DISC1 in Astrocytes Influences Adult Neurogenesis and Hippocampus-Dependent Behaviors in Mice

Pathology and Astrocytes in Autism

A distinct pathology for autism spectrum disorder (ASD) remains elusive. Human and animal studies have focused on investigating the role of neurons in ASD. However, recent studies have hinted that glial cell pathology could be a characteristic of ASD. Astrocytes are the most abundant glial cell in the brain and play an important role in neuronal function, both during development and in adult. They regulate neuronal migration, dendritic and spine development, and control the concentration of neurotransmitters at the synaptic cleft. They are also responsible for synaptogenesis, synaptic development, and synaptic function. Therefore, any change in astrocyte number and/or function could contribute to the impairment of connectivity that has been reported in ASD. Data available to date is scarce but indicates that while the number of astrocytes is reduced, their state of activation and their GFAP expression is increased in ASD. Disruption of astrocyte function in ASD may affect proper neurotransmitter metabolism, synaptogenesis, and the state of brain inflammation. Astrocytes alterations are common to ASD and other neurodevelopmental disorders. Future studies about the role of astrocytes in ASD are required to better understand this disorder.

Electroacupuncture improves cognitive impairment in diabetic cognitive dysfunction rats by regulating the mitochondrial autophagy pathway

Background

Diabetes-associated cognitive dysfunction has become a major public health concern. However, the mechanisms driving this disease are elusive. Herein, we explored how electroacupuncture improves learning and memory function in diabetic rats.

Methods

The diabetic model was established by intraperitoneal injection of streptozotocin (STZ) in adult Sprague–Dawley rats. Rats were fed on high-fat and high-sugar diets. Learning and memory functions were assessed using behavioral tests. The hematoxylin and eosin (H&E) staining, Western blotting, real-time PCR, ELISA, immunohistochemistry, and transmission electronic microscopy (TEM) was performed to test related indicators.

Results

High-fat and high-sugar diets impaired learning and memory function in rats, while electroacupuncture treatment reversed these changes. The model group presented highly prolonged escape latency compared to the control group, indicating impaired learning and memory functions. The TEM examination showed that electroacupuncture enhanced Aβ clearance and mitochondrial autophagy in hippocampal neuronal cells by increasing DISC1 expression.

Conclusions

Electroacupuncture improves learning and memory function in diabetic rats by increasing DISC1 expression to promote mitophagy. This enhanced Aβ clearance, alleviating cytotoxicity in hippocampal neuronal cells.

In the pursuit of new social neurons. Neurogenesis and social behavior in mice: A systematic review

Social behaviors have become more relevant to our understanding of the human nervous system because relationships with our peers may require and modulate adult neurogenesis. Here, we review the pieces of evidence we have to date for the divergence of social behaviors in mice by modulation of adult neurogenesis or if social behaviors and the social environment can drive a change in neurogenic processes. Social recognition and memory are deeply affected by antimitotic drugs and irradiation, while NSC transgenic mice may run with lower levels of social discrimination. Interestingly, social living conditions can create a big impact on neurogenesis. Social isolation and social defeat reduce the number of new neurons, while social dominance and enrichment of the social environment increase their number. These new “social neurons” trigger functional modifications with amazing transgenerational effects. All of these suggest that we are facing two bidirectional intertwined variables, and the great challenge now is to understand the cellular and genetic mechanisms that allow this relationship to be used therapeutically.

Deficient mitochondrial respiration in astrocytes impairs trace fear conditioning and increases naloxone-precipitated aversion in morphine-dependent mice

Mitochondria are abundant in the fine processes of astrocytes, however, potential roles for astrocyte mitochondria remain poorly understood. In the present study, we performed a systematic examination of the effects of abnormal oxidative phosphorylation in astrocytes on several mouse behaviors. Impaired astrocyte oxidative phosphorylation was produced by astrocyte-specific deletion of the nuclear mitochondrial gene, Cox10, that encodes an accessory protein of complex IV, the protoheme:heme-O-farnesyl transferase. As expected, conditional deletion of the Cox10 gene in mice (cKO mice) significantly reduced expression of COX10 and Cytochrome c oxidase subunit I (MTCO1) of Complex IV, resulting in decreased oxidative phosphorylation without significantly affecting glycolysis. No effects of the deletion were observed on locomotor activity, anxiety-like behavior, nociception, or spontaneous alternation. Cox10 cKO female mice exhibited mildly impaired novel object recognition, while Cox10 cKO male mice were moderately deficient in trace fear conditioning. No group-related changes were observed in conditional place preference (CPP) that assessed effects of morphine on reward. In contrast to CPP, Cox10 cKO mice demonstrated significantly increased aversive behaviors produced by naloxone-precipitated withdrawal following chronic exposure to morphine, that is, jumping and avoidance behavior as assessed by conditional place aversion (CPA). Our study suggests that astrocyte oxidative phosphorylation may contribute to behaviors associated with greater cognitive load and/or aversive and stressful conditions.

Structural and Functional Deviations of the Hippocampus in Schizophrenia and Schizophrenia Animal Models

Schizophrenia is a grave neuropsychiatric disease which frequently onsets between the end of adolescence and the beginning of adulthood. It is characterized by a variety of neuropsychiatric abnormalities which are categorized into positive, negative and cognitive symptoms. Most therapeutical strategies address the positive symptoms by antagonizing D2-dopamine-receptors (DR). However, negative and cognitive symptoms persist and highly impair the life quality of patients due to their disabling effects. Interestingly, hippocampal deviations are a hallmark of schizophrenia and can be observed in early as well as advanced phases of the disease progression. These alterations are commonly accompanied by a rise in neuronal activity. Therefore, hippocampal formation plays an important role in the manifestation of schizophrenia. Furthermore, studies with animal models revealed a link between environmental risk factors and morphological as well as electrophysiological abnormalities in the hippocampus. Here, we review recent findings on structural and functional hippocampal abnormalities in schizophrenic patients and in schizophrenia animal models, and we give an overview on current experimental approaches that especially target the hippocampus. A better understanding of hippocampal aberrations in schizophrenia might clarify their impact on the manifestation and on the outcome of this severe disease.

