Daejong Jeon

Observational fear learning involves affective pain system and Cav1.2 Ca2+ channels in ACC

Fear can be acquired vicariously through social observation of others suffering from aversive stimuli. We found that mice (observers) developed freezing behavior by observing other mice (demonstrators) receive repetitive foot shocks. Observers had higher fear responses when demonstrators were socially related to themselves, such as siblings or mating partners. Inactivation of anterior cingulate cortex (ACC) and parafascicular or mediodorsal thalamic nuclei, which comprise the medial pain system representing pain affection, substantially impaired this observational fear learning, whereas inactivation of sensory thalamic nuclei had no effect. The ACC neuronal activities were increased and synchronized with those of the lateral amygdala at theta rhythm frequency during this learning. Furthermore, an ACC-limited deletion of Cav1.2 Ca2+ channels in mice impaired observational fear learning and reduced behavioral pain responses. These results demonstrate the functional involvement of the affective pain system and Cav1.2 channels of the ACC in observational social fear.

MicroRNAs Induced During Ischemic Preconditioning

Background and Purpose— MicroRNAs (miRNA) are single-stranded short RNA molecules that regulate gene expression by either degradation or translational repression of mRNA. Although miRNAs control a number of conditions and diseases, few neuroprotective miRNAs have been described. In this study, we investigated neuroprotective miRNAs induced early in ischemic preconditioning. Methods— Ischemic preconditioning or focal cerebral ischemia was induced in mice by transient occlusion of the middle cerebral artery for 15 or 120 minutes. We prepared RNA samples from the ischemic cortex at 3 or 24 hours after the onset of ischemia. Selective miRNAs then were synthesized and transfected into Neuro-2a cells before oxygen–glucose deprivation. Results— We detected a total of 360 miRNAs. Two miRNA families, miR-200 and miR-182, were selectively upregulated at 3 hours after ischemic preconditioning. Transfections of some of these were neuroprotective in in vitro ischemia. Among them, miR-200b, miR-200c, and miR-429 targeted prolyl hydroxylase 2 and had the best neuroprotective effect. Conclusion— Two miRNA families, miR-200 and miR-182, were upregulated early after ischemic preconditioning and the miR-200 family was neuroprotective mainly by downregulating prolyl hydroxylase 2 levels. These miRNAs may be useful in future research and therapeutic applications.

HUMAN NEURAL STEM CELL TRANSPLANTATION REDUCES SPONTANEOUS RECURRENT SEIZURES FOLLOWING PILOCARPINE-INDUCED STATUS EPILEPTICUS IN ADULT RATS

Transplantation of neural stem cells (NSCs) can replace lost neurons and improve the functional deficits. Cell transplantation strategies have been tried in the epileptic disorder, but the effect of exogenous NSCs is unknown. In this study, we attempted to test the anti-epileptogenic effect of NSCs in adult rats with status epilepticus. Experimental status epilepticus was induced by lithium-pilocarpine injection, and beta galactosidase-encoded human NSCs were transplanted intravenously on the next day of status epilepticus. Spontaneous recurrent seizures were monitored with Racines seizure severity scale. Immunohistochemistry with anti-beta gal, Tuj-1, NeuN, GFAP, CNPase, GluR2, parvalbumin, and GABA were performed and extracellular field excitatory postsynaptic potentials (fEPSP) were recorded. Human NSCs suppressed spontaneous recurrent seizure formation and transplanted NSCs were differentiated into GABA-immunoreactive interneurons in the damaged hippocampus. Amplitude of fEPSP in the hippocampal CA1 was reduced, which was reversed by picrotoxin. These findings suggest that NSCs could be differentiated into inhibitory interneurons and decrease neuronal excitability, which could prevent spontaneous recurrent seizure formation in adult rats with pilocarpine-induced status epilepticus.

Enhanced Learning and Memory in Mice Lacking Na+/Ca2+ Exchanger 2

The plasma membrane Na(+)/Ca(2+) exchanger (NCX) plays a role in regulation of intracellular Ca(2+) concentration via the forward mode (Ca(2+) efflux) or the reverse mode (Ca(2+) influx). To define the physiological function of the exchanger in vivo, we generated mice deficient for NCX2, the major isoform in the brain. Mutant hippocampal neurons exhibited a significantly delayed clearance of elevated Ca(2+) following depolarization. The frequency threshold for LTP and LTD in the hippocampal CA1 region was shifted to a lowered frequency in the mutant mice, thereby favoring LTP. Behaviorally, the mutant mice exhibited enhanced performance in several hippocampus-dependent learning and memory tasks. These results demonstrate that NCX2 can be a temporal regulator of Ca(2+) homeostasis and as such is essential for the control of synaptic plasticity and cognition.

