Spontaneous epileptic rats show changes in sleep architecture and hypothalamic pathology

Purpose: The goal of the present study was to investigate the relationship between sleep, hypothalamic pathology, and seizures in spontaneous epileptic rats. Methods: Rats were implanted with radiotelemetry transmitters for measuring electrocorticogram (ECoG) and stimulation electrodes in the hippocampus. Epileptogenesis was triggered by 2 h of electical stimulation-induced self-sustained status epilepticus (SSSE). After SSSE, ECoGs were monitored over a 15-week period for the occurrence of interictal high-amplitude low-frequency (HALF) activity and spontaneous reoccurring seizures (SRSs). Results: Spontaneous epileptic rats showed clinical features of temporal lobe epilepsy (TLE), such as spontaneous seizures, interictal activity and neuronal cell loss in the dorsomedial hypothalamus, a region important for normal sleep regulation. Interestingly, epileptic rats showed disturbances in sleep architecture, with a high percentage of the seizures occurring during sleep. Conclusions: Therefore we conclude that a close association exists between epileptiform activity and alterations in sleep architecture that may be related to hypothalamic pathology

Measurement of cortical and hippocampal epileptiform activity in freely moving rats by means of implantable radiotelemetry

Implanted radiotelemetry has been used for the measurement of cortical electroencephalogram (EEG), locomotor activity, body temperature and cardiovascular parameters. This technique allows high quality data acquisition from freely moving animals with no complications of externalised apparatus. This paper focuses on the methodology for short and long-term monitoring of epileptiform activity by simultaneous cortical EEG, hippocampal (HC) EEG and electromyogram (EMG) in rats. The circadian rhythm of temperature (CRT) was monitored after surgery to estimate the need for post surgical recovery of animals. Different placements of EMG electrodes were assessed in order to minimise artefacts and increase sensitivity. The occurrence of epileptiform ictal and interictal activity following an acute injection of either 40 mg/kg pentylenetetrazole (PTZ) or 13.8 mg/kg kainic acid (KA) was investigated. The occurrence of spontaneous seizures was also monitored 5-8 weeks after administration of KA. The present study demonstrated a sensitive method for monitoring cortical EEG, hippocampal EEG and EMG short and long-term by implantable radiotelemetry in freely moving rats