Neuroprotective effects of methanolic extract from Chuanxiong Rhizoma in mice with middle cerebral artery occlusion-induced ischemic stroke: suppression of astrocyte- and microglia-related inflammatory response.

BACKGROUND: In traditional Asian medicine, dried rhizomes of Ligusticum chuanxiong Hort. (Chuanxiong Rhizoma [CR]) have long been used to treat pain disorders that affect the head and face such as headaches. Furthermore, they have been used primarily for blood circulation improvement or as an analgesic and anti-inflammatory medicine. This study aimed to investigate the neuroprotective effects of a methanol extract of CR (CRex) on ischemic stroke in mice caused by middle cerebral artery occlusion (MCAO). METHODS: C57BL/6 mice were given a 1.5-h transient MCAO (MCAO control and CRex groups); CRex was administered in the mice of the CRex group at 1,000-3,000 mg/kg either once (single dose) or twice (twice dose) before MCAO. The mechanism behind the neuroprotective effects of CRex was examined using the following techniques: brain infarction volume, edema, neurological deficit, novel object recognition test (NORT), forepaw grip strength, and immuno-fluorescence staining. RESULTS: Pretreating the mice with CRex once at 1,000 or 3,000 mg/kg and twice at 1,000 mg/kg 1 h before MCAO, brought about a significantly decrease in the infarction volumes. Furthermore, pretreating mice with CRex once at 3,000 mg/kg 1 h before MCAO significantly suppressed the reduction of forepaw grip strength of MCAO-induced mice. In the MCAO-induced group, preadministration of CRex inhibited the reduction in the discrimination ratio brought on by MCAO in a similar manner. CRex exhibited these effects by suppressing the activation of astrocytes and microglia, which regulated the inflammatory response. CONCLUSIONS: This study proposes a novel development for the treatment of ischemic stroke and provides evidence favoring the use of L. chuanxiong rhizomes against ischemic stroke.

Synergistic amelioration between Ligusticum striatum DC and borneol against cerebral ischemia by promoting astrocytes-mediated neurogenesis.

ETHNOPHARMACOLOGICAL RELEVANCE: Ligusticum chuanxiong Hort (LCH), with the accepted name of Ligusticum striatum DC in "The Plant List" database, is a widely used ethnomedicine in treating ischemic stroke, and borneol (BO) is usually prescribed with LCH for better therapy. Our previous study confirmed their synergistic effect on neurogenesis against cerebral ischemia. However, the underlying mechanism is still unclear. AIM OF THE STUDY: More and more evidence indicated that astrocytes (ACs) might be involved in the modulation of neurogenesis via polarization reaction. The study was designed to explore the synergic mechanism between LCH and BO in promoting astrocyte-mediated neurogenesis. MATERIALS AND METHODS: After primary cultures and identifications of ACs and neural stem cells (NSCs), the oxygen-glucose deprivation (OGD) model and the concentrations of LCH and BO were optimized. After the OGD-injured ACs were treated by LCH, BO, and their combination, the conditioned mediums were used to culture the OGD-injured NSCs. The proliferation, migration, and differentiation of NSCs were assessed, and the secretions of BDNF, CNTF, and VEGF from ACs were measured. Then the expressions of C3 and PTX3 were detected. Moreover, the mice were performed a global cerebral ischemia/reperfusion model and treated with LCH and (or) BO. After the assessments of Nissl staining, the expressions of Nestin, DCX, GFAP, C3, PTX3, p65 and p-p65 were probed. RESULTS: The most appropriate duration of OGD for the injury of both NSCs and ACs was 6 h, and the optimized concentrations of LCH and BO were 1.30 µg/mL and 0.03 µg/mL, respectively. The moderate OGD environment induced NSCs proliferation, migration, astrogenesis, and neurogenesis, increased the secretions of CNTF and VEGF from ACs, and upregulated the expressions of C3 and PTX3. For the ACs, LCH further increased the secretions of BDNF and CNTF, enhanced PTX3 expression, and reduced C3 expression. Additionally, the conditioned medium from LCH-treated ACs further enhanced NSC proliferation, migration, and neurogenesis. The in vivo study showed that LCH markedly enhanced the Nissl score and neurogenesis, and decreased astrogenesis which was accompanied by downregulations of C3, p-p65, and p-p65/p65 and upregulation of PTX3. BO not only decreased the expression of C3 in ACs both in vitro and in vivo but also downregulated p-p65 and p-p65/p65 in vivo. Additionally, BO promoted the therapeutic effect of LCH for most indices. CONCLUSION: A certain degree of OGD might induce ACs to stimulate the proliferation, astrogenesis, and neurogenesis of NSCs. LCH and BO exhibited a marked synergy in promoting ACs-mediated neurogenesis and reducing astrogenesis, in which LCH played a dominant role and BO boosted the effect of LCH. The mechanism of LCH might be involved in switching the polarization of ACs from A1 to A2, while BO preferred to inhibit the formation of A1 phenotype via downregulating NF-κB pathway.

