New role of astrocytes in neuroprotective mechanisms after ischemic stroke / Novo papel dos astrócitos nos mecanismos neuroprotetores após acidente vascular cerebral isquêmico

Abstract Astrocytes are the most abundant cell subtypes in the central nervous system. Previous studies believed that astrocytes are supporting cells in the brain, which only provide nutrients for neurons. However, recent studies have found that astrocytes have more crucial and complex functions in the brain, such as neurogenesis, phagocytosis, and ischemic tolerance. After an ischemic stroke, the activated astrocytes can exert neuroprotective or neurotoxic effects through a variety of pathways. In this review, we will discuss the neuroprotective mechanisms of astrocytes in cerebral ischemia, and mainly focus on reactive astrocytosis or glial scar, neurogenesis, phagocytosis, and cerebral ischemic tolerance, for providing new strategies for the clinical treatment of stroke.

Resumo Os astrócitos são os subtipos de células mais abundantes no sistema nervoso central. Estudos anteriores acreditavam que os astrócitos são células de suporte no cérebro, que apenas fornecem nutrientes para os neurônios. No entanto, estudos recentes descobriram que os astrócitos têm funções mais cruciais e complexas no cérebro, como neurogênese, fagocitose e tolerância isquêmica. Após um acidente vascular cerebral isquêmico, os astrócitos ativados podem exercer efeitos neuroprotetores ou neurotóxicos através de uma variedade de vias. Nesta revisão, discutiremos os mecanismos neuroprotetores dos astrócitos na isquemia cerebral, e focaremos principalmente na astrocitose reativa ou cicatriz glial, neurogênese, fagocitose e tolerância isquêmica cerebral, para fornecer novas estratégias para o tratamento clínico do acidente vascular cerebral.

Click chemistry extracellular vesicle/peptide/chemokine nanocarriers for treating central nervous system injuries

Central nervous system (CNS) injuries, including stroke, traumatic brain injury, and spinal cord injury, are essential causes of death and long-term disability and are difficult to cure, mainly due to the limited neuron regeneration and the glial scar formation. Herein, we apply extracellular vesicles (EVs) secreted by M2 microglia to improve the differentiation of neural stem cells (NSCs) at the injured site, and simultaneously modify them with the injured vascular targeting peptide (DA7R) and the stem cell recruiting factor (SDF-1) on their surface via copper-free click chemistry to recruit NSCs, inducing their neuronal differentiation, and serving as the nanocarriers at the injured site (Dual-EV). Results prove that the Dual-EV could target human umbilical vascular endothelial cells (HUVECs), recruit NSCs, and promote the neuronal differentiation of NSCs in vitro. Furthermore, 10 miRNAs are found to be upregulated in Dual-M2-EVs compared to Dual-M0-EVs via bioinformatic analysis, and further NSC differentiation experiment by flow cytometry reveals that among these miRNAs, miR30b-3p, miR-222-3p, miR-129-5p, and miR-155-5p may exert effect of inducing NSC to differentiate into neurons. In vivo experiments show that Dual-EV nanocarriers achieve improved accumulation in the ischemic area of stroke model mice, potentiate NSCs recruitment, and increase neurogenesis. This work provides new insights for the treatment of neuronal regeneration after CNS injuries as well as endogenous stem cells, and the click chemistry EV/peptide/chemokine and related nanocarriers for improving human health.

Inhibition of Foxp4 Disrupts Cadherin-based Adhesion of Radial Glial Cells, Leading to Abnormal Differentiation and Migration of Cortical Neurons in Mice / 神经科学通报·英文版

Heterozygous loss-of-function variants of FOXP4 are associated with neurodevelopmental disorders (NDDs) that exhibit delayed speech development, intellectual disability, and congenital abnormalities. The etiology of NDDs is unclear. Here we found that FOXP4 and N-cadherin are expressed in the nuclei and apical end-feet of radial glial cells (RGCs), respectively, in the mouse neocortex during early gestation. Knockdown or dominant-negative inhibition of Foxp4 abolishes the apical condensation of N-cadherin in RGCs and the integrity of neuroepithelium in the ventricular zone (VZ). Inhibition of Foxp4 leads to impeded radial migration of cortical neurons and ectopic neurogenesis from the proliferating VZ. The ectopic differentiation and deficient migration disappear when N-cadherin is over-expressed in RGCs. The data indicate that Foxp4 is essential for N-cadherin-based adherens junctions, the loss of which leads to periventricular heterotopias. We hypothesize that FOXP4 variant-associated NDDs may be caused by disruption of the adherens junctions and malformation of the cerebral cortex.

