Barrel cortex development lacks a key stage of hyperconnectivity from deep to superficial layers in a rat model of Absence Epilepsy

During development of the sensory cortex, the ascending innervation from deep to upper layers provides a temporary scaffold for the construction of other circuits that remain at adulthood. Whether an alteration in this sequence leads to brain dysfunction in neuro-developmental diseases remains unknown. Using functional approaches in a genetic model of Absence Epilepsy (GAERS), we investigated in barrel cortex, the site of seizure initiation, the maturation of excitatory and inhibitory innervations onto layer 2/3 pyramidal neurons and cell organization into neuronal assemblies. We found that cortical development in GAERS lacks the early surge of connections originating from deep layers observed at the end of the second postnatal week in normal rats and the concomitant structuring into multiple assemblies. Later on, at seizure onset (1 month old), excitatory neurons are hyper-excitable in GAERS when compared to Wistar rats. These findings suggest that early defects in the development of connectivity could promote this typical epileptic feature and/or its comorbidities.

The Effect of Ciprofloxacin Injection on Genetically Absence Prone (Wag/Rij) Rat's Electroencephalogram Characteristics

INTRODUCTION

Ciprofloxacin which was used in this study is a Fluoroquinolone (FQ). This kind of drug may cause epileptic seizures probably because of the inhibition of GABA binding to its receptors. Wag/Rij rats (an animal model for generalized absence epilepsy), were used as experimental subjects.

METHODS

For EEG study, electrodes were inserted into the cortex of animals according to paxinos coordinates. After and before ciprofloxacin injection, EEG was recorded and their SWDs were compared with each others.

RESULTS

Findings showed a significant increase in the mean number of seizures during recording period. But the mean number of SWDs during seizures did not show any significant differences between groups.

DISCUSSION

These results may be due to involvement of GABA antagonistic effects of FQs and/or Mg2+ linked blockade of NMDA receptors. More researches are going to determine physiopathology of SWDs and find new effective substance against this kind of epilepsy.