Physiological synaptic activity and recognition memory require astroglial glutamine.

Presynaptic glutamate replenishment is fundamental to brain function. In high activity regimes, such as epileptic episodes, this process is thought to rely on the glutamate-glutamine cycle between neurons and astrocytes. However the presence of an astroglial glutamine supply, as well as its functional relevance in vivo in the healthy brain remain controversial, partly due to a lack of tools that can directly examine glutamine transfer. Here, we generated a fluorescent probe that tracks glutamine in live cells, which provides direct visual evidence of an activity-dependent glutamine supply from astroglial networks to presynaptic structures under physiological conditions. This mobilization is mediated by connexin43, an astroglial protein with both gap-junction and hemichannel functions, and is essential for synaptic transmission and object recognition memory. Our findings uncover an indispensable recruitment of astroglial glutamine in physiological synaptic activity and memory via an unconventional pathway, thus providing an astrocyte basis for cognitive processes.

The protective effect of Centella asiatica and its constituent, araliadiol on neuronal cell damage and cognitive impairment.

Alzheimer's disease (AD) is characterized by progressive cognitive decline, and the number of affected individuals has increased worldwide. However, there are no effective treatments for AD. Therefore, it is important to prevent the onset of dementia. Oxidative stress and endoplasmic reticulum (ER) stress are increased in the brains of AD patients, and are postulated to induce neuronal cell death and cognitive dysfunction. In this study, Centella asiatica, a traditional Indian medicinal herb, were fractionated and compared for their protective effects against glutamate and tunicamycin damage. Araliadiol was identified as a component from the fraction with the highest activity. Further, murine hippocampal cells (HT22) were damaged by glutamate, an oxidative stress inducer. C. asiatica and araliadiol suppressed cell death and reactive oxygen species production. HT22 cells were also injured by tunicamycin, an ER stress inducer. C. asiatica and araliadiol prevented cell death by mainly inhibiting PERK phosphorylation; additionally, C. asiatica also suppressed the expression levels of GRP94 and BiP. In Y-maze test, oral administration of araliadiol (10 mg/kg/day) for 7 days ameliorated the arm alternation ratio in mice with scopolamine-induced cognitive impairment. These results suggest that C. asiatica and its active component, araliadiol, have neuroprotective effects, which may prevent cognitive dysfunction.

Long-lasting impact of perinatal dietary supplementation of omega 3 fatty acids on mevalonate pathway: potential role on neuron trophism in male offspring hippocampal formation.

Objective: We were aimed at evaluating the long-term impact of perinatal an omega-3 fatty acid-enriched diet on the mevalonate/cholesterol pathway in the brain of male offspring.Methods: Female rats were fed with standard or omega-3 fatty acid-enriched diet during pregnancy and lactation. Liver, brain and plasma were collected from infant, adolescent and adult male offspring for subsequent biochemical and morphological analyses.Results: The omega-3 enriched diet induced region-dependent changes of the 3-hydroxy 3-methylglutaryl Coenzyme A reductase in the brain and affected notably RhoA/CREB signaling and the nerve growth factor content in the hippocampus. Our data reveal a long-lasting impact of perinatal omega-3 fatty acid supplementation on hippocampal nerve growth factor levels mediated by reduced 3-hydroxy 3-methylglutaryl Coenzyme A reductase activation state and enhanced CREB signaling.Discussion: These data underline the importance of the perinatal omega-3 enriched diet for adult brain function and reveal a new pathway important for nerve growth factor regulation.

Neuroprotective Properties of Quinone Reductase 2 Inhibitor M-11, a 2-Mercaptobenzimidazole Derivative.

The ability of NQO2 to increase the production of free radicals under enhanced generation of quinone derivatives of catecholamines is considered to be a component of neurodegenerative disease pathogenesis. The present study aimed to investigate the neuroprotective mechanisms of original NQO2 inhibitor M-11 (2-[2-(3-oxomorpholin-4-il)-ethylthio]-5-ethoxybenzimidazole hydrochloride) in a cellular damage model using NQO2 endogenous substrate adrenochrome (125 µM) and co-substrate BNAH (100 µM). The effects of M-11 (10-100 µM) on the reactive oxygen species (ROS) generation, apoptosis and lesion of nuclear DNA were evaluated using flow cytometry and single-cell gel electrophoresis assay (comet assay). Results were compared with S29434, the reference inhibitor of NQO2. It was found that treatment of HT-22 cells with M-11 results in a decline of ROS production triggered by incubation of cells with NQO2 substrate and co-substrate. Pre-incubation of HT-22 cells with compounds M-11 or S29434 results in a decrease of DNA damage and late apoptotic cell percentage reduction. The obtained results provide a rationale for further development of the M-11 compound as a potential neuroprotective agent.

