with literature mining and PharmMapper prediction was used to uncover baicalin targets. Ischemic stroke-related targets were gathered with the help of DrugBank, Online Mendelian Inheritance in Man (OMIM), Genetic Association Database (GAD), and Therapeutic Target Database (TTD). Protein-protein interaction (PPI) networks were constructed through the Cytoscape plugin BisoGenet and analyzed by topological methods. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were carried out via the Database for Annotation, Visualization, and Integrated Discovery (DAVID) server. We obtained a total of 386 potential targets and 5 signaling pathways, including mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT), hypoxia-inducible factor-1 (HIF-1), nuclear factor kappa B (NF-κB), and forkhead box (FOXO) signaling pathways. GO analysis showed that these targets were associated with antiapoptosis, antioxidative stress, anti-inflammation, and other physiopathological processes that are involved in anti-ischemic stroke effects. In summary, the mechanism of baicalin against ischemic stroke involved multiple targets and signaling pathways. Our study provides a network pharmacology framework for future research on traditional Chinese medicine.

Baicalin reverses the impairment of synaptogenesis induced by dopamine burden via the stimulation of GABAAR-TrkB interaction in minimal hepatic encephalopathy

BACKGROUND

It has been reported that D1 receptor (D₁R) activation reduces GABA_A receptor (GABA_AR) current, and baicalin (BAI) displays therapeutic efficacy in diseases involving cognitive impairment.

METHODS

We investigated the mechanisms by which BAI could improve DA-induced minimal hepatic encephalopathy (MHE) using immunoblotting, immunofluorescence, and co-immunoprecipitation.

RESULTS

BAI did not induce toxicity on the primary cultured neurons. And no obvious toxicity of BAI to the brain was found in rats. DA activated D₁R/dopamine and adenosine 3'5'-monophosphate-regulated phospho-protein (DARPP32) to reduce the GABA_AR current; BAI treatment did not change the D₁R/DARPP32 levels but blocked DA-induced reduction of GABA_AR levels in primary cultured neurons. DA decreased the interaction of GABA_AR with TrkB and the expression of downstream AKT, which was blocked by BAI treatment. Moreover, BAI reversed the decrease in the expression of GABA_AR/TrkB/AKT and prevented the impairment of synaptogenesis and memory deficits in MHE rats.

CONCLUSIONS

These results suggest that BAI has neuroprotective and synaptoprotective effects on MHE which are not related to upstream D₁R/DARPP32 signaling, but to the targeting of downstream GABA_AR signaling to TrkB.

Neuroprotective effect of baicalin on focal cerebral ischemia in rats

Baicalin, a flavonoid compound from the root of the herb Scutellaria baicalensis Georgi, has been widely used to treat patients with inflammatory disease. The aim of this study was to assess the efficacy of baicalin in a rat model of focal cerebral ischemia. Adult male Sprague-Dawley rat models of cerebral artery occlusion were established and then randomly and equally divided into three groups: ischemia (cerebral ischemia and reperfusion), valproic acid (cerebral ischemia and reperfusion + three intraperitoneal injections of valproic acid; positive control), and baicalin (cerebral ischemia and reperfusion + intraperitoneal injection of baicalin for 21 days). Neurological deficits were assessed using the postural reflex test and forelimb placing test at 3, 7, 14, and 21 days after ischemia. Rat cerebral infarct volume was measured using 2,3,5-triphenyltetrazolium chloride (TTC) staining method. Pathological change of ischemic brain tissue was assessed using hematoxylin-eosin staining. In the baicalin group, rat neurological function was obviously improved, cerebral infarct volume was obviously reduced, and the pathological impairment of ischemic brain tissue was obviously alleviated compared to the ischemia group. Cerebral infarct volume was similar in the valproic acid and baicalin groups. These findings suggest that baicalin has a neuroprotective effect on cerebral ischemia.

