Expression of prosaposin and its receptors in the rat cerebellum after kainic acid injection.
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ABSTRACT:
SUBMITTER: Li X
PROVIDER: S-EPMC6084904 | biostudies-literature | 2017 Jun
REPOSITORIES: biostudies-literature
Publications
Expression of prosaposin and its receptors in the rat cerebellum after kainic acid injection.
Li Xuan X Nabeka Hiroaki H Saito Shouichiro S Shimokawa Tetsuya T Khan Md Sakirul Islam MSI Yamamiya Kimiko K Shan Fengping F Gao Huiling H Li Cheng C Matsuda Seiji S
IBRO reports 20170224
Prosaposin (PSAP), a highly conserved glycoprotein, is a precursor of saposins A-D. Accumulating evidence suggests that PSAP is a neurotrophic factor that induces differentiation and prevents death in a variety of neuronal cells through the active region within the saposin C domain both <i>in vivo</i> and <i>in vitro</i>. Recently, GPR37 and GPR37L1 were recognized as PSAP receptors. In this study, we examined the alteration in expression of PSAP and its receptors in the cerebellum using rats in ...[more]
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Project description:Because excessive glutamate release is believed to play a pivotal role in numerous neuropathological disorders, such as ischemia or seizure, we aimed to investigate whether intrinsic prosaposin (PS), a neuroprotective factor when supplied exogenously in vivo or in vitro, is up-regulated after the excitotoxicity induced by kainic acid (KA), a glutamate analog. In the present study, PS immunoreactivity and its mRNA expression in the hippocampal and cortical neurons showed significant increases on day 3 after KA injection, and high PS levels were maintained even after 3 weeks. The increase in PS, but not saposins, detected by immunoblot analysis suggests that the increase in PS-like immunoreactivity after KA injection was not due to an increase in saposins as lysosomal enzymes after neuronal damage, but rather to an increase in PS as a neurotrophic factor to improve neuronal survival. Furthermore, several neurons with slender nuclei inside/outside of the pyramidal layer showed more intense PS mRNA expression than other pyramidal neurons. Based on the results from double immunostaining using anti-PS and anti-GABA antibodies, these neurons were shown to be GABAergic interneurons in the extra- and intra-pyramidal layers. In the cerebral cortex, several large neurons in the V layer showed very intense PS mRNA expression 3 days after KA injection. The choroid plexus showed intense PS mRNA expression even in the normal rat, and the intensity increased significantly after KA injection. The present study indicates that inhibitory interneurons as well as stimulated hippocampal pyramidal and cortical neurons synthesize PS for neuronal survival, and the choroid plexus is highly activated to synthesize PS, which may prevent neurons from excitotoxic neuronal damage. To the best of our knowledge, this is the first study that demonstrates axonal transport and increased production of neurotrophic factor PS after KA injection.
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Project description:Prosaposin (PS) is a secretory neurotrophic factor, as well as a regulator of lysosomal enzymes. We previously reported the up-regulation of PS and the possibility of its axonal transport by GABAergic interneurons after exocitotoxicity induced by kainic acid (KA), a glutamate analog. In the present study, we performed double immunostaining with PS and three calcium binding protein markers: parvalbumin (PV), calbindin, and calretinin, for the subpopulation of GABAergic interneurons, and clarified that the increased PS around the hippocampal pyramidal neurons after KA injection existed mainly in the axons of PV positive interneurons. Electron microscopy revealed PS containing vesicles in the PV positive axon. Double immunostaining with PS and secretogranin or synapsin suggested that PS is secreted with secretogranin from synapses. Based on the results from in situ hybridization with two alternative splicing forms of PS mRNA, the increase of PS in the interneurons was due to the increase of PS + 0 (mRNA without 9-base insertion) as in the choroid plexus, but not PS + 9 (mRNA with 9-base insertion). These results were similar to those from the choroid plexus, which secretes an intact form PS + 0 to the cerebrospinal fluid. Neurons, especially PV positive GABAergic interneurons, produce and secrete the intact form of PS around hippocampal pyramidal neurons to protect them against KA neurotoxicity.
