Intravenous injection of neural progenitor cells improved depression-like behavior after cerebral ischemia

Combination of panax ginseng and ginkgo biloba extracts attenuate cerebral ischemia injury with modulation of NLRP3 inflammasome and CAMK4/CREB pathway

Stroke is a major cause of death and disability throughout the world. A combination of Panax Ginseng and Ginkgo biloba extracts (CGGE) is an effective treatment for nervous system diseases, but the neuroprotective mechanism underlying CGGE remains unclear. Both network analysis and experimental research were employed to explore the potential mechanism of CGGE in treating ischemic stroke (IS). Network analysis identified a total number of 133 potential targets for 34 active ingredients and 239 IS-related targets. What’s more, several processes that might involve the regulation of CGGE against IS were identified, including long-term potentiation, cAMP signaling pathway, neurotrophin signaling pathway, and Nod-like receptor signaling pathway. Our studies in animal models suggested that CGGE could reduce inflammatory response by inhibiting the activity of Nod-like receptor, pyrin containing 3 (NLRP3) inflammasome, and maintain the balance of glutamate (Glu)/gamma-aminobutyric acid (GABA) via activating calmodulin-dependent protein kinase type Ⅳ (CAMK4)/cyclic AMP-responsive element-binding protein (CREB) pathway. These findings indicated the neuroprotective effects of CGGE, possibly improving neuroinflammation and excitotoxicity by regulating the NLRP3 inflammasome and CAMK4/CREB pathway.

Panax notoginseng Saponins Stimulates Neurogenesis and Neurological Restoration After Microsphere-Induced Cerebral Embolism in Rats Partially Via mTOR Signaling

P. Notoginseng Saponins (PNS), the main active component of herbal medicine Panax notoginseng, has been widely used to treat cerebrovascular diseases. It has been acknowledged that PNS exerted protection on nerve injuries induced by ischemic stroke, however, the long-term impacts of PNS on the restoration of neurological defects and neuroregeneration after stroke have not been thoroughly studied and the underlying molecular mechanism of stimulating neurogenesis is difficult to precisely clarify, much more in-depth researches are badly needed. In the present study, cerebral ischemia injury was induced by microsphere embolism (ME) in rats. After 14 days, PNS administration relieved cerebral ischemia injury as evidenced by alleviating neurological deficits and reducing hippocampal pathological damage. What’s more, PNS stimulated hippocampal neurogenesis by promoting cell proliferation, migration and differentiation activity and modulated synaptic plasticity. Increased number of BrdU/Nestin, BrdU/DCX and NeuroD1-positive cells and upregulated synapse-related GAP43, SYP, and PSD95 expression were observed in the hippocampus. We hypothesized that upregulation of brain-derived neurotrophic factor (BDNF) expression and activation of Akt/mTOR/p70S6K signaling after ME could partially underlie the neuroprotective effects of PNS against cerebral ischemia injury. Our findings offer some new viewpoints into the beneficial roles of PNS against ischemic stroke.

Effect of Progranulin on Proliferation and Differentiation of Neural Stem/Progenitor Cells after Oxygen/Glucose Deprivation

We previously demonstrated that sivelestat, a selective neutrophil elastase inhibitor, attenuates the cleavage of progranulin (PGRN) and ischemia-induced cell injury in the brain. To obtain further insight into the role of PGRN, in the present study we evaluated the direct effects of sivelestat and recombinant PGRN (rPGRN) on the proliferation and differentiation of neural stem cells in cultures of neural stem/progenitor cells (NS/PC) under the ischemic condition in vitro. We demonstrated that oxygen/glucose deprivation (OGD)-induced cell proliferation of NS/PC was increased by rPGRN treatment. In addition, this increase was accompanied by increased phosphorylation of Akt and GSK-3β (Ser9) after OGD. But none of these responses occurred by treatment with sivelestat. Therefore, activation of the Akt/GSK-3β pathway could well be involved in this proliferative effect of rPGRN. Although OGD and reoxygenation-induced changes in the differentiation of NS/PC into neurons or astrocytes was not affected by treatment with rPGRN or sivelestat, it is noteworthy that rPGRN enhanced neurite outgrowth of β3-tubulin-positive neurons that had differentiated from the NS/PC. These findings suggest that enhancement of proliferation of endogenous NS/PC and neurite outgrowth of differentiated neurons from NS/PC by PGRN could be useful for a new therapeutic approach for cerebral ischemia.

