AGS-induced expression of Narp is concomitant with expression of AMPA receptor subunits GluR1 and GluR2 in hippocampus but not inferior colliculus of P77PMC rats

Inhibition of neuronal pentraxin 2 relieved epileptic seizure via reducing GluA1 phosphorylation

Neuronal pentraxin 2 (Nptx2), a member of the synaptic protein family linked to excitatory synaptic formation, is found to be upregulated in epileptic mice, yet its role in epilepsy has been unclear. In vivo, we constructed a mouse model of epilepsy by using kainic acid induction. In vitro experiments, a Mg2+-free medium was used to induce epileptiform discharges in neurons. The results showed that the Nptx2 was upregulated in epileptic mice. Moreover, Nptx2 knockdown reduced the number of seizures and seizure duration. Knocking down Nptx2 not only reduced the number and duration of seizures but also showed a decrease in electroencephalogram amplitude. Behavioral tests indicated improvements in learning and memory abilities after Nptx2 knockdown. The Nissl staining and Timms staining revealed that Nptx2 silencing mitigated epilepsy-induced brain damage. The immunofluorescence staining revealed that Nptx2 absence resulted in a reduction of apoptosis. Nptx2 knockdown reduced Bax, cleaved caspase3, and cleaved caspase9 expression, while increased Bcl-2 expression. Notably, Nptx2 knockdown inhibited GluA1 phosphorylation at the S831 site and reduced the GluA1 membrane expression. The PSD95 expression declined in the epilepsy model, while the Nptx2 knockdown reversed it. Collectively, our study indicated that Nptx2 silencing not only alleviated brain damage and neuron apoptosis but also improved learning and memory ability in epileptic mice, suggesting Nptx2 as a promising target for epilepsy treatment.

Association between serum NPTX2 and cognitive function in patients with vascular dementia

OBJECTIVE

Neuronal Pentraxin 2 (NPTX2) has recently been widely reported as a novel biomarker for Alzheimer's disease (AD), but its correlation with vascular dementia (VaD) has not been elucidated. This study aimed to explore the correlation between NPTX2 and the cognitive function of VaD patients.

METHODS

112 VaD patients and 76 healthy controls were included in the study. Upon admission, clinical baseline data for all subjects were collected. Serum NPTX2 levels were determined using enzyme-linked immunosorbent assay (ELISA). At the same time, the Montreal cognitive assessment (MoCA) scale was used to measure cognitive function. Multivariate regression analysis was used to determine the relationship between serum NPTX2 level and the cognitive function of VaD patients.

RESULTS

Compared with healthy controls, VaD patients had lower serum NPTX2 levels (p < .001). The results of Spearman's correlation analysis showed that serum NPTX2 levels in VaD patients were positively correlated with MoCA scores (r = .347, p = .042). The results of multivariate regression analysis showed that after adjusting for common risk factors, serum NPTX2 levels in VaD patients were still significantly associated with MoCA scores (β = 0.346, p = .039).

CONCLUSIONS

Serum NPTX2 level was independently associated with cognitive function in patients with VaD. Serum NPTX2 level may be a novel predictor for cognitive function in VaD.

The Wistar Audiogenic Rat (WAR) strain and its contributions to epileptology and related comorbidities: History and perspectives

In the context of modeling epilepsy and neuropsychiatric comorbidities, we review the Wistar Audiogenic Rat (WAR), first introduced to the neuroscience international community more than 25years ago. The WAR strain is a genetically selected reflex model susceptible to audiogenic seizures (AS), acutely mimicking brainstem-dependent tonic-clonic seizures and chronically (by audiogenic kindling), temporal lobe epilepsy (TLE). Seminal neuroethological, electrophysiological, cellular, and molecular protocols support the WAR strain as a suitable and reliable animal model to study the complexity and emergent functions typical of epileptogenic networks. Furthermore, since epilepsy comorbidities have emerged as a hot topic in epilepsy research, we discuss the use of WARs in fields such as neuropsychiatry, memory and learning, neuroplasticity, neuroendocrinology, and cardio-respiratory autonomic regulation. Last, but not least, we propose that this strain be used in "omics" studies, as well as with the most advanced molecular and computational modeling techniques. Collectively, pioneering and recent findings reinforce the complexity associated with WAR alterations, consequent to the combination of their genetically-dependent background and seizure profile. To add to previous studies, we are currently developing more powerful behavioral, EEG, and molecular methods, combined with computational neuroscience/network modeling tools, to further increase the WAR strain's contributions to contemporary neuroscience in addition to increasing knowledge in a wide array of neuropsychiatric and other comorbidities, given shared neural networks. During the many years that the WAR strain has been studied, a constantly expanding network of multidisciplinary collaborators has generated a growing research and knowledge network. Our current and major wish is to make the WARs available internationally to share our knowledge and to facilitate the planning and execution of multi-institutional projects, eagerly needed to contribute to paradigm shifts in epileptology. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".