Knock-Down of CD24 in Astrocytes Aggravates Oxyhemoglobin-Induced Hippocampal Neuron Impairment

Subarachnoid hemorrhage (SAH), as one of the most severe hemorrhagic strokes, is closely related to neuronal damage. Neurogenesis is a promising therapy, however, reliable targets are currently lacking. Increasing evidence has indicated that CD24 is associated with the growth of hippocampal neurons and the regulation of neural stem/precursor cell proliferation. To investigate the potential effect of CD24 in astrocytes on neuron growth in the hippocampus, we used a Transwell co-culture system of hippocampal astrocytes and neurons, and oxyhemoglobin (OxyHb) was added to the culture medium to mimic SAH in vitro. A specific lentivirus was used to knock down CD24 expression in astrocytes, which was verified by western blot, quantitative real-time polymerase chain reaction, and immunofluorescent staining. Astrocyte activation, neurite elongation, neuronal apoptosis, and cell viability were also assessed. We first determined the augmented expression level of CD24 in hippocampal astrocytes after SAH. A similar result was observed in cultured astrocytes exposed to OxyHb, and a corresponding change in SHP2/ERK was also noticed. CD24 in astrocytes was then downregulated by the lentivirus, which led to the impairment of axons and dendrites on the co-cultured neurons. Aggravated neuronal apoptosis was induced by the CD24 downregulation in astrocytes, which might be a result of a lower level of brain derived neurotrophic factor (BDNF). In conclusion, the knock-down of CD24 in astrocytes suppressed hippocampal neuron growth, in which the SHP2-ERK signaling pathway and BNDF were possibly involved.

Hypobaric Hypoxia Induces Deficits in Adult Neurogenesis and Social Interaction via Cyclooxygenase-1/ EP1 Receptor Pathway Activating NLRP3 Inflammasome

Low oxygen environments, like hypobaric hypoxia (HH), are common nodes in a number of diseases characterized by neuroinflammation, which is detrimental to the structural and functional aspects of hippocampal circuitry. Hypoxic conditions lead to elevation of inflammasome-mediated inflammation that may contribute to cognitive deficits. However, a systematic investigation of the impact of inflammasome-mediated neuroinflammation on the components of neurogenic niche during HH remains to be elusive. Cerebral hypoxia was induced in adult male Sprague Dawley rats via decreasing partial pressure of oxygen. The effect of HH (1, 3, and 7 days at 25,000 ft) on social memory, anxiety, adult neurogenesis, and NLRP3- (NLR family pyrin domain containing 3) mediated neuroinflammation in the dentate gyrus (DG) was explored in detail. Furthermore, we explored the therapeutic efficacy of cyclooxygenase-1 inhibitor (valeryl salicylate, 5 mg/kg/day, i.p.) and EP1 receptor (EP1R) antagonist (SC19220, 1 mg/kg/day, i.p.) on HH-induced deficits. Seven days of HH exposure induced alteration in social and anxiety-like behavior along with perturbation in adult neurogenesis. Elevation in NLRP3, caspase-1, and IL-1β levels was observed during HH from day 1. A notable increase in the COX-1/EP1R pathway in activated glial cells in DG was evident during HH. COX-1 inhibitor and EP1R antagonist mitigated the detrimental effects of HH on social memory, adult neurogenesis via blunting NLRP3-mediated inflammation. Our data showed induction of the COX-1/EP1R pathway in the glial cells, which is detrimental to neurogenesis and social memory, opening up the possibility that the COX-1/EP1R pathway is a plausible target for inflammasome-related neurogenesis impairments.

Astrocyte Bioenergetics and Major Psychiatric Disorders

Ongoing research continues to add new elements to the emerging picture of involvement of astrocyte energy metabolism in the pathophysiology of major psychiatric disorders, including schizophrenia, mood disorders, and addictions. This review outlines what is known about the energy metabolism in astrocytes, the most numerous cell type in the brain, and summarizes the recent work on how specific perturbations of astrocyte bioenergetics may contribute to the neuropsychiatric conditions. The role of astrocyte energy metabolism in mental health and disease is reviewed on the organism, organ, and cell level. Data arising from genomic, metabolomic, in vitro, and neurobehavioral studies is critically analyzed to suggest future directions in research and possible metabolism-focused therapeutic interventions.

CTRP4 ablation impairs associative learning and memory

C1q/TNF-related protein (CTRP) family comprises fifteen highly conserved secretory proteins with diverse central and peripheral functions. In zebrafish, mouse, and human, CTRP4 is most highly expressed in the brain. We previously showed that CTRP4 is a metabolically responsive regulator of food intake and energy balance, and mice lacking CTRP4 exhibit sexually dimorphic changes in ingestive behaviors and systemic metabolism. Recent single-cell RNA sequencing also revealed Ctrp4/C1qtnf4 expression in diverse neuronal cell types across distinct anatomical brain regions, hinting at additional roles in the central nervous system not previously characterized. To uncover additional central functions of CTRP4, we subjected Ctrp4 knockout (KO) mice to a battery of behavioral tests. Relative to wild-type (WT) littermates, loss of CTRP4 does not alter exploratory, anxiety-, or depressive-like behaviors, motor function and balance, sensorimotor gating, novel object recognition, and spatial memory. While pain-sensing mechanisms in response to thermal stress and mild shock are intact, both male and female Ctrp4 KO mice have increased sensitivity to pain induced by higher-level shock, suggesting altered nociceptive function. Importantly, CTRP4 deficiency impairs hippocampal-dependent associative learning and memory as assessed by trace fear conditioning paradigm. This deficit is sex-dependent, affects only female mice, and is associated with altered expression of learning and memory genes (Arc, c-fos, and Pde4d) in the hippocampus and cortex. Altogether, our behavioral and gene expression analyses have uncovered novel aspects of the CTRP4 function and provided a physiological context to further investigate its mechanism of action in the central and peripheral nervous system.

