Microglial functions are linked to Ca²⁺ signaling, with endoplasmic reticulum (ER) calcium stores playing a crucial role. Microglial abnormality is a hallmark of Alzheimer's disease (AD), but how ER Ca²⁺ receptors regulate microglial functions under physiological and AD conditions remains unclear. We found reduced ryanodine receptor 2 (Ryr2) expression in microglia from an AD mouse model. Modulation of RyR2 using S107, a RyR-Calstabin stabilizer, blunted spontaneous Ca²⁺ transients in controls and normalized Ca²⁺ transients in AD mice. S107 enhanced ATP-induced migration and phagocytosis while reducing ramification in control microglia; however, these effects were absent in AD microglia. Our findings indicate that RyR2 stabilization promotes an activation state shift in control microglia, a mechanism impaired in AD. These results highlight the role of ER Ca²⁺ receptors in both homeostatic and AD microglia, providing insights into microglial Ca²⁺ malfunctions in AD.
Animals ; Microglia/pathology* ; Alzheimer Disease/pathology* ; Phagocytosis/drug effects* ; Ryanodine Receptor Calcium Release Channel/metabolism* ; Disease Models, Animal ; Mice ; Cell Movement/drug effects* ; Mice, Transgenic ; Calcium Signaling/physiology* ; Calcium/metabolism* ; Mice, Inbred C57BL ; Male ; Endoplasmic Reticulum/metabolism*

Astrocytes in the spinal dorsal horn (SDH) exhibit diverse reactive phenotypes under neuropathic conditions, yet the mechanisms driving this diversity and its implications in chronic pain remain unclear. Here, we report that spared nerve injury (SNI) induces marked upregulation of both complement component 3 (C3⁺, A1-like) and S100 calcium-binding protein A10 (S100A10⁺, A2-like) astrocyte subpopulations in the SDH, with elevated microglial cytokines including interleukin-1α, tumor necrosis factor-α, and complement component 1q. Transcriptomic, immunohistochemical, and Western blot analyses reveal co-activation of multiple reactive astrocyte states over a unidirectional shift toward an A1-like phenotype. Fibroblast growth factor 8 (FGF8), a neuroprotective factor via FGFR3, mitigated microglia-induced C3⁺ astrocyte reactivity in vitro and suppressed spinal C3 expression and mechanical allodynia following intrathecal administration in SNI mice. These findings reveal a microglia-astrocyte signaling axis that promotes A1 reactivity and position FGF8 as a promising therapeutic candidate for neuropathic pain by modulating astrocyte heterogeneity.
Animals ; Astrocytes/drug effects* ; Neuralgia/pathology* ; Receptor, Fibroblast Growth Factor, Type 3/metabolism* ; Signal Transduction/physiology* ; Male ; Mice ; Microglia/drug effects* ; Fibroblast Growth Factor 8/pharmacology* ; Mice, Inbred C57BL ; Hyperalgesia/drug therapy* ; Spinal Cord/drug effects* ; Complement C3/metabolism* ; Spinal Cord Dorsal Horn/metabolism*

Occupational exposure to 1-bromopropane (1-BP) induces learning and memory deficits. However, no therapeutic strategies are currently available. Accumulating evidence has suggested that N-methyl-D-aspartate receptors (NMDARs) and neuroinflammation are involved in the cognitive impairments in neurodegenerative diseases. In this study we aimed to investigate whether the noncompetitive NMDAR antagonist MK801 protects against 1-BP-induced cognitive dysfunction. Male Wistar rats were administered with MK801 (0.1 mg/kg) prior to 1-BP intoxication (800 mg/kg). Their cognitive performance was evaluated by the Morris water maze test. The brains of rats were dissected for biochemical, neuropathological, and immunological analyses. We found that the spatial learning and memory were significantly impaired in the 1-BP group, and this was associated with neurodegeneration in both the hippocampus (especially CA1 and CA3) and cortex. Besides, the protein levels of phosphorylated NMDARs were increased after 1-BP exposure. MK801 ameliorated the 1-BP-induced cognitive impairments and degeneration of neurons in the hippocampus and cortex. Mechanistically, MK801 abrogated the 1-BP-induced disruption of excitatory and inhibitory amino-acid balance and NMDAR abnormalities. Subsequently, MK801 inhibited the microglial activation and release of pro-inflammatory cytokines in 1-BP-treated rats. Our findings, for the first time, revealed that MK801 protected against 1-BP-induced cognitive dysfunction by ameliorating NMDAR function and blocking microglial activation, which might provide a potential target for the treatment of 1-BP poisoning.
Animals ; Brain ; drug effects ; metabolism ; pathology ; Cognitive Dysfunction ; drug therapy ; metabolism ; pathology ; Disease Models, Animal ; Dizocilpine Maleate ; pharmacology ; Excitatory Amino Acid Antagonists ; pharmacology ; Hydrocarbons, Brominated ; Inflammasomes ; drug effects ; metabolism ; Male ; Maze Learning ; drug effects ; physiology ; Microglia ; drug effects ; metabolism ; pathology ; NLR Family, Pyrin Domain-Containing 3 Protein ; metabolism ; Neurons ; drug effects ; metabolism ; pathology ; Nootropic Agents ; pharmacology ; Random Allocation ; Rats, Wistar ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors ; metabolism ; Spatial Memory ; drug effects ; physiology ; Specific Pathogen-Free Organisms