The Effects of Baicalin and Baicalein on Cerebral Ischemia: A Review

Ischemic stroke, producing a high mortality and morbidity rate, is a common clinical disease. Enhancing the prevention and control of ischemic stroke is particularly important. Baicalin and its aglycon baicalein are flavonoids extracted from Scutellaria baicalensis, an important traditional Chinese herb. In recent years, a growing body of evidences has shown that baicalin and baicalein could be effective in the treatment of cerebral ischemia. Pharmacokinetic studies have shown that baicalin could penetrate the blood-brain barrier and distribute in cerebral nuclei. Through a variety of in vitro and in vivo models of ischemic neuronal injury, numerous studies have demonstrated that baicalin and baicalein have salutary effect for neuroprotection. Especially, the studies on the pharmacological mechanism showed that baicalin and baicalein have several pharmacological activities, which include antioxidant, anti-apoptotic, anti-inflammatory and anti-excitotoxicity effects, protection of the mitochondria, promoting neuronal protective factors expression and adult neurogenesis effects and many more. This review focuses on the neuroprotective effects of baicalin and baicalein in ischemia or stroke-induced neuronal cell death. We aimed at collecting all important information regarding the neuroprotective effect and its pharmacological mechanism of baicalin and baicalein in various in vivo and in vitro experimental models of ischemic neuronal injury.

Neurotrophic function of phytochemicals for neuroprotection in aging and neurodegenerative disorders: modulation of intracellular signaling and gene expression

Bioactive compounds in food and beverages have been reported to promote health and prevent age-associated decline in cognitive, motor and sensory activities, and emotional function. Phytochemicals, a ubiquitous class of plant secondary metabolites, protect neuronal cells by interaction with cellular activities, in addition to the antioxidant and anti-inflammatory function. In aging and age-associated neurodegenerative disorders, phytochemicals protect neuronal cells by neurotrophic factor-mimic activity, in addition to suppression of apoptosis signaling in mitochondria. This review presents the cellular mechanisms underlying anti-apoptotic function and neurotrophic function of phytochemicals in the brain. Phytochemicals bind to receptors of neurotrophic factors, and also receptors for γ-aminobutyric acid, acetylcholine, serotonin, and glutamate and estrogen, and activate downstream signal pathways. Phytochemicals also directly intervene intracellular signaling molecules to modify the brain function. Finally, phytochemicals enhance the endogenous biosynthesis of genes coding anti-apoptotic Bcl-2 and neurotrophic factors, such as brain-derived and glial cell line-derived neurotrophic factor. The gene induction may play a major role in the neuroprotective function of dietary compounds shown by epidemiological studies. Quantitative measurement of neurotrophic factors induced by phytochemicals in the serum, cerebrospinal fluid, and other clinical samples is proposed as a surrogate assay method to evaluate the neuroprotective potency. Development of novel neuroprotective compounds is expected among compounds chemically synthesized from the brain-permeable basic structure of phytochemicals.

Remote ischemic preconditioning protects liver ischemia-reperfusion injury by regulating eNOS-NO pathway and liver microRNA expressions in fatty liver rats

BACKGROUND

Ischemic preconditioning (IPC) is a strategy to reduce ischemia-reperfusion (I/R) injury. The protective effect of remote ischemic preconditioning (RIPC) on liver I/R injury is not clear. This study aimed to investigate the roles of RIPC in liver I/R in fatty liver rats and the involvement of endothelial nitric oxide synthase-nitric oxide (eNOS-NO) pathway and microRNA expressions in this process.

METHODS

A total of 32 fatty rats were randomly divided into the sham group, I/R group, RIPC group and RIPC+I/R group. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and nitric oxide (NO) were measured. Hematoxylin-eosin staining was used to observe histological changes of liver tissues, TUNEL to detect hepatocyte apoptosis, and immunohistochemistry assay to detect heat shock protein 70 (HSP70) expression. Western blotting was used to detect liver inducible NOS (iNOS) and eNOS protein levels and real-time quantitative polymerase chain reaction to detect miR-34a, miR-122 and miR-27b expressions.

RESULTS

Compared with the sham and RIPC groups, serum ALT, AST and iNOS in liver tissue were significantly higher in other two groups, while serum NO and eNOS in liver tissue were lower, and varying degrees of edema, degeneration and inflammatory cell infiltration were found. Cell apoptosis number was slightly lower in the RIPC+I/R group than that in I/R group. Compared with the sham group, HSP70 expressions were significantly increased in other three groups (all P<0.05). Compared with the sham and RIPC groups, elevated miR-34a expressions were found in I/R and RIPC+I/R groups (P<0.05). MiR-122 and miR-27b were found significantly decreased in I/R and RIPC+I/R groups compared with the sham and RIPC groups (all P<0.05).