Reduced Firing of Nucleus Accumbens Parvalbumin Interneurons Impairs Risk Avoidance in DISC1 Transgenic Mice

A strong animal survival instinct is to approach objects and situations that are of benefit and to avoid risk. In humans, a large proportion of mental disorders are accompanied by impairments in risk avoidance. One of the most important genes involved in mental disorders is disrupted-in-schizophrenia-1 (DISC1), and animal models in which this gene has some level of dysfunction show emotion-related impairments. However, it is not known whether DISC1 mouse models have an impairment in avoiding potential risks. In the present study, we used DISC1-N terminal truncation (DISC1-N^TM) mice to investigate risk avoidance and found that these mice were impaired in risk avoidance on the elevated plus maze (EPM) and showed reduced social preference in a three-chamber social interaction test. Following EPM tests, c-Fos expression levels indicated that the nucleus accumbens (NAc) was associated with risk-avoidance behavior in DISC1-N^TM mice. In addition, in vivo electrophysiological recordings following tamoxifen administration showed that the firing rates of fast-spiking neurons (FS) in the NAc were significantly lower in DISC1-N^TM mice than in wild-type (WT) mice. In addition, in vitro patch clamp recording revealed that the frequency of action potentials stimulated by current injection was lower in parvalbumin (PV) neurons in the NAc of DISC1-N^TM mice than in WT controls. The impairment of risk avoidance in DISC1-N^TM mice was rescued using optogenetic tools that activated NAc^PV neurons. Finally, inhibition of the activity of NAc^PV neurons in PV-Cre mice mimicked the risk-avoidance impairment found in DISC1-N^TM mice during tests on the elevated zero maze. Taken together, our findings confirm an impairment in risk avoidance in DISC1-N^TM mice and suggest that reduced excitability of NAc^PV neurons is responsible.

The Role of Astrocytes in the Neurorepair Process

Astrocytes are highly specialized glial cells responsible for trophic and metabolic support of neurons. They are associated to ionic homeostasis, the regulation of cerebral blood flow and metabolism, the modulation of synaptic activity by capturing and recycle of neurotransmitters and maintenance of the blood-brain barrier. During injuries and infections, astrocytes act in cerebral defense through heterogeneous and progressive changes in their gene expression, morphology, proliferative capacity, and function, which is known as reactive astrocytes. Thus, reactive astrocytes release several signaling molecules that modulates and contributes to the defense against injuries and infection in the central nervous system. Therefore, deciphering the complex signaling pathways of reactive astrocytes after brain damage can contribute to the neuroinflammation control and reveal new molecular targets to stimulate neurorepair process. In this review, we present the current knowledge about the role of astrocytes in brain damage and repair, highlighting the cellular and molecular bases involved in synaptogenesis and neurogenesis. In addition, we present new approaches to modulate the astrocytic activity and potentiates the neurorepair process after brain damage.

Reducing l-lactate release from hippocampal astrocytes by intracellular oxidation increases novelty induced activity in mice

Astrocytes are in control of metabolic homeostasis in the brain and support and modulate neuronal function in various ways. Astrocyte-derived l-lactate (lactate) is thought to play a dual role as a metabolic and a signaling molecule in inter-cellular communication. The biological significance of lactate release from astrocytes is poorly understood, largely because the tools to manipulate lactate levels in vivo are limited. We therefore developed new viral vectors for astrocyte-specific expression of a mammalianized version of lactate oxidase (LOx) from Aerococcus viridans. LOx expression in astrocytes in vitro reduced their intracellular lactate levels as well as the release of lactate to the extracellular space. Selective expression of LOx in astrocytes of the dorsal hippocampus in mice resulted in increased locomotor activity in response to novel stimuli. Our findings suggest that a localized decreased intracellular lactate pool in hippocampal astrocytes could contribute to greater responsiveness to environmental novelty. We expect that use of this molecular tool to chronically limit astrocytic lactate release will significantly facilitate future studies into the roles and mechanisms of intercellular lactate communication in the brain.

Astrocytes in schizophrenia

Schizophrenia is a severe and clinically heterogenous mental disorder affecting approximately 1% of the population worldwide. Despite tremendous achievements in the field of schizophrenia research, its precise aetiology remains elusive. Besides dysfunctional neuronal signalling, the pathophysiology of schizophrenia appears to involve molecular and functional abnormalities in glial cells, including astrocytes. This article provides a concise overview of the current evidence supporting altered astrocyte activity in schizophrenia, which ranges from findings obtained from post-mortem immunohistochemical analyses, genetic association studies and transcriptomic investigations, as well as from experimental investigations of astrocyte functions in animal models. Integrating the existing data from these research areas strongly suggests that astrocytes have the capacity to critically affect key neurodevelopmental and homeostatic processes pertaining to schizophrenia pathogenesis, including glutamatergic signalling, synaptogenesis, synaptic pruning and myelination. The further elucidation of astrocytes functions in health and disease may, therefore, offer new insights into how these glial cells contribute to abnormal brain development and functioning underlying this debilitating mental disorder.

Hippocampal regenerative medicine: neurogenic implications for addiction and mental disorders

Psychiatric illness is a prevalent and highly debilitating disorder, and more than 50% of the general population in both middle- and high-income countries experience at least one psychiatric disorder at some point in their lives. As we continue to learn how pervasive psychiatric episodes are in society, we must acknowledge that psychiatric disorders are not solely relegated to a small group of predisposed individuals but rather occur in significant portions of all societal groups. Several distinct brain regions have been implicated in neuropsychiatric disease. These brain regions include corticolimbic structures, which regulate executive function and decision making (e.g., the prefrontal cortex), as well as striatal subregions known to control motivated behavior under normal and stressful conditions. Importantly, the corticolimbic neural circuitry includes the hippocampus, a critical brain structure that sends projections to both the cortex and striatum to coordinate learning, memory, and mood. In this review, we will discuss past and recent discoveries of how neurobiological processes in the hippocampus and corticolimbic structures work in concert to control executive function, memory, and mood in the context of mental disorders.

A region of the brain called the hippocampus and its connections to other parts of the brain via what are called cortico-limbic structures are implicated in a variety of mental health disorders. These disorders can be accompanied by reduced hippocampal volume. Mi-Hyeon Jang, Doo-Sup Choi and colleagues at the Mayo Clinic College of Medicine and Science, Rochester, USA, review the role of hippocampal and cortico-limbic neurobiology in memory and mood in mental disorders. They focus particular attention on the role of neurogenesis, the production and growth of new nerve cells and connections. Disrupted neurogenesis in the adult hippocampus is implicated in conditions including addiction, depression, schizophrenia and related psychotic disorders. Learning more about neural regeneration in the hippocampus could yield insights into mental health conditions and open new avenues toward developing drug-based treatments.