A preliminary study of fecal microbiota transplantation alleviating inhibition of radiation-induced hippocampal neurogenesis in mice / 中华放射肿瘤学杂志

Objective:To evaluate the effects of whole brain irradiation (WBI) and fecal microbiota transplantation (FMT) on hippocampal neurogenesis and the composition of gut microbiota in mice.Methods:Forty specific pathogen free ICR male mice (8-week-old, weighed 30 g) were divided into four groups by simple random sample method: control group (group C), radiation group (group R), group C+FMT and group R+FMT, 10 in each group. Animal models were established by WBI at a dose of 10 Gy by 4 MeV electron beam. In group C+FMT and group R+FMT, mice were gavaged with normal fecal bacteria suspension on day 2 post-irradiation, while those in group C and group R were gavaged with phosphate buffered saline as alternative. Hippocampal tissues and feces in four groups were collected on day 15 post-irradiation. 16S rRNA sequencing was used to detect the species and abundance of fecal flora. BrdU +/NeuN + immunofluorescence staining was performed to observe the neurogenesis in hippocampus of mice. Results:WBI and FMT had no effect on survival rate and body weight of mice. WBI induced the inhibition of hippocampal neurogenesis and flora disorder. The quantity of Bacteroideae and Rumen bacteria was increased by 28.6% and 102.9%, whereas that of Lactobacillus was significantly decreased by 70.6% ( P<0.05). FMT regulated the abundance of bacteria. The abundance of Enterobacteriaceae was significantly declined by 65.1% ( P=0.028), while that of Lactobacillus was increased by 58.2% ( P=0.015). FMT also promoted hippocampal neurogenesis to some extent after WBI. Conclusions:This preliminary study demonstrates that FMT alleviates the inhibition of hippocampal neurogenesis and flora disorder induced by WBI in mice. Ionizing radiation directly acting on the whole brain of mice indirectly disturbs the composition of gut microbiota, which in turn affects the degree of hippocampal neurogenesis in the brain of mice. There is a bidirectional interaction between gut microbiota and brain.

An experimental study on the ameliorating effect of terazosin on whole-brain irradiation-induced cognitive dysfunction / 中华放射肿瘤学杂志

Objective:To verify the protective effect of terazosin on cognitive function of rats after whole-brain irradiation (WBI) and to investigate its mechanism.Methods:A total of 64 1-month-old male SD rats were randomly divided into the untreated control group, terazosin group, irradiation group and irradiation plus terazosin group (combination group). WBI was administered at a single dose of 20 Gy in the irradiation and combination groups. The open field test and the Morris water maze (MWM) test were used to evaluate the effect of terazosin on cognitive function after WBI.Starting from the three aspects of juvenile neuron apoptosis, neurogenesis disorderand microglia activation, the possible cellular mechanism wasassayed by double-label immunofluorescence staining for BrdU (bromodeoxyuridine) / NeuN, DCX(Doublecortin) / Caspase-3 and single-label immunofluorescence staining for Iba-1 (ionized calcium binding adaptor molecule-1).Results:Terazosin intervention improved the short-term memory retention of irradiated rats ( P=0.032). After terazosin treatment, the number of DCX + cells in the combination groupwas increased by approximately 35% compared with that in the irradiation group ( P=0.038). The number of BrdU +/NeuN + cells in the combination group was increased by approximately 15% than that in the irradiation group ( P>0.05). The number of Iba-1 + cells in the irradiation plus terazosin group was decreased by 49% compared with that in the irradiation group ( P=0.036). Conclusion:Terazosin may reduce the hippocampal juvenile neuron loss and inhibit neuroinflammation via microglia activation, which can alleviate WBI-induced cognitive dysfunction to a certain extent.

Chronic intermittent hypobaric hypoxia improved the memory and cognitive impairment of mice with whole brain irradiation / 中华放射医学与防护杂志

Objective:To observe the changes in hippocampus (CA1) and study the effect of chronic intermittent hypobaric hypoxia (CIHH) preconditioning on the memory and cognitive function of mice exposed to the whole brain irradiation.Methods:A total of 48 C57BL/6 male mice were randomly divided into control group, CIHH group, irradiation group (IR group) and CIHH+ IR group. For IR group, the whole brain of mice were irradiated with 10 Gy of 6 MV X-rays in a single fraction. Pretreatment with CIHH was performed by placing mice in a hypobaric chamber before radiation. The mirrors water maze experiment was performed in the four groups to observe the escape latency, the number of crossing platforms and the target quadrant residence time. Nissl staining was used to observe the changes of neuronal cells in hippocampal CA1 region. Immunofluorescence was used to detect the expression of microtubule-associated protein cells (DCX) in the subgranular zone (SGZ) of hippocampal dentate gyrus (DG) to evaluate neurogenesis.Results:After 30 days of whole brain irradiation, the escape latency of mice prolonged gradually, the frequency of crossing platform decreased ( P< 0.001), and the exploration time in the target quadrant decreased ( P<0.001). X-ray irradiation caused disorder of mice neuronal cells, degeneration and necrosis of neuronal cells, and decrease of DCX expression in CA1 region of mice. Compared with IR group, the CIHH+ IR group had shortened the escape latency, increased the frequency of crossing platform [(2.08±0.26) vs. (0.83±0.24), P<0.001], and also increased the exploration time in the target quadrant [(14.12±0.82)s vs. (7.42±0.73)s, P<0.001]. Pretreatment with CIHH also alleviated the deformation and necrosis of neurons in hippocampus, and increased DCX expression in CA1 region. Conclusions:Pretreatment of mice with CIHH plays a protective role in radiation induced hippocampal injury.

