Prostaglandin EP4 receptor agonist protects against acute neurotoxicity

Under various abnormal physiologic conditions, overactivation of glutamate-gated ion channel receptor family members, including NMDA receptors, causes increase in COX-2 expression and generation of prostaglandins. PGE(2) exerts its physiologic actions mainly through its PGE(2) prostanoid (EP) receptors. In the present study, the role of the EP4 receptor against NMDA-induced excitotoxicity was investigated. Using the EP4 receptor agonist ONO-AE1-329, which has relative selectivity toward murine EP receptors on the order of EP1:EP2:EP3:EP4 of >1000:210:120:1, respectively, we questioned whether activation of the EP4 receptors has the potential to attenuate injury in brain. Mice were pretreated by intracerebroventricular injection with different doses of ONO-AE1-329 (0.1, 1, and 10 nmol; n = 9/group) and, after 20 min, by a single unilateral intrastriatal injection of NMDA (15 nmol, n = 12). NMDA injection produced a significant lesion in the ipsilateral striatum. This lesion volume was significantly reduced in groups that were pretreated with ONO-AE1-329, with maximum protection of more than 32% at 10 nmol. This is the first study revealing the protective effect of ONO-AE1-329 in an acute model of excitotoxicity in brain, and it suggests that preferential stimulation of EP4 receptors attenuates excitotoxic brain injury.