Glial Cells and Their Contribution to the Mechanisms of Action of Cannabidiol in Neuropsychiatric Disorders

Cannabidiol (CBD) is a phytocannabinoid with a broad-range of therapeutic potential in several conditions, including neurological (epilepsy, neurodegenerative diseases, traumatic and ischemic brain injuries) and psychiatric disorders (schizophrenia, addiction, major depressive disorder, and anxiety). The pharmacological mechanisms responsible for these effects are still unclear, and more than 60 potential molecular targets have been described. Regarding neuropsychiatric disorders, most studies investigating these mechanisms have focused on neuronal cells. However, glial cells (astrocytes, oligodendrocytes, microglia) also play a crucial role in keeping the homeostasis of the central nervous system. Changes in glial functions have been associated with neuropathological conditions, including those for which CBD is proposed to be useful. Mostly in vitro studies have indicated that CBD modulate the activation of proinflammatory pathways, energy metabolism, calcium homeostasis, and the proliferative rate of glial cells. Likewise, some of the molecular targets proposed for CBD actions are f expressed in glial cells, including pharmacological receptors such as CB1, CB2, PPAR-γ, and 5-HT1A. In the present review, we discuss the currently available evidence suggesting that part of the CBD effects are mediated by interference with glial cell function. We also propose additional studies that need to be performed to unveil the contribution of glial cells to CBD effects in neuropsychiatric disorders.

Disrupted-in-schizophrenia 1 enhances the quality of circadian rhythm by stabilizing BMAL1

Disrupted-in-schizophrenia 1 (DISC1) is a scaffold protein that has been implicated in multiple mental disorders. DISC1 is known to regulate neuronal proliferation, signaling, and intracellular calcium homeostasis, as well as neurodevelopment. Although DISC1 was linked to sleep-associated behaviors, whether DISC1 functions in the circadian rhythm has not been determined yet. In this work, we revealed that Disc1 expression exhibits daily oscillating pattern and is regulated by binding of circadian locomotor output cycles kaput (CLOCK) and Brain and muscle Arnt-like protein-1 (BMAL1) heterodimer to E-box sequences in its promoter. Interestingly, Disc1 deficiency increases the ubiquitination of BMAL1 and de-stabilizes it, thereby reducing its protein levels. DISC1 inhibits the activity of GSK3β, which promotes BMAL1 ubiquitination, suggesting that DISC1 regulates BMAL1 stability by inhibiting its ubiquitination. Moreover, Disc1-deficient cells and mice show reduced expression of other circadian genes. Finally, Disc1-LI (Disc1 knockout) mice exhibit damped circadian physiology and behaviors. Collectively, these findings demonstrate that the oscillation of DISC1 expression is under the control of CLOCK and BMAL1, and that DISC1 contributes to the core circadian system by regulating BMAL1 stability.

Neurogenesis After Stroke: A Therapeutic Perspective

Stroke is a major cause of death and disability worldwide. Yet therapeutic strategies available to treat stroke are very limited. There is an urgent need to develop novel therapeutics that can effectively facilitate functional recovery. The injury that results from stroke is known to induce neurogenesis in penumbra of the infarct region. There is considerable interest in harnessing this response for therapeutic purposes. This review summarizes what is currently known about stroke-induced neurogenesis and the factors that have been identified to regulate it. Additionally, some key studies in this field have been highlighted and their implications on future of stroke therapy have been discussed. There is a complex interplay between neuroinflammation and neurogenesis that dictates stroke outcome and possibly recovery. This highlights the need for a better understanding of the neuroinflammatory process and how it affects neurogenesis, as well as the need to identify new mechanisms and potential modulators. Neuroinflammatory processes and their impact on post-stroke repair have therefore also been discussed.

MCT1 Deletion in Oligodendrocyte Lineage Cells Causes Late-Onset Hypomyelination and Axonal Degeneration

Oligodendrocytes (OLs) are important for myelination and shuttling energy metabolites lactate and pyruvate toward axons through their expression of monocarboxylate transporter 1 (MCT1). Recent studies suggest that loss of OL MCT1 causes axonal degeneration. However, it is unknown how widespread and chronic loss of MCT1 in OLs specifically affects neuronal energy homeostasis with aging. To answer this, MCT1 conditional null mice were generated that allow for OL-specific MCT1 ablation. We observe that MCT1 loss from OL lineage cells is dispensable for normal myelination and axonal energy homeostasis early in life. By contrast, loss of OL lineage MCT1 expression with aging leads to significant axonal degeneration with concomitant hypomyelination. These data support the hypothesis that MCT1 is important for neuronal energy homeostasis in the aging central nervous system (CNS). The reduction in OL MCT1 that occurs with aging may enhance the risk for axonal degeneration and atrophy in neurodegenerative diseases.

Using conditional cell-specific deletion of MCT1, Philips et al. learn that oligodendrocyte lineage cells are actually dispensable for normal myelination and axonal energy homeostasis during early life but that the oligodendroglial lactate/MCT1-based support is critical for the aging of the nervous system.

Mitophagy: A New Player in Stem Cell Biology

The fundamental importance of functional mitochondria in the survival of most eukaryotic cells, through regulation of bioenergetics, cell death, calcium dynamics and reactive oxygen species (ROS) generation, is undisputed. However, with new avenues of research in stem cell biology these organelles have now emerged as signaling entities, actively involved in many aspects of stem cell functions, including self-renewal, commitment and differentiation. With this recent knowledge, it becomes evident that regulatory pathways that would ensure the maintenance of mitochondria with state-specific characteristics and the selective removal of organelles with sub-optimal functions must play a pivotal role in stem cells. As such, mitophagy, as an essential mitochondrial quality control mechanism, is beginning to gain appreciation within the stem cell field. Here we review and discuss recent advances in our knowledge pertaining to the roles of mitophagy in stem cell functions and the potential contributions of this specific quality control process on to the progression of aging and diseases.

Glial cells in Parkinson´s disease: protective or deleterious?

Glial cells have been identified more than 100 years ago, and are known to play a key role in the central nervous system (CNS) function. A recent piece of evidence is emerging showing that in addition to the capacity of CNS modulation and homeostasis, glial cells are also being looked like as a promising cell source not only to study CNS pathologies initiation and progression but also to the establishment and development of new therapeutic strategies. Thus, in the present review, we will discuss the current evidence regarding glial cells' contribution to neurodegenerative diseases as Parkinson's disease, providing cellular, molecular, functional, and behavioral data supporting its active role in disease initiation, progression, and treatment. As so, considering their functional relevance, glial cells may be important to the understanding of the underlying mechanisms regarding neuronal-glial networks in neurodegeneration/regeneration processes, which may open new research opportunities for their future use as a target or treatment in human clinical trials.