Effects of laminin-111 peptide coatings on rat neural stem/progenitor cell culture

Neurons require adhesive scaffolds for their growth and differentiation. Laminins are a major cell adhesive component of basement membranes and have various biological activities in the peripheral and central nervous systems. Here, we evaluated the biological activities of 5 peptides derived from laminin-111 as a scaffold for mouse neuroblastoma Neuro2a cells and rat neural stem/progenitor cells (NPCs). The 5 peptides showed Neuro2a cell attachment activity similar to that of poly-d-lysine. However, when NPCs were cultured on the peptides, 2 syndecan-binding peptides, AG73 (RKRLQVQLSIRT, mouse laminin α1 chain 2719-2730) and C16 (KAFDITYVRLKF, laminin γ1 chain 139-150), demonstrated significantly higher cell attachment and neurite extension activities than other peptides including integrin-binding ones. Long-term cell culture experiments showed that both AG73 and C16 supported the growth of neurons and astrocytes that had differentiated from NPCs. Furthermore, C16 markedly promoted the expression of neuronal markers such as synaptosomal-associated protein-25 and syntaxin 1A. These results indicate that AG73 and C16 are useful for NPC cultures and that C16 can be applied to specialized research on synapses in differentiated neurons. These peptides have the potential for use as valuable biomaterials for NPC research.

Ligusticum chuanxiong exerts neuroprotection by promoting adult neurogenesis and inhibiting inflammation in the hippocampus of ME cerebral ischemia rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cerebral ischemia, also known as stroke, can stimulate the proliferation and migration of endogenous neural stem cells (NSC_S) in subventricular zone of the lateral ventricle and subgranularzone of the dentate gyrus in the adult hippocampus as a defense response to damage. However, the proliferation of endogenous NSC_S is insufficient for central nervous system repair. Neurogenesis and anti-neuroinflammation are two important aspects for neuroprotection. Rhizome Ligusticum chuanxiong (LC), the dried rhizomes of Ligusticum striatum DC., has been widely used to treat stroke for over hundreds of years in Traditional Chinese Medicine.

PURPOSE

of the study: Previous reports on pharmacological mechanism of LC mainly focus on the cerebral blood flow and thrombolysis. We aim to explore whether LC provides neuroprotective effect by increasing neurogenesis and inhibiting the IL-1β, TNF-α and expressions of glial fibrillary acidic protein.

MATERIALS AND METHODS

LC extract was delivered to microsphere-embolized (ME) cerebral ischemia Wister rats to examine its neuroprotection. Body weight, neurological scores, hematoxylin-eosin staining (HE), TUNEL assay were conducted for neurological damage. Neurogenesis was evaluated by assessing the expression of Doublecortin (DCX) and neurogenic differentiation1 (NeuroD1) through immunofluorescence staining. Western blot performed to measure the protein levels of growth associated protein-43(GAP-43), glial fibrillary acidic protein (GFAP). IL-1β and TNF-α was detected by Elisa.

RESULTS

LC alleviated pathomorphological change and apoptosis of neurons in the hippocampus caused by ME surgery. Furthermore, LC significantly increased the DCX in the DG of adult rat hippocampus at 14 days after surgery. A significant upregulation of GAP-43 compared to the ME after LC was administered. Besides, LC decreased pro-inflammatory cytokine (IL-1β, TNF-α) and protein level of GFAP.

CONCLUSION

The finding suggested that LC had the ability to protect neurons by promoting the endogenous proliferation of neuroblast and production of neural differentiation factor in rats after ischemia injury. Meanwhile, LC can anti-neuroinflammation, which is important for the treatment of neuron injury. Accordingly, LC perhaps a promising medicine for neuron damage therapy after cerebral ischemia.

Shuyu capsules relieve liver-qi depression by regulating ERK-CREB-BDNF signal pathway in central nervous system of rat

The purpose of this study was to investigate the possible therapeutic mechanism of Shuyu capsules in liver-qi depression. Liver-qi depression rats were prepared based on chronic unpredictable mild stress (CUMS) and delayed constraint. Rats were gavaged with Shuyu capsule, fluoxetine, Radix Bupleuri and Radix Paeoniae Alba to constrct rat models. Body weight test, sucrose preference test and open-field test were applied to test rat models. Western blot analysis and quantitative real-time PCR was applied to determine the relative expression of extracellular signal-regulated protein kinase (ERK), cyclic AMP response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in hippocampus and frontal lobe tissues. ELISA was used to detect the content of BDNF in serum. Body weight, sugar intake and total distance were significantly decreased in depression group compared with control. The four drugs significantly increased levels of these factors. Compared with control group, ERK, CREB and BDNF expression were significantly decreased in depression group in both hippocampus and frontal lobe tissues at both mRNA and protein level. Shuyu capsule and fluoxetine group showed a significant increase in the expression of ERK, CREB and BDNF at mRNA, p-ERK and p-BDNF at protein level. Compared with Radix Paeoniae Alba, Radix Bupleuri were better in the rescue of ERK, CREB and BDNF expression. In conclusion, the pathogenesis of liver-qi depression associated with lower expression of ERK, CREB and BDNF in hippocampus and frontal. Shuyu capsule and main constitution alleviated the depressive-like behaviors and reversed the disruptions of the p-ERK, p-CREB and BDNF in stressed rats.

