ABSTRACT
BACKGROUND: Despite the high prevalence of neuropathic pain, treating this neurological disease remains challenging, given the limited efficacy and numerous side effects associated with current therapies. The complexity in patient management is largely attributed to an incomplete understanding of the underlying pathological mechanisms. Central sensitization, that refers to the adaptation of the central nervous system to persistent inflammation and heightened excitatory transmission within pain pathways, stands as a significant contributor to persistent pain. Considering the role of the cystine/glutamate exchanger (also designated as system xc-) in modulating glutamate transmission and in supporting neuroinflammatory responses, we investigated the contribution of this exchanger in the development of neuropathic pain. METHODS: We examined the implication of system xc- by evaluating changes in the expression/activity of this exchanger in the dorsal spinal cord of mice after unilateral partial sciatic nerve ligation. In this surgical model of neuropathic pain, we also examined the consequence of the genetic suppression of system xc- (using mice lacking the system xc- specific subunit xCT) or its pharmacological manipulation (using the pharmacological inhibitor sulfasalazine) on the pain-associated behavioral responses. Finally, we assessed the glial activation and the inflammatory response in the spinal cord by measuring mRNA and protein levels of GFAP and selected M1 and M2 microglial markers. RESULTS: The sciatic nerve lesion was found to upregulate system xc- at the spinal level. The genetic deletion of xCT attenuated both the amplitude and the duration of the pain sensitization after nerve surgery, as evidenced by reduced responses to mechanical and thermal stimuli, and this was accompanied by reduced glial activation. Consistently, pharmacological inhibition of system xc- had an analgesic effect in lesioned mice. CONCLUSION: Together, these observations provide evidence for a role of system xc- in the biochemical processes underlying central sensitization. We propose that the reduced hypersensitivity observed in the transgenic mice lacking xCT or in sulfasalazine-treated mice is mediated by a reduced gliosis in the lumbar spinal cord and/or a shift in microglial M1/M2 polarization towards an anti-inflammatory phenotype in the absence of system xc-. These findings suggest that drugs targeting system xc- could contribute to prevent or reduce neuropathic pain.
Subject(s)
Amino Acid Transport System y+ , Neuralgia , Neuroinflammatory Diseases , Animals , Female , Mice , Amino Acid Transport System y+/antagonists & inhibitors , Amino Acid Transport System y+/deficiency , Amino Acid Transport System y+/genetics , Amino Acid Transport System y+/metabolism , Biomarkers/metabolism , Glial Fibrillary Acidic Protein/genetics , Glial Fibrillary Acidic Protein/metabolism , Gliosis/complications , Gliosis/drug therapy , Gliosis/physiopathology , Glutamic Acid/metabolism , Hyperalgesia/drug therapy , Mice, Transgenic , Microglia/drug effects , Microglia/metabolism , Microglia/pathology , Neuralgia/complications , Neuralgia/drug therapy , Neuralgia/physiopathology , Neuralgia/prevention & control , Neuroinflammatory Diseases/complications , Neuroinflammatory Diseases/drug therapy , Neuroinflammatory Diseases/physiopathology , Neuroinflammatory Diseases/prevention & control , Phenotype , Reproducibility of Results , RNA, Messenger/drug effects , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sciatic Neuropathy/complications , Sciatic Neuropathy/physiopathology , Spinal Cord/drug effects , Spinal Cord/pathology , Spinal Cord/physiopathology , Sulfasalazine/pharmacology , Sulfasalazine/therapeutic useABSTRACT
Although numerous studies have acknowledged disparities in epilepsy-related disease processes between young and aged animals, little is known about how epilepsy changes from young adulthood to middle age. This study investigates the impact of aging on 6-Hz corneal kindling in young-adult mice and middle-aged mice. We found that the kindling acquisition of the 6-Hz corneal kindling model was delayed in middle-aged mice when compared to young-adult mice. While the seizure stage and incidence of generalized seizures (GS) were similar between the two age groups, the duration of GS in the kindled middle-aged mice was shorter than that in the kindled young-adult mice. Besides, all kindled mice, regardless of age, were resistant to phenytoin sodium (PHT), valproate sodium (VPA), and lamotrigine (LGT), whereas middle-aged mice exhibited higher levetiracetam (LEV) resistance compared to young-adult mice. Both age groups of kindled mice displayed hyperactivity and impaired memory, which are common behavioral characteristics associated with epilepsy. Furthermore, middle-aged mice displayed more pronounced astrogliosis in the hippocampus. Additionally, the expression of Brain-Derived Neurotrophic Factor (BDNF) was lower in middle-aged mice than in young-adult mice prior to kindling. These data demonstrate that both the acquisition and expression of 6-Hz corneal kindling are attenuated in middle-aged mice, while hippocampal astrogliosis and pharmacological resistance are more pronounced in this age group. These results underscore the importance of considering age-related factors when utilizing the 6-Hz corneal kindling model in mice of varying age groups.