Hypothalamic astrocyte NAD+ salvage pathway mediates the coupling of dietary fat overconsumption in a mouse model of obesity.

Nicotinamide adenine dinucleotide (NAD)+ serves as a crucial coenzyme in numerous essential biological reactions, and its cellular availability relies on the activity of the nicotinamide phosphoribosyltransferase (NAMPT)-catalyzed salvage pathway. Here we show that treatment with saturated fatty acids activates the NAD+ salvage pathway in hypothalamic astrocytes. Furthermore, inhibition of this pathway mitigates hypothalamic inflammation and attenuates the development of obesity in male mice fed a high-fat diet (HFD). Mechanistically, CD38 functions downstream of the NAD+ salvage pathway in hypothalamic astrocytes burdened with excess fat. The activation of the astrocytic NAMPT-NAD+-CD38 axis in response to fat overload induces proinflammatory responses in the hypothalamus. It also leads to aberrantly activated basal Ca2+ signals and compromised Ca2+ responses to metabolic hormones such as insulin, leptin, and glucagon-like peptide 1, ultimately resulting in dysfunctional hypothalamic astrocytes. Our findings highlight the significant contribution of the hypothalamic astrocytic NAD+ salvage pathway, along with its downstream CD38, to HFD-induced obesity.

Icariin mitigates anxiety-like behaviors induced by hemorrhagic shock and resuscitation via inhibiting of astrocytic activation.

BACKGROUND: Abnormal activation of astrocytes in the amygdala contributes to anxiety after hemorrhagic shock and resuscitation (HSR). Nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB)-associated epigenetic reprogramming of astrocytic activation is crucial to anxiety. A bioactive monomer derived from Epimedium icariin (ICA) has been reported to modulate NF-κB signaling and astrocytic activation. PURPOSE: The present study aimed to investigate the effects of ICA on post-HSR anxiety disorders and its potential mechanism of action. METHODS: We first induced HSR in mice through a bleeding and re-transfusion model and selectively inhibited and activated astrocytes in the amygdala using chemogenetics. Then, ICA (40 mg/kg) was administered by oral gavage once daily for 21 days. Behavioral, electrophysiological, and pathological changes were assessed after HSR using the light-dark transition test, elevated plus maze, recording of local field potential (LFP), and immunofluorescence assays. RESULTS: Exposure to HSR reduced the duration of the light chamber and attenuated open-arm entries. Moreover, HSR exposure increased the theta oscillation power in the amygdala and upregulated NF-κB p65, H3K27ac, and H3K4me3 expression. Contrarily, chemogenetic inhibition of astrocytes significantly reversed these changes. Chemogenetic inhibition in astrocytes was simulated by ICA, but chemogenetic activation of astrocytes blocked the neuroprotective effects of ICA. CONCLUSION: ICA mitigated anxiety-like behaviors induced by HSR in mice via inhibiting astrocytic activation, which is possibly associated with NF-κB-induced epigenetic reprogramming.

