Ephrin‑b3 modulates hippocampal neurogenesis and the reelin signaling pathway in a pilocarpine‑induced model of epilepsy

Abstract

Ephrin-B3 is important in the regulation of cell proliferation, differentiation and migration via cell-cell contact, and can activate the reelin pathway during brain development. However, the effect of ephrin-B3 on hippocampal neurogenesis and the reelin pathway in epilepsy remains to be fully elucidated. In the present study, the expression of ephrin-B3 in pilocarpine-induced status epilepticus (SE) rats was investigated. SYBR Green-based reverse transcription-quantitative polymerase chain reaction analysis, immunohistochemical labeling and western blot analysis were used to detect the gene and protein expression levels of ephrin-B3 and reelin pathway proteins. Immunofluorescence staining of doublecortin (DCX) was utilized to analyze hippocampal neurogenesis. The data revealed that the mRNA and protein expression levels of ephrin-B3 in the hippocampus decreased during the spontaneous seizure period. Of note, the expression of reelin and its downstream phosphorylation disabled 1 (p-Dab1) were also notably decreased during the spontaneous seizure period, which showed similar dynamic changes as in the expression of ephrin-B3. In addition, it was found that the number of DCX-labeled neuronal progenitor cells was increased in the hippocampus following pilocarpine-induced SE. To further clarify the role of ephrin-B3 in neurogenesis and the reelin pathway in epilepsy, an exogenous ephrin-B3 clustering stimulator, EphB3-Fc, was infused into the bilateral hippocampus of the rats post-SE. Following EphB3-Fc injection, it was found that the expression levels of reelin and p-Dab1 were significantly increased in the epileptic rats following EphB3-Fc injection. The number of DCX-labeled neuronal progenitor cells was reduced in the hippocampus of the epileptic rats. Furthermore, the intensity and frequency of spontaneous recurrent seizures and electroencephalographic seizures were attenuated in the epileptic rats post-injection. These results demonstrated the critical role of ephrin-B3 in regulation of the reelin pathway and hippocampal neurogenesis in epilepsy, providing experimental evidence that ephrin-B3 functions as a potential protective factor in epilepsy, at least in animals.

Ursolic Acid Protects Neurons in Temporal Lobe Epilepsy and Cognitive Impairment by Repressing Inflammation and Oxidation

“…Reelin is an extracellular protein involved in synaptic homeostasis, which affects the shapes, sizes, and types of dendritic spines. Reelin dysregulation occurs in epileptogenesis ( Liu, et al, 2018 ). The immunofluorescence results revealed obvious repression of reelin in rat hippocampal DG regions in the SE group compared to the NC group ( p = 0.0234).…”

The Role of Hippocampal Neurogenesis in ANT-DBS for LiCl-Pilocarpine-Induced Epileptic Rats

“…Doublecortin (DCX) is a protein that is associated with cell migration and differentiation [24, 25]. DCX expression is specific to immature neurons [26, 27].…”

Reelin Is Required for Maintenance of Granule Cell Lamination in the Healthy and Epileptic Hippocampus

“…Also, the presence of small fragments bound to the beads before placement must be considered. These small Reelin fragments were then able to diffuse away from their original position, activating the Reelin signaling pathway by binding to the receptors located on the membrane of dentate GCs (Clatworthy et al, 1999;Sakai et al, 2009; reviewed in Reddy et al, 2011;Dlugosz and Nimpf, 2018;Liu et al, 2018). It is controversially discussed whether Reelin acts as a stopping signal (Dulabon et al, 2000;Chai et al, 2009;Sekine et al, 2011), as a global and locally active attractant signal (Rice and Curran, 2001;Courtès et al, 2011;Wang et al, 2018) or as a locally active repelling signal (D'Arcangelo and Curran, 1998;Wang et al, 2018) during neuronal migration in development.…”