BACKGROUNDThe pain caused by orthodontic treatment has been considered as tough problems in orthodontic practice. Danggui-shaoyao-san (DSS) is a traditional Chinese medicine (TCM) prescription which has long been used for pain treatment and possesses antioxidative, cognitive enhancing and antidepressant effects. We raise the hypothesis that DSS exerts analgesic effect for orthodontic pain via inhibiting the activations of neuron and microglia.

METHODSDSS was given twice a day from day 5 prior to experimental tooth movement (ETM). Directed face grooming and vacuous chewing movements (VCM) were evaluated. Immunofluorescent histochemistry and Western blot analysis were used to quantify the Iba-1 (microglia activation) and Fos (neuronal activation) expression levels in the trigeminal spinal nucleus caudalis (Vc).

RESULTSETM significantly increased directed face grooming and VCM which reached the peak at post-operative day (POD) 1 and gradually decreased to the baseline at POD 7. However, a drastic peak increase of Fos expression in Vc was observed at 4 hours and gradually decreased to baseline at POD 7; while the increased Iba-1 level reached the peak at POD 1 and gradually decreased to baseline at POD 7. Furthermore, pre-treatment with DSS significantly attenuated the ETM induced directed face grooming and VCM as well as the Fos and Iba-1 levels at POD 1.

CONCLUSIONTreatment with DSS had significant analgesic effects on ETM-induced pain, which was accompanied with inhibition of both neuronal and microglial activation.

Animals ; Drugs, Chinese Herbal ; therapeutic use ; Face ; physiology ; Male ; Mastication ; physiology ; Medicine, Chinese Traditional ; methods ; Microglia ; drug effects ; physiology ; Neurons ; drug effects ; physiology ; Pain ; drug therapy ; Pain Management ; methods ; Postoperative Period ; Rats ; Rats, Sprague-Dawley ; Tooth Movement Techniques ; adverse effects

Chronic neuroinflammation is an integral pathological feature of major neurodegenerative diseases. The recruitment of microglia to affected brain regions and the activation of these cells are the major events leading to disease-associated neuroinflammation. In a previous study, we showed that neuron-released alpha-synuclein can activate microglia through activating the Toll-like receptor 2 (TLR2) pathway, resulting in proinflammatory responses. However, it is not clear whether other signaling pathways are involved in the migration and activation of microglia in response to neuron-released alpha-synuclein. In the current study, we demonstrated that TLR2 activation is not sufficient for all of the changes manifested by microglia in response to neuron-released alpha-synuclein. Specifically, the migration of and morphological changes in microglia, triggered by neuron-released alpha-synuclein, did not require the activation of TLR2, whereas increased proliferation and production of cytokines were strictly under the control of TLR2. Construction of a hypothetical signaling network using computational tools and experimental validation with various peptide inhibitors showed that beta1-integrin was necessary for both the morphological changes and the migration. However, neither proliferation nor cytokine production by microglia was dependent on the activation of beta1-integrin. These results suggest that beta1-integrin signaling is specifically responsible for the recruitment of microglia to the disease-affected brain regions, where neurons most likely release relatively high levels of alpha-synuclein.
Animals ; Antigens, CD29/genetics/*metabolism ; Cell Line, Tumor ; *Cell Movement ; Cells, Cultured ; Culture Media, Conditioned/*pharmacology ; Gene Regulatory Networks ; Humans ; Mice ; Mice, Inbred C57BL ; Microglia/drug effects/metabolism/*physiology ; Neurons/*metabolism ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Toll-Like Receptor 2/metabolism ; alpha-Synuclein/*pharmacology