Communication defects with astroglia contribute to early impairments in the motor cortex plasticity of SOD1G93A mice.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease, involving the selective degeneration of cortical upper synapses in the primary motor cortex (M1). Excitotoxicity in ALS occurs due to an imbalance between excitation and inhibition, closely linked to the loss/gain of astrocytic function. Using the ALS SOD1G93A mice, we investigated the astrocytic contribution for the electrophysiological alterations observed in the M1 of SOD1G93A mice, throughout disease progression. Results showed that astrocytes are involved in synaptic dysfunction observed in presymptomatic SOD1G93A mice, since astrocytic glutamate transport currents are diminished and pharmacological inhibition of astrocytes only impaired long-term potentiation and basal transmission in wild-type mice. Proteomic analysis revealed major differences in neuronal transmission, metabolism, and immune system in upper synapses, confirming early communication deficits between neurons and astroglia. These results provide valuable insights into the early impact of upper synapses in ALS and the lack of supportive functions of cortical astrocytes, highlighting the possibility of manipulating astrocytes to improve synaptic function.

Vitamin D Reduces GABA-Positive Astrocytes in the 5xFAD Mouse Model of Alzheimer's Disease.

Background: Vitamin D has neuroprotective and immunomodulating functions that may impact glial cell function in the brain. Previously, we reported molecular and behavioral changes caused by deficiency and supplementation of vitamin D in an Alzheimer's disease (AD) mouse model. Recent studies have highlighted reactive astrocytes as a new therapeutic target for AD treatment. However, the mechanisms underlying the therapeutic effects of vitamin D on the glial cells of AD remain unclear. Objective: To investigate the potential association between vitamin D deficiency/supplementation and the pathological progression of AD, including amyloid-ß (Aß) pathology and reactive astrogliosis. Methods: Transgenic hemizygous 5XFAD male mice were subjected to different dietary interventions and intraperitoneal vitamin D injections to examine the effects of vitamin D deficiency and supplementation on AD. Brain tissue was then analyzed using immunohistochemistry for Aß plaques, microglia, and astrocytes, with quantifications performed via ImageJ software. Results: Our results demonstrated that vitamin D deficiency exacerbated Aß plaque formation and increased GABA-positive reactive astrocytes in AD model mice, while vitamin D supplementation ameliorated these effects, leading to a reduction in Aß plaques and GABA-positive astrocytes. Conclusions: Our findings highlight the significant impact of vitamin D status on Aß pathology and reactive astrogliosis, underscoring its potential role in the prevention and treatment of AD. This study provides the first in vivo evidence of the association between vitamin D and reactive astrogliosis in AD model mice, indicating the potential for targeting vitamin D levels as a novel therapeutic approach for AD.

Xiaoyaosan promotes neurotransmitter transmission and alleviates CUMS-induced depression by regulating the expression of Oct1 and Oct3 in astrocytes of the prefrontal cortex.

ETHNOPHARMACOLOGICAL RELEVANCE: Xiaoyaosan (XYS) is a traditional prescription for the treatment of liver depression and qi stagnation, and pharmacological studies have shown that XYS has great potential to reverse depression. However, anti-depression targets and the mechanism of XYS are still not entirely clear. AIM OF THE STUDY: The present study aims to explore and verify the anti-depression mechanism of XYS. MATERIALS AND METHODS: The antidepressant effect of XYS was assessed in rats with depression induced by chronic unpredictable mild stimulation (CUMS). The levels of 5-hydroxytryptamine (5-HT), dopamine (DA), and norepinephrine (NE) in different brain regions were measured using ELISA. The expression of organic cation transporters (Octs) were detected by western blot and immunohistochemical techniques. Then, Decynium-22 (D22), an Octs inhibitor, was injected into the prefrontal cortex (PFC) to verify the correlation between Octs and depression-like behavior. Then, the effects of XYS on the behavior, neurotransmitter concentration, and Octs expression in D22-induced rats were examined. Finally, primary astrocytes were used to verify the mechanism of XYS exerting anti-depressant activity by regulating Octs. RESULTS: The result showed that XYS had a significant positive impact on the behavior of depression rats induced by CUMS. XYS also improved the secretion of 5-HT, DA, and NE in the PFC, as well as the promotion of Oct1, Oct2, and Oct3 expression in the PFC. These results suggest that XYS has the potential to alleviate depression by enhancing the secretion of neurotransmitters. This may be related to XYS regulation of Oct's expression. When the expression of Octs was inhibited in the PFC, rats exhibited behavior similar to depression, and XYS was able to reverse this behavior, indicating that Octs play a significant role in the development of depression and XYS may exert its antidepressant effects through the regulation of Octs. Furthermore, the study also found that dopamine uptake decreased after inhibiting the expression of Octs, and XYS-containing serum could reverse the downregulation of Oct1 and Oct3 and promote intracellular dopamine homeostasis in the astrocytes. Overall, XYS may exert antidepressant effects by promoting dopamine uptake to improve neurotransmitter transport by regulating the protein expression of Oct1 and Oct3 in astrocytes. CONCLUSIONS: The antidepressant effect of XYS may be attributed to its ability to regulate the expression of Oct1 and Oct3 in astrocytes of the PFC, thereby promoting neurotransmitter transport.

