Alarin potentiates ongoing epileptiform activity in rat brain slices: an in vitro electrophysiological study

Abstract

Alarin is a newly discovered neuropeptide that belongs to the galanin peptide family and has a wide range of bioactivity in the nervous system. Its function in the brain's autonomic areas has been studied, and it has been reported that it is involved in the regulation of excitability in hypothalamic neurons. Its role in the regulation of excitability in the hippocampus, however, is unknown. In this study, we investigated if alarin induced any synchronous discharges or epileptiform activity, and if it has any effect on previously initiated epileptiform discharges. We used 350 µm thick acute horizontal hippocampal slices obtained from 30- to 35-day-old rats. Extracellular field potential recordings were evaluated in the hippocampus CA1 region. Our data demonstrated that, alarin application did not initiate any epileptiform activity or abnormal discharges. 4-Aminopyridine was applied to induce epileptiform activity in the slices. We found that 200 nM alarin increased the frequency of interictal-like events and mean power of local field potentials in the hippocampus CA1 region which was induced by 4-aminopyridine. These results exhibited for the first time that alarin has a modulatory effect on synchronized neuronal discharges which should be considered in future therapeutic approaches.