Changes in Hippocampal Plasticity in Depression and Therapeutic Approaches Influencing These Changes

Depression is a common neurological disease that seriously affects human health. There are many hypotheses about the pathogenesis of depression, and the most widely recognized and applied is the monoamine hypothesis. However, no hypothesis can fully explain the pathogenesis of depression. At present, the brain-derived neurotrophic factor (BDNF) and neurogenesis hypotheses have highlighted the important role of plasticity in depression. The plasticity of neurons and glial cells plays a vital role in the transmission and integration of signals in the central nervous system. Plasticity is the adaptive change in the nervous system in response to changes in external signals. The hippocampus is an important anatomical area associated with depression. Studies have shown that some antidepressants can treat depression by changing the plasticity of the hippocampus. Furthermore, caloric restriction has also been shown to affect antidepressant and hippocampal plasticity changes. In this review, we summarize the latest research, focusing on changes in the plasticity of hippocampal neurons and glial cells in depression and the role of BDNF in the changes in hippocampal plasticity in depression, as well as caloric restriction and mitochondrial plasticity. This review may contribute to the development of antidepressant drugs and elucidating the mechanism of depression.

Application of stem cell biology in treating neurodegenerative diseases

BACKGROUND

The appropriate strategies are needed for stimulating the endogenous neurogenesis or introducing extrinsic neural progenitors, which could be harnessed as the regenerative resources for cueing the neurodegenerations. Adult neurogenesis is the endogenous continuing physiology in limited brain regions such as hippocampus, olfactory system, and hypothalamus. Besides adult neurogenesis, induced pluripotent stem cells (iPSCs) induced functional neurons could be another option for regenerative therapies.

OBJECTIVE

Current studies are trying to improve the adult neurogenesis and enable the iPSCs induced neurons into neural regeneration. Methods: Here in this review, we mainly introduced the recent progress in neural stem cell biology and its application in the treatment of the neurodegenerations. We main separated the strategy in summarizing the mediators and potential targets to promoting endogenous neural regeneration and transplantation of neural progenitors.

CONCLUSION

By collecting and comparing the advantages disadvantages between above-mentioned two strategies, we will offer the insight on future development of stem cell therapy in treating neurodegenerative patients.

Developmental, cellular, and behavioral phenotypes in a mouse model of congenital hypoplasia of the dentate gyrus

In the hippocampus, a widely accepted model posits that the dentate gyrus improves learning and memory by enhancing discrimination between inputs. To test this model, we studied conditional knockout mice in which the vast majority of dentate granule cells (DGCs) fail to develop – including nearly all DGCs in the dorsal hippocampus – secondary to eliminating Wntless (Wls) in a subset of cortical progenitors with Gfap-Cre. Other cells in the Wls^fl/-;Gfap-Cre hippocampus were minimally affected, as determined by single nucleus RNA sequencing. CA3 pyramidal cells, the targets of DGC-derived mossy fibers, exhibited normal morphologies with a small reduction in the numbers of synaptic spines. Wls^fl/-;Gfap-Cre mice have a modest performance decrement in several complex spatial tasks, including active place avoidance. They were also modestly impaired in one simpler spatial task, finding a visible platform in the Morris water maze. These experiments support a role for DGCs in enhancing spatial learning and memory.

Astrocyte DISC1 contributes to cognitive function in a brain region-dependent manner

Our understanding of the contribution of genetic risk factors to neuropsychiatric diseases is limited to abnormal neurodevelopment and neuronal dysfunction. Much less is known about the mechanisms whereby risk variants could affect the physiology of glial cells. Our prior studies have shown that a mutant (dominant-negative) form of a rare but highly penetrant psychiatric risk factor, Disrupted-In-Schizophrenia-1 (DISC1), impairs metabolic functions of astrocytes and leads to cognitive dysfunction. In order to overcome the limitations of the mutant DISC1 model and understand the putative regional properties of astrocyte DISC1, we assessed whether knockdown of Disc1 (Disc1-KD) in mature mouse astrocytes of the prefrontal cortex (PFC) or the hippocampus would produce behavioral abnormalities that could be attributed to astrocyte bioenergetics. We found that Disc1-KD in the hippocampus but not PFC impaired trace fear conditioning in adult mice. Using the innovative deep learning approach and convolutional deep neural networks (cDNNs), ResNet50 or ResNet18, and single cell-based analysis, we found that Disc1-KD decreased the spatial density of astrocytes associated with abnormal levels and distribution of the mitochondrial markers and the glutamate transporter, GLAST. Disc1-KD in astrocytes also led to decreased expression of the glutamatergic and increased expression of the GABA-ergic synaptic markers, possibly via non-apoptotic activation of caspase 3 in neurons located within the individual territories of Disc1-KD astrocytes. Our results indicate that altered expression of DISC1 in astrocytes could impair astrocyte bioenergetics, leading to abnormalities in synaptic neurotransmission and cognitive function in a region-dependent fashion.

The innate immune system and neurogenesis as modulating mechanisms of electroconvulsive therapy in pre-clinical studies

BACKGROUND

Electroconvulsive therapy (ECT) is a powerful and fast-acting anti-depressant strategy, often used in treatment-resistant patients. In turn, patients with treatment-resistant depression often present an increased inflammatory response. The impact of ECT on several pathophysiological mechanisms of depression has been investigated, with a focus which has largely been on cellular and synaptic plasticity. Although changes in the immune system are known to influence neurogenesis, these processes have principally been explored independently from each other in the context of ECT.

OBJECTIVE

The aim of this review was to compare the time-dependent consequences of acute and chronic ECT on concomitant innate immune system and neurogenesis-related outcomes measured in the central nervous system in pre-clinical studies.

RESULTS

During the few hours following acute electroconvulsive shock (ECS), the expression of the astrocytic reactivity marker glial fibrillary acidic protein (GFAP) and inflammatory genes, such as cyclooxygenase-2 (COX2), were significantly increased together with the neurogenic brain-derived neurotrophic factor (BDNF) and cell proliferation. Similarly, chronic ECS caused an initial upregulation of the same astrocytic marker, immune genes, and neurogenic factors. Interestingly, over time, inflammation appeared to be dampened, while glial activation and neurogenesis were maintained, after either acute or chronic ECS.

CONCLUSION

Regardless of treatment duration ECS would seemingly trigger a rapid increase in inflammatory molecules, dampened over time, as well as a long-lasting activation of astrocytes and production of growth and neurotrophic factors, leading to cell proliferation. This suggests that both innate immune system response and neurogenesis might contribute to the efficacy of ECT.