Effect of Zishen Huoxue Prescription on Regulation of Mitophagy and Neurogenesis in Hippocampal CA1 Region of Vascular Dementia Rats / 中国实验方剂学杂志

ObjectiveTo investigate the effect of Zishen Huoxue prescription on promoting neurogenesis in hippocampal CA1 region of vascular dementia （VD） rats by regulating mitophagy. MethodThe 2-VO method was used to establish the VD rat model and 60 SD rats were randomly divided into sham operation group， model group， donepezil hydrochloride group， and Zishen Huoxue prescription low-dose（8.9 g·kg-1）， medium-dose（17.8 g·kg-1） and high-dose（35.6 g·kg-1） groups. Morris water maze test was performed to detect the escape latency and the number of crossing platform in each group. The expression of phosphatase and tensin homology-induced kinase 1 （PINK1） and Parkinson protein （Parkin） mRNA in hippocampal CA1 region was detected by Real-time fluorescent quantitative polymerase chain reaction（Real-time PCR）. Western blot was used to determine the expression of mitochondrial autophagy signaling pathway-related proteins Parkin， prohibitin 2 （PHB2）， mitofusin 2 （Mfn2） and dynamin-related protein 1 （Drp1） in hippocampal CA1 region. The neurogenesis in hippocampal CA1 region was tested by Brdu method. ResultCompared with the conditions in the sham operation group， the learning and spatial memory abilities of the model group were decreased （P<0.05）， with damaged mitochondrial structure and autolysosome formation in the hippocampal CA1 region. The expressions of Parkin， Pink1 mRNA and Parkin， PHB2， and Drp1 proteins were up-regulated （P<0.05）， while the expression of Mfn2 protein and the neuronal regeneration in hippocampal CA1 region were reduced （P<0.05， P<0.05）. Compared with the conditions in the model group， Zishen Huoxue prescription enhanced the learning and spatial memory abilities of VD rats （P<0.05）， increased the number of autophagosomes in hippocampal CA1 region and improved the mitochondrial structure. The expression of Parkin， Pink1 mRNA and Parkin， PHB2， and Drp1 proteins in hippocampal CA1 region was up-regulated （P<0.05， P<0.01）while the expression of Mfn2 protein was down-regulated（P<0.05， P<0.01）. The number of new neurons in hippocampal CA1 region was also increased（P<0.05， P<0.01）. ConclusionThe promoting effect of Zishen Huoxue prescription on the neurogenesis in hippocampal CA1 region of VD rats was related to the mitophagy mediated by Pink1/Parkin signaling pathway.

Effects of paraquat on proliferation and neurogenesis of neural stem cells by promoting secretion of IL-1β by microglia / 环境与职业医学

Background Paraquat (PQ) is a widely used herbicide that exerts neurotoxicity. The effects of PQ on neural stem cells (NSCs) through microglia mediated neuroinflammation remain limitedly studied. Objective To investigate the effects of PQ on the proliferation and neurogenesis of NSCs through neuroinflammation mediated by microglia. Methods Microglial cell lines (BV2 cells) and primary NSCs were used. BV2 cells were exposed to 0, 1, 3.3, 10, 33, and 100 μmol·L−1 of PQ for 6 h followed by viability assessment. The highest PQ concentration that had no effect on cell viability was selected as the final exposure concentration (33 μmol·L−1). To exclude the direct effect of PQ on NSCs, after the BV2 cells were cultured in complete medium containing 33 μmol·L−1 PQ for 6 h, the BV2 culture medium was replaced by NSCs complete medium without PQ for 24 h. The concentration of interleukin-1β (IL-1β) in supernatant was detected by enzyme-linked immune sorbent assay. Besides, in order to detect the effects of IL-1β on NSCs proliferation and neurogenesis, NSCs isolated from hippocampus of adult mice were cultured in the supernatant obtained above and divided into four groups: control supernatant + control antibody, control supernatant + IL-1β neutralizing antibody (10 ng·mL−1), PQ supernatant + control antibody, PQ supernatant + IL-1β neutralizing antibody (10 ng·mL−1). Proportion of Ki67-positive NSCs was detected by flow cytometry (FCS) and immunofluorescence after 24 h culture, and neurogenesis was detected by FCS and immunofluorescence after 3-7 d of culture. Results The IL-1β concentration in the supernatant of BV2 cells was significantly increased after the 33 μmol·L−1 PQ exposure compared with the control group (t=3.020, P<0.05). After the NSCs were cultured with the supernatant of PQ-treated BV2 cells, the proportion of Ki67-positive NSCs (t=9.129, P<0.01) and the proportion of newborn neurons (t=4.638, P<0.01) were significantly decreased compared to the control group. After neutralizing IL-1β, the proportion of Ki67-positive NSCs (t=22.05, P<0.01) and the proportion of newborn neurons (t=11.09, P<0.01) were significantly higher than those in the un-neutralized group. The results of immunofluorescence detection also showed that after neutralizing IL-1β secreted by 33 μmol·L−1 PQ-treated BV2 cells, the number of Ki67-positive NSCs and the number of newborn neurons were significantly higher than those in the un-neutralized group. Conclusion The secretion of IL-1β by microglia is increased after PQ treatment, resulting in a decrease in the proliferation and neurogenesis of NSCs. These results suggest that neuroinflammation is involved in NSCs damage caused by PQ.

