Antiepileptogenic effects of the selective COX-2 inhibitor etoricoxib, on the development of spontaneous absence seizures in WAG/Rij rats

• Early long-term treatment with etoricoxib is antiepileptogenic in WAG/Rij rat model.
• Etoricoxib effects are long-lasting, at least up to 5 months after drug withdrawal.
• Acutely administered etoricoxib also has anti-absence effects in this model.
• COX2 are involved in absence seizure generation and epileptogenesis in WAG/Rij rats.

Different data suggest the involvement of specific inflammatory pathways in the pathogenesis of epilepsy. Cyclooxygenase (COX), which catalyses the production of pro-inflammatory prostaglandins, may play a significant role in seizure-induced neuroinflammation and neuronal hyperexcitability. COX-2 is constitutively expressed in the brain and also increased during/after seizures. COX-2 inhibitors may thus attenuate inflammation associated with brain disorders. We studied whether early long-term treatment (17 consecutive weeks starting from 45 days postnatal age) with the non-steroidal anti-inflammatory drug etoricoxib (10 mg/kg/day per os), a selective COX-2 inhibitor, was able to prevent/reduce the development of absence seizures in WAG/Rij rats, a recognized animal model of absence epilepsy and epileptogenesis. Drug effects on the incidence, duration and properties of absence seizure spike-wave discharges (SWDs) were measured both 1 and 5 months after treatment withdrawal; furthermore, the acute effects of etoricoxib on SWDs in 6-month-old WAG/Rij rats were measured. Early long-term treatment (ELTT) with etoricoxib led to an ∼40% long-lasting (5 months) reduction in the development of spontaneous absence seizures in adult WAG/Rij rats thus exhibiting antiepileptogenic effects. Acutely administered etoricoxib (10 and 20 mg/kg i.p.) also had anti-absence properties, significantly reducing the number and duration of SWDs by ∼50%. These results confirm the antiepileptogenic effects of COX-2 inhibitors and suggest the possible role of COX-2, prostaglandin synthesis and consequent neuroinflammation in the epileptogenic process underlying the development of absence seizures in WAG/Rij rats.