Banhasasim-Tang Ameliorates Spatial Memory by Suppressing Oxidative Stress through Regulation of ERK/p38 Signaling in Hippocampus of Mice.

Since ancient times, Banhasasim-tang (BHS) has been used to treat functional dyspepsia in East Asia. Here, we aimed to determine the protective action of BHS on hippocampal neurons against oxidative stress. We investigated the functional effect of BHS on a scopolamine-induced mouse model, and molecular analysis was performed in glutamate-induced HT22 cells. We observed that BHS administration ameliorated memory dysfunction in scopolamine-treated mice. BHS administration also increased neuronal survival and acetylcholine activity and phosphorylation of extracellular signal-regulated kinase (ERK) and cAMP response element-binding protein (CREB) in the hippocampus of mice. In hippocampal cells, BHS treatment rescued glutamate-induced cytotoxicity, apoptosis, and oxidative stress. We observed an increase of HO-1 and a decrease of Nrf2 protein expression in glutamate-induced oxidative stress; however, the expression level of these proteins was significantly rescued by BHS treatment. BHS treatment also regulated phosphorylation of p38, p53, ERK, and CREB. Therefore, our data indicated that BHS may reduce oxidative stress through regulation of ERK-CREB and p38-p53 signaling in the hippocampus, resulting in decreased neuronal damage and improved memory in rodent models of neurodegenerative disease.

[Effects of spicy leaves on cognitive function and apoptosis of hippocampal neurons in diabetic rats].

Objective: To investigate the effects of Moringa leaves on the cognitive dysfunction and apoptosis of hippocampal neurons in diabetic rats induced by streptozotocin (STZ). Methods: Fifty male SD rats were selected, and 10 rats were randomly selected as the control group. The other 40 rats were treated with STZ at the dose of 25 mg/kg by intraperitoneal injection. The 40 diabetic rats were randomly divided into model group, Moringa oleifera low-dose, medium-dose and high-dose group. The rats in Moringa oleifera groups were treated with Moringa oleifera at the doses of 2.0, 4.0 and 8.0 g/kg by gavage, the control group and model group were treated with the same amount of normal saline once a day, for 8 weeks. Morris water maze test was used to evaluate the learning and memory ability of rats. Pathological changes of hippocampal neurons and expressions of Bax, caspase-3 and bcl-2 protein in each group were observed by the sections were stained with HE staining and immunohistochemistry. Enzyme linked immunosorbent assay (ELISA) was used to detect tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in rat. Results: compared with the control group, the blood glucose of the model group was increased significantly (P＜0.01), and the blood insulin level was decreased significantly (P＜0.05); compared with the model group, the blood glucose values of Moringa oleifera groups were decreased significantly (P＜0.05, P＜0.01), and the blood insulin levels of middle and high dose Moringa oleifera group were increased significantly (P＜0.05, P＜0.01). There was no significant difference in FBG and INS among the three groups (P＞0.05). In Morris water maze test, compared with the model group, the latency of Moringa oleifera groups was significantly shorter (P＜0.05); the residence time in target quadrant of Moringa oleifera groups with different doses was significantly prolonged (P＜0.05). Compared with the model group, the contents of TNF - α, IL-6 and protein expression in low, medium and high dose groups of Moringa oleifera were decreased significantly (P＜0.05). HE staining and immunohistochemical staining results showed that Moringa oleifera medium dose group was positive, brown yellow, fine granular, compared with the model group. The number of neuronal apoptosis was significantly reduced in the middle dose group (53.21±7.19,P＜0.01); the protein expressions of Bax, caspase-3 and the ratio of Bax/Bcl-2 in hippocampus were significantly decreased in the middle dose group (P＜0.05). Conclusion: The mechanisms of Moringa leaves on the cognitive dysfunction and apoptosis of hippocampal neurons may be related to regulating the protein expressions of Bax, Bcl-2 and Caspase-3, reducing the contents of inflammatory factors TNF-α and IL-6.