Subject(s)
Aging , Brain-Derived Neurotrophic Factor , Cornea , Disease Models, Animal , Hippocampus , Kindling, Neurologic , Animals , Kindling, Neurologic/physiology , Kindling, Neurologic/drug effects , Male , Cornea/pathology , Cornea/physiopathology , Aging/physiology , Mice , Hippocampus/physiopathology , Hippocampus/metabolism , Brain-Derived Neurotrophic Factor/metabolism , Anticonvulsants/pharmacology , Anticonvulsants/therapeutic use , Seizures/physiopathology , Mice, Inbred C57BL , Gliosis/pathology , Gliosis/physiopathologyABSTRACT
For Alzheimer's disease (AD), aging is the main risk factor, but whether cognitive impairments due to aging resemble early AD deficits is not yet defined. When working with mouse models of AD, the situation is just as complicated, because only a few studies track the progression of the disease at different ages, and most ignore how the aging process affects control mice. In this work, we addressed this problem by comparing the aging process of PS2APP (AD) and wild-type (WT) mice at the level of spontaneous brain electrical activity under anesthesia. Using local field potential recordings, obtained with a linear probe that traverses the posterior parietal cortex and the entire hippocampus, we analyzed how multiple electrical parameters are modified by aging in AD and WT mice. With this approach, we highlighted AD specific features that appear in young AD mice prior to plaque deposition or that are delayed at 12 and 16 months of age. Furthermore, we identified aging characteristics present in WT mice but also occurring prematurely in young AD mice. In short, we found that reduction in the relative power of slow oscillations (SO) and Low/High power imbalance are linked to an AD phenotype at its onset. The loss of SO connectivity and cortico-hippocampal coupling between SO and higher frequencies as well as the increase in UP-state and burst durations are found in young AD and old WT mice. We show evidence that the aging process is accelerated by the mutant PS2 itself and discuss such changes in relation to amyloidosis and gliosis.
Subject(s)
Aging/pathology , Alzheimer Disease/pathology , Action Potentials/physiology , Alzheimer Disease/complications , Alzheimer Disease/physiopathology , Amyloidosis/complications , Amyloidosis/pathology , Amyloidosis/physiopathology , Animals , Delta Rhythm/physiology , Disease Progression , Gliosis/complications , Gliosis/pathology , Gliosis/physiopathology , Hippocampus/pathology , Mice, Inbred C57BL , Nerve Net/physiopathology , Plaque, Amyloid/complications , Plaque, Amyloid/pathology , Plaque, Amyloid/physiopathologyABSTRACT
Ischemia injury can cause cell death or impairment of neuron and astrocytes, and thus induce loss of nerve function. central nervous systems injury induces an aberrant activation of astrocytes called astrogliosis. Pyroptosis, which is a kind of programmed cell death, was proved play an important role in ischemia injury. Zinc Finger E-Box Binding Homeobox 2 (ZEB2) promoted neuron astrogliosis, which play a protected role in neuron regeneration. However, its precise mechanism remains unclear. This study investigated the mechanism of ZEB2 on astrogliosis and neuron regeneration after cerebral ischemia reperfusion condition. To confirm our hypothesis, Neurons and astrocytes were isolated from fetal Sprague Dawley rats, in vivo Middle Cerebral Artery Occlusion/reperfusion (MCAO/R) rat model and in vitro oxygen-glucose deprivation/reperfusion (OGD/R)-treated astrocytes and neurocytes model were constructed. Our results showed that ZEB2 was expressed in nucleus of astrocyte and upregulated after OGD/R induction, ZEB2 promoted astrogliosis. Further upregulation of ZEB2 promoted the astrogliosis, which promoted neuron proliferation and regeneration by decreased pyroptosis. Moreover, this finding was further confirmed in vivo MCAO/R rat model. Overexpression of ZEB2 promoted astrogliosis, which decreased infarct volume and accumulated recovery of neurological function by alleviated pyroptosis. This finding revealed that ZEB2 was a regulator of the astrogliosis after ischemia/reperfusion injury, and then astrogliosis promoted neuron regeneration via decreased neuron pyroptosis. Therefore, ZEB2 may be a potential therapeutic target for ischemia/reperfusion injury.
