Panax notoginseng saponin relieving the inflammatory pain caused by complete Freund’s adjuvant by inhibiting the activation of astrocytes in mice / 解剖学报

Objective To analyse the analgesic effect and possible mechanism of panax notoginseng saponin (PNS) on mouse models of chronic inflammatory pain caused by complete Freund’s adjuvant (CFA). Methods A total of 48 male C57BL/ 6J mice were divided randomly into four groups: normal saline control group (Ctrl), CFA group (CFA), CFA + PNS group (CFA+PNS), CFA + dexamethasone (DEX) group (CFA+DEX). Von Frey filaments were used to detect mechanical pain in mice. Immunohistochemistry was used to detect the number and morphological changes of glial fibrillary acidic protein (GFAP) positive astrocytes. Western blotting was used to detect the expressions of GFAP, nucleotide-binding and oligomerization domain(NOD)-like receptor thermal protein domain associated protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), Caspase-1, interleukin (IL)-1β, and IL-18 in mice’s spinal cord segments in each group. Results Compared with the Ctrl group, mice in the CFA group showed a significant decrease in mechanical pain thresholds at day 1, day 3, day 5, day 7, and day 14. Additionally, there was a significant decrease in NLRP3, ASC, Caspase-1, IL-1β and IL-18 in the spinal cord of the mice. PNS intervention could relieve mechanical pain and down-regulate the expressions of NLRP3, ASC, Caspase-1, IL-1β and IL-18 in the spinal cord of mice, with no significant difference compared with the CFA+DEX group. CFA group mice had significantly more GFAP positive cells in their posterior horns than Ctrl group mice, as measured by immunohistochemistry; PNS intervention decreased the number of GFAP positive cells in the posterior horn of the spinal cord in model mice;DEX had no effect on the number of GFAP positive cells in the dorsal horn of spinal cord. According to Western blotting results, GFAP expression in the spinal cord of the CFA group was significantly more than that of the Ctrl group; PNS intervention significantly reduced GFAP expression in the spinal cord of CFA group mice;DEX had no effect on the expression of GFAP in the posterior horn of spinal cord. Conclusion PNS has a good alleviating effect on inflammatory pain, and its mechanism may be related to inhibition of astrocyte activation and NLRP3 inflammasome activation.

Temporal-spatial Generation of Astrocytes in the Developing Diencephalon / 神经科学通报·英文版

Astrocytes are the largest glial population in the mammalian brain. However, we have a minimal understanding of astrocyte development, especially fate specification in different regions of the brain. Through lineage tracing of the progenitors of the third ventricle (3V) wall via in-utero electroporation in the embryonic mouse brain, we show the fate specification and migration pattern of astrocytes derived from radial glia along the 3V wall. Unexpectedly, radial glia located in different regions along the 3V wall of the diencephalon produce distinct cell types: radial glia in the upper region produce astrocytes and those in the lower region produce neurons in the diencephalon. With genetic fate mapping analysis, we reveal that the first population of astrocytes appears along the zona incerta in the diencephalon. Astrogenesis occurs at an early time point in the dorsal region relative to that in the ventral region of the developing diencephalon. With transcriptomic analysis of the region-specific 3V wall and lateral ventricle (LV) wall, we identified cohorts of differentially-expressed genes in the dorsal 3V wall compared to the ventral 3V wall and LV wall that may regulate astrogenesis in the dorsal diencephalon. Together, these results demonstrate that the generation of astrocytes shows a spatiotemporal pattern in the developing mouse diencephalon.

Effect of Astrocyte-neuron Coupling Imbalance in Development of Alzheimer's Disease and Intervention Mechanism of Kidney-tonifying and Marrow-filling TCM Prescriptions / 中国实验方剂学杂志

Astrocytes are important nerve cells in the central nervous system （CNS）， which mainly play a key role in nutrition and support. Astrocytes and neurons undergo close energy coupling and substance coupling， which are closely related and interact with each other. In recent years， many studies have shown that the astrocyte-neuron coupling imbalance plays a central role in the occurrence and progression of Alzheimer's disease （AD） and serves as an important therapeutic target receiving increasing attention. According to traditional Chinese medicine （TCM） theory， the main pathogenesis of AD is kidney deficiency and marrow inadequacy， and in clinical medication， kidney-tonifying and marrow-filling TCM prescriptions are often employed with satisfactory results achieved. As reported， many kidney-tonifying and marrow-filling prescriptions exhibit regulatory and protective effects on the imbalance of astrocyte-neuron coupling， suggesting that the effect of kidney-tonifying and marrow-filling prescriptions in treating AD may have some internal relationship with its regulation of the imbalance of astrocyte-neuron coupling. This article reviewed the underlying internal relationship between the imbalance of astrocyte-neuron coupling and the pathogenesis of kidney deficiency and marrow inadequacy in AD and the research progress in the intervention mechanism of TCM for tonifying the kidney and filling the marrow.