Chrysanthemum indicum Prevents Hydrogen Peroxide-Induced Neurotoxicity by Activating the TrkB/Akt Signaling Pathway in Hippocampal Neuronal Cells.

Oxidative stress-mediated neuronal damage is associated with the pathogenesis and development of neurodegenerative diseases. Chrysanthemum indicum has antioxidant properties. However, the neuroprotective effects and the cellular mechanism of C. indicum ethanol extract (CIE) against oxidative damage in hippocampal neuronal cells have not been clearly elucidated. Therefore, this study investigated whether CIE has protective effects against hydrogen peroxide (H2O2)-induced oxidative toxicity in HT22 cells. CIE pretreatment significantly improved neuronal cell viability. Moreover, the formation of intracellular reactive oxygen species and apoptotic bodies, and mitochondrial depolarization were significantly reduced in HT22 cells with H2O2-induced oxidative toxicity. Furthermore, CIE increased the phosphorylation of tropomyosin-related kinase receptor B (TrkB), protein kinase B (Akt), cAMP response element-binding protein, the expression of brain-derived neurotrophic factor, antioxidant enzymes, and the nuclear translocation of nuclear factor erythroid 2-related factor 2 by activating the TrkB/Akt signaling pathway. In contrast, the addition of K252a, a TrkB inhibitor, or MK-2206, an Akt-selective inhibitor, reduced the neuroprotective and antioxidant effects of CIE. Taken together; CIE exhibits neuroprotective and antioxidant effects against oxidative damage. Therefore, it can be a potential agent for treating oxidative stress-related neurodegenerative diseases.

Neuroprotective effects of macamide from maca (Lepidium meyenii Walp.) on corticosterone-induced hippocampal impairments through its anti-inflammatory, neurotrophic, and synaptic protection properties.

The present study aims to investigate the protective effects of N-(3-methoxybenzyl)-(9Z,12Z,15Z)-octadecatrienamide (M 18:3) on corticosterone-induced neurotoxicity. A neurotoxic model was established by subcutaneous injection of corticosterone (40 mg per kg bw) for 21 days. Depressive behaviors (the percentage of sucrose consumption, the immobility time in the forced swimming test, and the total distance in the open field test) were observed. The levels of the brain-derived neurotrophic factor, the contents of tumor necrosis factor-α and interleukin-6, and the numbers of positive cells of doublecortin and bromodeoxyuridine in the hippocampus were measured. The density of hippocampal neurons was calculated. The morphological changes of hippocampal neurons (the density of dendritic spines, the dendritic length, and the area and volume of dendritic cell bodies) were observed. The expression levels of synaptophysin, synapsin I, and postsynaptic density protein 95 were measured. Behavioral experiments showed that M 18:3 (5 and 25 mg per kg bw) could remarkably improve the depressive behaviors. The enzyme-linked immunosorbent assay showed that M 18:3 could considerably reduce hippocampal neuroinflammation and increase hippocampal neurotrophy. Nissl staining showed that M 18:3 could remarkably improve the corticosterone-induced decrease in the hippocampal neuron density. Immunofluorescence analysis showed that M 18:3 could considerably promote hippocampal neurogenesis. Golgi staining showed that M 18:3 could remarkably improve the corticosterone-induced changes in the hippocampal dendritic structure. Western blotting showed that M 18:3 could considerably increase the expression levels of synaptic-structure-related proteins in the hippocampus. In conclusion, the protective effects of M 18:3 may be attributed to the anti-inflammatory, neurotrophic, and synaptic protection properties.

Electroacupuncture Promotes the Survival of the Grafted Human MGE Neural Progenitors in Rats with Cerebral Ischemia by Promoting Angiogenesis and Inhibiting Inflammation.