Interacting partners of AMPA-type glutamate receptors

Glutamate is the principal excitatory neurotransmitter in the brain. The alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionic (AMPA) receptors, as one of several types of endogenous ionotropic glutamate receptors, mediate the fast excitatory synaptic transmission that is essential for information processing and integration in the mammalian brain. Modifications of AMPA receptors are assumed to be the molecular basis underlying learning and memory, and impairments of AMPA receptors cause certain neurological diseases, including epilepsy, autism spectrum disorders, and Alzheimer's disease. Thus, extensive studies have been conducted, and these have revealed a complex protein-protein network controlling the expression, trafficking, and function of AMPA receptors in neurons. Here, we summarize the interacting partners of AMPA-type glutamate receptors and the functional implications of these interactions.

Increased expression of GluR2-flip in the hippocampus of the Wistar audiogenic rat strain after acute and kindled seizures

The Wistar Audiogenic Rat (WAR) is an epileptic-prone strain developed by genetic selection from a Wistar progenitor based on the pattern of behavioral response to sound stimulation. Chronic acoustic stimulation protocols of WARs (audiogenic kindling) generate limbic epileptogenesis, confirmed by ictal semiology, amygdale, and hippocampal EEG, accompanied by hippocampal and amygdala cell loss, as well as neurogenesis in the dentate gyrus (DG). In an effort to identify genes involved in molecular mechanisms underlying epileptic process, we used suppression-subtractive hybridization to construct normalized cDNA library enriched for transcripts expressed in the hippocampus of WARs. The most represented gene among the 133 clones sequenced was the ionotropic glutamate receptor subunit II (GluR2), a member of the alpha-amino-3-hydroxy-5-methyl-4-isoxazoleopropionic acid (AMPA) receptor. Although semiquantitative RT-PCR analysis shows that the hippocampal levels of the GluR2 subunits do not differ between naïve WARs and their Wistar counterparts, we observed that the expression of the transcript encoding the splice-variant GluR2-flip is increased in the hippocampus of WARs submitted to both acute and kindled audiogenic seizures. Moreover, using in situ hybridization, we verified upregulation of GluR2-flip mainly in the CA1 region, among the hippocampal subfields of audiogenic kindled WARs. Our findings on differential upregulation of GluR2-flip isoform in the hippocampus of WARs displaying audiogenic seizures is original and agree with and extend previous immunohistochemical for GluR2 data obtained in the Chinese P77PMC audiogenic rat strain, reinforcing the association of limbic AMPA alterations with epileptic seizures.

Extracellular matrix in plasticity and epileptogenesis

Extracellular matrix (ECM) in the brain is composed of molecules synthesized and secreted by neurons and glial cells in a cell-type-specific and activity-dependent manner. During development, ECM plays crucial roles in proliferation, migration and differentiation of neural cells. In the mature brain, ECM undergoes a slow turnover and supports multiple physiological processes, while restraining structural plasticity. In the first part of this review, we discuss the contribution of ECM molecules to different forms of plasticity, including developmental plasticity in the cortex, long-term potentiation and depression in the hippocampus, homeostatic scaling of synaptic transmission and metaplasticity. In the second part, we focus on pathological changes associated with epileptogenic mutations in ECM-related molecules or caused by seizure-induced remodeling of ECM. The available data suggest that ECM components regulating physiological plasticity are also engaged in different aspects of epileptogenesis, such as dysregulation of excitatory and inhibitory neurotransmission, sprouting of mossy fibers, granule cell dispersion and gliosis. At the end, we discuss combinatorial approaches that might be used to counteract seizure-induced dysregulation of both ECM molecules and extracellular proteases. By restraining ECM modification and preserving the status quo in the brain, these treatments might prove to be valid therapeutic interventions to antagonize the progression of epileptogenesis.

Puzzling challenges in contemporary neuroscience: insights from complexity and emergence in epileptogenic circuits

The brain is a complex system that, in the normal condition, has emergent properties like those associated with activity-dependent plasticity in learning and memory, and in pathological situations, manifests abnormal long-term phenomena like the epilepsies. Data from our laboratory and from the literature were classified qualitatively as sources of complexity and emergent properties from behavior to electrophysiological, cellular, molecular, and computational levels. We used such models as brainstem-dependent acute audiogenic seizures and forebrain-dependent kindled audiogenic seizures. Additionally we used chemical or electrical experimental models of temporal lobe epilepsy that induce status epilepticus with behavioral, anatomical, and molecular sequelae such as spontaneous recurrent seizures and long-term plastic changes. Current computational neuroscience tools will help the interpretation, storage, and sharing of the exponential growth of information derived from those studies. These strategies are considered solutions to deal with the complexity of brain pathologies such as the epilepsies.