Systemic delivery of selective EP1 and EP3 receptor antagonists attenuates pentylenetetrazole-induced seizures in mice

Abstract

Neuroinflammation plays a major role in brain excitability and may contribute to the development of epilepsy. Prostaglandin E ₂ (PGE ₂) is a direct mediator of inflammatory responses and, through EP receptors, plays an important role in neuronal excitability. Pharmacological evidence supports that centrally-administered EP1 and EP3 receptor antagonists reduced acutely evoked seizures in rats. Translation of these findings would benefit from evidence of efficacy with a more clinically relevant route of delivery and validation in another species. In the current study we investigated whether the systemic administration of EP1 and EP3 agonists and antagonists modulate pentylenetetrazole (PTZ)-induced seizures in mice. In addition, it was examined whether these compounds alter Na ⁺, K ⁺-ATPase activity, an enzyme responsible for the homeostatic ionic equilibrium and, consequently, for the resting membrane potential in neurons. While the systemic administration of EP1 and EP3 antagonists (ONO-8713 and ONO-AE3-240, respectively) attenuated, the respective agonists (ONO-DI-004 and ONO-AE-248) potentiated PTZ-induced seizures (all compounds injected at the dose of 10 µg/kg, s.c., 30 min before PTZ challenge). Co-administration of either EP1 or EP3 agonist with the respective antagonists nullified the anticonvulsant effects of EP1/3 receptor blockade. In addition, EP1 and EP3 agonists exacerbated PTZ-induced decrease of Na ⁺, K ⁺-ATPase activity in both cerebral cortex and hippocampus, whereas, EP1 and EP3 antagonists prevented PTZ-induced decrease of Na ⁺, K ⁺-ATPase activity in both structures. Our findings support and extend evidence that EP1 and EP3 receptors may be novel targets for the development of anticonvulsant drugs.