Activation of ATP-sensitive K-channel promotes the anticonvulsant properties of cannabinoid receptor agonist through mitochondrial ATP level reduction

Abstract

Cannabinoid receptor (CBR) agonist could act as a protective agent against seizure susceptibility in animal models of epilepsy. Studies have shown that potassium channels could play a key role in ameliorating neuronal excitability. In this study, we attempted to evaluate how CBRs and Adenosine Tri-Phosphate (ATP)-sensitive potassium channels collaborate to affect seizure susceptibility by changing the clonic seizure threshold (CST). We used male Naval Medical Research Institute (NMRI) mice and treated them with the following drugs: cromakalim (a potassium channel opener, 10 μg/kg), glibenclamide (a potassium channel blocker, 0.03 and 1 mg/kg), 0.5 mg/kg of AM-251 (a selective CB1 antagonist), AM-630 (a selective CB2 antagonist), and 0.5, 3, and 10 mg/kg of WIN 55,212-2 (a nonselective agonist of CBRs); and CST was appraised after each type of administration. Also, we evaluated the ATP level of the hippocampus in each treatment to clarify the interaction between the cannabinoid system and potassium channel. Our results showed that administration of WIN 55,212-2 at 10 mg/kg significantly increased CST (P < 0.001). This change could be reversed by using AM-251(P < 0.001) but not AM-630. Also, either cromakalim (10 μg/kg) or glibenclamide (0.03 and 1 mg/kg) could not significantly affect the CST. In addition, glibenclamide (1 mg/kg) could reverse the anticonvulsant effect of WIN 55,212-2 (10 mg/kg) on CST (P < 0.001). However, the anticonvulsant effect was observed when cromakalim (10 μg/kg) was added to WIN 55,212-2 at its subeffective dose (3 mg/kg) in comparison to single-treated animals. Interestingly, we observed that CB1 agonist could significantly decrease ATP level. In conclusion, CB1 agonist accomplishes at least a part of its anticonvulsant actions through ATP-sensitive potassium channels, probably by decreasing the mitochondrial ATP level to open the potassium channel to induce its anticonvulsant effect.