CONCLUSION

RIPC can reduce fatty liver I/R injury by affecting the eNOS-NO pathway and liver microRNA expressions.

Poly-dimensional network comparative analysis reveals the pure pharmacological mechanism of baicalin in the targeted network of mouse cerebral ischemia

AIM

This study aimed to investigate the pure pharmacological mechanisms of baicalin/baicalein (BA) in the targeted network of mouse cerebral ischemia using a poly-dimensional network comparative analysis.

METHODS

Eighty mice with induced focal cerebral ischemia were randomly divided into four groups: BA, Concha Margaritifera (CM), vehicle and sham group. A poly-dimensional comparative analysis of the expression levels of 374 stroke-related genes in each of the four groups was performed using MetaCore.

RESULTS

BA significantly reduced the ischemic infarct volume (P<0.05), whereas CM was ineffective. Two processes and 10 network nodes were shared between "BA vs CM" and vehicle, but there were no overlapping pathways. Two pathways, three processes and 12 network nodes overlapped in "BA vs CM" and BA. The pure pharmacological mechanism of BA resulted in targeting of pathways related to development, G-protein signaling, apoptosis, signal transduction and immunity. The biological processes affected by BA were primarily found to correlate with apoptotic, anti-apoptotic and neurophysiological processes. Three network nodes changed from up-regulation to down-regulation, while mitogen-activated protein kinase kinase 6 (MAP2K6, also known as MEK6) changed from down-regulation to up-regulation in "BA vs CM" and vehicle. The changed nodes were all related to cell death and development.

CONCLUSION

The pure pharmacological mechanism of BA is related to immunity, apoptosis, development, cytoskeletal remodeling, transduction and neurophysiology, as ascertained using a poly-dimensional network comparative analysis.

Clinical and Preclinical Cognitive Function Improvement after Oral Treatment of a Botanical Composition Composed of Extracts from Scutellaria baicalensis and Acacia catechu

Dementia and cognitive impairment have become the major concerns worldwide due to a significantly aging population, increasing life span and lack of effective pharmacotherapy. In light of limited pharmaceutical drug choices and the socioeconomic implications of these conditions, the search for safe and effective alternatives from natural sources has gained many attractions within the medical food and dietary supplement industry. Two polyphenol extracts derived from roots of Scutellaria baicalensis and heartwoods of Acacia catechu containing free-B-ring flavonoids and flavans, respectively, were combined into a proprietary blend called UP326. A similar bioflavonoid composition, UP446, has been reported with modulation of pathways related to systemic inflammation. To test the effect of UP326 on memory and learning, a radial arm water maze (RAWM) and contextual fear conditioning (CF) were utilized in aged F344 rats fed with UP326 at doses of 3, 7, and 34 mg/kg for 11 weeks. The 7 and 34 mg/kg dosage groups had significantly fewer errors than aged vehicle control animals and their performance was equivalent to young animal controls. In a separate human clinical trial, test subjects orally given 300 mg of UP326 BID for 30 days showed marked improvement in speed and accuracy of processing complex information in computer tasks and reduced their standard deviation of performance compared to baseline and the placebo group. This data suggest that UP326 may help maintain memory, sustain speed of processing, and reduce the number or memory errors as we age.

Quantitative Identification of Compound-Dependent On-Modules and Differential Allosteric Modules From Homologous Ischemic Networks

Module‐based methods have made much progress in deconstructing biological networks. However, it is a great challenge to quantitatively compare the topological structural variations of modules (allosteric modules [AMs]) under different situations. A total of 23, 42, and 15 coexpression modules were identified in baicalin (BA), jasminoidin (JA), and ursodeoxycholic acid (UA) in a global anti‐ischemic mice network, respectively. Then, we integrated the methods of module‐based consensus ratio (MCR) and modified Z_summary module statistic to validate 12 BA, 22 JA, and 8 UA on‐modules based on comparing with vehicle. The MCRs for pairwise comparisons were 1.55% (BA vs. JA), 1.45% (BA vs. UA), and 1.27% (JA vs. UA), respectively. Five conserved allosteric modules (CAMs) and 17 unique allosteric modules (UAMs) were identified among these groups. In conclusion, module‐centric analysis may provide us a unique approach to understand multiple pharmacological mechanisms associated with differential phenotypes in the era of modular pharmacology.