METTL3-dependent N6-methyladenosine modification is involved in berberine-mediated neuroprotection in ischemic stroke by enhancing the stability of NEAT1 in astrocytes.

Ischemic stroke (IS) is one of the principal causes of disability and death worldwide. Berberine (BBR), derived from the traditional Chinese herbal medicine Huang Lian, has been reported to inhibit the progression of stroke, but the specific mechanism whereby BBR modulates the progression of ischemic stroke remains unclear. N6-methyladenosine (m6A) modification is the most typical epigenetic modification of mRNA post-transcriptional modifications, among which METTL3 is the most common methylation transferase. During the study, the middle cerebral artery occlusion/reperfusion (MCAO/R) was established in mice, and the mice primary astrocytes and neurons induced by oxygen-glucose deprivation/reoxygenation (OGD/R) was simulated in vitro. Level of LncNEAT1, miR-377-3p was detected via RT-qPCR. The levels of Nampt and METTL3 were measured by Western blot. CCK8 and LDH assay was performed to detect cell viability. Here, we found that berberine alleviates MCAO/R-induced ischemic injury and up-regulates the expression of Nampt in astrocytes, miR-377-3p inhibits the expression of Nampt in astrocytes after OGD/R, thus promoting neuronal injury. NEAT1 binds to miR-377-3p in OGD/R astrocytes and plays a neuronal protective role as a ceRNA. METTL3 can enhance NEAT1 stability in OGD/R astrocytes by modulating m6A modification of NEAT1. Taken together, our results demonstrate that berberine exerts neuroprotective effects via the m6A methyltransferase METTL3, which regulates the NEAT1/miR-377-3p/Nampt axis in mouse astrocytes to ameliorate cerebral ischemia/reperfusion (I/R) injury.

The Role of Glutamine Homeostasis in Emotional and Cognitive Functions.

Glutamine (Gln), a non-essential amino acid, is synthesized de novo by glutamine synthetase (GS) in various organs. In the brain, GS is exclusively expressed in astrocytes under normal physiological conditions, producing Gln that takes part in glutamatergic neurotransmission through the glutamate (Glu)-Gln cycle. Because the Glu-Gln cycle and glutamatergic neurotransmission play a pivotal role in normal brain activity, maintaining Gln homeostasis in the brain is crucial. Recent findings indicated that a neuronal Gln deficiency in the medial prefrontal cortex in rodents led to depressive behaviors and mild cognitive impairment along with lower glutamatergic neurotransmission. In addition, exogenous Gln supplementation has been tested for its ability to overcome neuronal Gln deficiency and reverse abnormal behaviors induced by chronic immobilization stress (CIS). Although evidence is accumulating as to how Gln supplementation contributes to normalizing glutamatergic neurotransmission and the Glu-Gln cycle, there are few reviews on this. In this review, we summarize recent evidence demonstrating that Gln supplementation ameliorates CIS-induced deleterious changes, including an imbalance of the Glu-Gln cycle, suggesting that Gln homeostasis is important for emotional and cognitive functions. This is the first review of detailed mechanistic studies on the effects of Gln supplementation on emotional and cognitive functions.

Synaptic plasticity and the role of astrocytes in central metabolic circuits.

