Anticonvulsant-like effect of thromboxane receptor agonist U-46619 against pentylenetetrazol-induced seizures.

Increasing evidence suggests that prostanoid receptors and their ligands may constitute valuable tools for development of new antiepileptic drugs. Thromboxane A2 (TXA2) is a major eicosanoid in cardiovascular homeostasis. TXA2 exerts its action through the specific G protein-coupled TXA2 receptor (TP). In addition to its crucial role in the cardiovascular system, TXA2 and TPs play a role in the brain. Nevertheless, previously identified roles have been limited to cell protection of neurotoxicity, and the role of TPs on seizure activity was not investigated. Here we evaluated the effect of potent and selective TP agonist U-46619 on seizures induced by pentylenetetrazol (PTZ). Adult C57BL/6 mice received increasing doses of U-46619 (0, 30, 100 or 300 μg/kg). After 30 min we measured the latencies to myoclonic and generalized seizures induced by PTZ (60 mg/kg). We found that U-46619 increased the latency to PTZ-induced myoclonic jerks and tonic-clonic seizures. Moreover, U-46619 increased the immunocontent of phosphorylated Ser657 at protein kinase C (PKC) alpha subunit, indicating PKC activation in the hippocampus and cerebral cortex. Levels of TPs were not altered by the agonist. Administration of a TP antagonist, SQ 29,548, did not alter seizures and did not blunt the anticonvulsant-like effect of the agonist. In summary, we showed that a potent and selective TP agonist, U-46619, increased seizure latency in mice. Activation of PKC signaling pathways may underlie the anticonvulsant-like effect. Further investigation is needed to understand the potential of TPs in seizure treatment.