The effect of Scutellaria baicalensis stem-leaf flavonoids on spatial learning and memory in chronic cerebral ischemia-induced vascular dementia of rats

Flavonoids have been shown to improve cognitive function and delay the dementia progression. However, the underlying mechanisms remain elusive. In the present study, we examined the effect of Scutellaria baicalensis stem-leaf total flavonoids (SSTFs) extracted from S. baicalensis Georgi on spatial learning and memory in a vascular dementia (VaD) rat model and explored its molecular mechanisms. The VaD rats were developed by permanent bilateral occlusion of the common carotid artery. Seven days after recovery, the VaD rats were treated with either 50 or 100 mg/kg of SSTF for 60 days. The spatial learning and memory was evaluated in the Morris water maze (MWM) test. The tau hyperphosphorylation and the levels of the related protein kinases or phosphatases were examined by western blot analysis. In VaD rats, SSTF treatment at 100 mg/kg significantly reduced the escape latency in training trial in MWM test. In the probe trial, SSTF treatment increased the searching time and travel distance in the target quadrant. SSTF treatment inhibited the tau phosphorylation in both cortex and hippocampus in VaD rats. Meanwhile, SSTF reduced the activity of glycogen synthase kinase 3β and cyclin-dependent kinase 5 in VaD rats. In contrast, SSTF treatment increased the level of the protein phosphatase 2A subunit B in VaD rats. SSTF treatment significantly improved the spatial cognition in VaD rats. Our results suggest that SSTF may alleviate tau-hyperphosphorylation-induced neurotoxicity through coordinating the activity of kinases and phosphatase after a stroke. SSTF may be developed into promising novel therapeutics for VaD.

An Analysis of the Combination Frequencies of Constituent Medicinal Herbs in Prescriptions for the Treatment of Stroke in Korean Medicine: Determination of a Group of Candidate Prescriptions for Universal Use

In contrast to Western medicine, which typically prescribes one medicine to treat a specific disease, traditional East Asian medicine uses any one of a large number of different prescriptions (mixtures of medicinal herbs), according to the patient's characteristics. Although this can be considered an advantage, the lack of a universal prescription for a specific disease is considered a drawback of traditional East Asian medicine. The establishment of universally applicable prescriptions for specific diseases is therefore required. As a basic first step in this process, this study aimed to select prescriptions used in the treatment of stroke and, through the analysis of medicinal herb combination frequencies, select a high-frequency medicinal herb combination group for further experimental and clinical research. As a result, we selected some candidates of a medicinal herb combination and 13 candidates of a medicinal herb for the treatment of stroke.

Baicalin alleviates ischemia-induced memory impairment by inhibiting the phosphorylation of CaMKII in hippocampus

Baicalin has a significant neuroprotective effect in stroke. However, the mechanism remains unclear. This study was to reveal the mechanisms by which baicalin protected hippocampal neurons and improved learning and memory impairment after global cerebral ischemia/reperfusion in gerbil. In the present study, the Morris water maze test showed that baicalin significantly improved learning and memory impairment after global cerebral ischemia/reperfusion in gerbils. Laser scanning confocal fluorescence microscope examination showed that baicalin suppressed OGD-induced augmentation of intracellular calcium concentration. Western blotting analysis indicated that baicalin suppressed ischemia-caused elevated phosphorylation level of CaMKII in vivo, in hippocampal neurons in culture, and in SH-SY5Y cells in culture. Western blotting, TUNEL and RNA interference technology were applied to detect effects of baicalin on neuronal apoptosis. We found that baicalin, a CaMKII inhibitor and knocking down the CaMKII prevented OGD-induced apoptosis of hippocampal or SH-SY5Y cells in culture. Therefore, these results suggested that baicalin improves learning and memory impairment induced by global cerebral ischemia/reperfusion in gerbils via attenuating the phosphorylation level of CaMKII and further preventing hippocampal neuronal apoptosis.