Effects of mesencephalic astrocyte-derived neurotrophic factor on sepsis-associated acute kidney injury / 世界急诊医学杂志（英文）

@#BACKGROUND: To determine the protective role of mesencephalic astrocyte-derived neurotrophic factor (MANF) in regulating sepsis-associated acute kidney injury (S-AKI). METHODS: A total of 96 mice were randomly divided into the control group, control+MANF group, S-AKI group, and S-AKI+MANF group. The S-AKI model was established by injecting lipopolysaccharide (LPS) at 10 mg/kg intraperitoneally. MANF (200 μg/kg) was administered to the control+MANF and S-AKI+MANF groups. An equal dose of normal saline was administered daily intraperitoneally in the control and S-AKI groups. Serum and kidney tissue samples were obtained for biochemical analysis. Western blotting was used to detect the protein expression of MANF in the kidney, and enzyme-linked immunosorbent assay (ELISA) was used to determine expression of MANF in the serum, pro-inflammatory cytokines (tumor necrosis factor-α [TNF-α] and interleukin-6 [IL-6]). Serum creatinine (SCr), and blood urea nitrogen (BUN) were examined using an automatic biochemical analyzer. In addition, the kidney tissue was observed for pathological changes by hematoxylin-eosin staining. The comparison between two groups was performed by unpaired Student’s t-test, and statistics among multiple groups were carried out using Tukey’s post hoc test following one-way analysis of variance (ANOVA). A P-value <0.05 was considered statistically significant. RESULTS: At the early stage of S-AKI, MANF in the kidney tissue was up-regulated, but with the development of the disease, it was down-regulated. Renal function was worsened in the S-AKI group, and TNF-α and IL-6 were elevated. The administration of MANF significantly alleviated the elevated levels of SCr and BUN and inhibited the expression of TNF-α and IL-6 in the kidney. The pathological changes were more extensive in the S-AKI group than in the S-AKI+MANF group. CONCLUSION: MANF treatment may significantly alleviate renal injury, reduce the inflammatory response, and alleviate or reverse kidney tissue damage. MANF may have a protective effect on S-AKI, suggesting a potential treatment for S-AKI.

Changes to GFAP Immunoreactive Astrocytes in Medial Prefrontal Cortex Following Exposure to Chronic Stress and Antioxidant Supplementation in Rat Model

@#Introduction: Astrocytes are responsible for many essential functions of neurons in CNS. It has been recognised that chronic stress affects the morphology of astrocyte. Natural antioxidant such as honey has been used as one of the therapeutic strategies to lessen the damaging effect of chronic stress on our body. Therefore, the aim of the study is to explore the effect of natural antioxidant, Tualang honey (TH) on the morphology of astrocytes following chronic stress exposure. Methods: Thirty-two male rats were randomly divided into the 4 groups: (i) control, (ii) stress, (iii) honey, (iv) stress plus honey groups.TH was administered via oral gavage at dose of 1.0 g/kg body weight pre and post experiment. Chronic stress was exposed to animals in group (ii) and (iv) for consecutive 21 days. Anti GFAP immunohistochemistry method was employed to label astrocytes in the medial prefrontal cortex. The number of GFAP+ astrocytes and several parameters related to astrocyte processes were measured. Results: The present study showed that chronic stress reduced the GFAP immunoreactive astrocyte number and percentage of GFAP immunoreactive material. Chronic stress also caused a reduction in astrocyte process ramification as indicated by a reduction in astrocyte total number of processes, average length of processes and maximum number of intersections. However, antioxidant treatment using TH could not reverse these stress-induced changes to the astrocytes. Conclusion: These results demonstrate that chronic stress decreases the number of GFAP immunoreactive astrocyte and cause shrinking of astrocyte processes in stress-sensitive brain region, but these changes cannot be reversed by antioxidant treatment.