Ablation of Ca2+ Channel β3 Subunit Leads to Enhanced N-Methyl-d-aspartate Receptor-dependent Long Term Potentiation and Improved Long Term Memory

The β subunits of voltage-dependent Ca2+ channels (VDCCs) have marked effects on the properties of the pore-forming α1 subunits of VDCCs, including surface expression of channel complexes and modification of voltage-dependent kinetics. Among the four different β subunits, the β3 subunit (Cavβ3) is abundantly expressed in the hippocampus. However, the role of Cavβ3 in hippocampal physiology and function in vivo has never been examined. Here, we investigated Cavβ3-deficient mice for hippocampus-dependent learning and memory and synaptic plasticity at hippocampal CA3-CA1 synapses. Interestingly, the mutant mice exhibited enhanced performance in several hippocampus-dependent learning and memory tasks. However, electrophysiological studies revealed no alteration in the Ca2+ current density, the frequency and amplitude of miniature excitatory postsynaptic currents, and the basal synaptic transmission in the mutant hippocampus. On the other hand, however, N-methyl-d-aspartate receptor (NMDAR)-mediated synaptic currents and NMDAR-dependent long term potentiation were significantly increased in the mutant. Protein blot analysis showed a slight increase in the level of NMDAR-2B in the mutant hippocampus. Our results suggest a possibility that, unrelated to VDCCs regulation, Cavβ3 negatively regulates the NMDAR activity in the hippocampus and thus activity-dependent synaptic plasticity and cognitive behaviors in the mouse.

Early diagnosis of Alzheimer's disease from elevated olfactory mucosal miR-206 level.

MicroRNA-206, which suppresses the expression of brain-derived neurotrophic factor, is known to be elevated in the brains of Alzheimer’s disease (AD) patients. We performed intranasal biopsy of the olfactory epithelia of early dementia patients (n = 24) and cognitively healthy controls (n = 9). Patients with significant depression (n = 8) were analyzed separately, as their cognitive impairments were thought to be caused by their depression. Real-time PCR was performed on the biopsied tissues. The relative microRNA-206 level exhibited a 7.8-fold increase (P = 0.004) in the mild cognitive impairment group (CDR 0.5; n = 13) and a 41.5-fold increase (P < 0.001) in the CDR 1 group (n = 11). However, this level was not increased in the depression group, even in those with cognitive decline. Using the optimal cutoff value, the sensitivity/specificity for diagnosing CDR 0.5 and CDR 1 dementia were 87.5%/94.1% and 90.9%/93.3%, respectively. In ROC analysis, the AUCs were 0.942 and 0.976 in the CDR 0.5 and CDR 1 groups, respectively. The olfactory mucosal microRNA-206 level and cognitive assessment scores were significantly correlated in the non-depressed subjects with cognitive impairment. In conclusion, the olfactory mucosal microRNA-206 level can be easily measured, and it can be utilized as an excellent biomarker for the diagnosis of early AD, including mild cognitive impairment.

Distinct intrathecal interleukin-17/interleukin-6 activation in anti-N-methyl-d-aspartate receptor encephalitis

The aim of this study was to compare serum and cerebrospinal fluid (CSF) cytokine/chemokine levels between anti-NMDAR and anti-LGI1 encephalitis patients. Samples from fourteen anti-NMDAR encephalitis patients, ten anti-LGI1 encephalitis patients, and ten controls were analyzed for the following cytokines/chemokines: IL-1b, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, IL-13, IL-17A, IL-23, GM-CSF, IFN-gamma, TNF-alpha, and CXCL13. Compared with controls, CSF IL-17A, IL-6 and CXCL13 were elevated in anti-NMDAR encephalitis patients (post-hoc p-values 0.002, 0.011, and 0.011, respectively) but not in anti-LGI1 encephalitis patients. In the serum, only IL-2 was increased in anti-NMDAR encephalitis. Intrathecal IL-17/IL-6 activation is a characteristic of anti-NMDAR encephalitis.