Neural mechanism of environmental enrichment improving depression / 中华行为医学与脑科学杂志

Depression is a common psychiatric disorder characterized by low mood with complex pathophysiological mechanisms and poor effect of pharmacological treatment.The animals were placed in greater sensory, physical and/or social stimuli than those of the standard feeding environment, so that they can obtain positive plasticity and adaptability.Environmental enrichment(EE) is a common intervention to improve brain function in laboratory.A large number of studies have shown that EE had significant ameliorative effects on various animal models of depression, but the mechanisms have not been yet fully understood with outcome heterogeneity in ethology.There was no universally accepted and unified paradigm and standard for EE due to its multi-dimensionality and complexity.Therefore, it is necessary to improve the structural components and implementation steps of EE by integrating the existing data.Combined with recent studies on animal models of depression, this paper reviewed the anti-depression mechanism of EE from promoting hippocampal neurogenesis, reducing neuroinflammation, regulating neuroendocrine and affecting epigenetic modifications, in order to provide new ideas for mechanisms research and treatment of depression.As the rise of precision medicine and individualized medicine brings human growing interest in exploring the sources and mechanisms of inter-individual differences and intra-group effects of depression, it will be a challenge to translate EE to the human society in a rational way.

Effects of Chaihu-Shugan San on behavior and hippocampal neurogenesis in depression model mice / 中华行为医学与脑科学杂志

Objective:To explore the effects of Chaihu-Shugan San (CSS) on the behavior and neurogenesis function of depression model mice induced by chronic unpredictable mild stress (CUMS).Methods:Thirty clean grade healthy male C57BL/6 adult mice were randomly divided into control group (Con group), model group (CUMS group) and Chaihu-Shugan San treatment group (CSS group), with 10 mice in each group.The mice in CUMS group and CSS group were given CUMS intervention to establish depression model. At the same time of modeling, the mice in CUMS group and CSS group were given distilled water and CSS(2.7 g/kg) by gavage respectively.While the mice in Con group were only given equal volume distilled water by gavage without CUMS stimulation.After the intervention, the depressive-like behavior of mice was evaluated by increased body weight, sugar water preference test (SPT), forced swimming test (FST) and tail suspension test (TST). The number of newborn neurons was detected by immunofluorescence staining. The mRNA expression levels of brain-derived neurotrophic factor (BDNF), fibroblast growth factor 2 (FGF2) and spindle and kinetochore-associated protein 2(SKA2) in mice hippocampus were detected by qRT-PCR.Statistical analysis was performed by SPSS 22.0 software. One-way ANOVA was used for multi group comparison, and Tukey test was used for pairwise comparison.Results:(1) After modeling, there was significant difference in body weight increment among the three groups ( F=8.859, P <0.05). The body weight increment of CUMS group was lower than those of Con group and CSS group (both P< 0.05). There were significant differences in sugar water preference rate, tail suspension immobility time and swimming immobility time among the three groups ( F=10.544, 12.957, 8.095, all P<0.05). The sugar water preference rate in CUMS group was lower than that in Con group ((87.46±2.78)%, (93.90±3.31)%, P<0.05), and that in CSS group was higher than that in CUMS group ((91.65±2.61)%)( P<0.05). The tail suspension immobility time ((198.00±27.57) s) and swimming immobility time ((322.20±46.98) s) in CUMS group were higher than those in Con group ((138.80±38.50) s, (238.50±50.51) s, both P<0.05). The tail suspension immobility time ((139.00±21.29) s) and swimming immobility time ((265.20±44.90) s) in CSS group were lower than those in CUMS group (both P<0.05). (2) Immunofluorescence showed that there was significant difference in the number of newborn neurons labeled by BrdU and NeuN in the dentate gyrus of hippocampus among the three groups ( F=9.486, P<0.05). The number of double labeled cells (31.66±3.21) in CUMS group was lower than that in Con group(63.66±15.17) and CSS group (58.00±6.00) (both P<0.05). (3) RT-PCR results showed that the mRNA levels of BDNF, FGF2, SKA2 in hippocampal dentate gyrus of the three group were significantly different( F=14.522, 9.337, 8.701, all P<0.05). The levels of BDNF mRNA (0.79±0.06), FGF2 mRNA (0.74±0.18) and SKA2 mRNA (0.52±0.32) in the dentate gyrus of hippocampus in CUMS group were lower than those in Con group (BDNF mRNA (1.03±0.10), FGF2 mRNA (1.04±0.11), SKA2 mRNA (1.05±0.37), all P<0.05). Compared with CUMS group, the mRNA levels of BDNF (1.07±0.80), FGF2 (1.30±0.29) and SKA2 (1.40±0.55) in CSS group were higher (all P<0.05). Conclusion:CSS can alleviate the depressive like behavior of depression model mice, which may be related with increasing the mRNA expression levels of BDNF, FGF2, SKA2 and promoting the proliferation of neural stem cells in hippocampus.