The effects of microglia‐ and astrocyte‐derived factors on neurogenesis in health and disease

Hippocampal neurogenesis continues throughout life and has been suggested to play an essential role in maintaining spatial cognitive function under physiological conditions. An increasing amount of evidence has indicated that adult neurogenesis is tightly controlled by environmental conditions in the neurogenic niche, which consists of multiple types of cells including microglia and astrocytes. Microglia maintain the environment of neurogenic niche through their phagocytic capacity and interaction with neurons via fractalkine‐CX3CR1 signaling. In addition, microglia release growth factors such as brain‐derived neurotrophic factor (BDNF) and cytokines such as tumor necrosis factor (TNF)‐α to support the development of adult born neurons. Astrocytes also manipulate neurogenesis by releasing various soluble factors including adenosine triphosphate and lactate. Whereas, under pathological conditions such as Alzheimer's disease, depression, and epilepsy, microglia and astrocytes play a leading role in inflammation and are involved in attenuating the normal process of neurogenesis. The modulation of glial functions on neurogenesis in these brain diseases are attracting attention as a new therapeutic target. This review describes how these glial cells play a role in adult hippocampal neurogenesis in both health and disease, especially focusing glia‐derived factors.

Interferon-gamma Facilitates Neurogenesis by Activating Wnt/β-catenin Cell Signaling Pathway via Promotion of STAT1 Regulation of the β-Catenin Promoter

Interferon-gamma (IFN-γ) is critical for central nervous system (CNS) functions and it may be a promising treatment to stimulate CNS regeneration. However, previous studies reported inconsistent results, and the molecular mechanisms remain controversial. Here we show that IFN-γ-treated mice via intraperitoneal injection have elevated IFN-γ level in central hippocampus and superior cognitive behaviors IFN-γ could activates the level of protein expression of Wnt7a, β-catenin, and CyclinD1 in Wnt/β-catenin signaling pathway of mice hippocampus. Functional and mechanism analysis in vitro revealed that IFN-γ promoted the proliferation and differentiation in primary cultured neural stem cells (NSCs). STAT1 was accountable for IFN-γ-induced activation of the β-catenin promoter, and IFN-γ increased the binding affinity of STAT1 to β-catenin promoter based on luciferase activity and chromatin immunoprecipitation. Our results suggest that IFN-γ exerts many effects ranging from cognitive function in vivo to NSC proliferation, self-renewal, and differentiation in vitro. It does so by recruiting STAT1 to the β-catenin promoter, enhancing cis-regulation by STAT1, and ultimately activating Wnt/β-catenin signaling. In this study, we first found that STAT1 was recruited into the promoter of β-catenin to activate β-catenin expression, and this effect was regulated by IFN-γ. It is also discovered firstly that Wnt/β-catenin and JAK/STAT pathways form cross-links through STAT1. Promoting neurogenesis through immune stimulation might be a promising strategy for repairing the diseased/injured CNS. This study provides a scientific basis for immunomodulation to promote nerve regeneration and offer a new therapeutic direction for central nervous system regeneration.

D-Serine as the gatekeeper of NMDA receptor activity: implications for the pharmacologic management of anxiety disorders

Fear, anxiety, and trauma-related disorders, including post-traumatic stress disorder (PTSD), are quite common and debilitating, with an estimated lifetime prevalence of ~28% in Western populations. They are associated with excessive fear reactions, often including an inability to extinguish learned fear, increased avoidance behavior, as well as altered cognition and mood. There is an extensive literature demonstrating the importance of N-methyl-D-aspartate receptor (NMDAR) function in regulating these behaviors. NMDARs require the binding of a co-agonist, D-serine or glycine, at the glycine modulatory site (GMS) to function. D-serine is now garnering attention as the primary NMDAR co-agonist in limbic brain regions implicated in neuropsychiatric disorders. L-serine is synthesized by astrocytes, which is then transported to neurons for conversion to D-serine by serine racemase (SR), a model we term the 'serine shuttle.' The neuronally-released D-serine is what regulates NMDAR activity. Our review discusses how the systems that regulate the synaptic availability of D-serine, a critical gatekeeper of NMDAR-dependent activation, could be targeted to improve the pharmacologic management of anxiety-related disorders where the desired outcomes are the facilitation of fear extinction, as well as mood and cognitive enhancement.

D-Serine, the Shape-Shifting NMDA Receptor Co-agonist

Shape-shifting, a phenomenon wide-spread in folklore, refers to the ability to physically change from one identity to another, typically from an innocuous entity to a destructive one. The amino acid D-serine over the last 25 years has "shape-shifted" into several identities: a purported glial transmitter activating N-methyl-D-aspartate receptors (NMDARs), a co-transmitter concentrated in excitatory glutamatergic neurons, an autocrine that is released at dendritic spines to prime their post-synaptic NMDARs for an instantaneous response to glutamate and an excitotoxic moiety released from inflammatory (A1) astrocytes. This article will review evidence in support of these scenarios and the artifacts that misled investigators of the true identity of D-serine.

FAM19A1, a brain-enriched and metabolically responsive neurokine, regulates food intake patterns and mouse behaviors

Cytokines and chemokines play diverse roles in different organ systems. Family with sequence similarity 19, member A1-5 (FAM19A1-A5; also known as TAFA1-5) is a group of conserved chemokine-like proteins enriched in the CNS of mice and humans. Their functions are only beginning to emerge. Here, we show that the expression of Fam19a1-a5 in different mouse brain regions are induced or suppressed by unfed and refed states. The striking nutritional regulation of Fam19a family members in the brain suggests a potential central role in regulating metabolism. Using a knockout (KO) mouse model, we show that loss of FAM19A1 results in sexually dimorphic phenotypes. In male mice, FAM19A1 deficiency alters food intake patterns during the light and dark cycle. Fam19a1 KO mice are hyperactive, and locomotor hyperactivity is more pronounced in female KO mice. Behavior tests indicate that Fam19a1 KO female mice have reduced anxiety and sensitivity to pain. Spatial learning and exploration, however, is preserved in Fam19a1 KO mice. Altered behaviors are associated with elevated norepinephrine and dopamine turnover in the striatum. Our results establish an in vivo function of FAM19A1 and highlight central roles for this family of neurokines in modulating animal physiology and behavior.-Lei, X., Liu, L., Terrillion, C. E., Karuppagounder, S. S., Cisternas, P., Lay, M., Martinelli, D. C., Aja, S., Dong, X., Pletnikov, M. V., Wong, G. W. FAM19A1, a brain-enriched and metabolically responsive neurokine, regulates food intake patterns and mouse behaviors.

