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

Alarin is a newly discovered neuropeptide that belongs to the galanin peptide family with 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 alarin 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 had any effect on already initiated epileptiform discharges. We used thick acute horizontal hippocampal slices obtained from 30‑ to 35‑day‑old rats. Extracellular field potential recordings were evaluated in the CA1 region of the hippocampus. Our data demonstrated that, alarin application did not result in any epileptiform activity or abnormal discharges. 4‑aminopyridine was applied to induce epileptiform activity in the slices. We found that alarin increased the frequency of interictal‑like events and the mean power of local field potentials in the CA1 region of the hippocampus, which was induced by 4‑aminopyridine. These results demonstrated for the first time that alarin has a modulatory effect on synchronized neuronal discharges and showed the contribution of the neuropeptide alarin to epilepsy‑like conditions.