Stem cells have the potential as a regenerative therapy for cerebral ischemia by improving functional outcomes. However, cell transplantation has some limitations, including a low rate of the grafted cell survival. There is still a major challenge of promoting the harmonious symbiosis between grafted cells and the host. Acupuncture can effectively improve the functional outcome after cerebral ischemia. The present study evaluated the therapeutic effects and explored the mechanism of combined medial ganglionic eminence (MGE) neural progenitors differentiated from human embryonic stem cells (hESCs) with electroacupuncture (EA) in a bilateral common carotid artery occlusion (2VO) rat model. The results showed that EA could promote the survival of the grafted MGE neural progenitors differentiated from hESCs and alleviate learning and memory impairment in rats with cerebral ischemia. This may have partially resulted from inhibited expression of TNF-α and IL-1ß and increased vascular endothelial growth factor (VEGF) expression and blood vessel density in the hippocampus. Our findings indicated that EA could promote the survival of the grafted MGE neural progenitors and enhance transplantation therapy's efficacy by promoting angiogenesis and inhibiting inflammation.

Electroacupuncture promotes the survival and synaptic plasticity of hippocampal neurons and improvement of sleep deprivation-induced spatial memory impairment.

AIMS: This study aimed to investigate whether electroacupuncture (EA) promotes the survival and synaptic plasticity of hippocampal neurons by activating brain-derived neurotrophic factor (BDNF)/tyrosine receptor kinase (TrkB)/extracellular signal-regulated kinase (Erk) signaling, thereby improving spatial memory deficits in rats under SD. METHODS: In vivo, Morris water maze (MWM) was used to detect the effect of EA on learning and memory, at the same time Western blotting (WB), immunofluorescence (IF), and transmission electron microscopy (TEM) were used to explore the plasticity of hippocampal neurons and synapses, and the expression of BDNF/TrkB/Erk signaling. In vitro, cultured hippocampal neurons were treated with exogenous BDNF and the TrkB inhibitor K252a to confirm the relationship between BDNF/TrkB/Erk signaling and synaptic plasticity. RESULTS: Our results showed that EA mitigated the loss of hippocampal neurons and synapses, stimulated hippocampal neurogenesis, and improved learning and memory of rats under SD accompanied by upregulation of BDNF and increased phosphorylation of TrkB and Erk. In cultured hippocampal neurons, exogenous BDNF enhanced the expression of synaptic proteins, the frequency of the postsynaptic currents, and the phosphorylation of TrkB and Erk; these effects were reversed by treatment with K252a. CONCLUSIONS: Electroacupuncture alleviates SD-induced spatial memory impairment by promoting hippocampal neurogenesis and synaptic plasticity via activation of BDNF/TrkB/Erk signaling, which provided evidence for EA as a therapeutic strategy for countering the adverse effects of SD on cognition.

Hippocampal and thalamic afferents form distinct synaptic microcircuits in the mouse infralimbic frontal cortex.

The selection of goal-directed behaviors is supported by neural circuits located within the frontal cortex. Frontal cortical afferents arise from multiple brain areas, yet the cell-type-specific targeting of these inputs is unclear. Here, we use monosynaptic retrograde rabies mapping to examine the distribution of afferent neurons targeting distinct classes of local inhibitory interneurons and excitatory projection neurons in mouse infralimbic frontal cortex. Interneurons expressing parvalbumin, somatostatin, or vasoactive intestinal peptide receive a large proportion of inputs from the hippocampus, while interneurons expressing neuron-derived neurotrophic factor receive a large proportion of inputs from thalamic regions. A similar dichotomy is present among the four different excitatory projection neurons. These results show a prominent bias among long-range hippocampal and thalamic afferent systems in their targeting to specific sets of frontal cortical neurons. Moreover, they suggest the presence of two distinct local microcircuits that control how different inputs govern frontal cortical information processing.

Vitamin B12-folic acid supplementation regulates neuronal immediate early gene expression and improves hippocampal dendritic arborization and memory in old male mice.