PURPOSE: Lamotrigine, a novel anticonvulsant, is a sodium channel blocker that is efficacious in certain forms of neuropathic pain. Recently, microglial and astrocytic activation has been implicated in the development of nerve injury-induced neuropathic pain. We have assessed the effects of continuous intrathecal administration of lamotrigine on the development of neuropathic pain and glial activation induced by L5/6 spinal-nerve ligation in rats. MATERIALS AND METHODS: Following left L5/6 spinal nerve ligation (SNL), Sprague-Dawley male rats were intrathecally administered lamotrigine (24, 72, or 240 microg/day) or saline continuously for 7 days. Mechanical allodynia of the left hind paw to von Frey filament stimuli was determined before surgery (baseline) and once daily for 7 days postoperatively. On day 7, spinal activation of microglia and astrocytes was evaluated immunohistochemically, using antibodies to the microglial marker OX-42 and the astrocyte marker glial fibrillary acidic protein (GFAP). RESULTS: Spinal-nerve ligation induced mechanical allodynia in saline-treated rats, with OX-42 and GFAP immunoreactivity being significantly increased on the ipsilateral side of the spinal cord. Continuously administered intrathecal lamotrigine (240 microg/day) prevented the development of mechanical allodynia, and lower dose of lamotrigine (72 microg/day) ameliorated allodynia. Intrathecal lamotrigine (72 and 240 microg/day) inhibited nerve ligation-induced microglial and astrocytic activation, as evidenced by reduced numbers of cells positive for OX-42 and GFAP. CONCLUSION: Continuously administered intrathecal lamotrigine blocked the development of mechanical allodynia induced by SNL with suppression of microglial and astrocytic activation. Continuous intrathecal administration of lamotrigine may be a promising therapeutic intervention to prevent neuropathy.
Animals ; Astrocytes/drug effects/*physiology ; Disease Models, Animal ; Hyperalgesia/*drug therapy ; Infusions, Spinal ; Ligation ; Male ; Microglia/drug effects/*physiology ; Neuralgia/drug therapy ; Rats ; Rats, Sprague-Dawley ; Spinal Nerves/*injuries ; Triazines/administration & dosage/*therapeutic use ; Voltage-Gated Sodium Channel Blockers/administration & dosage/*therapeutic use

Microglia are the principal immune effectors in brain and participate in a series ofneurodegenerative diseases. The microglial shapes are highly plastic. The morphology is closely related with their activation status and biological functions. Cerebral ischemia could induce microglial activation, and microglial activation is subjected to precise regulation. Microglia could play either protective or neurotoxic roles in cerebral ischemia. Therefore, regulating the expression of receptors or protein molecules on microglia, inhibiting the excessive activation of microglia and production of pro-inflammatory factors, promoting the release of neuroprotective substances might be beneficial to the treatment of cerebral ischemia. The study about relationship between microglia and cerebral ischemia will shed a light on the treatment of cerebral ischemia. This paper is a review of microglial activation and regulation during cerebral ischemia as well as related therapeutic methods.
Animals ; Brain Ischemia ; metabolism ; pathology ; Class Ib Phosphatidylinositol 3-Kinase ; metabolism ; Humans ; Inflammation ; metabolism ; Microglia ; cytology ; drug effects ; metabolism ; physiology ; Neuroprotective Agents ; pharmacology ; Nitric Oxide Synthase ; metabolism ; Receptors, Purinergic P2X7 ; metabolism ; Regeneration ; TNF-Related Apoptosis-Inducing Ligand ; metabolism ; Toll-Like Receptors ; metabolism

OBJECTIVETo observe the effect of normobaric hyperoxia exposure on the functions of N9 microglia and explore the underlying mechanism of hyperoxia-induced immature brain injury.

METHODSN9 microglial cells were exposed to 900 ml/L O(2) for 2, 6, 12, 24 or 48 h, and the cell apoptotic rate was assessed using flow cytometry. The intracellular oxidative stress was measured using a fluorescent DCFH-DA probe, and the expression of Toll-like receptor 4 (TLR4) mRNA was detected using RT-PCR. Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations in the supernatant of the cell cultures were tested with ELISA following the exposures. TLR4 protein expression was observed using immunofluorescence staining.

RESULTSSignificant cell apoptosis was detected after oxygen exposures for 12-24 h. Accumulation of reactive oxygen species (ROS) were detected after a 2-h exposure. After prolonged hyperoxia exposure, TLR4 expression and IL-1β and TNF-α levels significantly increased in the cells.

