The Electrophysiological Consequences of Artemisia dracunculus L. (Tarragon) Extract on Pentylenetetrazol-Induced Epileptiform Activity in Snail Neurons

Abstract

Objective: Plant extracts are of considerable interest because of their antiepileptic activities.However, the mechanisms of action are not clearly defined.Materials and Methods: Here, the effects of Artemisia dracunculus L. (tarragon) leavesextract on excitability and electrophysiological characteristics of snail neurones were investigated,using an intracellular recording technique.Results: Application of tarragon extract (0.05%) resulted in complete disappearanceof paroxysmal depolarization shift (PDS) as elicited by pentylenetetrazol (PTZ), an epileptogenicdrug. It also significantly decreased the firing frequency and shifted the firingpattern from bursting in the presence of PTZ to an irregular doublet activity. Changesin excitability properties were associated with a significant increase and decrease inthe duration of action potential, and in the amplitude of after-hyperpolarization (AHP),respectively. When tarragon extract was applied alone, spontaneous activity becameirregular and was interrupted by large inhibitory postsynaptic potentials (IPSPs), whichdisappeared following application of picrotoxin (100 μM). Tarragon also caused a significantdecrease both in the amplitude of action potentials and AHP, and broadened theaction potentials. However, pretreatment with extract did not prevent the induction ofepileptiform activity by PTZ.Conclusion: The findings suggest that tarragon extract may affect membrane ion channelsand/or GABAA receptors leading to a reduction in neuronal excitability.

Keywords

• Epilepsy
• Action Potential
• Artemisia
• Pentylenetetrazol