Ischemia-Induced Changes of PRAS40 and p-PRAS40 Immunoreactivities in the Gerbil Hippocampal CA1 Region After Transient Cerebral Ischemia

Proline-rich Akt substrate of 40-kDa (PRAS40) is one of the important interactive linkers between Akt and mTOR signaling pathways. The increase of PRAS40 is related with the reduction of brain damage induced by cerebral ischemia. In the present study, we investigated time-dependent changes in PRAS40 and phospho-PRAS40 (p-PRAS40) immunoreactivities in the hippocampal CA1 region of the gerbil after 5 min of transient cerebral ischemia. PRAS40 immunoreactivity in the CA1 region was decreased in pyramidal neurons from 12 h after ischemic insult in a time-dependent manner, and, at 5 days post-ischemia, PRAS40 immunoreactivity was newly expressed in astrocytes. p-PRAS40 immunoreactivity in the CA1 pyramidal neurons was hardly found 12 h and apparently detected again 1 and 2 days after ischemic insult. At 5 days post-ischemia, p-PRAS40 immunoreactivity in the CA1 pyramidal neurons was not found. These results indicate that ischemia-induced changes in PRAS40 and p-PRAS40 immunoreactivities in CA1 pyramidal neurons and astrocytes may be closely associated with delayed neuronal death in the hippocampal CA1 region following transient cerebral ischemia.

Baicalin alleviates diabetes‑associated cognitive deficits via modulation of mitogen-activated protein kinase signaling, brain‑derived neurotrophic factor and apoptosis

Baicalin is an important active component of the medicinal herb Scutellaria baicalensis Georgi and has shown a variety of pharmacological actions. The present study aimed to evaluate the neuroprotective effects of baicalin against diabetes‑associated cognitive deficits (DACD) in rats and to elucidate the potential molecular mechanisms of action. A rat model of diabetes mellitus was prepared by intraperitoneal injection of streptozotocin. After the successful establishment of the diabetic rat model, baicalin (50, 100 and 200 mg/kg) or vehicle was administrated for seven weeks. Learning and memory function were assessed using the Morris water maze test. At the end of the experiment, the activities of acetylcholinesterase (AChE) and choline acetylase (ChAT) were determined using commercial kits. Furthermore, the expression of proteins involved in mitogen‑activated protein kinase (MAPK) cascades [extracellular signal‑regulated kinase (ERK), c‑Jun N‑terminal kinase (JNK) and p38], brain‑derived neurotrophic factor (BDNF) and apoptosis‑associated proteins [caspase‑3, B-cell lymphoma 2 (Bcl‑2) and Bcl-2-associated X protein (Bax)] were detected by western blot analysis. Caspase‑3 activity was also analyzed using a commercial kit. The results demonstrated that diabetic rats exhibited decreases in body weight, decreases in the percentage of time spent in the target quadrant and the number of times of crossing the platform in the water maze test, as well as decreases in neuronal survival, ChAT, phosphorylated (p)ERK, BDNF and Bcl‑2. Furthermore, diabetic rats showed increases in escape latency and mean path length in the water maze test, increases in the levels of hippocampal AChE, p‑JNK, p‑p38, caspase‑3 and Bax as well as plasma glucose. However, in diabetic rats treated with baicalin, all of the abovementioned observations were obviously reversed. The findings suggested that baicalin exerts neuroprotective effects against DACD via modulation of MAPK cascades, BDNF and apoptosis.

Effects of ischemic preconditioning on VEGF and pFlk-1 immunoreactivities in the gerbil ischemic hippocampus after transient cerebral ischemia

Ischemia preconditioning (IPC) displays an important adaptation of the CNS to sub-lethal ischemia. In the present study, we examined the effect of IPC on immunoreactivities of VEGF-, and phospho-Flk-1 (pFlk-1) following transient cerebral ischemia in gerbils. The animals were randomly assigned to four groups (sham-operated-group, ischemia-operated-group, IPC plus (+) sham-operated-group, and IPC+ischemia-operated-group). IPC was induced by subjecting gerbils to 2 min of ischemia followed by 1 day of recovery. In the ischemia-operated-group, a significant loss of neurons was observed in the stratum pyramidale (SP) of the hippocampal CA1 region (CA1) alone 5 days after ischemia-reperfusion, however, in all the IPC+ischemia-operated-groups, pyramidal neurons in the SP were well protected. In immunohistochemical study, VEGF immunoreactivity in the ischemia-operated-group was increased in the SP at 1 day post-ischemia and decreased with time. Five days after ischemia-reperfusion, strong VEGF immunoreactivity was found in non-pyramidal cells, which were identified as pericytes, in the stratum oriens (SO) and radiatum (SR). In the IPC+sham-operated- and IPC+ischemia-operated-groups, VEGF immunoreactivity was significantly increased in the SP. pFlk-1 immunoreactivity in the sham-operated- and ischemia-operated-groups was hardly found in the SP, and, from 2 days post-ischemia, pFlk-1 immunoreactivity was strongly increased in non-pyramidal cells, which were identified as pericytes. In the IPC+sham-operated-group, pFlk-1 immunoreactivity was significantly increased in both pyramidal and non-pyramidal cells; in the IPC+ischemia-operated-groups, the similar pattern of VEGF immunoreactivity was found in the ischemic CA1, although the VEGF immunoreactivity was strong in non-pyramidal cells at 5 days post-ischemia. In brief, our findings show that IPC dramatically augmented the induction of VEGF and pFlk-1 immunoreactivity in the pyramidal cells of the CA1 after ischemia-reperfusion, and these findings suggest that the increases of VEGF and Flk-1 expressions may be necessary for neurons to survive from transient ischemic damage.