Subject(s)
Brain Ischemia/pathology , Gliosis/metabolism , Gliosis/pathology , Neuroprotection , Pyroptosis , Reperfusion Injury/pathology , Zinc Finger E-box Binding Homeobox 2/metabolism , Animals , Astrocytes/metabolism , Astrocytes/pathology , Brain/pathology , Brain/physiopathology , Brain Ischemia/complications , Brain Ischemia/metabolism , Brain Ischemia/physiopathology , Gliosis/complications , Gliosis/physiopathology , Glucose/deficiency , Nerve Regeneration , Oxygen , Rats, Sprague-Dawley , Reperfusion Injury/complications , Reperfusion Injury/metabolism , Reperfusion Injury/physiopathologyABSTRACT
BACKGROUND: Following stroke, changes in neuronal connectivity in tissue surrounding the infarct play an important role in both spontaneous recovery of neurological function and in treatment-induced improvements in function. Microglia and astrocytes influence this process through direct interactions with the neurons and as major determinants of the local tissue environment. Subpopulations of peri-infarct glia proliferate early after stroke providing a possible target to modify recovery. Treatment with cell cycle inhibitors can reduce infarct volume and improve functional recovery. However, it is not known whether these inhibitors can influence neurological function or alter the responses of peri-infarct glia without reducing infarction. The present study aimed to address these issues by testing the effects of the cell cycle inhibitor, olomoucine, on recovery and peri-infarct changes following photothrombotic stroke. METHODS: Stroke was induced by photothrombosis in the forelimb sensorimotor cortex in Sprague-Dawley rats. Olomoucine was administered at 1 h and 24 h after stroke induction. Forelimb function was monitored up to 29 days. The effects of olomoucine on glial cell responses in peri-infarct tissue were evaluated using immunohistochemistry and Western blotting. RESULTS: Olomoucine treatment did not significantly affect maximal infarct volume. Recovery of the affected forelimb on a placing test was impaired in olomoucine-treated rats, whereas recovery in a skilled reaching test was substantially improved. Olomoucine treatment produced small changes in aspects of Iba1 immunolabelling and in the number of CD68-positive cells in cerebral cortex but did not selectively modify responses in peri-infarct tissue. The content of the astrocytic protein, vimentin, was reduced by 30% in the region of the lesion in olomoucine-treated rats. CONCLUSIONS: Olomoucine treatment modified functional recovery in the absence of significant changes in infarct volume. The effects on recovery were markedly test dependent, adding to evidence that skilled tasks requiring specific training and general measures of motor function can be differentially modified by some interventions. The altered recovery was not associated with specific changes in key responses of peri-infarct microglia, even though these cells were considered a likely target for early olomoucine treatment. Changes detected in peri-infarct reactive astrogliosis could contribute to the altered patterns of functional recovery.
Subject(s)
Astrocytes/drug effects , Kinetin/pharmacology , Microglia/drug effects , Motor Cortex/drug effects , Recovery of Function/drug effects , Stroke/physiopathology , Animals , Cell Cycle/drug effects , Disease Models, Animal , Gliosis/pathology , Gliosis/physiopathology , Male , Microglia/pathology , Motor Cortex/pathology , Motor Cortex/physiopathology , Neurons/drug effects , Neurons/pathology , Rats , Rats, Sprague-Dawley , Stroke/pathologyABSTRACT
Several preclinical and clinical studies have attempted to elucidate the pathophysiological mechanism associated with spinal cord injury. However, investigations have been unable to define the precise related mechanisms, and this has led to the lack of effective therapeutic agents for the condition. Neuroinflammation is one of the predominant processes that hinder spinal cord injury recovery. Resveratrol is a compound that has several biological features, such as antioxidation, antibacterial, and antiinflammation. Herein, we reviewed preclinical and clinical studies to delineate the role of toll-like receptors, nod-like receptors, and astrocytes in neuroinflammation. In particular, the alteration of astrocytes in SCI causes glial scar formation that impedes spinal cord injury recovery. Therefore, to improve injury recovery would be to prevent the occurrence of this process. Resveratrol is safe and effective in the significant modulation of neuroinflammatory factors, particularly those mediated by astrocytes. Thus, its potential ability to enhance the injury recovery process and ameliorate spinal cord injury.
Subject(s)
Astrocytes/drug effects , Gliosis/prevention & control , Neuroinflammatory Diseases/prevention & control , Resveratrol/therapeutic use , Spinal Cord Injuries/drug therapy , Animals , Gliosis/physiopathology , Inflammasomes/metabolism , Models, Immunological , NF-kappa B/metabolism , NLR Proteins/physiology , Nerve Tissue Proteins/physiology , Neuroinflammatory Diseases/etiology , Neuroinflammatory Diseases/physiopathology , Recovery of Function/drug effects , Recovery of Function/physiology , Resveratrol/pharmacology , Toll-Like Receptors/physiologyABSTRACT
BACKGROUND: Chronic pain is a major issue affecting more than 50% of the older population and up to 80% of nursing homes residents. Research on pain in the elderly focuses mainly on the development of clinical tools to assess pain in patients with dementia and cognitive impairment or on the efficacy and tolerability of medications. In this review, we searched for evidence of specific pain mechanisms or modifications in pain signals processing either at the cellular level or in the central nervous system. METHODS: Narrative review. RESULTS: Investigation on pain sensitivity led to conflicting results, with some studies indicating a modest decrease in age-related pain sensitivity, while other researchers found a reduced pain threshold for pressure stimuli. Areas of the brain involved in pain perception and analgesia are susceptible to pathological changes such as gliosis and neuronal death and the effectiveness of descending pain inhibitory mechanisms, particularly their endogenous opioid component, also appears to deteriorate with advancing age. Hyperalgesia is more common at older age and recovery from peripheral nerve injury appears to be delayed. In addition, peripheral nociceptors may contribute minimally to pain sensation at either acute or chronic time points in aged populations. CONCLUSIONS: Elderly subjects appear to be more susceptible to prolonged pain development, and medications acting on peripheral sensitization are less efficient. Pathologic changes in the central nervous system are responsible for different pain processing and response to treatment. Specific guidelines focusing on specific pathophysiological changes in the elderly are needed to ensure adequate treatment of chronic pain conditions.
