Changes in the structure and function of the hippocampus contribute to epilepsy, schizophrenia and other neurological or mental disorders of the brain. Since the function of the hippocampus depends heavily on the glutamate (Glu) signaling pathways, in situ real-time detection of Glu neurotransmitter release and electrophysiological signals in hippocampus is of great significance. To achieve the dual-mode detection in mouse hippocampus in vivo, a 16-channel implantable microelectrode array (MEA) was fabricated by micro-electromechanical system (MEMS) technology. Twelve microelectrode sites were modified with platinum black for electrophysiological recording and four sites were modified with glutamate oxidase (GluOx) and 1,3-phenylenediamine (mPD) for selective electrochemical detection of Glu. The MEA was implanted from cortex to hippocampus in mouse brain for in situ real-time monitoring of Glu and electrophysiological signals. It was found that the Glu concentration in hippocampus was roughly 50 μM higher than that in the cortex, and the firing rate of concurrently recorded spikes declined from 6.32 ± 4.35 spikes/s in cortex to 0.09 ± 0.06 spikes/s in hippocampus. The present results demonstrated that the dual-mode MEA probe was capable in neurological detections in vivo with high spatial resolution and dynamical response, which lays the foundation for further pathology studies in the hippocampus of mouse models with nervous or mental disorders.

Neuronal polarity is involved in multiple developmental stages, including cortical neuron migration, multipolar-to-bipolar transition, axon initiation, apical/basal dendrite differentiation, and spine formation. All of these processes are associated with the cytoskeleton and are regulated by precise timing and by controlling gene expression. The P-Rex1 (phosphatidylinositol-3,4,5-trisphosphate dependent Rac exchange factor 1) gene for example, is known to be important for cytoskeletal reorganization, cell motility, and migration. Deficiency of P-Rex1 protein leads to abnormal neuronal migration and synaptic plasticity, as well as autism-related behaviors. Nonetheless, the effects of P-Rex1 overexpression on neuronal development and higher brain functions remain unclear. In the present study, we explored the effect of P-Rex1 overexpression on cerebral development and psychosis-related behaviors in mice. In utero electroporation at embryonic day 14.5 was used to assess the influence of P-Rex1 overexpression on cell polarity and migration. Primary neuron culture was used to explore the effects of P-Rex1 overexpression on neuritogenesis and spine morphology. In addition, P-Rex1 overexpression in the medial prefrontal cortex (mPFC) of mice was used to assess psychosis-related behaviors. We found that P-Rex1 overexpression led to aberrant polarity and inhibited the multipolar-to-bipolar transition, leading to abnormal neuronal migration. In addition, P-Rex1 overexpression affected the early development of neurons, manifested as abnormal neurite initiation with cytoskeleton change, reduced the axon length and dendritic complexity, and caused excessive lamellipodia in primary neuronal culture. Moreover, P-Rex1 overexpression decreased the density of spines with increased height, width, and head area in vitro and in vivo. Behavioral tests showed that P-Rex1 overexpression in the mouse mPFC caused anxiety-like behaviors and a sensorimotor gating deficit. The appropriate P-Rex1 level plays a critical role in the developing cerebral cortex and excessive P-Rex1 might be related to psychosis-related behaviors.

Epilepsy is a common, chronic neurological disorder that has been associated with impaired neurodevelopment and immunity. The chemokine receptor CXCR5 is involved in seizures via an unknown mechanism. Here, we first determined the expression pattern and distribution of the CXCR5 gene in the mouse brain during different stages of development and the brain tissue of patients with epilepsy. Subsequently, we found that the knockdown of CXCR5 increased the susceptibility of mice to pentylenetetrazol- and kainic acid-induced seizures, whereas CXCR5 overexpression had the opposite effect. CXCR5 knockdown in mouse embryos via viral vector electrotransfer negatively influenced the motility and multipolar-to-bipolar transition of migratory neurons. Using a human-derived induced an in vitro multipotential stem cell neurodevelopmental model, we determined that CXCR5 regulates neuronal migration and polarization by stabilizing the actin cytoskeleton during various stages of neurodevelopment. Electrophysiological experiments demonstrated that the knockdown of CXCR5 induced neuronal hyperexcitability, resulting in an increased number of seizures. Finally, our results suggested that CXCR5 deficiency triggers seizure-related electrical activity through a previously unknown mechanism, namely, the disruption of neuronal polarity.

