Abstracts

Epilepsy is a chronic neurological disorder characterized by long-term spontaneous recurrent seizures (SRS) that cause structural and functional alterations in the brain. Seizure activity induces significant neuroinflammatory responses while prostaglandin E2 receptor subtype 2 (EP2) is critically involved in neuroinflammation and neurodegeneration following status epilepticus (SE). We reported that EP2 receptor antagonism mitigates multiple deleterious consequences of SE [1]. But there is no research investigating the effect of EP2 antagonism on alleviating long-term SRS in free moving animal, which is more representative to seizure occurrence in patients.

TG11-77, a novel potent selective EP2 receptor antagonist, has demonstrated efficacy in reducing microgliosis 4 days after SE and memory deficits 8-17 days after SE [2]. Our data shows that TG11-77 treatment significantly decreases long-term SRS burden accumulation compared to vehicle control, suggesting its potential as a therapeutic intervention for spontaneous epilepsy management.

Terbutaline (4 mg/kg) and methylscopolamine (4 mg/kg) in saline were i.p. injected into 8-12 weeks old C57BL/6 male mice. 30 minutes later, pilocarpine HCl (280 mg/kg) was i.p. injected to induce status epilepticus (SE) for 1 hour, followed by diazepam (10 mg/kg) to interrupt SE. Mice were randomized to two groups based on the seizure severity score (Racin scale) and treated with either TG11-77 (9 mg/kg) or vehicle (10% DMSO, 50% PEG400 and 40% Water), with 3 injections at 4, 8, and 19 hours post-SE. After 11 weeks post-SE, a modified 3D-printed headcap [3] was implanted on tested mice skull. Free moving mice were recorded EEG for SRS for 3 weeks starting at the 12^th week post-SE.

Reference

1.            Jiang, J., et al., Inhibition of the prostaglandin receptor EP2 following status epilepticus reduces delayed mortality and brain inflammation. Proc Natl Acad Sci U S A, 2013. 110(9): p. 3591-6.

2.            Varvel, N.H., et al., Preclinical development of an EP2 antagonist for post-seizure cognitive deficits. Neuropharmacology, 2023. 224: p. 109356.

3.            Zhu, K.J., L.M. Aiani, and N.P. Pedersen, Reconfigurable 3D-Printed headplates for reproducible and rapid implantation of EEG, EMG and depth electrodes in mice. J Neurosci Methods, 2020. 333: p. 108566.

Acute 9 mg/kg TG11-77 administration significantly slow down the accumulation of SRS burden over the 2^nd week recording period (Fig. 1. p = 0.0082, Kolmogorov-Smirnov test. Veh, n=11; TG11-77, n=9). Even without significantly affect the averaged SRS duration (Veh 33.57 ± 1.17 s, TG11-77 35.98 ± 1.96 s, p = 0.287), nor the SRS frequency per day (Veh 1.41 ± 0.61 / day, TG11-77 1.15 ± 0.55 / day, p = 0.757, student’s t-test, respectively).

This study reveals the critical link between neuroinflammation and long-term spontaneous epileptogenesis, and a proof-of-concept that EP2 receptor antagonism may be a novel therapeutic strategy for reducing seizure burden long after-SE.