Mechanism of anterior cingulate cortex in modulating pain and anxiety-like behavior in chronic non-specific low back pain model rats / 中华行为医学与脑科学杂志

Objective:To explore the potential mechanisms of anterior cingulate cortex (ACC) in modulating pain behavior and anxiety-like behavior of rats with chronic non-specific low back pain induced by nerve growth factor (NGF).Methods:Ninety-six male SPF grade SD rats aged 8 weeks were randomly divided into four groups according the random number table method: control group, model group, control+ D-2-amino-5-phosphonopentanoate (D-AP5) group (control+ D-AP5 group) and model+ D-AP5 group, with 24 rats in each group.Low back pain model of rat was established by injection of NGF into multifidus muscle (left side) of the low backs of rats(two times with a five-day interval). Five days after modeling, rats in model+ D-AP5 group and control+ D-AP5 group were injected with the N-methyl-D-aspartate (NMDA) receptor antagonist D-AP5(2 μg, 0.3 μL) at the right side of the ACC once a day for consecutive 3 days, and rats in control group and model group were injected with the same amount of 0.9% sodium chloride solution. Seven days after modeling, the pain threshold of rats was evaluated by mechanical stimulation test and hot and cold plate test.The anxiety-like behavior was tested by open field test.The density of glial fibrillary acidic protein (GFAP) positive cells and c-Fos(a kind of immediate early gene) positive cells of the spinal cord were observed by immunofluorescence. The expression of GFAP, c-Fos, phosphorylated-c-Jun N-terminal kinases (p-JNK), monocyte chemoattractant protein-1 (MCP-1), and chemokine (C-X-C motif) ligand 1 (CXCL-1) proteins in the L2 segment of the spinal cord were detected by Western blot. SPSS 23.0 software was used for statistical analysis. One-way ANOVA was used to analyze normal distribution measurement data for comparison among multiple groups, and Tukey test was used for further pairwise comparisons. The Kruakal-Wallis H test was used for non-normal distribution measurement data, and Mann-Whitney U test was used for further pairwise comparisons with Bonferroni-corrected P-values. Results:In the experiments measuring pressure pain threshold (PPT) and paw withdrawal threshold (PWT), there were statistically significant differences in the PPT and PWT of rats among the four groups ( F=53.498, 41.939, both P<0.001). Seven days after modeling, PPT ((418.5±46.9) g) and PWT ( (55.6±7.1) g) in the ipsilateral side of the rats in model+ D-AP5 group were higher than those in model group ((290.0±32.0) g, (30.5±7.5) g) (both P<0.001). In the open field test, there were statistically significant differences in percentage of the inner zone distance ( H=11.922, P<0.01) and the percentage of inner zone time ( H=21.614, P<0.001) of rats among the four groups. The percentage of inner zone time in model+ D-AP5 group was higher than that in model group (5.6(4.3, 7.9) %, 3.1(2.1, 3.8) %) ( P<0.01). The results of immunofluorescence showed that there were statistically significant differences in the density of GFAP positive cells and c-Fos positive cells at the ipsilateral side of the superficial laminae of rats among the four groups ( H=49.085, F=18.120, both P<0.001). The density of GFAP positive cells (34.3(21.1, 47.5) cells/mm 2) and c-Fos positive cells ((52.7±39.4) cells/mm 2) at the ipsilateral side of the superficial laminae in model+ D-AP5 group were less than those in model group (76.5(68.6, 94.9) cells/mm 2, (112.4±63.7) cells/mm 2) (both P<0.001). The Western blot results showed that there were statistically significant differences in the protein expression of GFAP, c-Fos, p-JNK, MCP-1 and CXCL-1 in the L2 segment of rats among the four groups ( F=49.413, 38.437, 41.867, 36.735, 130.951, all P<0.001). The protein expression of GFAP (1.7±0.5), c-Fos (1.1±0.1), p-JNK (1.7±0.3), MCP-1 (1.0±0.4) and CXCL-1 (0.8±0.1) in the L2 segment in model+ D-AP5 group were lower than those in model group ((4.3±0.7), (2.6±0.5), (2.8±0.4), (2.9±0.4), (3.5±0.4)) (all P<0.01). Conclusion:ACC modulates mechanical hyperalgesia and anxiety-like behavior in chronic non-specific low back pain rats, which might be associated with the involvement of spinal astrocytes, p-JNK signal pathway and chemokines such as MCP-1 and CXCL-1.