CONCLUSIONHyperoxia exposure activates TLR4 signaling pathway in N9 microglial cells in vitro, leading to massive production of ROS, IL-1β, and TNF-α and thus triggering cell apoptosis.

Animals ; Apoptosis ; drug effects ; Cell Hypoxia ; Cells, Cultured ; Interleukin-1beta ; metabolism ; Mice ; Mice, Inbred ICR ; Microglia ; cytology ; drug effects ; physiology ; Oxygen ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Reactive Oxygen Species ; metabolism ; Toll-Like Receptor 4 ; genetics ; metabolism

The immunocytes microglia in the central nervous system (CNS) were reported to play a crucial role in neurodegeneration. As a member of P2 receptors family, purinoceptor P2Y6 has attracted much attention recently. Previous studies showed that purinoceptor P2Y6 mainly contributed to microglia activation and their later phagocytosis in CNS, while in immune system, it participated in the secretion of interleukin (IL)-8 from monocytes and macrocytes. So there raises a question: whether purinoceptor P2Y6 also takes part in neuroinflammation? Thus, this review mainly concerns about the properties and roles of purinoceptor P2Y6, including (1) structure of purinoceptor P2Y6; (2) distribution and properties of purinoceptor P2Y6; (3) relationships between purinoceptor P2Y6 and microglia; (4) relationships between purinoceptor P2Y6 and immunoinflammation. Itos proposed that purinoceptor P2Y6 may play a role in neuroinflammation in CNS, although further research is still required.
Animals ; Humans ; Inflammation ; immunology ; metabolism ; Microglia ; drug effects ; metabolism ; Monocytes ; metabolism ; Phagocytosis ; physiology ; Receptors, Purinergic P2 ; chemistry ; genetics ; metabolism

OBJECTIVENeuroinflammation with microglial activation has been implicated to have a strong association with the progressive dopaminergic neuronal loss in Parkinson's disease (PD). The present study was undertaken to evaluate the activation profile of microglia in 1-methyl-4-phenyl pyridinium (MPP+)-induced hemiparkinsonian rats. Triptolide, a potent immunosuppressant and microglia inhibitor, was then examined for its efficacy in protecting dopaminergic neurons from injury and ameliorating behavioral disabilities induced by MPP+.

METHODSThe rat model of PD was established by intranigral microinjection of MPP+. At baseline and on day 1, 3, 7, 14, 21 following MPP+ injection, the degree of microglial activation was examined by detecting the immunodensity of OX-42 (microglia marker) in the substantia nigra (SN). The number of viable dopaminergic neurons was determined by measuring tyrosine hydroxylase (TH) positive neurons in the SN. Behavioral performances were evaluated by counting the number of rotations induced by apomorphine, calculating scores of forelimb akinesia and vibrissae-elicited forelimb placing asymmetry.

RESULTSIntranigral injection of MPP+ resulted in robust activation of microglia, progressive depletion of dopaminergic neurons, and ongoing aggravation of behavioral disabilities in rats. Triptolide significantly inhibited microglial activation, partially prevented dopaminergic cells from death and improved behavioral performances.

CONCLUSIONThese data demonstrated for the first time a neuroprotective effect of triptolide on dopaminergic neurons in MPP+-induced hemiparkinsonian rats. The protective effect of triptolide may, at least partially, be related to the inhibition of MPP+-induced microglial activation. Our results lend strong support to the use of immunosuppressive agents in the management of PD.

1-Methyl-4-phenylpyridinium ; antagonists & inhibitors ; toxicity ; Animals ; Biomarkers ; metabolism ; CD11b Antigen ; analysis ; metabolism ; Cell Count ; Cell Survival ; drug effects ; physiology ; Disability Evaluation ; Diterpenes ; pharmacology ; therapeutic use ; Dopamine ; metabolism ; Encephalitis ; drug therapy ; immunology ; prevention & control ; Epoxy Compounds ; pharmacology ; therapeutic use ; Gliosis ; drug therapy ; immunology ; prevention & control ; Herbicides ; antagonists & inhibitors ; toxicity ; Immunosuppression ; methods ; Immunosuppressive Agents ; pharmacology ; therapeutic use ; Male ; Microglia ; drug effects ; immunology ; Neurons ; drug effects ; immunology ; pathology ; Parkinsonian Disorders ; drug therapy ; immunology ; physiopathology ; Phenanthrenes ; pharmacology ; therapeutic use ; Rats ; Rats, Sprague-Dawley ; Substantia Nigra ; drug effects ; immunology ; physiopathology ; Treatment Outcome ; Tyrosine 3-Monooxygenase ; analysis ; metabolism