Neurotherapeutic activity of the recombinant heat shock protein Hsp70 in a model of focal cerebral ischemia in rats

Recombinant 70 kDa heat shock protein (Hsp70) is an antiapoptotic protein that has a cell protective activity in stress stimuli and thus could be a useful therapeutic agent in the management of patients with acute ischemic stroke. The neuroprotective and neurotherapeutic activity of recombinant Hsp70 was explored in a model of experimental stroke in rats. Ischemia was produced by the occlusion of the middle cerebral artery for 45 minutes. To assess its neuroprotective capacity, Hsp70, at various concentrations, was intravenously injected 20 minutes prior to ischemia. Forty-eight hours after ischemia, rats were sacrificed and brain tissue sections were stained with 2% triphenyl tetrazolium chloride. Preliminary treatment with Hsp70 significantly reduced the ischemic zone (optimal response at 2.5 mg/kg). To assess Hsp70’s neurotherapeutic activity, we intravenously administered Hsp70 via the tail vein 2 hours after reperfusion (2 hours and 45 minutes after ischemia). Rats were then kept alive for 72 hours. The ischemic region was analyzed using a high-field 11 T MRI scanner. Administration of the Hsp70 decreased the infarction zone in a dose-dependent manner with an optimal (threefold) therapeutic response at 5 mg/kg. Long-term treatment of the ischemic rats with Hsp70 formulated in alginate granules with retarded release of protein further reduced the infarct volume in the brain as well as apoptotic area (annexin V staining). Due to its high neurotherapeutic potential, prolonged delivery of Hsp70 could be useful in the management of acute ischemic stroke.

KCC2 expression changes in Diazepam-treated neonatal rats with hypoxia-ischaemia brain damage

Hypoxia-ischaemia brain damage (HIBD) is a major type of perinatal brain injury in newborns. In this study, we investigate the short- and long-term neuroprotective effects of Diazepam on neonatal rats with HIBD and the potential mechanisms underlying its protective effects. Seven-day-old Sprague-Dawley rats were subjected to left carotid artery ligation followed by a 2-h exposure to 8% oxygen and 92% nitrogen. Diazepam was administered immediately via intraperitoneal (i.p.) injection after inducing HIBD at a dose of 10 mg kg(-1)8h(-1) for three consecutive days. Three days after HIBD, rats were decapitated, and the extent of brain injury was evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining. Additionally, the expression of Potassium-chloride cotransporter-2 (KCC2) was analysed using real-time PCR, Western blot analysis and immunohistochemistry. Three weeks after HIBD, rats were subjected to the Morris water maze (MWM) test and the locomotor activity test to determine the long-term therapeutic effects of Diazepam. We observed that the volume of infarction in the Diazepam group was significantly less (P<0.01) compared with the HIBD group. We also observed that the learning and memory abilities of the Diazepam rats improved significantly compared with the untreated rats (P<0.05) and that the decrease in KCC2 expression was prevented (P<0.01). Early treatment with Diazepam appears to attenuate HIBD and can efficiently improve the long-term learning and memory capabilities of the animal. A potential mechanism underlying these effects may involve preventing the decrease in KCC2 expression.