Characterization and identification of primarily cultured astrocytes and microglia / 生物工程学报

The aim of this study was to investigate the growth characteristics of primarily cultured astrocytes and microglia of different generations and then optimize the method for obtaining primary astrocytes and microglia effectively. Primarily cultured microglia were isolated and purified from the cortices of neonatal mice. The proliferation curve of mixed glia cells was measured by Cell Counting Kit-8 (CCK-8) assay, the proportion of astrocytes and microglia was detected by flow cytometry, and the polarization of the two types of glia cells was identified by immunofluorescence staining. Cell growth results showed that the mixed glia cells of P0 and P1 generation had the best proliferative activity; 97.3% of the high purity microglia could be obtained by mechanical shaking at 170 r/min for 30 min, and there was no significant difference in the morphology of ionized calcium-binding adapter molecule 1 (Iba-1) positive microglia and the proportion of M1 and M2 phenotype among the P0, P1 and P2 generations of microglia isolated by the above methods. Moreover, 95.7 % of the high purity astrocytes could be obtained by astrocyte cell surface antigen-2 (ACSA-2) magnetic beads separation, and there was no significant difference in the morphology of glial fibrillary acidic protein (GFAP) positive astrocyte and the proportion of A1 and A2 phenotype among the P0, P1 and P2 generations of astrocyte isolated by the above methods. Taken together, this study observed the growth characteristics of primarily cultured microglia and astrocyte in vitro, and then proved the best generations for purifying microglia and astrocytes. Finally, we optimized the methods of obtaining microglia and astrocyte, and verified that continuous culture within 2 generations will not affect the functional phenotypes of glia cells. These results provide technical support for studying the molecular mechanism of inflammation-associated diseases in nervous system.

Effects of astrocytes on the proliferation of neural stem cells in the hippocampal microenvironment of old and young adults / 解剖学报

Objective To investigate the effect and mechanism of astrocytes on the proliferation of neural stem cells (NSCs) in adult and juvenile hippocampus microenvironment. Methods Hippocampal astrocytes were isolated and cultured from 5 female SD rats at day 1 and week 30 postnatal, respectively; Embryonic hippocampus NSCs was isolated and cultured from 1 SD rat at day 15 of gestation; Conditioned astrocyte culture medium(CM) was collected for NSCs culture; Flow cytometry and CCK-8 were used to detect the proliferation of NSCs cultured in CM. Colony stimulating factor 1 (CSF-1) with differential expression was screened by mass spectrometry after cultured astrocyte CM. Western blotting and ELISA were used to verify the result of mass spectrometry. Immunofluorescence, flow cytometry and CCK-8 were used to detect the proliferation of NSCs treated with different concentrations of CSF-1 recombinant protein (20 μg/ L, 100 μg/ L, 1 mg/ L and 5 mg/ L). Results Compared with the adult group, the CM of hippocampal astrocytes in the young group could promote the proliferation of NSCs(P<0. 01); Compared with the conditioned medium of hippocampal astrocytes in the juvenile group, the expression of CSF-1 in the hippocampus of the elder group was significantly up-regulated(P<0. 01); At 20 μg/ L, CSF-1 promoted the proliferation of NSCs(P<0. 01), and 5 mg/ L CSF-1 inhibited significantly the proliferation of NSCs(P<0. 01). Conclusion The secretion of CSF-1 by astrocytes in hippocampal microenvironment can regulate the proliferation of NSCs with the development of the times.

Research on cellular damages and astrocyte activation after cerebral ischemia and reperfusion / 中国药理学通报