Subject(s)
Aging , Chronic Pain/diagnosis , Chronic Pain/therapy , Geriatrics , Pain Threshold , Adult , Age Factors , Aged , Aged, 80 and over , Brain/physiopathology , Central Nervous System/physiopathology , Gliosis/physiopathology , Humans , Hyperalgesia , Middle Aged , Neurons/metabolism , Pain Management , Pain Measurement , Perception , Peripheral Nervous System/physiopathology , Pressure , Spinal Cord/physiopathology , Young AdultABSTRACT
Amyotrophic lateral sclerosis (ALS) is an intractable neurodegenerative disease. CD68-positive bone marrow (BM)-derived cells (BMDCs) accumulate in the pathological lesion in the SOD1(G93A) ALS mouse model after BM transplantation (BMT). Therefore, we investigated whether BMDCs can be applied as gene carriers for cell-based gene therapy by employing the accumulation of BMDCs. In ALS mice, YFP reporter signals were observed in 12-14% of white blood cells (WBCs) and in the spinal cord via transplantation of BM after lentiviral vector (LV) infection. After confirmation of gene transduction by LV with the CD68 promoter in 4-7% of WBCs and in the spinal cord of ALS mice, BM cells were infected with LVs expressing glutamate transporter (GLT) 1 that protects neurons from glutamate toxicity, driven by the CD68 promoter, which were transplanted into ALS mice. The treated mice showed improvement of motor behaviors and prolonged survival. Additionally, interleukin (IL)-1ß was significantly suppressed, and IL-4, arginase 1, and FIZZ were significantly increased in the mice. These results suggested that GLT1 expression by BMDCs improved the spinal cord environment. Therefore, our gene therapy strategy may be applied to treat neurodegenerative diseases such as ALS in which BMDCs accumulate in the pathological lesion by BMT.
Subject(s)
Amyotrophic Lateral Sclerosis/physiopathology , Bone Marrow Cells/metabolism , Excitatory Amino Acid Transporter 2/genetics , Gene Transfer Techniques , Motor Activity/physiology , Amyotrophic Lateral Sclerosis/complications , Animals , Biomarkers/metabolism , Bone Marrow Transplantation , Cell Survival , Cytokines/genetics , Cytokines/metabolism , Disease Models, Animal , Disease Progression , Gene Expression Regulation , Genetic Therapy , Gliosis/complications , Gliosis/pathology , Gliosis/physiopathology , Glutamic Acid/metabolism , Lentivirus/metabolism , Mice, Inbred C57BL , Mice, Transgenic , Microglia/metabolism , Motor Neurons/metabolism , Muscular Atrophy/complications , Muscular Atrophy/pathology , Muscular Atrophy/physiopathology , Nerve Degeneration/complications , Nerve Degeneration/pathology , Nerve Degeneration/physiopathology , RNA, Messenger/genetics , RNA, Messenger/metabolism , Spinal Cord/metabolism , Superoxide Dismutase-1/metabolism , Survival AnalysisABSTRACT
Methotrexate (MTX), an antifolate drug, is widely used in chemotherapeutic protocols for metastatic and primary brain tumors and some autoimmune diseases. Its efficacy for brain tumors is limited by the high incidence of central nervous system (CNS) complications. This investigation aimed to observe the morphological effects, including astroglial and microglial responses, following systemic short-term MTX administration in adult rats. Male Wistar rats received 5 or 10 mg/kg/day of MTX by intraperitoneal route for 4 consecutive days (respectively, MTX5 and MTX10 groups) or the same volume of 0.9% saline solution (control group). On the 5th day, brain samples were collected for hematoxylin-eosin and luxol fast blue staining techniques, as well as for immunohistochemical staining for glial fibrillary acidic protein (GFAP) expression in astrocytes and Iba1 (ionized calcium binding adaptor molecule 1) for microglia in the frontal cortex, hippocampus, hypothalamus and molecular/granular layers of the cerebellum. Morphometric analyses were performed using Image Pro-Plus software. Brain levels of the proinflammatory cytokines TNF-α and IL-1ß were determined by ELISA. No signs of neuronal loss or demyelination were observed in all groups. Increased GFAP and Iba1 expression was found in all areas from the MTX groups, although it was slightly higher in the MTX10 group compared to the MTX5. Both TNF-α and IL-1ß levels were decreased in the MTX5 group compared to controls. In the MTX10 group, TNF-α decreased, although IL-1ß was increased relative to controls. MTX administration induced microglial reaction and astrogliosis in several CNS areas. In the MTX5 group, it apparently occurred in the presence of decreased proinflammatory cytokines.