Scutellaria baicalensis in stroke management: nature's blessing in traditional Eastern medicine

Scutellaria baicalensis Georgi is the most widely used medicinal plant in traditional Eastern medicine, especially in Chinese medicine. The major phytochemicals isolated from S. baicalensis are flavonoids, glycosides and their glucoronides such as baicalin, baicalein, wogonin etc. More than 30 different kinds of flavonoids are isolated from this plant. S. baicalensis and its flavonoids are reported to have several pharmacological activities, which includes anti-allergic, antioxidant, anti apoptic, anti-inflammatory effects and many more. Recently, S. baicalensis and its isolated flavonoids have been studied for their neuroprotective effects, through a variety of in vitro and in vivo models of neurodegenerative diseases, plausibly suggesting that S. baicalensis has salutary effect as a nature's blessing for neuroprotection. In this review, we are focousing on the neuroprotective effects of S. baicalensis and its flavonoids in ischemia or stroke-induced neuronal cell death. We aimed at compiling all the information regarding the neuroprotective effect of S. baicalensis in various experimental models of cerebral ischemia or stroke.

Argon gas: a potential neuroprotectant and promising medical therapy

Argon is a noble gas element that has demonstrated narcotic and protective abilities that may prove useful in the medical field. The earliest records of argon gas have exposed its ability to exhibit narcotic symptoms at hyperbaric pressures greater than 10 atmospheres with more recent evidence seeking to display argon as a potential neuroprotective agent. The high availability and low cost of argon provide a distinct advantage over using similarly acting treatments such as xenon gas. Argon gas treatments in models of brain injury such as in vitro Oxygen-Glucose-Deprivation (OGD) and Traumatic Brain Injury (TBI), as well as in vivo Middle Cerebral Artery Occlusion (MCAO) have largely demonstrated positive neuroprotective behavior. On the other hand, some warning has been made to potential negative effects of argon treatments in cases of ischemic brain injury, where increases of damage in the sub-cortical region of the brain have been uncovered. Further support for argon use in the medical field has been demonstrated in its use in combination with tPA, its ability as an organoprotectant, and its surgical applications. This review seeks to summarize the history and development of argon gas use in medical research as mainly a neuroprotective agent, to summarize the mechanisms associated with its biological effects, and to elucidate its future potential.

Convergent and divergent pathways decoding hierarchical additive mechanisms in treating cerebral ischemia-reperfusion injury

INTRODUCTION

Cerebral ischemia is considered to be a highly complex disease resulting from the complicated interplay of multiple pathways. Disappointedly, most of the previous studies were limited to a single gene or a single pathway. The extent to which all involved pathways are translated into fusing mechanisms of a combination therapy is of fundamental importance.

AIMS

We report an integrative strategy to reveal the additive mechanism that a combination (BJ) of compound baicalin (BA) and jasminoidin (JA) fights against cerebral ischemia based on variation of pathways and functional communities.

RESULTS

We identified six pathways of BJ group that shared diverse additive index from 0.09 to 1, which assembled broad cross talks from seven pathways of BA and 16 pathways of JA both at horizontal and vertical levels. Besides a total of 60 overlapping functions as a robust integration background among the three groups based on significantly differential subnetworks, additive mechanism with strong confidence by networks altered functions.

CONCLUSIONS

These results provide strong evidence that the additive mechanism is more complex than previously appreciated, and an integrative analysis of pathways may suggest an important paradigm for revealing pharmacological mechanisms underlying drug combinations.

Systemic revealing pharmacological signalling pathway networks in the hippocampus of ischaemia-reperfusion mice treated with baicalin

Background. Baicalin (BA) exhibits ill understood neuroprotective, anti-inflammatory, and antioxidative effects in brain injury. Objective. To identify the differential network pathways associated with BA-related biological effects. Methods. MCAO-induced mice received BA 5 mg/Kg (BA group). Controls received vehicle only. Following ischaemia-reperfusion, ArrayTrack analysed the whole genome microarray of hippocampal genes, and MetaCore analysed differentially expressed genes. Results. Four reversing pathways were common to BA and controls, but only 6 were in the top 10 for BA. Three of the top 5 signalling pathways in controls were not observed in BA. BA treatment made absent 3 pathways of the top 5 signalling pathways from the top 5 in controls. There were 2 reversing pathways between controls and BA that showed altered gene expression. Controls had 6 networks associated with cerebral ischaemia. After BA treatment, 9 networks were associated with cerebral ischaemia. Enrichment analysis identified 10 significant biological processes in BA and controls. Of the 10 most significant molecular functions, 7 were common to BA and controls, and only 3 occurred in BA. BA and controls had 7 significant cellular components. Conclusions. This study showed that the clinical effectiveness of BA was based on the complementary effects of multiple pathways and networks.