Neural circuits in the brain, primarily in the hypothalamus, are paramount to the homeostatic control of feeding and energy utilization. They integrate hunger, satiety, and body adiposity cues from the periphery and mediate the appropriate behavioral and physiological responses to satisfy the energy demands of the animal. Notably, perturbations in central homeostatic circuits have been linked to the etiology of excessive feeding and obesity. Considering the ever-changing energy requirements of the animal and required adaptations, it is not surprising that brain-feeding circuits remain plastic in adulthood and are subject to changes in synaptic strength as a consequence of nutritional status. Indeed, synapse density, probability of presynaptic transmitter release, and postsynaptic responses in hypothalamic energy balance centers are tailored to behavioral and physiological responses required to sustain survival. Mounting evidence supports key roles of astrocytes facilitating some of this plasticity. Here we discuss these synaptic plasticity mechanisms and the emerging roles of astrocytes influencing energy and glucose balance control in health and disease. This article is categorized under: Cancer > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology.

Buyang Huanwu Decoction promotes neurovascular remodeling by modulating astrocyte and microglia polarization in ischemic stroke rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Buyang Huanwu Decoction (BYHWD), one of the most commonly utilized traditional Chinese medicine prescription for treatment of cerebral ischemic stroke. However, the understanding of BYHWD on neurovascular repair following cerebral ischemia is so far limited. AIM OF THE STUDY: This research investigated the influence of BYHWD on neurovascular remodeling by magnetic resonance imaging (MRI) technology and revealed the potential neurovascular repair mechanism underlying post-treatment with BYHWD after ischemic stroke. MATERIALS AND METHODS: Male Sprague-Dawley rats were utilized as an ischemic stroke model by permanent occlusion of the middle cerebral artery (MCAO). BYHWD was intragastrically administrated once daily for 30 days straight. Multimodal MRI was performed to detect brain tissue injuries, axonal microstructural damages, cerebral blood flow and intracranial vessels on the 30th day after BYHWD treatment. Proangiogenic factors, axonal/synaptic plasticity-related factors, energy transporters and adenosine monophosphate-activated protein kinase (AMPK) signal pathway were evaluated using western blot. Double immunofluorescent staining and western blot were applied to evaluate astrocytes and microglia polarization. RESULTS: Administration of BYHWD significantly alleviated infarct volume and brain tissue injuries and ameliorated microstructural damages, accompanied with improved axonal/synaptic plasticity-related factors, axonal growth guidance factors and decreased axonal growth inhibitors. Meanwhile, BYHWD remarkably improved cerebral blood flow, cerebral vascular signal and promoted the expression of proangiogenic factors. Particularly, treatment with BYHWD obviously suppressed astrocytes A1 and microglia M1 polarization accompanied with promoted astrocyte A2 and microglia M2 polarization. Furthermore, BYHWD effectively improved energy transporters. Especially, BYHWD markedly increased expression of phosphorylated AMPK, cyclic AMP-response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) accompanied by inactivation of the NF-κB. CONCLUSION: Taken together, these findings identified that the beneficial roles of BYHWD on neurovascular remodeling were related to AMPK pathways -mediated energy transporters and NFκB/CREB pathways.

Photobiomodulation Activates Microglia/Astrocytes and Relieves Neuropathic Pain in Inferior Alveolar Nerve Injury.

Objective: This study aimed to determine microglial/astrocyte changes and their associated analgesic effect in inferior alveolar nerve injury (IANI) model rats treated with photobiomodulation therapy (PBMT) using a 940-nm diode laser. Background: Very few basic studies have investigated microglial/astrocyte dynamics following PBMT aimed at relieving neuropathic pain caused by IANI. Methods: Rats were divided into an IANI-PBM group, IANI+PBM group, and sham+PBM group. Observations were made on the day before IANI or the sham operation and on postoperative days 3, 5, 7, 14, and 28. PBMT was delivered for 7 consecutive days, with an energy density of 8 J/cm2. Behavioral analysis was performed to determine pain thresholds, and immunohistological staining was performed for the microglia marker Iba1 and astrocyte marker glial fibrillary acidic protein, which are observed in the spinal trigeminal nucleus. Results: Behavioral analysis showed that the pain threshold returned to the preoperative level on postoperative day 14 in the IANI+PBM group, but decreased starting from postoperative day 1 and did not improve thereafter in the IANI-PBM group (p ≤ 0.001). Immunological analysis showed that microglial and astrocyte cell counts were similar in the IANI+PBM group and IANI-PBM group shortly after IANI (day 3), but the expression area was larger (p ≤ 0.001) and hypertrophy of microglia and astrocyte cell bodies and end-feet extension (i.e., indicators of activation) were more prominent in the IANI+PBM group. Conclusions: PBMT after IANI prevented hyperalgesia and allodynia by promoting glial cell activation shortly after injury.