Subject(s)
Antimetabolites, Antineoplastic/administration & dosage , Astrocytes/drug effects , Calcium-Binding Proteins/metabolism , Glial Fibrillary Acidic Protein/metabolism , Gliosis/physiopathology , Methotrexate/administration & dosage , Microfilament Proteins/metabolism , Microglia/drug effects , Animals , Astrocytes/metabolism , Astrocytes/pathology , Dose-Response Relationship, Drug , Gliosis/chemically induced , Gliosis/pathology , Male , Microglia/metabolism , Microglia/pathology , Rats , Rats, WistarABSTRACT
Microglia activation following peripheral nerve injury has been shown to contribute to central sensitization of the spinal cord for the development of neuropathic pain. In a recent study, we reported that the amount of nerve damage does not necessarily correlate with chronic pain development. Here we compared the response of spinal microglia, using immunohistochemistry as a surrogate of microglial activation, in mice with two different types of crush injury of the sciatic nerve. We confirmed that incomplete crush of the sciatic nerve (partial crush injury, PCI) resulted in tactile hypersensitivity after the recovery of sensory function (15 days after surgery), whereas the hypersensitivity was not observed after the complete crush (full crush injury, FCI). We observed that immunoreactivity for Iba-1, a microglial marker, was greater in the ipsilateral dorsal horn of lumbar (L4) spinal cord of mice 2 days after FCI compared to PCI, positively correlating with the intensity of crush injury. Ipsilateral Iba-1 reactivity was comparable between injuries at 7 days with a significant increase compared to the contralateral side. By day 15 after injury, ipsilateral Iba-1 immunoreactivity was much reduced compared to day 7 and was not different between the groups. Our results suggest that the magnitude of the early microgliosis is dependent on injury severity, but does not necessarily correlate with the long-term development of chronic pain-like hypersensitivity after peripheral nerve injury.
Subject(s)
Gliosis/physiopathology , Hyperalgesia/physiopathology , Microglia/physiology , Neuralgia/physiopathology , Peripheral Nerve Injuries/physiopathology , Sciatic Nerve/injuries , Spinal Cord/physiopathology , Animals , Gliosis/complications , Hyperalgesia/etiology , Mice , Nerve Crush , Neuralgia/etiology , Peripheral Nerve Injuries/complications , Sciatic Nerve/physiopathologyABSTRACT
Traumatic brain injury (TBI) is often associated with sustained attention and memory deficits. As persisting neuroinflammation and neurodegeneration may contribute to posttraumatic psychomotor dysfunction, we studied the relationship of brain cellular reactions three months after a weight-drop closed head injury in male mice with posttraumatic learning and memory using automated home-cage monitoring of socially housed mice in IntelliCages as well as tests for locomotor activity, anxiety and forepaw fine motor skills. One month after TBI, deficits in place learning and cognitive flexibility in reverse learning were clearly detectable in IntelliCages and these memory deficits correlated with the initial trauma severity on the functional neuroscore. While sucrose preference or its extinction were not influenced by TBI, traumatized mice performed significantly worse in a complex episodic memory learning task. In consecutive locomotor and forepaw skilled use tests, posttraumatic hyperactivity and impairment of contralateral paw use were evident. Analysis of cellular reactions to TBI three months after injury in selected defined regions of interest in the immediate lesion, ipsi- and contralateral frontoparietal cortex and hippocampus revealed a persistent microgliosis and astrogliosis which were accompanied by iron-containing macrophages and myelin degradation in the lesion area as well as with axonal damage in the neighboring cortical regions. Microglial and astroglial reactions in cortex showed a positive correlation with the initial trauma severity and a negative correlation with the spatial and episodic memory indicating a role of brain inflammatory reactions in posttraumatic memory deficits.
Subject(s)
Brain Injuries, Traumatic/pathology , Brain Injuries, Traumatic/physiopathology , Gliosis/pathology , Gliosis/physiopathology , Severity of Illness Index , Spatial Learning/physiology , Animals , Brain Injuries, Traumatic/complications , Gliosis/etiology , Locomotion/physiology , Male , Maze Learning/physiology , Mice , Mice, Inbred C57BLABSTRACT
Reactive astrogliosis is characterized by a profound change in astrocyte phenotype in response to all CNS injuries. Here, we present a revised in situ hybridization and immunohistochemistry (IHC) protocol to label the reactive astrocytes in the mouse brain. Several approaches for quantifying astrocyte reactivity lacked sensitivity to discriminate across the spectrum. We optimized in situ hybridization followed by IHC. We provide a staining protocol for quantitative measures of astrocyte reactivity as an independent confirmation of the magnitude of reactive gliosis. For complete details on the use and execution of this protocol, please refer to Muraleedharan et al. (2020).