As the relationship among diet, brain aging and memory is complex, it provides ample opportunity for research in multiple directions including behaviour, epigenetics and neuroplasticity. Nutritional deficiencies together with genetic and environmental factors are the major cause of many age-associated pathologies including memory loss. A compromised vitamin B12-folate status in older people is highly prevalent worldwide. Researchers have established a close association between the adequate level of B12-folate and the maintenance of cognitive brain functions. One of the main reasons for age-associated memory loss is downregulation of neuronal immediate early genes (nIEGs). Therefore, we hypothesize here that vitamin B12-folic acid supplementation in old mice can improve memory by altering the expression status of nIEGs. To check this, 72-week-old male Swiss albino mice were orally administered with 2 µg of vitamin B12 and 22 µg of folic acid/mouse/day for eight weeks. Such supplementation improved recognition memory in old and altered the expression of nIEGs. The expression of nIEGs was further found to be regulated by changes in DNA methylation at their promoter regions and CREB phosphorylation (pCREB). In addition, Golgi-Cox staining showed significant improvement in dendritic length, number of branching points and spine density of hippocampal CA1 pyramidal neurons by B12-folic acid supplementation. Taken together, these findings suggest that vitamin B12-folic acid supplementation regulates nIEGs expression and improves dendritic arborization of hippocampal neurons and memory in old male mice.

Gastrodin promotes hippocampal neurogenesis via PDE9-cGMP-PKG pathway in mice following cerebral ischemia.

Gastrodin, which is extracted from the Chinese herbal medicine Gastrodia elata Blume, can ameliorate neurogenesis after cerebral ischemia. However, it's possible underlying mechanisms remain still elusive. PDE9-cGMP-PKG signaling pathway is involved in the proliferation of neural stem cells (NSCs) after cerebral ischemia. In this study, we investigated whether the beneficial effect of gastrodin on hippocampal neurogenesis after cerebral ischemia is correlated with the PDE9-cGMP-PKG signaling pathway. Bilateral common carotid artery occlusion (BCCAO) in mice and oxygen-glucose deprivation/reoxygenation (OGD/R) in primary cultured hippocampal NSCs were used to mimic brain ischemic injury. The Morris water maze (MWM) test was executed to detect spatial learning and memory. Proliferation, differentiation, and mature neurons were examined using immunofluorescence. The survival and proliferation of NSCs were assessed by CCK-8 assay and BrdU immunofluorescence staining, respectively. ELISA and western blot were used to detect the level of the PDE9-cGMP-PKG signaling pathway. In BCCAO mice, administering gastrodin (50 and 100 mg/kg) for 14 d restored cognitive behaviors; meanwhile, neurogenesis in hippocampus was stimulated, and PDE9 was inhibited and cGMP-PKG was activated by gastrodin. Consistent with the results, administering gastrodin (from 0.01-1 µmol/L) for 48 h dose-dependently ameliorated the cell viability and promoted greatly the proliferation in primary hippocampal NSCs exposed to OGD/R. Gastrodin further decreased PDE9 activity and up-regulated cGMP-PKG level. KT5823, a PKG inhibitor, markedly abrogated the protective effects of gastrodin on OGD/R-injured NSCs, accompanied by the down-regulation of PKG protein expression, but had no effects on PDE9 activity and cGMP level. Gastrodin could accelerate hippocampal neurogenesis after cerebral ischemia, which is mediated, at least partly, by PDE9-cGMP-PKG signaling pathway.

Astragaloside IV Ameliorates Cognitive Impairment and Neuroinflammation in an Oligomeric Aß Induced Alzheimer's Disease Mouse Model via Inhibition of Microglial Activation and NADPH Oxidase Expression.

Microglial activation and neuroinflammation induced by amyloid ß (Aß) play pivotal roles in Alzheimer's disease (AD) pathogenesis. Astragaloside IV (AS-IV) is one of the major active compounds of the traditional Chinese medicine Astmgali Radix. It has been reported that AS-IV could protect against Aß-induced neuroinflammation and cognitive impairment, but the underlying mechanisms need to be further clarified. In this study, the therapeutic effects of AS-IV were investigated in an oligomeric Aß (oAß) induced AD mice model. The effects of AS-IV on microglial activation, neuronal damage and reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase expression were further studied. Different doses of AS-IV were administered intragastrically once a day after intracerebroventricularly oAß injection. Results of behavioral experiments including novel object recognition (NOR) test and Morris water maze (MWM) test revealed that AS-IV administration could significantly ameliorate oAß-induced cognitive impairment in a dose dependent manner. Enzyme linked immunosorbent assay (ELISA) results showed that increased levels of reactive oxygen species (ROS), tumor necrosis factor α (TNF-α), interleukin-1ß (IL-1ß) and IL-6 in hippocampal tissues induced by oAß injection were remarkably inhibited after AS-IV treatment. OAß induced microglial activation and neuronal damage was significantly suppressed in AS-IV-treated mice brain, observed in immunohistochemistry results. Furthermore, oAß upregulated protein expression of NADPH oxidase subunits gp91phox, p47phox, p22phox and p67phox were remarkably reduced by AS-IV in Western blotting assay. These results revealed that AS-IV could ameliorate oAß-induced cognitive impairment, neuroinflammation and neuronal damage, which were possibly mediated by inhibition of microglial activation and down-regulation of NADPH oxidase protein expression. Our findings provide new insights of AS-IV for the treatment of neuroinflammation related diseases such as AD.

