Epileptogenesis following Kainic Acid-Induced Status Epilepticus in Cyclin D2 Knock-Out Mice with Diminished Adult Neurogenesis

PLoS One. 2015 May 28;10(5):e0128285. doi: 10.1371/journal.pone.0128285. eCollection 2015.

Abstract

The goal of this study was to determine whether a substantial decrease in adult neurogenesis influences epileptogenesis evoked by the intra-amygdala injection of kainic acid (KA). Cyclin D2 knockout (cD2 KO) mice, which lack adult neurogenesis almost entirely, were used as a model. First, we examined whether status epilepticus (SE) evoked by an intra-amygdala injection of KA induces cell proliferation in cD2 KO mice. On the day after SE, we injected BrdU into mice for 5 days and evaluated the number of DCX- and DCX/BrdU-immunopositive cells 3 days later. In cD2 KO control animals, only a small number of DCX+ cells was observed. The number of DCX+ and DCX/BrdU+ cells/mm of subgranular layer in cD2 KO mice increased significantly following SE (p<0.05). However, the number of newly born cells was very low and was significantly lower than in KA-treated wild type (wt) mice. To evaluate the impact of diminished neurogenesis on epileptogenesis and early epilepsy, we performed video-EEG monitoring of wt and cD2 KO mice for 16 days following SE. The number of animals with seizures did not differ between wt (11 out of 15) and cD2 KO (9 out of 12) mice. The median latency to the first spontaneous seizure was 4 days (range 2-10 days) in wt mice and 8 days (range 2-16 days) in cD2 KO mice and did not differ significantly between groups. Similarly, no differences were observed in median seizure frequency (wt: 1.23, range 0.1-3.4; cD2 KO: 0.57, range 0.1-2.0 seizures/day) or median seizure duration (wt: 51 s, range 23-103; cD2 KO: 51 s, range 23-103). Our results indicate that SE-induced epileptogenesis is not disrupted in mice with markedly reduced adult neurogenesis. However, we cannot exclude the contribution of reduced neurogenesis to the chronic epileptic state.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amygdala* / metabolism
  • Amygdala* / pathology
  • Amygdala* / physiopathology
  • Animals
  • Cyclin D2 / deficiency*
  • Doublecortin Protein
  • Electroencephalography
  • Kainic Acid / adverse effects*
  • Kainic Acid / pharmacology
  • Mice
  • Mice, Knockout
  • Neurogenesis* / drug effects
  • Neurogenesis* / genetics
  • Seizures* / chemically induced
  • Seizures* / genetics
  • Seizures* / metabolism
  • Seizures* / pathology
  • Seizures* / physiopathology
  • Status Epilepticus* / chemically induced
  • Status Epilepticus* / genetics
  • Status Epilepticus* / metabolism
  • Status Epilepticus* / pathology
  • Status Epilepticus* / physiopathology

Substances

  • Ccnd2 protein, mouse
  • Cyclin D2
  • Dcx protein, mouse
  • Doublecortin Protein
  • Kainic Acid

Grants and funding

The study was supported by Polish Ministry of Science and Higher Education grant 190/6, PR UE/2006/7 (KL), Polish Science Foundation grant MPD/2009/4 (DM, IK), statutory funds of the University of Finance and Management in Warsaw (RKF), and by the European Union structural funds – Innovative Economy Operational Program – Project No. POIG.01.01.02-00-109/09 (LK). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.