Aim To observe cellular damage and astrocyte activation at different time points of cerebral ischemia and reperfusion. Methods The middle cerebral artery of male SpragueDawley rats was occluded for 90 min followed by different time points of reperfusion. Eighty-five SPF male SD rats were randomly divided into control group (Sham), IR3, 6, 12, 24 and IR48h (MCAO followed by 48 h of reperfusion) group. Cerebral ischemia and reperfusion injury was observed by HE staining, and the structure of astrocytes was estimated with transmission electron microscopy (TEM). GFAP expression was detected by immunofluorescence staining and Western blot. Results Cerebral ischemia following by different time points of reperfusion led to different degrees of cellular damage, which was the most serious at 24 h of reperfusion. TEM showed destruction of astrocytes structure, swollen organelles and broken mitochondrial ridge. After cerebral ischemia-reperfusion, the expression levels of GFAP were significant up-regulated in the ischemic penumbra cortex and the highest was at 48 h of reperfusion, indicating astrocytes were activated. In addition, the results showed the gradual decrease in GFAP expression in the infarct core. Conclusions After cerebral ischemia-reperfusion, cellular damage is aggravated, and astrocytes are gradually activated in the ischemic penumbra. With the extension of reperfusion time, the boundaries of infarct area and ischemic area are gradually clear, and scarring may occur.

MANF brakes TLR4 signaling by competitively binding S100A8 with S100A9 to regulate macrophage phenotypes in hepatic fibrosis

The mesencephalic astrocyte-derived neurotrophic factor (MANF) has been recently identified as a neurotrophic factor, but its role in hepatic fibrosis is unknown. Here, we found that MANF was upregulated in the fibrotic liver tissues of the patients with chronic liver diseases and of mice treated with CCl4. MANF deficiency in either hepatocytes or hepatic mono-macrophages, particularly in hepatic mono-macrophages, clearly exacerbated hepatic fibrosis. Myeloid-specific MANF knockout increased the population of hepatic Ly6Chigh macrophages and promoted HSCs activation. Furthermore, MANF-sufficient macrophages (from WT mice) transfusion ameliorated CCl4-induced hepatic fibrosis in myeloid cells-specific MANF knockout (MKO) mice. Mechanistically, MANF interacted with S100A8 to competitively block S100A8/A9 heterodimer formation and inhibited S100A8/A9-mediated TLR4-NF-κB signal activation. Pharmacologically, systemic administration of recombinant human MANF significantly alleviated CCl4-induced hepatic fibrosis in both WT and hepatocytes-specific MANF knockout (HKO) mice. This study reveals a mechanism by which MANF targets S100A8/A9-TLR4 as a "brake" on the upstream of NF-κB pathway, which exerts an impact on macrophage differentiation and shed light on hepatic fibrosis treatment.

Bear bile powder alleviates Parkinson's disease-like behavior in mice by inhibiting astrocyte-mediated neuroinflammation / 中国天然药物

Parkinson's disease (PD) is a common neurodegenerative disease in middle-aged and elderly people. In particular, increasing evidence has showed that astrocyte-mediated neuroinflammation is involved in the pathogenesis of PD. As a precious traditional Chinese medicine, bear bile powder (BBP) has a long history of use in clinical practice. It has numerous activities, such as clearing heat, calming the liver wind and anti-inflammation, and also exhibits good therapeutic effect on convulsive epilepsy. However, whether BBP can prevent the development of PD has not been elucidated. Hence, this study was designed to explore the effect and mechanism of BBP on suppressing astrocyte-mediated neuroinflammation in a mouse model of PD. PD-like behavior was induced in the mice by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (30 mg·kg-1) for five days, followed by BBP (50, 100, and 200 mg·kg-1) treatment daily for ten days. LPS stimulated rat C6 astrocytic cells were used as a cell model of neuroinflammation. THe results indicated that BBP treatment significantly ameliorated dyskinesia, increased the levels of tyrosine hydroxylase (TH) and inhibited astrocyte hyperactivation in the substantia nigra (SN) of PD mice. Furthermore, BBP decreased the protein levels of glial fibrillary acidic protein (GFAP), cyclooxygenase 2 (COX2) and inducible nitric oxide synthase (iNOS), and up-regulated the protein levels of takeda G protein-coupled receptor 5 (TGR5) in the SN. Moreover, BBP significantly activated TGR5 in a dose-dependent manner, and decreased the protein levels of GFAP, iNOS and COX2, as well as the mRNA levels of GFAP, iNOS, COX2, interleukin (IL) -1β, IL-6 and tumor necrosis factor-α (TNF-α) in LPS-stimulated C6 cells. Notably, BBP suppressed the phosphorylation of protein kinase B (AKT), inhibitor of NF-κB (IκBα) and nuclear factor-κB (NF-κB) proteins in vivo and in vitro. We also observed that TGR5 inhibitor triamterene attenuated the anti-neuroinflammatory effect of BBP on LPS-stimulated C6 cells. Taken together, BBP alleviates the progression of PD mice by suppressing astrocyte-mediated inflammation via TGR5.