Cannabidiol reduces neuroinflammation and promotes neuroplasticity and functional recovery after brain ischemia

This study investigated the effects of cannabidiol (CBD), a non-psychotomimetic phytochemical present in Cannabis sativa, on the cognitive and emotional impairments induced by bilateral common carotid artery occlusion (BCCAO) in mice. Using a multi-tiered behavioral testing battery during 21days, we found that BCCAO mice exhibited long-lasting functional deficits reflected by increase in anxiety-like behavior (day 9), memory impairments (days 12-18) and despair-like behavior (day 21). Short-term CBD 10mg/kg treatment prevented the cognitive and emotional impairments, attenuated hippocampal neurodegeneration and white matter (WM) injury, and reduced glial response that were induced by BCCAO. In addition, ischemic mice treated with CBD exhibited an increase in the hippocampal brain derived neurotrophic factor (BDNF) protein levels. CBD also stimulated neurogenesis and promoted dendritic restructuring in the hippocampus of BCCAO animals. Collectively, the present results demonstrate that short-term CBD treatment results in global functional recovery in ischemic mice and impacts multiple and distinct targets involved in the pathophysiology of brain ischemic injury.

Involvement of GSK-3β Phosphorylation Through PI3-K/Akt in Cerebral Ischemia-Induced Neurogenesis in Rats

Glycogen synthase kinase (GSK)-3β, which is abundantly expressed in the central nervous system, regulates various cellular processes including gene expression, cell proliferation, and differentiation. However, involvement of GSK-3β in cerebral ischemia-induced endogenous neurogenesis is not yet fully understood. Appropriate strategies to prevent ischemic cell damage and subsequent severe sequelae are needed. The purpose of the present study was to determine the relationship between pathophysiological alteration of the GSK-3β signaling pathway and cerebral ischemia-induced endogenous neurogenesis in rats. Severe cerebral ischemia was produced by the injection of 700 microspheres into the right internal carotid artery of rats. We demonstrated that phosphorylation of GSK-3β at its Ser9 and that of Akt was significantly enhanced on day 7 after the cerebral ischemia, as was the number of NeuroD-positive cells. Treatment with a phosphatidylinositol 3-kinase (PI3-K) inhibitor decreased the cerebral ischemia-induced phosphorylation of Akt and that of GSK-3β at its Ser9. In addition, as the protein levels of insulin-like growth factor-1 (IGF-1) and brain-derived neurotrophic factor (BDNF) were decreased, they might not have been essential for activation of the PI3-K/Akt/GSK-3β pathway after severe cerebral ischemia. Although it remains to be determined what factors activate this pathway, our results suggest that PI3K/Akt-dependent GSK-3β signaling and subsequent expression of NeuroD were involved in the neurogenesis elicited by cerebral ischemia.

Alterations in the corticotropin-releasing hormone (CRH) neurocircuitry: Insights into post stroke functional impairments

Although it is well accepted that changes in the regulation of the hypothalamic-pituitary adrenal (HPA) axis may increase susceptibility to affective disorders in the general population, this link has been less examined in stroke patients. Yet, the bidirectional association between depression and cardiovascular disease is strong, and stress increases vulnerability to stroke. Corticotropin-releasing hormone (CRH) is the central stress hormone of the HPA axis pathway and acts by binding to CRH receptors (CRHR) 1 and 2, which are located in several stress-related brain regions. Evidence from clinical and animal studies suggests a role for CRH in the neurobiological basis of depression and ischemic brain injury. Given its importance in the regulation of the neuroendocrine, autonomic, and behavioral correlates of adaptation and maladaptation to stress, CRH is likely associated in the pathophysiology of post stroke emotional impairments. The goals of this review article are to examine the clinical and experimental data describing (1) that CRH regulates the molecular signaling brain circuit underlying anxiety- and depression-like behaviors, (2) the influence of CRH and other stress markers in the pathophysiology of post stroke emotional and cognitive impairments, and (3) context and site specific interactions of CRH and BDNF as a basis for the development of novel therapeutic targets. This review addresses how the production and release of the neuropeptide CRH within the various regions of the mesocorticolimbic system influences emotional and cognitive behaviors with a look into its role in psychiatric disorders post stroke.