Subject(s)
Gliosis/diagnostic imaging , Immunohistochemistry/methods , In Situ Hybridization/methods , Animals , Astrocytes/metabolism , Brain/metabolism , Brain/physiology , Cells, Cultured , Central Nervous System/metabolism , Gliosis/metabolism , Gliosis/physiopathology , Inflammation , Mice , Neurons/metabolismABSTRACT
Huntington's disease (HD) is an inherited neurodegenerative disorder caused by an abnormal CAG repeat expansion in the huntingtin gene coding for a protein with an elongated polyglutamine sequence. HD patients present choreiform movements, which are caused by the loss of neurons in the striatum and cerebral cortex. Previous reports indicate that the absence of the aryl hydrocarbon receptor (AhR) protects mice from excitotoxic insults and increases the transcription of neurotrophic factors. Based on these data, we evaluated the effects of the lack of the AhR on a mice model of HD, generating a double transgenic mouse, expressing human mutated huntingtin (R6/1 mice) and knockout for the AhR. Our results show that the body weight of 30-week-old double transgenic mice is similar to that of R6/1 mice; however, feet clasping, an indicative of neuronal damage in the R6/1 animals, was not observed. In addition, motor coordination and ambulatory behavior in double transgenic mice did not deteriorate over time as occur in the R6/1 mice. Moreover, the anxiety behavior of double transgenic mice was similar to wild type mice. Interestingly, astrogliosis is also reduced in the double transgenic mice. The present data demonstrate that the complete loss of the AhR reduces the motor and behavioral deterioration observed in R6/1 mice, suggesting that the pharmacological modulation of the AhR could be a therapeutic target in HD.
Subject(s)
Behavior, Animal/physiology , Gliosis/physiopathology , Huntingtin Protein/genetics , Huntington Disease/metabolism , Huntington Disease/physiopathology , Motor Activity/physiology , Receptors, Aryl Hydrocarbon/physiology , Animals , Disease Models, Animal , Huntington Disease/genetics , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , PhenotypeABSTRACT
Lafora disease (LD; OMIM#274780) is a fatal rare neurodegenerative disorder characterized by generalized epileptic seizures and the presence of polyglucosan inclusions (PGs), called Lafora bodies (LBs), typically in the brain. LD is caused by mutations in two genes EPM2A or EPM2B, which encode respectively laforin, a glucan phosphatase, and malin, an E3-ubiquitin ligase. Much remains unknown about the molecular bases of LD and, unfortunately, appropriate treatment is still missing; therefore patients die within 10 years from the onset of the disease. Recently, we have identified neuroinflammation as one of the initial determinants in LD. In this work, we have investigated anti-inflammatory treatments as potential therapies in LD. With this aim, we have performed a preclinical study in an Epm2b-/- mouse model with propranolol, a ß-adrenergic antagonist, and epigallocatechin gallate (EGCG), an antioxidant from green tea extract, both of which displaying additional anti-inflammatory properties. In vivo motor and cognitive behavioral tests and ex vivo histopathological brain analyses were used as parameters to assess the therapeutic potential of propranolol and EGCG. After 2 months of treatment, we observed an improvement not only in attention defects but also in neuronal disorganization, astrogliosis, and microgliosis present in the hippocampus of Epm2b-/- mice. In general, propranolol intervention was more effective than EGCG in preventing the appearance of astrocyte and microglia reactivity. In summary, our results confirm the potential therapeutic effectiveness of the modulators of inflammation as novel treatments in Lafora disease.
Subject(s)
Brain/pathology , Inflammation/pathology , Lafora Disease/pathology , Animals , Biomarkers/metabolism , Brain/drug effects , Brain/physiopathology , Catechin/analogs & derivatives , Catechin/pharmacology , Disease Models, Animal , Gliosis/complications , Gliosis/pathology , Gliosis/physiopathology , Glucans/pharmacology , Hippocampus/drug effects , Hippocampus/metabolism , Hippocampus/pathology , Hippocampus/physiopathology , Inclusion Bodies/drug effects , Inclusion Bodies/metabolism , Inflammation/complications , Inflammation/physiopathology , Lafora Disease/complications , Lafora Disease/physiopathology , Mice, Inbred C57BL , Mice, Knockout , Microglia/drug effects , Microglia/metabolism , Microglia/pathology , Motor Activity , Nerve Degeneration/complications , Nerve Degeneration/pathology , Nerve Degeneration/physiopathology , Neurons/drug effects , Neurons/pathology , Phenotype , Propranolol/pharmacology , Ubiquitin-Protein Ligases/deficiency , Ubiquitin-Protein Ligases/metabolismABSTRACT
Aside from the classical motor symptoms, Parkinson's disease also has various non-classical symptoms. Interestingly, orexin neurons, involved in the regulation of exploratory locomotion, spontaneous physical activity, and energy expenditure, are affected in Parkinson's. In this study, we hypothesized that Parkinson's-disease-associated pathology affects orexin neurons and therefore impairs functions they regulate. To test this, we used a transgenic animal model of Parkinson's, the A53T mouse. We measured body composition, exploratory locomotion, spontaneous physical activity, and energy expenditure. Further, we assessed alpha-synuclein accumulation, inflammation, and astrogliosis. Finally, we hypothesized that chemogenetic inhibition of orexin neurons would ameliorate observed impairments in the A53T mice. We showed that aging in A53T mice was accompanied by reductions in fat mass and increases in exploratory locomotion, spontaneous physical activity, and energy expenditure. We detected the presence of alpha-synuclein accumulations in orexin neurons, increased astrogliosis, and microglial activation. Moreover, loss of inhibitory pre-synaptic terminals and a reduced number of orexin cells were observed in A53T mice. As hypothesized, this chemogenetic intervention mitigated the behavioral disturbances induced by Parkinson's disease pathology. This study implicates the involvement of orexin in early Parkinson's-disease-associated impairment of hypothalamic-regulated physiological functions and highlights the importance of orexin neurons in Parkinson's disease symptomology.