Current antiepileptic drugs are ineffective in one‐third of patients with epilepsy; however, identification of genes involved in epilepsy can enable a precision medicine approach. Here, it is demonstrated that downregulating D‐2‐hydroxyglutarate dehydrogenase (D2HGDH) enhances susceptibility to epilepsy. Furthermore, its potential involvement in the seizure network through synaptic function modulation is investigated. D2HGDH knockdown reduces the glutathione reduced (GSH)/glutathione oxidized (GSSG) ratio and elevates reactive oxygen species (ROS) levels within neurons. Oxidative stress may play a crucial role in the pathogenesis of epilepsy. The specific contribution of each pathway varies among patients, highlighting the complexity of this disease. In this study, downregulation of D2HGDH affects modulation of ROS levels, synaptic transmission, and seizure susceptibility. Furthermore, the acid calcium‐independent phospholipase A2 (aiPLA2) inhibitor, MJ33, restores the GSH/GSSG balance and reverses the increase in ROS levels caused by D2HGDH knockdown, resulting in remission of epilepsy‐related behaviors. The results demonstrate that downregulation of D2HGDH affects synaptic function by regulating ROS production. These findings support the use of targeted gene therapy as a potential alternative to antioxidant‐based treatments for refractory epilepsy.

Schizophrenia patients show abnormalities in many eye movement tasks. Among them, exploratory eye movements (EEM) dysfunction seems to be specific to schizophrenia. However the mechanism of EEM disturbances in schizophrenia patients remains elusive. We investigate the relationship between EEM and single nucleotide polymorphisms (SNPs) or genes to identify susceptibility loci for EEM in schizophrenia. We firstly performed EEM test, then performed a genome-wide association study (GWAS) and gene-based association study of EEM in 128 individuals with schizophrenia and 143 healthy control subjects. Comparing to healthy controls, schizophrenia patients show significant decrease in NEF (22.99 ± 3.96 vs. 26.02 ± 5.72, P <0.001), TESL (368.78 ± 123.57 vs. 603.12 ± 178.63, P <0.001), MESL (16.86 ± 5.27 vs. 24.42 ± 6.46, P <0.001), RSS (8.22 ± 1.56 vs. 10.92 ± 1.09, P <0.001) and CSS (5.06 ± 0.97 vs. 6.64 ± 0.87, P <0.001). Five SNPs of the MAN2A1, at 5q21.3, were associated with EEM abnormalities (deceased CSS) and satisfied the criteria of GWAS significance threshold. One is localized near 5’-UTR (rs17450784) and four are in intron (rs1438663, rs17162094, rs6877440 and rs10067856) of the gene. Our findings suggest that the identified loci may control the schizophrenia-related quantitative EEM trait. And the identified gene, associated with the EEM phenotype, may lead to new insights into the etiology of schizophrenia.

Dishevelled, Egl-10 and Pleckstrin domain-containing 5 (DEPDC5), a key inhibitor of the mammalian/mechanistic target of rapamycin (mTOR) pathway, is frequently associated with epilepsy. However, the functional consequences of most DEPDC5 variants rely on in silico predictions and have not been experimentally confirmed.This study aimed to determine the functional consequences of a DEPDC5 variant identified in patients with epilepsy across multiple generations in a Chinese family. We identified a missense heterozygous variant (c. 2055C > A; p. Phe685Leu) in DEPDC5 in Chinese family affected by epilepsy across three generations. This variant has not been previously reported in the Chinese population. Primary neuron cultures transfected with the mutant plasmid exhibited altered subcellular localization. To explore the mechanisms of epilepsy linked to this variant, we created nervous system-specific conditional human DEPDC5 knock-in mouse using Cre-recombination under the Nestin promotor (hDEPDC5^WT mice, hDEPDC5^F685L mice). Compared to wildtype (WT) and hDEPDC5^WT mice, hDEPDC5^F685L mice exhibited histological signs of mTOR hyperactivation, enlarged neuronal soma, abnormal neurons, and heightened susceptibility to seizures and mortality. Administering rapamycin to hDEPDC5^F685L mice starting two weeks after birth normalized neuronal size and mTOR activity, decreased seizure susceptibility and mortality, and showed no effects in the WT or hDEPDC5^WT mice. Collectively, these results indicate that the DEPDC5 variant causes abnormal morphology and increased seizure vulnerability through modulation of mTOR signaling.