A preparation of Ginkgo biloba L. leaves extract inhibits the apoptosis of hippocampal neurons in post-stroke mice via regulating the expression of Bax/Bcl-2 and Caspase-3.

ETHNOPHARMACOLOGICAL RELEVANCE: Shuxuening injection (SXNI) is a Chinese medicine of Ginkgo biloba L. leaves extract (GBE), which is widely used clinically for cardiovascular diseases such as stroke and myocardial infarction, but the pharmacological mechanism of its therapeutic effect is not fully understood. AIM OF THE STUDY: Preclinical studies suggested that inhibition of neuronal apoptosis effectively improves brain damage after ischemic stroke. The purpose of this study was to investigate the inhibitory effect of SXNI on neuronal apoptosis in post-stroke mice and its underlying mechanism. MATERIALS AND METHODS: A mouse cerebral ischemia-reperfusion injury (CIRI) model was constructed by middle cerebral artery occlusion (MCAO) and treated with 3 mL/kg SXNI. TUNEL and immunohistochemistry experiments were performed on brain slices on the 7th day after stroke. The protein was extracted from the hippocampus region of the brain for western-blot assay. To simulate the in vivo ischemia-reperfusion process, the hippocampal neuron cell line HT-22 was subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro, and 200 µg/mL SXNI was administered. The HT-22 cells were then studied by RT-PCR and immunocytochemistry. RESULTS: In vivo, SXNI treatment significantly reduced hippocampal neuronal apoptosis. Immunohistochemistry showed that SXNI inhibited the activation of Caspase-3 protein in the hippocampus after ischemic stroke. Western blot analysis further confirmed that SXNI regulated the expression of the antagonizing protein pair Bax and Bcl-2 to exert anti-apoptotic effect in addition to reducing the expression of Cleaved-Caspase-3 in the hippocampus. In vitro, 200 µg/mL SXNI treatment significantly improved HT-22 apoptosis caused by OGD/R. Further RT-PCR and immunocytochemistry study showed that 200 µg/mL SXNI inhibited apoptosis of hippocampal neurons by regulating the mRNA and protein expressions of apoptotic molecules Bax, Bcl-2 and Caspase-3. CONCLUSIONS: CIRI can induce hippocampal neuronal apoptosis, which is inhibited by SXNI via regulating Bax/Bcl-2 and blocking Caspase-3 activation. Therefore, SXNI may be a promising treatment strategy to improve the prognosis of ischemic stroke.

The antidepressant-like effects of Danggui Buxue Decoction in GK rats by activating CREB/BDNF/TrkB signaling pathway.