Adolescent Δ9-Tetrahydrocannabinol Exposure and Astrocyte-Specific Genetic Vulnerability Converge on Nuclear Factor-κB-Cyclooxygenase-2 Signaling to Impair Memory in Adulthood

BACKGROUND

Although several studies have linked adolescent cannabis use to long-term cognitive dysfunction, there are negative reports as well. The fact that not all users develop cognitive impairment suggests a genetic vulnerability to adverse effects of cannabis, which are attributed to action of Δ9-tetrahydrocannabinol (Δ⁹-THC), a cannabis constituent and partial agonist of brain cannabinoid receptor 1. As both neurons and glial cells express cannabinoid receptor 1, genetic vulnerability could influence Δ⁹-THC-induced signaling in a cell type-specific manner.

METHODS

Here we use an animal model of inducible expression of dominant-negative disrupted in schizophrenia 1 (DN-DISC1) selectively in astrocytes to evaluate the molecular mechanisms, whereby an astrocyte genetic vulnerability could interact with adolescent Δ⁹-THC exposure to impair recognition memory in adulthood.

RESULTS

Selective expression of DN-DISC1 in astrocytes and adolescent treatment with Δ⁹-THC synergistically affected recognition memory in adult mice. Similar deficits in recognition memory were observed following knockdown of endogenous Disc1 in hippocampal astrocytes in mice treated with Δ⁹-THC during adolescence. At the molecular level, DN-DISC1 and Δ⁹-THC synergistically activated the nuclear factor-κB-cyclooxygenase-2 pathway in astrocytes and decreased immunoreactivity of parvalbumin-positive presynaptic inhibitory boutons around pyramidal neurons of the hippocampal CA3 area. The cognitive abnormalities were prevented in DN-DISC1 mice exposed to Δ⁹-THC by simultaneous adolescent treatment with the cyclooxygenase-2 inhibitor, NS398.

CONCLUSIONS

Our data demonstrate that individual vulnerability to cannabis can be exclusively mediated by astrocytes. Results of this work suggest that genetic predisposition within astrocytes can exaggerate Δ⁹-THC-produced cognitive impairments via convergent inflammatory signaling, suggesting possible targets for preventing adverse effects of cannabis within susceptible individuals.

Endogenous Cell Type-Specific Disrupted in Schizophrenia 1 Interactomes Reveal Protein Networks Associated With Neurodevelopmental Disorders

BACKGROUND

Disrupted in schizophrenia 1 (DISC1) has been implicated in a number of psychiatric diseases along with neurodevelopmental phenotypes such as the proliferation and differentiation of neural progenitor cells. While there has been significant effort directed toward understanding the function of DISC1 through the determination of its protein-protein interactions within an in vitro setting, endogenous interactions involving DISC1 within a cell type-specific setting relevant to neural development remain unclear.

METHODS

Using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) genome engineering technology, we inserted an endogenous 3X-FLAG tag at the C-terminus of the canonical DISC1 gene in human induced pluripotent stem cells (iPSCs). We further differentiated these cells and used affinity purification to determine protein-protein interactions involving DISC1 in iPSC-derived neural progenitor cells and astrocytes.

RESULTS

We were able to determine 151 novel cell type-specific proteins present in DISC1 endogenous interactomes. The DISC1 interactomes can be clustered into several subcomplexes that suggest novel DISC1 cell-specific functions. In addition, the DISC1 interactome in iPSC-derived neural progenitor cells associates in a connected network containing proteins found to harbor de novo mutations in patients affected by schizophrenia and contains a subset of novel interactions that are known to harbor syndromic mutations in neurodevelopmental disorders.

CONCLUSIONS

Endogenous DISC1 interactomes within iPSC-derived human neural progenitor cells and astrocytes are able to provide context to DISC1 function in a cell type-specific setting relevant to neural development and enables the integration of psychiatric disease risk factors within a set of defined molecular functions.

New Roles for Old Glue: Astrocyte Function in Synaptic Plasticity and Neurological Disorders

Previously believed to solely play a supportive role in the central nervous system, astrocytes are now considered active players in normal brain function. Evidence in recent decades extends their contributions beyond the classically held brain glue role; it's now known that astrocytes act as a unique excitable component with functions extending into local network modulation, synaptic plasticity, and memory formation, and postinjury repair. In this review article, we highlight our growing understanding of astrocyte function and physiology, the increasing role of gliotransmitters in neuron-glia communication, and the role of astrocytes in modulating synaptic plasticity and cognitive function. Owing to the duality of both beneficial and deleterious roles attributed to astrocytes, we also discuss the implications of this new knowledge as it applies to neurological disorders including Alzheimer disease, epilepsy, and schizophrenia.

The TRAX, DISC1, and GSK3 complex in mental disorders and therapeutic interventions

Psychiatric disorders (such as bipolar disorder, depression, and schizophrenia) affect the lives of millions of individuals worldwide. Despite the tremendous efforts devoted to various types of psychiatric studies and rapidly accumulating genetic information, the molecular mechanisms underlying psychiatric disorder development remain elusive. Among the genes that have been implicated in schizophrenia and other mental disorders, disrupted in schizophrenia 1 (DISC1) and glycogen synthase kinase 3 (GSK3) have been intensively investigated. DISC1 binds directly to GSK3 and modulates many cellular functions by negatively inhibiting GSK3 activity. The human DISC1 gene is located on chromosome 1 and is highly associated with schizophrenia and other mental disorders. A recent study demonstrated that a neighboring gene of DISC1, translin-associated factor X (TRAX), binds to the DISC1/GSK3β complex and at least partly mediates the actions of the DISC1/GSK3β complex. Previous studies also demonstrate that TRAX and most of its interacting proteins that have been identified so far are risk genes and/or markers of mental disorders. In the present review, we will focus on the emerging roles of TRAX and its interacting proteins (including DISC1 and GSK3β) in psychiatric disorders and the potential implications for developing therapeutic interventions.

