Anticonvulsant effect of aqueous extract of Valeriana officinalis in amygdala-kindled rats: Possible involvement of adenosine

Ethnopharmacological relevance: Valeriana officinalis L (valerian) root extract has been used as an antiepileptic herbal medicine in Iran. Aim of this study: In the present study the effect of valerian extracts on an experimental model of temporal lobe epilepsy (TLE) was evaluated. Moreover, the involvement of adenosine system in the actions of aqueous extract of valerian was evaluated. Materials and methods: Bipolar stimulating and monopolar recording electrodes were implanted stereotaxically in the right basolateral amygdala of male Sprague-Dawley rats. After kindling, the effect of aqueous (200, 500 and 800 mg/kg; intraperitoneal) and petroleum ether (PE; 50 and 100 mg/kg; intraperitoneal) extracts of valerian and CPT (selective A(1) receptor antagonist; 10 and 20 mu M; intracerebroventricular) on after discharge duration (ADD), duration of stage 5 seizure (S5D) and latency to the onset of bilateral forelimb clonuses (S4L) were measured. The effect of CPT (10 mu M) on the response of aqueous extract of valerian (500 mg/kg) was also determined. Results: The results showed that aqueous extract of valerian had anticonvulsant effect. However, PE extract and CPT (20 mu M) had proconvulsant effect. Administration of CPT (10 mu M) before the administration of aqueous extract decreased the anticonvulsant effect of valerian. Conclusions: The results showed significant anticonvulsant effect for aqueous but not PE extract of valerian. Moreover, CPT as a selective adenosine A, receptor antagonist decreased the anticonvulsant effect of valerian aqueous extract. Therefore, we concluded that part of anticonvulsant effect of valerian probably is mediated through activation of adenosine system. (C) 2009 Elsevier Ireland Ltd. All rights reserved.