[Effect of Xiaoxuming Decoction on activation of astrocytes in acute cerebral ischemia/reperfusion injury].

This study investigated the effect of Xiaoxuming Decoction(XXMD) on the activation of astrocytes after cerebral ischemia/reperfusion(I/R) injury. The model of cerebral IR injury was established using the middle cerebral artery occlusion method. Fluorocitrate(FC), an inhibitor of astrocyte activation, was applied to inhibit astrocyte activation. Rats were randomly divided into a sham group, a model group, a XXMD group, a XXMD+FC group, and a XXMD+Vehicle group. Neurobehavioral changes at 24 hours after cerebral IR injury, cerebral infarction, histopathological changes observed through HE staining, submicroscopic structure of astrocytes observed through transmission electron microscopy, fluorescence intensity of glial fibrillary acidic protein(GFAP) and thrombospondin 1(TSP1) measured through immunofluorescence, and expression of GFAP and TSP1 in brain tissue measured through Western blot were evaluated in rats from each group. The experimental results showed that neurobehavioral scores and cerebral infarct area significantly increased in the model group. The XXMD group, the XXMD+FC group, and the XXMD+Vehicle group all alleviated neurobehavioral changes in rats. The pathological changes in the brain were evident in the model group, while the XXMD group, the XXMD+FC group, and the XXMD+Vehicle group exhibited milder cerebral IR injury in rats. The submicroscopic structure of astrocytes in the model group showed significant swelling, whereas the XXMD group, the XXMD+FC group, and XXMD+Vehicle group protected the submicroscopic structure of astrocytes. The fluorescence intensity and protein expression of GFAP and TSP1 increased in the model group compared with those in the sham group. However, the XXMD group, the XXMD+FC group, and XXMD+Vehicle group all down-regulated the expression of GFAP and TSP1. The combination of XXMD and FC showed a more pronounced effect. These results indicate that XXMD can improve cerebral IR injury, possibly by inhibiting astrocyte activation and down-regulating the expression of GFAP and TSP1.

Electroacupuncture exerts prolonged analgesic and neuroprotective effects in a persistent dental pain model induced by multiple dental pulp injuries: GABAergic interneurons-astrocytes interaction.

Pain within the trigeminal system, particularly dental pain, is poorly understood. This study aimed to determine whether single or multiple dental pulp injuries induce persistent pain, its association with trigeminal central nociceptive pathways and whether electroacupuncture (EA) provides prolonged analgesic and neuroprotective effects in a persistent dental pain model. Models of single dental pulp injury (SDPI) and multiple dental pulp injuries (MDPI) were used to induce trigeminal neuropathic pain. The signs of dental pain-related behavior were assessed using the mechanical head withdrawal threshold (HWT). Immunofluorescence and western blot protocols were used to monitor astrocyte activation, changes in apoptosis-related proteins, and GABAergic interneuron plasticity. SDPI mice exhibited an initial marked decrease in HWT from days one to 14, followed by progressive recovery from days 21 to 42. From days 49 to 70, the HWT increased and returned to the control values. In contrast, MDPI mice showed a persistent decrease in HWT from days one to 70. MDPI increased glial fibrillary acidic protein (GFAP) and decreased glutamine synthetase (GS) and glutamate transporter-1 (GLT1) expression in the Vi/Vc transition zone of the brainstem on day 70, whereas no changes in astrocytic markers were observed on day 70 after SDPI. Increased expression of cleaved cysteine-aspartic protease-3 (cleaved caspase-3) and Bcl-2-associated X protein (Bax), along with decreased B-cell lymphoma/leukemia 2 (Bcl-2), were observed at day 70 after MDPI but not after SDPI. The downregulation of glutamic acid decarboxylase (GAD65) expression was observed on day 70 only after MDPI. The effects of MDPI-induced lower HWT from days one to 70 were attenuated by 12 sessions of EA treatment (days one to 21 after MDPI). Changes in astrocytic GFAP, GS, and GLT-1, along with cleaved caspase-3, Bax, Bcl-2, and GAD65 expression observed 70 days after MDPI, were reversed by EA treatment. The results suggest that persistent dental pain in mice was induced by MDPI but not by SDPI. This effect was associated with trigeminal GABAergic interneuron plasticity along with morphological and functional changes in astrocytes. EA exerts prolonged analgesic and neuroprotective effects that might be associated with the modulation of neuron-glia crosstalk mechanisms.