Time-course changes in immunoreactivities of glucokinase and glucokinase regulatory protein in the gerbil hippocampus following transient cerebral ischemia

Glucose is a main energy source for normal brain functions. Glucokinase (GK) plays an important role in glucose metabolism as a glucose sensor, and GK activity is modulated by glucokinase regulatory protein (GKRP). In this study, we examined the changes of GK and GKRP immunoreactivities in the gerbil hippocampus after 5 min of transient global cerebral ischemia. In the sham-operated-group, GK and GKRP immunoreactivities were easily detected in the pyramidal neurons of the stratum pyramidale of the hippocampus. GK and GKRP immunoreactivities in the pyramidal neurons were distinctively decreased in the hippocampal CA1 region (CA), not CA2/3, 3 days after ischemia-reperfusion (I-R). Five days after I-R, GK and GKRP immunoreactivities were hardly detected in the CA1, not CA2/3, pyramidal neurons; however, at this point in time, GK and GKRP immunoreactivities were newly expressed in astrocytes, not microglia, in the ischemic CA1. In brief, GK and GKRP immunoreactivities are changed in pyramidal neurons and newly expressed in astrocytes in the ischemic CA1 after transient cerebral ischemia. These indicate that changes of GK and GKRP expression may be related to the ischemia-induced neuronal damage/death.

Expression variations of chromogranin A and α1,2,4 GABA(A)Rs in discrete limbic and brainstem areas rescue cardiovascular alterations

Recent interferences of hemodynamic functions via modified brain neuronal mechanisms have proven to be major causes of dementia and sleeping disorders. In this work, cerebral expression differences of the neuroactive vesicular chromogranin A (CgA) and distinct α GABA(A)R subunits were detected in the facultative hibernating hamster. In particular, damaged neuronal fields of hypotensive torpor (TORP) state were correlated to elevated CgA and GABA(A)R α1, α4 mRNA levels in the paraventricular hypothalamic nucleus (PVN), central amygdalar nucleus (CeA) plus solitary tractus nucleus (NTS). Conversely, few neurodegeneration signals of hypertensive arousal (AROU) state, accounted for mostly lower CgA levels in the same areas. This state also provided increased α2-containing sites in amygdala, hippocampal and NTS neurons together with elevated α4-containing receptors in the periventricular hypothalamic nucleus (Pe). Interestingly in our hibernating model, CgA appeared to preferentially feature inhibitory neurosignals as indicated by preliminary perfusion of amygdalar sites with its highly specific antihypertensive derived peptide (catestatin) promoting GABA-dependent sIPSCs. Overall, evident neuronal damages plus altered expression capacities of CgA and α1-, α2-, α4-GABA(A)Rs in CeA, Pe, PVN as well as NTS during both hibernating states corroborate for the first time key molecular switching events guaranteeing useful cardiovascular rescuing abilities of neurodegenerative disorders.

Postsynaptic density protein (PSD)-95 expression is markedly decreased in the hippocampal CA1 region after experimental ischemia-reperfusion injury

Synaptic plasticity is important for functional recovery after cerebral ischemic injury. In the present study, we investigated chronological change in the immunoreactivity of PSD-95, a kind of postsynaptic density protein, in the hippocampus proper (CA1-3 regions) after 5 min of transient cerebral ischemia in gerbils. PSD-95 immunoreactivity was observed in MAP-2-immunoreactive dendrites in the CA1-3 regions of the sham group. The PSD-95 immunoreactivity was shown as beaded structure in the MAP-2-immunoreactive dendrites. However, PSD-95 immunoreactivity began to be dramatically decreased in MAP-2-immunoreactive dendrites in the CA1 region, not CA2-3 region, at early time after ischemia-reperfusion. At 5 days after ischemia-reperfusion, MAP-2 immunoreactivity almost disappeared in the ischemic CA1 region, and PSD-95 immunoreactivity was much lower than that in the sham group. In brief, PSD-95 immunoreactivity in the CA1 dendrites was markedly decreased at early time after ischemia-reperfusion. We suggest that decreased PSD-95 immunoreactivity in the ischemic CA1 region may lead to a deficit of postsynaptic plasticity in the brain.