Neuroglobin Facilitates Neuronal Oxygenation through Tropic Migration under Hypoxia or Anemia in Rat: How Does the Brain Breathe? / 神经科学通报·英文版

The discovery of neuroglobin (Ngb), a brain- or neuron-specific member of the hemoglobin family, has revolutionized our understanding of brain oxygen metabolism. Currently, how Ngb plays such a role remains far from clear. Here, we report a novel mechanism by which Ngb might facilitate neuronal oxygenation upon hypoxia or anemia. We found that Ngb was present in, co-localized to, and co-migrated with mitochondria in the cell body and neurites of neurons. Hypoxia induced a sudden and prominent migration of Ngb towards the cytoplasmic membrane (CM) or cell surface in living neurons, and this was accompanied by the mitochondria. In vivo, hypotonic and anemic hypoxia induced a reversible Ngb migration toward the CM in cerebral cortical neurons in rat brains but did not alter the expression level of Ngb or its cytoplasm/mitochondria ratio. Knock-down of Ngb by RNA interference significantly diminished respiratory succinate dehydrogenase (SDH) and ATPase activity in neuronal N2a cells. Over-expression of Ngb enhanced SDH activity in N2a cells upon hypoxia. Mutation of Ngb at its oxygen-binding site (His64) significantly increased SDH activity and reduced ATPase activity in N2a cells. Taken together, Ngb was physically and functionally linked to mitochondria. In response to an insufficient oxygen supply, Ngb migrated towards the source of oxygen to facilitate neuronal oxygenation. This novel mechanism of neuronal respiration provides new insights into the understanding and treatment of neurological diseases such as stroke and Alzheimer's disease and diseases that cause hypoxia in the brain such as anemia.

Peripheral origin exosomal microRNAs aggravate glymphatic system dysfunction in diabetic cognitive impairment

Cognitive dysfunction is one of the common central nervous systems (CNS) complications of diabetes mellitus, which seriously affects the quality of life of patients and results in a huge economic burden. The glymphatic system dysfunction mediated by aquaporin-4 (AQP4) loss or redistribution in perivascular astrocyte endfeet plays a crucial role in diabetes-induced cognitive impairment (DCI). However, the mechanism of AQP4 loss or redistribution in the diabetic states remains unclear. Accumulating evidence suggests that peripheral insulin resistance target tissues and CNS communication affect brain homeostasis and that exosomal miRNAs are key mediators. Glucose and lipid metabolism disorder is an important pathological feature of diabetes mellitus, and skeletal muscle, liver and adipose tissue are the key target insulin resistance organs. In this review, the changes in exosomal miRNAs induced by peripheral metabolism disorders in diabetes mellitus were systematically reviewed. We focused on exosomal miRNAs that could induce low AQP4 expression and redistribution in perivascular astrocyte endfeet, which could provide an interorgan communication pathway to illustrate the pathogenesis of DCI. Furthermore, the mechanisms of exosome secretion from peripheral insulin resistance target tissue and absorption to the CNS were summarized, which will be beneficial for proposing novel and feasible strategies to optimize DCI prevention and/or treatment in diabetic patients.

Diesel exhaust inhalation exposure induced toxicity on olfactory bulb in mice through inflammatory response mediated by activating glial cells / 环境与职业医学