Effect of early-life maternal deprivation on depressive-like behavior and neurogenesis in hippocampal granular layer of adolescent rat / 中华行为医学与脑科学杂志

Objective:To explore the effects of early-life maternal deprivation on depressive-like behavior and neurogenesis in the granular layer of hippocampus in adolescent rats (6-7 weeks old).Methods:Neonatal rats were randomly divided into maternal deprivation group and control group, with 3 litters in each group.Rats in the maternal deprivation group were given maternal deprivation from 1 to 14 days after birth and rats in the control group were caged with the mother rats and raised normally.The body weight of rats at 5-6 weeks old was recorded and the increased body weight was calculated.When the rats were 6 weeks old, the sucrose preference test was carried out.Then the rats were killed and immunofluorescence histochemistry was applied to compare the expression of Ki67 and Nestin positive cells in the dentate gyrus of hippocampus.SPSS 22.0 software was used for statistical analysis.The data of the two groups were tested to conform to the normal distribution, and then t-test was carried out. Results:There was significant difference in body weight growth between the two groups at the age of 5-6 weeks.Compared with the control group, rats in the maternal deprivation group had lower body weight growth ((20.57±2.19) g, (30.57±1.25) g, t=3.96, P<0.01)) and lower sucrose preference rate((58.38±53.14)%, (73.88±3.67)%, t=3.21, P<0.01). The results of immunofluorescence showed that the number of Ki67 positive cells in the granular layer of hippocampus in the maternal deprivation group was less than that in the control group ((5.13±0.31), (7.60±0.38), t=5.09, P<0.01), and the number of Nestin immunofluorescence positive cells was more than that in the control group ((16.65±0.79), (7.64±0.70), t=8.51, P<0.01). The Nestin immunofluorescence positive cells in the maternal deprivation group had more protrusions and branches, and the morphology was similar to astrocytes, while the immunofluorescence positive cells in the control group had fewer protrusions, and the cell body was oval. Conclusions:Early-life maternal deprivation leads to depressive-like behavior in adolescent rats, which may be associated with the decrease of neurogenesis and activation of astrocytes in the dentate gyrus of the hippocampus.

PINK1 kinase dysfunction triggers neurodegeneration in the primate brain without impacting mitochondrial homeostasis

In vitro studies have established the prevalent theory that the mitochondrial kinase PINK1 protects neurodegeneration by removing damaged mitochondria in Parkinson's disease (PD). However, difficulty in detecting endogenous PINK1 protein in rodent brains and cell lines has prevented the rigorous investigation of the in vivo role of PINK1. Here we report that PINK1 kinase form is selectively expressed in the human and monkey brains. CRISPR/Cas9-mediated deficiency of PINK1 causes similar neurodegeneration in the brains of fetal and adult monkeys as well as cultured monkey neurons without affecting mitochondrial protein expression and morphology. Importantly, PINK1 mutations in the primate brain and human cells reduce protein phosphorylation that is important for neuronal function and survival. Our findings suggest that PINK1 kinase activity rather than its mitochondrial function is essential for the neuronal survival in the primate brains and that its kinase dysfunction could be involved in the pathogenesis of PD.