Alpha-linolenic acid: an omega-3 fatty acid with neuroprotective properties-ready for use in the stroke clinic?

Alpha-linolenic acid (ALA) is plant-based essential omega-3 polyunsaturated fatty acids that must be obtained through the diet. This could explain in part why the severe deficiency in omega-3 intake pointed by numerous epidemiologic studies may increase the brain's vulnerability representing an important risk factor in the development and/or deterioration of certain cardio- and neuropathologies. The roles of ALA in neurological disorders remain unclear, especially in stroke that is a leading cause of death. We and others have identified ALA as a potential nutraceutical to protect the brain from stroke, characterized by its pleiotropic effects in neuroprotection, vasodilation of brain arteries, and neuroplasticity. This review highlights how chronic administration of ALA protects against rodent models of hypoxic-ischemic injury and exerts an anti-depressant-like activity, effects that likely involve multiple mechanisms in brain, and may be applied in stroke prevention. One major effect may be through an increase in mature brain-derived neurotrophic factor (BDNF), a widely expressed protein in brain that plays critical roles in neuronal maintenance, and learning and memory. Understanding the precise roles of ALA in neurological disorders will provide the underpinnings for the development of new therapies for patients and families who could be devastated by these disorders.

Effects of acute versus post-acute systemic delivery of neural progenitor cells on neurological recovery and brain remodeling after focal cerebral ischemia in mice

Intravenous transplantation of neural progenitor cells (NPCs) induces functional recovery after stroke, albeit grafted cells are not integrated into residing neural networks. However, a systematic analysis of intravenous NPC delivery at acute and post-acute time points and their long-term consequences does not exist. Male C57BL6 mice were exposed to cerebral ischemia, and NPCs were intravenously grafted on day 0, on day 1 or on day 28. Animals were allowed to survive for up to 84 days. Mice and tissues were used for immunohistochemical analysis, flow cytometry, ELISA and behavioral tests. Density of grafted NPCs within the ischemic hemisphere was increased when cells were transplanted on day 28 as compared with transplantation on days 0 or 1. Likewise, transplantation on day 28 yielded enhanced neuronal differentiation rates of grafted cells. Post-ischemic brain injury, however, was only reduced when NPCs were grafted at acute time points. On the contrary, reduced post-ischemic functional deficits due to NPC delivery were independent of transplantation paradigms. NPC-induced neuroprotection after acute cell delivery was due to stabilization of the blood–brain barrier (BBB), reduction in microglial activation and modulation of both peripheral and central immune responses. On the other hand, post-acute NPC transplantation stimulated post-ischemic regeneration via enhanced angioneurogenesis and increased axonal plasticity. Acute NPC delivery yields long-term neuroprotection via enhanced BBB integrity and modulation of post-ischemic immune responses, whereas post-acute NPC delivery increases post-ischemic angioneurogenesis and axonal plasticity. Post-ischemic functional recovery, however, is independent of NPC delivery timing, which offers a broad therapeutic time window for stroke treatment.

Intravenous injection of neural progenitor cells facilitates angiogenesis after cerebral ischemia

Earlier we demonstrated that the injection of neural progenitor cells (NPCs) has therapeutic potential for the improvement of learning dysfunction after cerebral ischemia. However, it remained to be clarified how transplantation of NPCs can improve ischemia-induced dysfunction. In this study, we examined whether intravenous injection of NPCs after cerebral ischemia could enhance angiogenesis by affecting the expression of angiogenic factors. The injection of NPCs on day 7 after cerebral ischemia enhanced angiogenesis on day 28. Vascular endothelial growth factor (VEGF) and its receptor VEGFR2 were increased in expression by the NPC injection. The level of angiopoietin-1 (Ang-1), an angiogenic factor, but not that of Ang-2, which acts as an antagonist for the Ang-1 receptor, was also increased on day 28. In addition, the expression of Ang-1 receptor Tie2 was enhanced in brain capillaries. Furthermore, the amounts of tight junctional proteins, which are in the blood-brain barrier and whose expression occurs downstream of Ang-1/Tie2 signaling, were increased by the NPC injection. These results suggest that the NPC injection promoted angiogenesis through Ang-1/Tie2 and/or VEGF/VEGFR2 signaling in brain capillaries after cerebral ischemia. Such signaling might have the potential for causing vascular stabilization and maturation for a long period after cerebral ischemia.