Neocortical slices from adult chronic epileptic rats exhibit discharges of higher voltages and broader spread

A New Approach of Modified Submerged Patch Clamp Recording Reveals Interneuronal Dynamics during Epileptiform Oscillations

“…We show that in the membrane chamber this activity can also be modeled in ex vivo slices from TeNT-treated rats. This is consistent with a recent study on neocortex which suggests that features of the chronic epileptic condition are maintained in ex vivo slice preparations (Serafini et al, 2016). The cellular correlates of fast ripple activity are unknown, and the membrane chamber provides a new type of recording system in which they could be easily and conveniently probed in brain slices.…”

“…It has been suggested that features of chronic epilepsy are retained in ex vivo neocortical slices (Serafini et al, 2016). All of the rats used for tissue preparation were confirmed by video recording to have experienced spontaneous seizures in vivo in response to TeNT injection.…”

A comparison of anticonvulsant efficacy and action mechanism of Mannitol vs Phenytoin in adult rat neocortical slices

“…Accordingly, we used Mannitol concentrations of 15 mM, 30 mM and 50 mM so as to increase extracellular osmolarity by values of mOsm/l similar to those utilized in clinical practice. We induced epileptiform discharges through perfusion with a medium with 0.1 mM 4-AP and with zero Mg as previously described ( Serafini et al, 2015 , Serafini et al, 2016 ). The effect of extracellular Mannitol-induced hyperosmolarity on epileptiform activity was studied through four distinct protocols: a short pulse (5 min) of a higher Mannitol concentration (50 mM) after the onset of epileptiform discharges ( post -treatment) to assess for evidence of an anti-seizure effect; a prolonged pulse (23 min) of a lower Mannitol concentration (30 mM) after the onset of epileptiform discharges ( post -treatment) to assess for an anti-seizure effect at a concentration with likely low toxicity, potentially to be applied for clinical use; continuous co-perfusion with Mannitol after the onset of epileptiform discharges ( post -treatment) to assess for the maximal anti-seizure effect; co-perfusion with Mannitol (15 mM and 30 mM) before the onset of epileptiform discharges (preventative pre -treatment).…”

“…A digital camera picture of the slice position was taken at the end of the recording. Epileptiform activity was induced by perfusion with 0.1 mM 4-Aminopyridine in a medium devoid of Magnesium following a rationale and a protocol previously utilized by this investigator ( Serafini et al, 2015 , Serafini et al, 2016 ).…”

“…They also exhibit a dose-dependent effect on their frequency and are inhibited from perfusion with an anticonvulsant (see data in Serafini et al, 2015 ). Discharges were classified as isolated discharges (Interictal Epileptiform Discharges, or IEDs) or as rhythmic repetitive discharges (seizures) as previously described ( Serafini et al, 2015 , Serafini et al, 2016 ), following criteria similar to those of clinical EEG practice. In each recording after the initial onset of epileptiform activity we assessed for its stability and persistence for at least 15 minutes before administering Mannitol or Phenytoin.…”