Background Air pollution is related to the occurrence and development of mental diseases. Olfactory bulb damage might be the potential prodromal symptom and sign of these diseases. The toxicity of diesel exhaust (DE), one of the main sources of air pollution, on olfactory bulb and the underlying mechanisms remain to be elucidated. Objective To explore the toxicity of DE on mouse olfactory bulb and underlying mechanisms. Methods A total of 40 C57BL/6 mice were randomly divided into four groups for exposure to DE by systemic inhalation: control group (filtered air), low exposure group (750 μg·m−3 DE), medium exposure group (1500 μg·m−3 DE), and high exposure group (3000 μg·m−3 DE). The mouse inhalation exposure to DE was performed 1 h per day for 28 d. HE staining was performed to observe pathological changes in mouse olfactory bulb tissue. TUNEL assay was used to observe apop-tosis in olfactory bulb. Kyoto Encyclopedia of Genes and Genomes (KEGG) was exhibited to explore potential mechanisms of olfactory bulb damage associated with DE. Quantitative real-time PCR (qPCR) was used to determine mRNA expression levels of inflammatory factors including tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Immunofluorescence staining was conducted to observed the microglia and astrocyte activation in olfactory bulb. Results The HE staining results showed that the number of periglomerular cells in the glomerular layer of olfactory bulb decreased in a dose-dependent manner, and the cells in the granule cell layer of olfactory bulb became disordered after DE exposure. The TUNEL staining showed that TUNEL positive cells in olfactory bulb tissue and neuronal apoptosis increased in the exposed groups compared with the control group (P＜0.05). The KEGG pathway analysis showed that DE associated with significant enrichment of TNF signaling pathway in olfactory bulb tissue. The qPCR results showed that the TNF-α relative expression level significantly increased by 67% and the IL-6 relative expression level by 340% in the DE high exposure dose group compared with the control group (P＜0.05). According to the immunofluorescence staining results, the numbers of activated microglia and astrocytes in olfactory bulb tissue significantly increased in the DE high exposure group, the relative fluorescence intensity of ionized calcium binding adaptor molecule 1 (IBA-1) increased by 120%, the granule cell layer relative fluorescence intensity of glial fibrillary acidic protein (GFAP) increased by 400%, and the glomerular layer relative fluorescence intensity of GFAP increased by 240% than those in the control group (P＜0.05). Conclusion Inhalation exposure to DE can lead to glial cell activation including microglia and astrocytes in olfactory bulb tissue by activating inflammatory pathways and releasing inflammatory factors TNF-α and IL-6, leading to neuronal apoptosis in olfactory bulb tissue.

Astrocytes in Chronic Pain: Cellular and Molecular Mechanisms / 神经科学通报·英文版

Chronic pain is challenging to treat due to the limited therapeutic options and adverse side-effects of therapies. Astrocytes are the most abundant glial cells in the central nervous system and play important roles in different pathological conditions, including chronic pain. Astrocytes regulate nociceptive synaptic transmission and network function via neuron-glia and glia-glia interactions to exaggerate pain signals under chronic pain conditions. It is also becoming clear that astrocytes play active roles in brain regions important for the emotional and memory-related aspects of chronic pain. Therefore, this review presents our current understanding of the roles of astrocytes in chronic pain, how they regulate nociceptive responses, and their cellular and molecular mechanisms of action.

Interactions Between Astrocytes and Oligodendroglia in Myelin Development and Related Brain Diseases / 神经科学通报·英文版

Astrocytes (ASTs) and oligodendroglial lineage cells (OLGs) are major macroglial cells in the central nervous system. ASTs communicate with each other through connexin (Cx) and Cx-based network structures, both of which allow for quick transport of nutrients and signals. Moreover, ASTs interact with OLGs through connexin (Cx)-mediated networks to modulate various physiological processes in the brain. In this article, following a brief description of the infrastructural basis of the glial networks and exocrine factors by which ASTs and OLGs may crosstalk, we focus on recapitulating how the interactions between these two types of glial cells modulate myelination, and how the AST-OLG interactions are involved in protecting the integrity of the blood-brain barrier (BBB) and regulating synaptogenesis and neural activity. Recent studies further suggest that AST-OLG interactions are associated with myelin-related diseases, such as multiple sclerosis. A better understanding of the regulatory mechanisms underlying AST-OLG interactions may inspire the development of novel therapeutic strategies for related brain diseases.

Association of Glial Activation and α-Synuclein Pathology in Parkinson's Disease / 神经科学通报·英文版

The accumulation of pathological α-synuclein (α-syn) in the central nervous system and the progressive loss of dopaminergic neurons in the substantia nigra pars compacta are the neuropathological features of Parkinson's disease (PD). Recently, the findings of prion-like transmission of α-syn pathology have expanded our understanding of the region-specific distribution of α-syn in PD patients. Accumulating evidence suggests that α-syn aggregates are released from neurons and endocytosed by glial cells, which contributes to the clearance of α-syn. However, the activation of glial cells by α-syn species produces pro-inflammatory factors that decrease the uptake of α-syn aggregates by glial cells and promote the transmission of α-syn between neurons, which promotes the spread of α-syn pathology. In this article, we provide an overview of current knowledge on the role of glia and α-syn pathology in PD pathogenesis, highlighting the relationships between glial responses and the spread of α-syn pathology.

