Effect of eugenol on spreading depression and epileptiform discharges in rat neocortical and hippocampal tissues

Eugenol, an aromatic molecule derived from several plants, has been receiving examination for clinical relevance in epilepsy and headache. To investigate the neurophysiologic properties of the action of eugenol, its effects on epileptiform field potentials elicited by omission of extracellular Mg2+, spreading depression induced by KCl microinjection, electrically evoked field potentials, and long-term potentiation were tested in rat neocortical and hippocampal tissues. Eugenol (10-100 micromol/l) dose-dependently and reversibly suppressed both epileptiform field potentials and spreading depression Eugenol also reversibly decreased the amplitude of the field postsynaptic potentials evoked in CA1 area of hippocampus and the third layer of neocortex. Eugenol significantly reduced the long-term potentiation by approximately 30% compared with controls. Thus, eugenol can suppress epileptiform field potentials and spreading depression, likely via inhibition of synaptic plasticity. The results indicate the potential for eugenol to use in the treatment of epilepsy and cephalic pain.