Neonatal Exposure to Propofol Interferes with the Proliferation and Differentiation of Hippocampal Neural Stem Cells and the Neurocognitive Function of Rats in Adulthood via the Akt/p27 Signaling Pathway / 生物医学与环境科学（英文）

Objective@#Neonatal exposure to propofol has been reported to cause neurotoxicity and neurocognitive decline in adulthood; however, the underlying mechanism has not been established.@*Methods@#SD rats were exposed to propofol on postnatal day 7 (PND-7). Double-immunofluorescence staining was used to assess neurogenesis in the hippocampal dentate gyrus (DG). The expression of p-Akt and p27 were measured by western blotting. The Morris water maze, novel object recognition test, and object location test were used to evaluate neurocognitive function 2-month-old rats.@*Results@#Phosphorylation of Akt was inhibited, while p27 expression was enhanced after neonatal exposure to propofol. Propofol also inhibited proliferation of neural stem cells (NSCs) and decreased differentiation to neurons and astroglia. Moreover, the neurocognitive function in 2-month-old rats was weakened. Of significance, intra-hippocampal injection of the Akt activator, SC79, attenuated the inhibition of p-AKT and increase of p27 expression. SC79 also rescued the propofol-induced inhibition of NSC proliferation and differentiation. The propofol-induced neurocognition deficit was also partially reversed by SC79.@*Conclusion@#Taken together, these results suggest that neurogenesis is hindered by neonatal propofol exposure. Specifically, neonatal propofol exposure was shown to suppress the proliferation and differentiation of NSCs by inhibiting Akt/p27 signaling pathway.

Cannabidiol prevents depressive-like behaviors through the modulation of neural stem cell differentiation / 医学前沿

Chronic stress impairs radial neural stem cell (rNSC) differentiation and adult hippocampal neurogenesis (AHN), whereas promoting AHN can increase stress resilience against depression. Therefore, investigating the mechanism of neural differentiation and AHN is of great importance for developing antidepressant drugs. The nonpsychoactive phytocannabinoid cannabidiol (CBD) has been shown to be effective against depression. However, whether CBD can modulate rNSC differentiation and hippocampal neurogenesis is unknown. Here, by using the chronic restraint stress (CRS) mouse model, we showed that hippocampal rNSCs mostly differentiated into astrocytes under stress conditions. Moreover, transcriptome analysis revealed that the FoxO signaling pathway was involved in the regulation of this process. The administration of CBD rescued depressive-like symptoms in CRS mice and prevented rNSCs overactivation and differentiation into astrocyte, which was partly mediated by the modulation of the FoxO signaling pathway. These results revealed a previously unknown neural mechanism for neural differentiation and AHN in depression and provided mechanistic insights into the antidepressive effects of CBD.

Electroacupuncture can promote hippocampal neurogenesis relieving chronic cerebral hypoperfusion / 中华物理医学与康复杂志

Objective:To observe the expression of noggin mRNA in the hippocampus of rats with chronic cerebral hypoperfusion, and explore the effect of electroacupuncture (EA) at the " baihui" and " dazhui" acupoints on their learning and memory and on hippocampal neurogenesis.Methods:In total, 120 Sprague-Dawley rats had cerebral hypoperfusion induced by permanent bilateral ligation of the common carotid artery. The 104 successfully induced were divided at random into a model group and an EA group, each of 52. The EA group was given EA on the baihui and dazhui acupoints for 20 minutes daily for seven days followed by a two-day break. The output current was 1mA at 15Hz. No special treatment was given to the model group. After one, two, four and six weeks of treatment, 6 rats were given BrdU injections to observe the proliferation and differentiation of neural stem cells. Learning and memory were assessed using the Morris Water Maze. The expression of noggin mRNA and neurogenesis in the dentate gyrus of the hippocampus were measured using reverse-transcription polymerase chain reactions and immunohistochemistry.Results:After one, two and five weeks of intervention, the average learning and memory ability of the EA group were significantly better than those of the control group. The average expression of noggin mRNA was significantly higher in the EA group than in the model group at the same time points. Compared with the model group, there were more BrdU-positive cells in the hippocampal dentate gyrus in the EA group, and the number decreased with the prolongation of ischemia. Pearson correlation analysis showed that the levels of noggin mRNA in the hippocampus of both groups were positively correlated with their number of BrdU-positive cells. The correlation was stronger in the EA group than in the model group.Conclusions:Electroacupuncture can promote hippocampal neurogenesis in rats with chronic cerebral hypoperfusion by regulating the expression of hippocampal noggin mRNA, thereby improving their spatial learning and memory ability.