Dysfunctional Characteristics of Circulating Angiogenic Cells in Alzheimer's Disease

Vascular senescence contributes to the progression of Alzheimers disease (AD) and circulating angiogenic cells (CACs) participate in the maintenance of the endothelium. As a step toward the development endothelial regeneration therapies for AD, we investigated the functional characteristics of CACs in AD patients. We enrolled AD patients and non-demented risk factor control subjects after matching for age, sex, and Framingham risk score. CACs were cultured from peripheral blood samples taken from subjects and used for various ex vivo assays. CACs from AD patients showed reduced chemotaxis, increased senescence, reduced paracrine angiogenic activity, and altered gene expression patterns compared to CACs from risk factor (RF) controls. Addition of high concentration Abeta{1-42} (200, 2000 ng/mL) to the CAC culture reduced CAC counts and endothelial nitric oxide synthase/Akt phosphorylation and induced apoptosis. However, lower concentration of Abeta{1-42} (2, 20 ng/mL) failed to reduce the CAC counts. CACs from AD patients were more susceptible to the cytotoxic effect of Abeta{1-42} than CACs from RF controls. In summary, AD patients have intrinsic dysfunctions of CACs which provides an extended understanding of vascular endothelial pathogenesis in AD.

Clustering of spontaneous recurrent seizures separated by long seizure-free periods: An extended video-EEG monitoring study of a pilocarpine mouse model

Seizure clustering is a common and significant phenomenon in patients with epilepsy. The clustering of spontaneous recurrent seizures (SRSs) in animal models of epilepsy, including mouse pilocarpine models, has been reported. However, most studies have analyzed seizures for a short duration after the induction of status epilepticus (SE). In this study, we investigated the detailed characteristics of seizure clustering in the chronic stage of a mouse pilocarpine-induced epilepsy model for an extended duration by continuous 24/7 video-EEG monitoring. A seizure cluster was defined as the occurrence of one or more seizures per day for at least three consecutive days and at least five seizures during the cluster period. We analyzed the cluster duration, seizure-free period, cluster interval, and numbers of seizures within and outside the seizure clusters. The video-EEG monitoring began 84.5±33.7 days after the induction of SE and continued for 53.7±20.4 days. Every mouse displayed seizure clusters, and 97.0% of the seizures occurred within a cluster period. The seizure clusters were followed by long seizure-free periods of 16.3±6.8 days, showing a cyclic pattern. The SRSs also occurred in a grouped pattern within a day. We demonstrate that almost all seizures occur in clusters with a cyclic pattern in the chronic stage of a mouse pilocarpine-induced epilepsy model. The seizure-free periods between clusters were long. These findings should be considered when performing in vivo studies using this animal model. Furthermore, this model might be appropriate for studying the unrevealed mechanism of ictogenesis.

Dysregulated Long Non-coding RNAs in the Temporal Lobe Epilepsy mouse model

PURPOSE To perform comprehensive profiling of long non-coding RNAs (LncRNAs) in temporal lobe epilepsy. METHODS We performed extensive profiling of LncRNAs and mRNAs in the mouse pilocarpine model in specific brain regions, the hippocampus and cortex, and compared the results to those of the control mouse. Differentially expressed LncRNAs and mRNAs were identified with a microarray analysis (Arraystar Mouse LncRNA Expression Microarray V3.0). Then, gene ontology (GO) and pathway analysis were performed to investigate the potential roles of the differentially expressed mRNAs in the pilocarpine model. Protein-protein interactions transcribed by dysregulated mRNAs with/without co-dysregulated LncRNAs were analyzed using STRING v10 (http://string-db.org/). RESULTS A total of 22 and 83 LncRNAs were up- and down-regulated (≥2.0-fold, all P < .05), respectively, in the hippocampus of the epilepsy model, while 46 and 659 LncRNAs were up- and down-regulated, respectively, in the cortex of the epilepsy model. GO and pathway analysis revealed that the dysregulated mRNAs were closely associated with a process already known to be involved in epileptogenesis: acute inflammation, calcium ion regulation, extracellular matrix remodeling, and neuronal differentiation. Among the LncRNAs, we identified 10 LncRNAs commonly dysregulated with corresponding mRNAs in the cortex. The STRING analysis showed that the dysregulated mRNAs were interconnected around two centers: the mTOR pathway-related genes and REST pathway-related genes. CONCLUSION LncRNAs were dysregulated in the pilocarpine mouse model according to the brain regions of the hippocampus and cortex. The dysregulated LncRNAs with co-dysregulated mRNAs might be possible therapeutic targets for the epigenetic regulation of chronic epilepsy.