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Project description:PurposeThe ketogenic diet has long been used to treat epilepsy, but its mechanism is not yet clearly understood. To explore the potential mechanism, we analyzed the changes in gene expression induced by the ketogenic diet in the rat kainic acid (KA) epilepsy model.Materials and methodsKA-administered rats were fed the ketogenic diet or a normal diet for 4 weeks, and microarray analysis was performed with their brain tissues. The effects of the ketogenic diet on cathepsin E messenger ribonucleic acid (mRNA) expression were analyzed in KA-administered and normal saline-administered groups with semi-quantitative and real-time reverse transcription polymerase chain reaction (RT-PCR). Brain tissues were dissected into 8 regions to compare differential effects of the ketogenic diet on cathepsin E mRNA expression. Immunohistochemistry with an anti-cathepsin E antibody was performed on slides of hippocampus obtained from whole brain paraffin blocks.ResultsThe microarray data and subsequent RT-PCR experiments showed that KA increased the mRNA expression of cathepsin E, known to be related to neuronal cell death, in most brain areas except the brain stem, and these increases of cathepsin E mRNA expression were suppressed by the ketogenic diet. The expression of cathepsin E mRNA in the control group, however, was not significantly affected by the ketogenic diet. The change in cathepsin E mRNA expression was greatest in the hippocampus. The protein level of cathepsin E in the hippocampus of KA-administered rat was elevated in immunohistochemistry and the ketogenic diet suppressed this increase.ConclusionOur results showed that KA administration increased cathepsin E expression in the rat brain and its increase was suppressed by the ketogenic diet.
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Project description:The ketogenic diet has long been used to treat epilepsy, but its mechanism is not yet clearly understood. To explore the potential mechanism, the changes in gene expression induced by the ketogenic diet in the rat kainic acid (KA) epilepsy model were analyzed.
2009-12-02 | GSE19277 | GEO
Project description:Dystonia is a neurological disorder characterized by excessive involuntary muscle contractions that lead to twisting movements. The exaggerated movements have been studied and have implicated basal ganglia as the point of origin. In more recent studies, the cerebellum has also been identified as the possible target of dystonia, in the search for alternative treatments. Tiagabine is a selective GABA transporter inhibitor, which blocks the reuptake and recycling of GABA. The study of GABAergic drugs as an alternative treatment for cerebellar induced dystonia has not been reported. In our study, tiagabine was i.p. injected into kainic acid induced, cerebellar dystonic adult rats, and the effects were compared with non-tiagabine injected and sham-operated groups. Beam walking apparatus, telemetric electromyography (EMG) recording, and histological verification were performed to confirm dystonic symptoms in the rats on post-surgery treatment. Involuntary dystonic spasm was observed with repetitive rigidity, and twisting movements in the rats were also confirmed by a high score on the dystonic scoring and a high amplitude on the EMG data. The rats with tiagabine treatment were scored based on motor amelioration assessed via beam walking. The result of this study suggests and confirms that low dose of kainic acid microinjection is sufficient to induce dystonia from the cerebellar vermis. In addition, from the results of the EMG recording and the behavioral assessment through beam walking, tiagabine is demonstrated as being effective in reducing dystonic spasm and may be a possible alternative therapeutic drug in the treatment of dystonia.
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Project description:Kainic acid (KA) binds to the AMPA/KA receptors and induces seizures that result in inflammation, oxidative damage and neuronal death. We previously showed that cyclooxygenase-2 deficient (COX-2(-/-)) mice are more vulnerable to KA-induced excitotoxicity. Here, we investigated whether the increased susceptibility of COX-2(-/-) mice to KA is associated with altered mRNA expression and editing of glutamate receptors. The expression of AMPA GluR2, GluR3 and KA GluR6 was increased in vehicle-injected COX-2(-/-) mice compared to wild type (WT) mice in hippocampus and cortex, whereas gene expression of NMDA receptors was decreased. KA treatment decreased the expression of AMPA, KA and NMDA receptors in the hippocampus, with a significant effect in COX-2(-/-) mice. Furthermore, we analyzed RNA editing levels and found that the level of GluR3 R/G editing site was selectively increased in the hippocampus and decreased in the cortex in COX-2(-/-) compared with WT mice. After KA, GluR4 R/G editing site, flip form, was increased in the hippocampus of COX-2(-/-) mice. Treatment of WT mice with the COX-2 inhibitor celecoxib for two weeks decreased the expression of AMPA/KA and NMDAR subunits after KA, as observed in COX-2(-/-) mice. After KA exposure, COX-2(-/-) mice showed increased mRNA expression of markers of inflammation and oxidative stress, such as cytokines (TNF-?, IL-1? and IL-6), inducible nitric oxide synthase (iNOS), microglia (CD11b) and astrocyte (GFAP). Thus, COX-2 gene deletion can exacerbate the inflammatory response to KA. We suggest that COX-2 plays a role in attenuating glutamate excitotoxicity by modulating RNA editing of AMPA/KA and mRNA expression of all ionotropic glutamate receptor subunits and, in turn, neuronal excitability. These changes may contribute to the increased vulnerability of COX-2(-/-) mice to KA. The overstimulation of glutamate receptors as a consequence of COX-2 gene deletion suggests a functional coupling between COX-2 and the glutamatergic system.