Bear bile powder alleviates Parkinson's disease-like behavior in mice by inhibiting astrocyte-mediated neuroinflammation.

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

A solid lipid particle formulation of long pepper extract reduces pain and astrocyte activation in a rat model of neuropathic pain.

OBJECTIVES: To investigate the effects of solid lipid microparticle (SLM) creams containing a long pepper extract (LPE) or piperine on neuropathy-related pain and the expression of glial fibrillary acidic protein (GFAP) as a measure of astrogliosis. METHODS: Neuropathic pain in male Spraque Dawley rats was induced by sciatic nerve ligation (SNL) and followed by treatment with LPE-SLM, piperine-SLM, capsaicin or vehicle creams. The pain score was assessed by thermal hyperalgesia test. The GFAP expression in the spinal cord was determined by immunohistochemistry. RESULTS: Pain scores were significantly increased after SNL and decreased when treated by LPE-SLM. The number of GFAP immunopositive cells was significantly increased in the SNL rats. Treated by LPE-SLM and capsaicin creams resulted in a significant reduction of the number of GFAP immunopositive cells. The LPE-SLM treated rats showed greater effects than the piperine and capsaicin preparations. CONCLUSIONS: The LPE-SLM cream has a potential effect on pain attenuation via a decrease of spinal astrocyte activation-related mechanism. The LPE in SLM preparation could provide an alternative therapeutic strategy for treating neuropathic pain.

Ginsenoside Rb1 protects hippocampal neurons in depressed rats based on mitophagy-regulated astrocytic pyroptosis.

BACKGROUND: Astrocytes play a vital role in offering functional support for neurons, which are related to the pathogenic mechanism of depression. Ginsenoside Rb1 (GRb1) is demonstrated with antidepressant-like activities. PURPOSE: We aimed to investigate whether GRb1 can inhibit mitophagy-mediated astrocytic pyroptosis to protect neurons in depression. STUDY DESIGN: Model rats were subjected to chronic unpredictable mild stress (CUMS) for determining the in vivo antidepressant activity of GRb1. METHODS: The mitophagy-mediated antipyroptosis role of GRb1 was assessed in lipopolysaccharide (LPS) + ATP-stimulated astrocytes. The mechanism by which GRb1 protects synaptic plasticity was investigated using hippocampal neurons incubated in an astrocyte medium. The rat depressive-like behaviors were determined through sucrose preference, forced swimming, and the open-field tests. Escitalopram was used in the anti-depression control of GRb1. Cyclosporin A (CsA), a mitophagy inhibitor, and interleukin (IL)-1ß were used to reverse the role of GRb1 in mitophagy and pyroptosis, respectively. RESULTS: GRb1 inhibited LPS-induced inflammation and activation in the astrocytes and repressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. Also, GRb1 repressed LPS + ATP-promoted astrocytic pyroptosis. During GRb1 treatment, the activation of mitophagy with a decrease in ROS was observed in LPS + ATPs-stimulated astrocytes. CsA enhanced GRb1-decreased ROS and promoted astrocytic pyroptosis. The GRb1-treated astrocyte medium suppressed neuron death and increased neuron viability and synaptic density. Escitalopram and GRb1 improved the depressive-like behaviors of the rats. GRb1 activated mitophagy and inhibited astrocytic activation and pyroptosis in rats with depression. It also reduced impairments in synaptic structures and increased synaptic density in depressive-like rats. IL-1ß increased astrocytic pyroptosis and reversed GRb1-enhanced synaptic plasticity in the rats exposed to CUMS. There were no statistical changes in depressive-like behaviors between GRb1 and Escitalopram groups. CONCLUSION: GRb1 modulates mitophagy and the NF-κB pathway to inhibit astrocytic pyroptosis, thereby maintaining neurological homeostasis by repressing inflammation and enhancing synaptic plasticity.