Neuroprotective efficacy of P7C3 compounds in primate hippocampus

There is a critical need for translating basic science discoveries into new therapeutics for patients suffering from difficult to treat neuropsychiatric and neurodegenerative conditions. Previously, a target-agnostic in vivo screen in mice identified P7C3 aminopropyl carbazole as capable of enhancing the net magnitude of postnatal neurogenesis by protecting young neurons from death. Subsequently, neuroprotective efficacy of P7C3 compounds in a broad spectrum of preclinical rodent models has also been observed. An important next step in translating this work to patients is to determine whether P7C3 compounds exhibit similar efficacy in primates. Adult male rhesus monkeys received daily oral P7C3-A20 or vehicle for 38 weeks. During weeks 2-11, monkeys received weekly injection of 5'-bromo-2-deoxyuridine (BrdU) to label newborn cells, the majority of which would normally die over the following 27 weeks. BrdU+ cells were quantified using unbiased stereology. Separately in mice, the proneurogenic efficacy of P7C3-A20 was compared to that of NSI-189, a proneurogenic drug currently in clinical trials for patients with major depression. Orally-administered P7C3-A20 provided sustained plasma exposure, was well-tolerated, and elevated the survival of hippocampal BrdU+ cells in nonhuman primates without adverse central or peripheral tissue effects. In mice, NSI-189 was shown to be pro-proliferative, and P7C3-A20 elevated the net magnitude of hippocampal neurogenesis to a greater degree than NSI-189 through its distinct mechanism of promoting neuronal survival. This pilot study provides evidence that P7C3-A20 safely protects neurons in nonhuman primates, suggesting that the neuroprotective efficacy of P7C3 compounds is likely to translate to humans as well.

DISC1 regulates lactate metabolism in astrocytes: implications for psychiatric disorders

Our knowledge of how genetic risk variants contribute to psychiatric disease is mainly limited to neurons. However, the mechanisms whereby the same genetic risk factors could affect the physiology of glial cells remain poorly understood. We studied the role of a psychiatric genetic risk factor, Disrupted-In-Schizophrenia-1 (DISC1), in metabolic functions of astrocytes. We evaluated the effects of knockdown of mouse endogenous DISC1 (DISC1-KD) and expression of a dominant-negative, C-terminus truncated human DISC1 (DN-DISC1) on the markers of energy metabolism, including glucose uptake and lactate production, in primary astrocytes and in mice with selective expression of DN-DISC1 in astrocytes. We also assessed the effects of lactate treatment on altered affective behaviors and impaired spatial memory in DN-DISC1 mice. Both DISC1-KD and DN-DISC1 comparably decreased mRNA and protein levels of glucose transporter 4 and glucose uptake by primary astrocytes. Decreased glucose uptake was associated with reduced oxidative phosphorylation and glycolysis as well as diminished lactate production in vitro and in vivo. No significant effects of DISC1 manipulations in astrocytes were observed on expression of the subunits of the electron transport chain complexes or mitofilin, a neuronal DISC1 partner. Lactate treatment rescued the abnormal behaviors in DN-DISC1 male and female mice. Our results suggest that DISC1 may be involved in the regulation of lactate production in astrocytes to support neuronal activity and associated behaviors. Abnormal expression of DISC1 in astrocytes and resulting abnormalities in energy supply may be responsible for aspects of mood and cognitive disorders observed in patients with major psychiatric illnesses.

Peptide Sharing Between Viruses and DLX Proteins: A Potential Cross-Reactivity Pathway to Neuropsychiatric Disorders

The present study seeks to determine potential associations between viral infections and neuropsychiatric diseases. To address this issue, we investigated the peptide commonalities between viruses that have been related to psychiatric and neurological disorders—such as rubella, human immunodeficiency virus, and herpesviruses—and human distal-less homeobox (DLX) proteins expressed in developing brain—namely, DLX1, DLX2, DLX5, and DLX6. Peptide matching analyses revealed a high degree of pentapeptide sharing. From an immunological perspective, this overlap is relevant because pentapeptides are endowed with immunogenicity and antigenicity—that is, they are immune determinants. Moreover, infection-induced immune cross-reactions might have functional, spatial, and temporal implications related to the functions and expression patterns of DLX1 and DLX5 in the fetal and adult human brain. In sum, our data support the hypothesis that viral infections may be linked to neuropsychiatric diseases through autoimmune cross-reactions caused by molecular mimicry between viral proteins and brain-specific DLX self-antigens.

Astrocytic Regulation of Glutamate Transmission in Schizophrenia

According to the glutamate hypothesis of schizophrenia, the abnormality of glutamate transmission induced by hypofunction of NMDA receptors (NMDARs) is causally associated with the positive and negative symptoms of schizophrenia. However, the underlying mechanisms responsible for the changes in glutamate transmission in schizophrenia are not fully understood. Astrocytes, the major regulatory glia in the brain, modulate not only glutamate metabolism but also glutamate transmission. Here we review the recent progress in understanding the role of astrocytes in schizophrenia. We focus on the astrocytic mechanisms of (i) glutamate synthesis via the glutamate-glutamine cycle, (ii) glutamate clearance by excitatory amino acid transporters (EAATs), (iii) D-serine release to activate NMDARs, and (iv) glutamatergic target engagement biomarkers. Abnormality in these processes is highly correlated with schizophrenia phenotypes. These findings will shed light upon further investigation of pathogenesis as well as improvement of biomarkers and therapies for schizophrenia.

Neuroprotective Effects and Mechanism of β-Asarone against Aβ1-42-Induced Injury in Astrocytes

Emerging evidence suggests that activated astrocytes play important roles in AD, and β-asarone, a major component of Acorus tatarinowii Schott, was shown to be a potential therapeutic candidate for AD. While our previous study found that β-asarone could improve the cognitive function of rats hippocampally injected with Aβ, the effects of β-asarone on astrocytes remain unclear, and this study aimed to investigate these effects. A rat model of Aβ1-42 (10 μg) was established, and the rats were intragastrically treated with β-asarone at doses of 10, 20, and 30 mg/kg or donepezil at a dose of 0.75 mg/kg. The sham and model groups were intragastrically injected with an equal volume of saline. Animals were sacrificed on the 28th day after administration of the drugs. In addition, a cellular model of Aβ1-42 (1.1 μM, 6 h) was established, and cells were treated with β-asarone at doses of 0, 2.06, 6.17, 18.5, 55.6, and 166.7 μg/mL. β-Asarone improved cognitive impairment, alleviated Aβ deposition and hippocampal damage, and inhibited GFAP, AQP4, IL-1β, and TNF-α expression. These results suggested that β-asarone could alleviate the symptoms of AD by protecting astrocytes, possibly by inhibiting TNF-α and IL-1β secretion and then downregulating AQP4 expression.