BACKGROUND: High rates of co-morbidity have been reported in patients with diabetes mellitus with depression (DD). Danggui Buxue Decoction (DBD), a Traditional Chinese Medicine formula composed of Angelica and Astragalus, has been historically used for the treatment of diabetes. PURPOSE: This study aimed to investigated whether DBD and its main active component, ferulic acid (FA) from Angelica, could ameliorate depression-like behavior in DD and the underlying mechanisms. METHODS: Goto-Kakizaki (GK) rats were administered DBD (4 or 8 g/kg) by oral gavage during a 4-week period of chronic unpredictable mild stress. After 4 weeks, blood glucose, glycated serum protein, serum insulin, oral glucose tolerance and depression-like behavior were examined, along with brain-derived neurotrophic factor (BDNF)-related signaling pathway proteins and the ultrastructure of hippocampal tissues. UPLC-QTOF-MS was adopted to detect the absorption of FA in the serum and hippocampus. Rat primary hippocampal cells were cultured in a DD model. Protein and mRNA levels of genes involved in BDNF-related signaling and neuroplasticity were analyzed. RESULTS: DBD effectively improved glucose tolerance in DD rats and relieved depression-like behavior. Upregulation of cAMP response element binding protein (CREB), BDNF, and tropomyosin receptor kinase B (TrkB) and improvement of the hippocampal neuron ultrastructure supported the antidepressant-Like effects of DBD on the hippocampal neurons. In addition, DBD enhanced the protein and mRNA levels of components of the CREB/BDNF/TrkB pathway in rat primary hippocampal cells induced by elevated glycemia and cortisol. Interestingly, FA, the main component of DBD absorbed in the blood and hippocampus, showed similar effects as DBD on primary hippocampal cells. CONCLUSION: This study suggests that the TCM formula DBD effectively serves as a potential therapeutic agent for prevention of DD through regulatory effects on the CREB/BDNF/TrkB pathway to protect and remodel hippocampal neurons. Moreover, FA contributes significantly to the treatment effects of DBD.

Green tea protects against hippocampal neuronal apoptosis in diabetic encephalopathy by inhibiting JNK/MLCK signaling.

Although diabetic encephalopathy (DE) is a major late complication of diabetes, the pathophysiology of postural instability in DE remains poorly understood. Prior studies have suggested that neuronal apoptosis is closely associated with cognitive function, but the mechanism remains to be elucidated. Green tea, which is a non­fermented tea, contains a number of tea polyphenols, alkaloids, amino acids, polysaccharides and other components. Some studies have found that drinking green tea can reduce the incidence of neurodegenerative diseases and improve cognitive dysfunction. We previously found that myosin light chain kinase (MLCK) regulates apoptosis in high glucose­induced hippocampal neurons. In neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease, activation of the JNK signaling pathway promotes neuronal apoptosis. However, the relationship between JNK and MLCK remains to be elucidated. Green tea serum was obtained using seropharmacological methods and applied to hippocampal neurons. In addition, a type 1 diabetes rat model was established and green tea extract was administered, and the Morris water maze test, Cell Counting Kit­8 assays, flow cytometry, western blotting and terminal deoxynucleotidyl transferase­mediated dUTP nick end­labelling assays were used to examine the effects of green tea on hippocampal neuronal apoptosis in diabetic rats. The results demonstrated that green tea can protect against hippocampal neuronal apoptosis by inhibiting the JNK/MLCK pathway and ultimately improves cognitive function in diabetic rats. The present study provided novel insights into the neuroprotective effects of green tea.

Angelica sinensis extract promotes neuronal survival by enhancing p38 MAPK-mediated hippocampal neurogenesis and dendritic growth in the chronic phase of transient global cerebral ischemia in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Angelica sinensis (Oliv.) Diels (ASD), commonly known as Dang Gui, is a popular Chinese herb that has long been used to treat ischemic stroke. However, the effects of ASD in chronic cerebral ischemia and its underlying mechanisms still remain unclear. AIM OF THE STUDY: This study aimed to determine the effects of the ASD extract on hippocampal neuronal survival at 28 d after transient global cerebral ischemia (GCI) and to investigate the precise mechanisms underlying the p38 mitogen-activated protein kinase (MAPK)-related signaling pathway's involvement in hippocampal neurogenesis. MATERIALS AND METHODS: Rats underwent 25 min of four-vessel occlusion. The ASD extract was intragastrically administered at doses of 0.25 g/kg (ASD-0.25 g), 0.5 g/kg (ASD-0.5 g), 1 g/kg (ASD-1 g), 1 g/kg after dimethyl sulfoxide administration (D + ASD-1 g), or 1 g/kg after SB203580 (a p38 MAPK inhibitor) administration (SB + ASD-1 g) at 1, 3, 7, 10, 14, 17, 21, and 24 d after transient GCI. RESULTS: ASD-0.5 g, ASD-1 g, and D + ASD-1 g treatments had the following effects: upregulation of bromodeoxyuridine (BrdU) and Ki67 expression, and BrdU/neuronal nuclei (NeuN) and Ki67/nestin co-expression in the hippocampal dentate gyrus (DG); upregulation of microtubule-associated protein 2/NeuN co-expression, and NeuN and glial fibrillary acidic protein (GFAP) expression, and downregulation of tumor necrosis factor-α/GFAP co-expression in the hippocampal CA1 region; upregulation of phospho-p38 MAPK (p-p38 MAPK), phospho-cAMP response element-binding protein (p-CREB), brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and vascular endothelial growth factor A (VEGF-A) expression in the hippocampus. SB + ASD-1 g treatment abrogated the effects of ASD-1 g on the expression of these proteins. CONCLUSIONS: ASD-0.5 g and ASD-1 g treatments promotes neuronal survival by enhancing hippocampal neurogenesis. The effects of the ASD extract on astrocyte-associated hippocampal neurogenesis and dendritic growth are caused by the activation of p38 MAPK-mediated CREB/BDNF, GDNF, and VEGF-A signaling pathways in the hippocampus at 28 d after transient GCI.