Hypothalamic astrocytic-BMAL1 regulates energy homeostasis in a sex-dependent manner.

Here, we demonstrate that hypothalamic astrocytic BMAL1 computes cyclic metabolic information to optimize energetic resources in a sexually dimorphic manner. Knockdown of BMAL1 in female astrocytes leads to negative energy balance and alters basal metabolic cycles without affecting circadian locomotor activity. Thus, astrocytic BMAL1 contributes to the control of energy balance through the modulation of the metabolic rate, hepatic and white adipose tissue lipogenesis, and the activity of brown adipose tissue. Importantly, most of these alterations are specific to hypothalamic astrocytic BMAL1. Moreover, female mice with BMAL1 knockdown in astrocytes exhibited a "male-like" metabolic obese phenotype when fed a high-fat diet. Overall, our results suggest a sexually dimorphic effect of astrocytic BMAL1 on the regulation of energy homeostasis, which may be of interest in the physiopathology of obesity and related comorbidities.

Pilot Study of Cytoprotective Mechanisms of Selenium Nanorods (SeNrs) under Ischemia-like Conditions on Cortical Astrocytes.

The cytoprotective properties of the trace element selenium, its nanoparticles, and selenium nanocomplexes with active compounds are shown using a number of models. To date, some molecular mechanisms of the protective effect of spherical selenium nanoparticles under the action of ischemia/reoxygenation on brain cells have been studied. Among other things, the dependence of the effectiveness of the neuroprotective properties of nanoselenium on its diameter, pathways, and efficiency of penetration into astrocytes was established. In general, most research in the field of nanomedicine is focused on the preparation and study of spherical nanoparticles of various origins due to the ease of their preparation; in addition, spherical nanoparticles have a large specific surface area. However, obtaining and studying the mechanisms of action of nanoparticles of a new form are of great interest since nanorods, having all the positive properties of spherical nanoparticles, will also have a number of advantages. Using the laser ablation method, we managed to obtain and characterize selenium nanorods (SeNrs) with a length of 1 µm and a diameter of 100 nm. Using fluorescence microscopy and inhibitory analysis, we were able to show that selenium nanorods cause the generation of Ca2+ signals in cortical astrocytes in an acute experiment through the mobilization of Ca2+ ions from the thapsigargin-sensitive pool of the endoplasmic reticulum. Chronic use of SeNrs leads to a change in the expression pattern of genes encoding proteins that regulate cell fate and protect astrocytes from ischemia-like conditions and reoxygenation through the inhibition of a global increase in the concentration of cytosolic calcium ([Ca2+]i). An important component of the cytoprotective effect of SeNrs during ischemia/reoxygenation is the induction of reactive A2-type astrogliosis in astrocytes, leading to an increase in both baseline and ischemia/reoxygenation-induced phosphoinositide 3-kinase (PI3K) activity and suppression of necrosis and apoptosis. The key components of this cytoprotective action of SeNrs are the actin-dependent process of endocytosis of nanoparticles into cells and activation of the Ca2+ signaling system of astrocytes.

The presence of pyruvate carboxylase in the human brain and its role in the survival of cultured human astrocytes.

Pyruvate carboxylase (PC) is a mitochondrial, biotin-containing enzyme catalyzing the ATP-dependent synthesis of oxaloacetate from pyruvate and bicarbonate, with a critical anaplerotic role in sustaining the brain metabolism. Based on the studies performed on animal models, PC expression was assigned to be glia-specific. To study PC distribution among human neural cells, we probed the cultured human astrocytes and brain sections with antibodies against PC. Additionally, we tested the importance of PC for the viability of cultured human astrocytes by applying the PC inhibitor 3-chloropropane-1,2-diol (CPD). Our results establish the expression of PC in mitochondria of human astrocytes in culture and brain tissue and also into a subpopulation of the neurons in situ. CPD negatively affected the viability of astrocytes in culture, which could be partially reversed by supplementing media with malate, 2-oxoglutarate, citrate, or pyruvate. The provided data estimates PC expression in human astrocytes and neurons in human brain parenchyma. Furthermore, the enzymatic activity of PC is vital for sustaining the viability of cultured astrocytes.