Subject(s)
Disease Models, Animal , Energy Metabolism/genetics , Motor Activity/genetics , Neurons/metabolism , Orexins/genetics , Parkinson Disease/genetics , alpha-Synuclein/genetics , Animals , Body Composition/genetics , Gliosis/genetics , Gliosis/physiopathology , Humans , Male , Mice, Inbred C57BL , Mice, Transgenic , Motor Activity/physiology , Orexins/metabolism , Parkinson Disease/metabolism , Parkinson Disease/physiopathology , alpha-Synuclein/metabolismABSTRACT
Dementia is a pathological condition characterized by a decline in memory, as well as in other cognitive and social functions. The cellular and molecular mechanisms of brain damage in dementia are not completely understood; however, neuroinflammation is involved. Evidence suggests that chronic inflammation may impair cognitive performance and that dietary protein source may differentially influence this process. Dietary protein source has previously been shown to modify systemic inflammation in mouse models. Thus, we aimed to investigate the effect of chronic dietary protein source substitution in an ageing and dementia male mouse model, the senescence-accelerated mouse-prone 8 (SAMP8) model. We observed that dietary protein source differentially modified memory as shown by inhibitory avoidance testing at 4 months of age. Also, dietary protein source differentially modified neuroinflammation and gliosis in male SAMP8 mice. Our results suggest that chronic dietary protein source substitution may influence brain ageing and memory-related mechanisms in male SAMP8 mice. Moreover, the choice of dietary protein source in mouse diets for experimental purposes may need to be carefully considered when interpreting results.
Subject(s)
Aging/pathology , Dementia/pathology , Dementia/physiopathology , Dietary Proteins/adverse effects , Encephalitis/pathology , Encephalitis/physiopathology , Memory , Animals , Astrocytes/pathology , Autophagy , Biomarkers/metabolism , Body Weight , Cognition , Dementia/complications , Disease Models, Animal , Encephalitis/complications , Feeding Behavior , Gliosis/complications , Gliosis/pathology , Gliosis/physiopathology , Male , Microglia/pathology , Nerve Growth Factor/metabolism , Neurogenesis , Oligodendroglia/pathologyABSTRACT
Astrocytes play a crucial role in neuronal firing activity. Their abnormal state may lead to the pathological transition of neuronal firing patterns and even induce seizures. However, there is still little evidence explaining how the astrocyte network modulates seizures caused by structural abnormalities, such as gliosis. To explore the role of gliosis of the astrocyte network in epileptic seizures, we first established a direct astrocyte feedback neuronal network model on the basis of the hippocampal CA3 neuron-astrocyte model to simulate the condition of gliosis when astrocyte processes swell and the feedback to neurons increases in an abnormal state. We analyzed the firing pattern transitions of the neuronal network when astrocyte feedback starts to change via increases in both astrocyte feedback intensity and the connection probability of astrocytes to neurons in the network. The results show that as the connection probability and astrocyte feedback intensity increase, neuronal firing transforms from a nonepileptic synchronous firing state to an asynchronous firing state, and when astrocyte feedback starts to become abnormal, seizure-like firing becomes more severe and synchronized; meanwhile, the synchronization area continues to expand and eventually transforms into long-term seizure-like synchronous firing. Therefore, our results prove that astrocyte feedback can regulate the firing of the neuronal network, and when the astrocyte network develops gliosis, there will be an increase in the induction rate of epileptic seizures.