Active fraction combination from Liuwei Dihuang decoction improves adult hippocampal neurogenesis and neurogenic microenvironmentin cranially irradiated mice / 中国药理学与毒理学杂志

OBJECTIVE Cranial radiotherapy is clinically used in the treatment of brain tumors;however, the conse?quent cognitive and emotional dysfunctions seriously impair the life quality of patients. LW-AFC, an active fraction combi?nation extracted from classical traditional Chinese medicine prescription Liuwei Dihuang decoction, can improve cogni?tive and emotional dysfunctions in many animal models;however, the protective effect of LW-AFC on cranial irradiation-induced cognitive and emotional dysfunctions has not been reported. Recent studies indicate that impairment of adult hippocampal neurogenesis (AHN) and alterations of the neurogenic microenvironment in the hippocampus constitute crit?ical factors in cognitive and emotional dysfunctions following cranial irradiation. Here, our research further investigated the potential protective effects and mechanisms of LW-AFC on cranial irradiation-induced cognitive and emotional dys?functions in mice. METHODS LW-AFC (1.6 g·kg-1) was intragastrically administered to mice for 14 d before cranial irra?diation (7 Gyγ-ray). AHN was examined by quantifying the number of proliferative neural stem cells and immature neu?rons in the dorsal and ventral hippocampus. The contextual fear conditioning test, open field test, and tail suspension test were used to assess cognitive and emotional functions in mice. To detect the change of the neurogenic microenvi?ronment, colorimetry and multiplex bead analysis were performed to measure the level of oxidative stress, neurotrophic and growth factors, and inflammation in the hippocampus. RESULTS LW-AFC exerted beneficial effects on the contex?tual fear memory, anxiety behavior, and depression behavior in irradiated mice. Moreover, LW-AFC increased the num?ber of proliferative neural stem cells and immature neurons in the dorsal hippocampus, displaying a regional specificity of neurogenic response. For the neurogenic microenvironment, LW-AFC significantly increased the contents of superox?ide dismutase, glutathione peroxidase, glutathione, and catalase and decreased the content of malondialdehyde in the hippocampus of irradiated mice, accompanied by the increase in brain-derived neurotrophic factor, insulin-like growth factor-1, and interleukin-4 content. Together, LW-AFC improved cognitive and emotional dysfunctions, promoted AHN preferentially in the dorsal hippocampus, and ameliorated disturbance in the neurogenic microenvironment in irradiated mice. CONCLUSION LW-AFC ameliorates cranial irradiation-induced cognitive and emotional dysfunctions, and the underlying mechanisms are mediated by promoting AHN in the dorsal hippocampus and improving the neurogenic micro?environment. LW-AFC might be a promising therapeutic agent to treat cognitive and emotional dysfunctions in patients receiving cranial radiotherapy.

Effects of brain-specific knockout of Sirt6 gene on cerebral cortex in aged mice / 中华行为医学与脑科学杂志

Objective:To study the effect of senescence gene silent information regulator 6 (Sirt6) knockout on the brain of aged mice.Methods:Sirt6-flox transgenic mice were constructed, and the mouse brain tissue was specifically knocked out by Emx1-Cre tool mice.According to genotyping, 11 wild-type mice were selected as control group(WT group) and 10 Sirt6 gene konckout mice were selected as conditional knockout group(cKO group). Body size and body weight of the aged mice were measured and cerebral cortex thickness was measured by HE staining.Brain neurogenesis was analyzed with EdU markers.The expression of RNA-binding protein HuR and apoptosis-related protein Caspase-3 were detected by Western blot.Meanwhile, histone acetylation levels in the cortex were detected.Results:Sirt6 brain tissue-specific knocked out mice were successfully constructed.Compared with the brain tissue area((2.07±0.22) cm 2)and cortical thickness ((970.56±80.91) μm) of WT mice in the 12-month-old group, the brain tissue area ((1.61±0.14)cm 2) and cortical thickness ((822.88±53.94) μm) in Sirt6 cKO group were smaller, and the differences were statistically significant (both P<0.05). EdU incorporation into nerve cells showed that the number of EdU incorporation into periventricular nerve cells in cKO group was lower ((4.75±1.48)) than that in WT group ((10.29±1.93)). The difference was statistically significant ( P<0.001). In the experiment of 17 months age group, mice in cKO group were smaller in body size, lower in body weight ((29.00±1.08) g) and smaller in brain area ((1.54±0.55)cm 2)compared with WT group in body size, body weight ((35.25±4.17) g) and brain tissue area ((1.98±0.18) cm 2)(both P<0.05). The expression of Caspase-3 and HuR in cortical proteins of these two age groups decreased( t=2.95, 5.38, both P<0.05), and the expression of H3K9ac and H3K56ac increased( t=3.53, 2.78, both P<0.05), but the expression of Sirt1 homologous gene remained unchanged( t=1.26, P>0.05). Conclusion:The specific deletion of Sirt6 in brain tissue can lead to the decrease of brain neurogenesis in aged mice, and the aggravation of aging and the increase of apoptosis, which may be the reason for the thinning of cerebral cortex and brain tissue atrophy.The molecular mechanism is speculated to be related to the increase of acetylation level after Sirt6 knockout

Neurogenesis and neuroinflammation under exercise: Alteration and regulation / 中国组织工程研究

