Inhibitory effects of glucagon-like peptide-1 receptor on epilepsy

Abstract Glucagon-like peptide-1 (GLP-1) and its receptor, GLP-1R, are valuable tools in the therapy of type 2 diabetes mellitus. Although GLP-1R stimulation is also potentially applicable to neurological disorders, few investigators have evaluated its beneficial effects in neurological disease models. Thus, we aimed to look into the antiepileptic effects of GLP-1R on epilepsy and its underlying mechanisms. The cerebral cortex of 22 patients with temporal lobe epilepsy (TLE) and 16 patients with trauma were collected to the epilepsy and control groups, respectively. Seizures were induced by pentylenetetrazole (PTZ) in rats. Liraglutide was used to up-regulate GLP-1R, and exendin fragment 9–39 (ex9-39) was used to down-regulate GLP-1R. The motor responses and scalp electroencephalograms of rats were recorded, and the interaction between GLP-1R and neuronal receptors (GABA A Rβ2/3, GluA1-4, GluNR1, GluN2A and GluN2B) was evaluated by coimmunoprecipitation. GLP-1R expression was investigated by immunohistochemistry and immunofluorescence staining, and the levels of GLP-1R and neuronal receptors were evaluated by western blotting. The results indicated that GLP-1R was decreased in patients with TLE and in PTZ-treated rats and the administration of liraglutide decreased seizure severity, which indicates that liraglutide exerts antiepileptic effects. Moreover, liraglutide significantly up-regulated GLP-1R and GABA A Rβ2/3 and down-regulated GluA1-4, GluNR1, GluN2A and GluN2B. In addition, ex9-39 exerted adverse effects and weakened the effects of liraglutide. Therefore, GLP-1R might suppress seizures by regulating the levels of neuronal receptors.