Targeting microglial GLP1R in epilepsy: A novel approach to modulate neuroinflammation and neuronal apoptosis

Background: Epilepsy is a prevalent disorder of the central nervous system. Approximately, one-third of patients show resistance to pharmacological interventions. The pathogenesis of epilepsy is complex, and neuronal Apoptosis plays a critical role. Aberrantly reactive astrocytes, induced by cytokine release from activated microglia, may lead to neuronal Apoptosis. This study investigated the role of glucagon-like peptide 1 receptor (GLP1R) in microglial activation in epilepsy and its impact on astrocyte-mediated neurotoxicity.

Methods: We used human hippocampal tissue from patients with temporal lobe epilepsy and a pilocarpine-induced epileptic mouse model to assess neurobiological changes in epilepsy. BV2 microglial cells and primary astrocytes were used to evaluate cytokine release and astrocyte activation in vitro. The involvement of GLP1R was explored using the GLP1R agonist, Exendin-4 (Ex-4).

Results: Our findings indicated that reduced GLP1R expression in hippocampal microglia in both epileptic mouse models and human patients, correlated with increased cytokine release and astrocyte activation. Ex-4 treatment restored microglial homeostasis, decreased cytokine secretion, and reduced astrocyte activation, particularly of the A1 phenotype. These changes were associated with a reduction in neuronal Apoptosis. In addition, Ex-4 treatment significantly decreased the frequency and duration of seizures in epileptic mice.

Conclusions: This study highlights the crucial role of microglial GLP1R in epilepsy pathophysiology. GLP1R downregulation contributes to microglial- and astrocyte-mediated neurotoxicity, exacerbating neuronal death and seizures. Activation of GLP1R with Ex-4 has emerged as a promising therapeutic strategy to reduce neuroinflammation, protect neuronal cells, and control seizures in epilepsy. This study provides a foundation for developing novel antiepileptic therapies targeting microglial GLP1R, with the potential to improve outcomes in patients with epilepsy.

A1 astrocyte; Activated microglia; Epileptic mice; Exendin-4; GLP1R; Glia-crosstalk; Homeostatic microglia; Neuronal apoptosis; Neuronal protection; Reactive astrocytes.