Research progress on the role of astrocytes in radiation-induced brain injury / 中华放射肿瘤学杂志

Radiation-induced brain injury (RBI) is one of the complications after radiotherapy for head and neck malignant tumors, which seriously affects the quality of life of patients. The pathophysiological mechanism of RBI is not completely clear. Current studies suggest that it is involved in a variety of cells in the central nervous system (CNS), whereas astrocyte, as the largest number of glial cells in the CNS, plays an important role in maintaining the CNS homeostasis and responding to CNS injury. In this article, the role of astrocytes in RBI was reviewed.

Baicalin treats cerebral ischemia reperfusion-induced brain edema in rats by inhibiting TRPV4 and AQP4 of astrocytes / 中国中药杂志

This study aims to explore the pharmacodynamic effect of baicalin on rat brain edema induced by cerebral ischemia reperfusion injury and discuss the mechanism from the perspective of inhibiting astrocyte swelling, which is expected to serve as a refe-rence for the treatment of cerebral ischemia with Chinese medicine. To be specific, middle cerebral artery occlusion(suture method) was used to induce cerebral ischemia in rats. Rats were randomized into normal group, model group, high-dose baicalin(20 mg·kg~(-1)) group, and low-dose baicalin(10 mg·kg~(-1)) group. The neurobehavior, brain index, brain water content, and cerebral infarction area of rats were measured 6 h and 24 h after cerebral ischemia. Brain slices were stained with hematoxylin and eosin(HE) for the observation of pathological morphology of cerebral cortex after baicalin treatment. Enzyme-linked immunosorbent assay(ELISA) was employed to determine the content of total L-glutathione(GSH) and glutamic acid(Glu) in brain tissue, Western blot to measure the content of glial fibrillary acidic protein(GFAP), aquaporin-4(AQP4), and transient receptor potential vanilloid type 4(TRPV4), and immunohistochemical staining to observe the expression of GFAP. The low-dose baicalin was used for exploring the mechanism. The experimental results showed that the neurobehavioral scores(6 h and 24 h of cerebral ischemia), brain water content, and cerebral infarction area of the model group were increased, and both high-dose and low-dose baicalin can lower the above three indexes. The content of GSH dropped but the content of Glu raised in brain tissue of rats in the model group. Low-dose baicalin can elevate the content of GSH and lower the content of Glu. According to the immunohistochemical staining result, the model group demonstrated the increase in GFAP expression, and swelling and proliferation of astrocytes, and the low-dose baicalin can significantly improve this situation. The results of Western blot showed that the expression of GFAP, TRPV4, and AQP4 in the cerebral cortex of the model group increased, and the low-dose baicalin reduce their expression. The cerebral cortex of rats in the model group was severely damaged, and the low-dose baicalin can significantly alleviate the damage. The above results indicate that baicalin can effectively relieve the brain edema caused by cerebral ischemia reperfusion injury in rats, possibly by suppressing astrocyte swelling and TRPV4 and AQP4.

Astrocytic Gap Junctions Contribute to Aberrant Neuronal Synchronization in a Mouse Model of MeCP2 Duplication Syndrome / 神经科学通报·英文版

Abnormal synchronous neuronal activity has been widely detected by brain imaging of autistic patients, but its underlying neural mechanism remains unclear. Compared with wild-type mice, our in vivo two-photon imaging showed that transgenic (Tg1) mice over-expressing human autism risk gene MeCP2 exhibited higher neuronal synchrony in the young but lower synchrony in the adult stage. Whole-cell recording of neuronal pairs in brain slices revealed that higher neuronal synchrony in young postnatal Tg1 mice was attributed mainly to more prevalent giant slow inward currents (SICs). Both in vivo and slice imaging further demonstrated more dynamic activity and higher synchrony in astrocytes from young Tg1 mice. Blocking astrocytic gap junctions markedly decreased the generation of SICs and overall cell synchrony in the Tg1 brain. Furthermore, the expression level of Cx43 protein and the coupling efficiency of astrocyte gap junctions remained unchanged in Tg1 mice. Thus, astrocytic gap junctions facilitate but do not act as a direct trigger for the abnormal neuronal synchrony in young Tg1 mice, revealing the potential role of the astrocyte network in the pathogenesis of MeCP2 duplication syndrome.