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Project description:GABAA receptors are pentameric GABA-gated chloride channels. The existence of 19 different subunits (six ?, three ?, three ?, ?, ?, ?, ?, and three ?) in mammalian systems gives rise to an enormous theoretical diversity of GABAA receptor subtypes with distinct subunit composition and unique pharmacological properties. These receptors are already now the drug targets of several clinically used compounds, such as benzodiazepines, anesthetics, and many more. There is a constant quest to identify novel molecules and possible future drug targets: Currently, ?6-containing GABAA receptors are being discussed in the context of treating sensorimotor gating deficits in neuropsychiatric disorders, such as tic disorders and schizophrenia. Therefore, we aim to learn more about ?6-containing GABAA receptors. They are mostly expressed in the cerebellar granule cell layer, where they form the following subtypes: ?6?x?2, ?1?6?x?2, ?6?x?, and ?1?6?x?. In former studies, ?1?6?x?2-containing GABAA receptors were considered a single receptor population. In the current study, we investigate the possibility, that this population can consist of two subgroups with alternative arrangements depending if ?1 neighbors ?2 (forming a "diazepam-sensitive" receptor), or if ?6 neighbors ?2 (forming a "diazepam-insensitive" receptor) and aimed to prove the existence of both subtypes in native tissue. We performed immunoprecipitation experiments on rat cerebellar lysates using ?1- or ?6 subunit-specific antibodies followed by radioligand binding assays with either 3H-flunitrazepam or 3H-Ro 15-4513. Indeed, we were able to prove the existence of two distinct populations of ?1?6-containing GABAA-receptors and could quantify the different receptor populations: ?1?x?2 receptors constitute approximately 60% of all ?2-containing receptors in the rat cerebellum, ?6?x?2 about 20%, and both isoforms of ?1?6?x?2 9-15% each. The simple classification of GABAA-receptors into ?x-containing subtypes seems not to reflect the complexity of nature; those receptors are more diverse than previously thought.
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Project description:ObjectiveIn order to better investigate the cause/effect relationships of human mesial temporal lobe epilepsy (mTLE), we hereby describe a new non-human primate model of mTLE.MethodsTen macaques were studied and divided into 2 groups: saline control group (n?=?4) and kainic acid (KA) injection group (n?=?6). All macaques were implanted bilaterally with subdural electrodes over temporal cortex and depth electrodes in CA3 hippocampal region. KA was stereotaxically injected into the right hippocampus of macaques. All animals were monitored by video and electrocorticography (ECoG) to assess status epilepticus (SE) and subsequent spontaneous recurrent seizures (SRS). Additionally, in order to evaluate brain injury produced by SE or SRS, we used both neuroimaging, including magnetic resonance image (MRI) & magnetic resonance spectroscopy (MRS), and histological pathology, including Nissl stainning and glial fibrillary acid protein (GFAP) immunostaining.ResultsThe typical seizures were observed in the KA-injected animal model. Hippocampal sclerosis could be found by MRI & MRS. Hematoxylin and eosin (H&E) staining and GFAP immunostaining showed neuronal loss, proliferation of glial cells, formation of glial scars, and hippocampal atrophy. Electron microscopic analysis of hippocampal tissues revealed neuronal pyknosis, partial ribosome depolymerization, an abnormal reduction in rough endoplasmic reticulum size, expansion of Golgi vesicles and swollen star-shaped cells. Furthermore, we reported that KA was able to induce SE followed by SRS after a variable period of time. Similar to human mTLE, brain damage is confined to the hippocampus. Accordingly, hippocampal volume is in positive correlations with the neuronal cells count in the CA3, especially the ratio of neuron/glial cell.ConclusionsThe results suggest that a model of mTLE can be developed in macaques by intra-hippocampal injection of KA. Brain damage is confined to the hippocampus which is similar to the human mTLE. The hippocampal volume correlates with the extension of the hippocampal damage.
| S-EPMC3753347 | biostudies-literature