Subject(s)
Action Potentials/physiology , Astrocytes/physiology , Cell Communication/physiology , Nerve Net/physiology , Neurons/physiology , Computer Simulation , Epilepsy/physiopathology , Gliosis/physiopathology , Humans , Neural Networks, ComputerABSTRACT
Progressive fetal infection/inflammation is strongly associated with neural injury after preterm birth. We aimed to test the hypotheses that progressively developing fetal inflammation leads to neuroinflammation and impaired white matter development and that the histopathological changes can be detected using high-field diffusion tensor magnetic resonance imaging (MRI). Chronically instrumented preterm fetal sheep at 0.7 of gestation were randomly assigned to receive intravenous saline (control; n = 6) or a progressive infusion of lipopolysaccharide (LPS, 200 ng intravenous over 24 h then doubled every 24 h for 5 days to induce fetal inflammation, n = 7). Sheep were killed 10 days after starting the infusions, for histology and high-field diffusion tensor MRI. Progressive LPS infusion was associated with increased circulating interleukin (IL)-6 concentrations and moderate increases in carotid artery perfusion and the frequency of electroencephalogram (EEG) activity (p < 0.05 vs. control). In the periventricular white matter, fractional anisotropy (FA) was increased, and orientation dispersion index (ODI) was reduced (p < 0.05 vs. control for both). Histologically, in the same brain region, LPS infusion increased microglial activation and astrocyte numbers and reduced the total number of oligodendrocytes with no change in myelination or numbers of immature/mature oligodendrocytes. Numbers of astrocytes in the periventricular white matter were correlated with increased FA and reduced ODI signal intensities. Astrocyte coherence was associated with increased FA. Moderate astrogliosis, but not loss of total oligodendrocytes, after progressive fetal inflammation can be detected with high-field diffusion tensor MRI.
Subject(s)
Gliosis/diagnostic imaging , Inflammation/diagnostic imaging , Leukoencephalopathies/diagnostic imaging , Magnetic Resonance Imaging , Animals , Gliosis/physiopathology , Gliosis/veterinary , Inflammation/physiopathology , Inflammation/veterinary , Leukoencephalopathies/physiopathology , Leukoencephalopathies/veterinary , Sheep , White Matter/diagnostic imaging , White Matter/physiopathologyABSTRACT
Diverse vascular diseases such as diabetic retinopathy, occlusion of retinal veins or arteries and ocular ischemic syndrome can lead to retinal ischemia. To investigate pathological mechanisms of retinal ischemia, relevant experimental models need to be developed. Anatomically, a main retinal blood supplying vessel is the ophthalmic artery (OpA) and OpA originates from the internal carotid artery of the common carotid artery (CCA). Thus, disruption of CCA could effectively cause retinal ischemia. Here, we established a mouse model of retinal ischemia by transient bilateral common carotid artery occlusion (tBCCAO) to tie the right CCA with 6-0 silk sutures and to occlude the left CCA transiently for 2 seconds via a clamp, and showed that tBCCAO could induce acute retinal ischemia leading to retinal dysfunction. The current method reduces reliance on surgical instruments by only using surgical needles and a clamp, shortens occlusion time to minimize unexpected animal death, which is often seen in mouse models of middle cerebral artery occlusion, and maintains reproducibility of common retinal ischemic findings. The model can be utilized to investigate the pathophysiology of ischemic retinopathies in mice and further can be used for in vivo drug screening.
Subject(s)
Arterial Occlusive Diseases/complications , Carotid Artery, Common/pathology , Ischemia/etiology , Retina/injuries , Animals , Arterial Occlusive Diseases/diagnostic imaging , Arterial Occlusive Diseases/physiopathology , Circle of Willis/pathology , Disease Models, Animal , Electroretinography , Gliosis/complications , Gliosis/diagnostic imaging , Gliosis/pathology , Gliosis/physiopathology , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Ischemia/diagnostic imaging , Ischemia/pathology , Ischemia/physiopathology , Male , Mice , Perfusion , Protein Stability , Reproducibility of Results , Retina/diagnostic imaging , Retina/pathology , Retina/physiopathology , Tomography, Optical CoherenceABSTRACT
Cobalamin deficiency affects human physiology with sequelae ranging from mild fatigue to severe neuropsychiatric abnormalities. The cellular and molecular aspects of the nervous system disorders associated with hypovitaminosis B12 remain largely unknown. Growing evidence indicates that astrogliosis is an underlying component of a wide range of neuropathologies. Previously, we developed an in vitro model of cobalamin deficiency in normal human astrocytes (NHA) by culturing the cells with c-lactam of hydroxycobalamin (c-lactam OH-Cbl). We revealed a non-apoptotic activation of caspases (3/7, 8, 9) in cobalamin-deficient NHA, which may suggest astrogliosis. The aim of the current study was to experimentally verify this hypothesis. We indicated an increase in the cellular expression of two astrogliosis markers: glial fibrillary acidic protein and vimentin in cobalamin-deficient NHA using Western blot analysis and immunocytochemistry with confocal laser scanning microscopy. In the next step of the study, we revealed c-lactam OH-Cbl as a potential non-toxic vitamin B12 antagonist in an in vivo model using zebrafish embryos. We believe that the presented results will contribute to a better understanding of the cellular mechanism underlying neurologic pathology due to cobalamin deficiency and will serve as a foundation for further studies.