BACKGROUND: Studies have found that exercise can regulate neuroinflammation and adult hippocampal neurogenesis, and improve cognitive function. However, the interaction between exercise and neuroinflammation-induced changes in hippocampal neurogenesis and cognitive function is unclear. OBJECTIVE: To analyze and summarize the mechanism by which neuroinflammation-mediated exercise improves adult hippocampus neurogenesis and cognition. METHOD: Using “exercise; neuroinflammation; neurogenesis; Alzheimer’s disease; aging; depression; cerebral ischemia; traumatic brain injury; cognition” as keywords, we retrieved literature regarding the effects or mechanisms of exercise on neuroinflammation, adult hippocampus neurogenesis and cognition in CNKI and Web of Science, and logically analyzed and summarized the included studies. RESULTS AND CONCLUSION: Neuroinflammation can cause nerve damage, and may lead to cognitive impairment, while exercise can effectively produce anti-inflammatory effects in the brain, and promote adult hippocampal neurogenesis, thereby improving cognitive ability. Exercise cannot only directly increase the expression of neurotrophic factors in the hippocampus and promote hippocampal neurogenesis, but also affect the expression of neurotrophic factors in the hippocampus and the process of neurogenesis through its anti-inflammatory mechanism. However, there is still much work to be done to better understand how the neurogenic and inflammatory environment changes under exercise conditions, and how this altered process can be modulated to promote cognition.

Effect of nicotinamide mononucleotide on neurogenesis decline in sleep-deprived infancy rats / 中华麻醉学杂志

Objective:To evaluate the effect of nicotinamide mononucleotide (NMN) on neurogenesis decline in sleep-deprived infancy rats.Methods:Seventy-eight clean-grade healthy male Sprague-Dawley rats, aged 7 days, weighing 10-15 g, were divided into 3 groups ( n=26 each) using a random number table method: control group (group Con), sleep deprivation group (group SD) and sleep deprivation plus NMN group (group SD+ NMN). Sleep deprivation model was established by gentle stimulation method with a brush (10 h per day) for 14 consecutive days.NMN 500 mg/kg was intraperitoneally injected in group SD+ NMN, while the equal volume of aqua pura was given instead in Con and SD groups.5′-bromo-2′-deoxyuridine (BrdU) 100 mg/kg was intraperitoneally injected immediately after the end of sleep deprivation to label the new-born cells.At 24 h after completion of sleep deprivation, the stem cell pluripotency transcription factor (SOX2) and doublecortin (DCX) positive cells in the hippocampal DG region were counted using immunofluorescence and immunohistochemical methods, and positron emission tomography-computed tomography was used to observe the metabolism of 18F-fluorodeoxyglucose in the hippocampus.At 4 weeks after completion of sleep deprivation, the number of neuronal nuclei antigen (NeuN)/BrdU and glial fibrillary acid protein (GFAP)/BrdU positive cells in hippocampal DG region was recorded using immunofluorescence, and novel object recognition test was performed to evaluate the cognitive function. Results:Compared with group Con, the number of SOX2 and DCX positive cells was significantly reduced, the standard uptake value of glucose in the hippocampus was decreased, the number of NeuN/BrdU and GFAP/BrdU positive cells was reduced, and discrimination index in novel object recognition test was decreased in group SD ( P<0.05). Compared with group SD, the number of SOX2, DCX NeuN/BrdU and GFAP/BrdU positive cells was increased, the standard uptake value of glucose in the hippocampus was increased, and discrimination index in novel object recognition test was increased in group SD+ NMN ( P<0.05). Conclusion:Nicotinamide mononucleotide can promote neurogenesis, thus improving cognitive function, and the mechanism is related to increasing the metabolism of hippocampal glucose in sleep-deprived infancy rats.

Visualization analysis of traditional Chinese medicine for neurogenesis research based on CiteSpace / 中国中药杂志

To analyze the research hotspots and trends of traditional Chinese medicine(TCM) for neurogenesis with use of CiteSpace 5.7.R3 software. The bibliometrics analysis on the literatures of TCM for neurogenesis from 1987 to 2020 included in the CNKI database was conducted to visualize the number of papers, authors, institutions and keywords. Totally 736 literatures were included and the volume of annual publications showed an upward in volatility. At present, several stable research teams have been formed, which were represented by DING Fei, ZHOU Chong-jian and ZHOU Yong-hong, but the cooperation was not close among the teams. According to the analysis of research institutions, Institute of Diagnostics of Hunan University of Chinese Medicine and Acupuncture Research Center of Tianjin University of Traditional Chinese Medicine produced largest number of literatures. The cooperation among institutions, with universities of TCM and affiliated hospitals as the main research force, was characterized by dominant cooperation among regional institutions and less cross-regional cooperation. Keywords analysis showed that in the field of TCM for neurogenesis, a lot of studies mainly focused on the disease field, treatment and medication, TCM therapy and molecular mechanism. The research on TCM therapy and molecular mechanism for neurogenesis of central nervous system will be the research hotspots in future.