Gastrodiae rhizoma attenuates brain aging via promoting neuritogenesis and neurodifferentiation.

BACKGROUND: Gastrodiae Rhizoma (Tianma), the dried tuber of Gastrodia elata Bl. (Orchidaceae), is listed as a top-grade herbal medicine in Shen-nong Ben-ts'ao Jing and has been used for treating headaches, dizziness, vertigo and convulsion. It has a neuroprotective effect and extends the lifespan in mouse models of Huntington's disease and Niemann-Pick type C disease. However, its effect on senescence remains unknown. PURPOSE: This study aimed to investigate the anti-aging effects and the underlying mechanism of Gastrodiae Rhizoma. METHODS: D-galactose (D-gal)- and BeSO4-induced cellular senescence and senescence-associated ß-galactosidase (SA-ß-gal) activity were evaluated in SH-SY5Y and PC12 cells. D-gal-induced aging mice were used as an in vivo model. Animal behaviors including nesting and burrowing and Morris water maze were conducted. Neurogenesis in the hippocampus was assessed by immunohistochemistry and confocal microscopy, and the aging-related proteins were assessed by Western blot analysis. The potential neuritogenesis activity of the partially purified fraction of Gastrodiae Rhizoma (TM-2) and its major ingredients were investigated in PC12 cells. RESULTS: TM-2 could improve D-gal-induced learning and memory impairement by inhibiting oxidative stress, increasing hippocampal neurogenesis and regulating the SH2B1-Akt pathway. Moreover, N6-(4-hydroxybenzyl)adenine riboside (T1-11) and parishins A and B, three constituents of TM-2, had anti-aging activity, as did T1-11 and parishin A induced neuritogenesis. CONCLUSION: Our data suggested that TM-2 slowed down D-gal-induced cellular and mouse brain aging. These results indicate that Gastrodiae Rhizoma has a beneficial effect on senescence. It may be used for neuroprotection and promoting neurogenesis.

Meningeal lymphatics affect microglia responses and anti-Aß immunotherapy.

Alzheimer's disease (AD) is the most prevalent cause of dementia1. Although there is no effective treatment for AD, passive immunotherapy with monoclonal antibodies against amyloid beta (Aß) is a promising therapeutic strategy2,3. Meningeal lymphatic drainage has an important role in the accumulation of Aß in the brain4, but it is not known whether modulation of meningeal lymphatic function can influence the outcome of immunotherapy in AD. Here we show that ablation of meningeal lymphatic vessels in 5xFAD mice (a mouse model of amyloid deposition that expresses five mutations found in familial AD) worsened the outcome of mice treated with anti-Aß passive immunotherapy by exacerbating the deposition of Aß, microgliosis, neurovascular dysfunction, and behavioural deficits. By contrast, therapeutic delivery of vascular endothelial growth factor C improved clearance of Aß by monoclonal antibodies. Notably, there was a substantial overlap between the gene signature of microglia from 5xFAD mice with impaired meningeal lymphatic function and the transcriptional profile of activated microglia from the brains of individuals with AD. Overall, our data demonstrate that impaired meningeal lymphatic drainage exacerbates the microglial inflammatory response in AD and that enhancement of meningeal lymphatic function combined with immunotherapies could lead to better clinical outcomes.