Inhibition of endocannabinoid degradation in astrocytes reprograms glial reactivity and prevents seizure sequelae

Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy and is characterized by a pathological cascade of excitotoxicity that leads to neuroinflammation, progressive neuronal loss, and subsequent cognitive decline. Despite its prevalence, effective therapies remain lacking. Previous studies have demonstrated that the dysregulation of the endocannabinoid system contributes to epileptic activity. In particular, inactivation of monoacylglycerol lipase (MAGL), the key rate-limiting enzyme responsible for the degradation of the endocannabinoid 2-arachidonoylglycerol (2-AG), an endogenous lipid mediator with anti-inflammatory and neuroprotective properties, suppresses seizures and reduces neuroinflammation. However, the cellular and molecular mechanisms underlying these protective effects remain unclear.

To dissect the cellular mechanisms underlying MAGL-mediated neuroprotection, we employed a kainic acid (KA)-induced status epilepticus model in mice with global, astrocyte-specific (aKO), and neuron-specific (nKO) deletion of mgll. We combined single-nucleus RNA sequencing (snRNA-seq) to map the transcriptomic landscape of glial responses with pharmacological interventions and AAV-mediated gene manipulation to validate key signaling pathways, as well as behavioral assays to assess functional recovery.

We demonstrated that astrocyte-specific mgll deletion attenuated seizure susceptibility and hippocampal neuroinflammation, whereas neuron-specific, mgll deletion did not reproduce this broader protective phenotype. Transcriptomic profiling revealed that astrocytic MAGL deficiency fundamentally reshaped the glial response to injury by preventing the transition to pro-inflammatory reactive astrocyte states and suppressing the activation of disease-associated microglia (DAM). Mechanistically, we identified a signaling pathway in which the neuroprotective effects of MAGL inhibition depend on cannabinoid receptor 1 (CB1) activation and are mediated by downstream peroxisome proliferator-activated receptor γ (PPARγ) signaling. Genetic deletion of CB1 abolished the protective effects, whereas pharmacological blockade or AAV-mediated knockdown of PPARγ attenuated these effects. Furthermore, aKO mice exhibited reduced neuronal loss, preserved synaptic structural integrity and protection against post-seizure cognitive deficits.

These findings reveal astrocytic MAGL as a crucial regulatory node after status epilepticus and support a model in which CB1-dependent mechanisms and astrocytic PPARγ-dependent regulation jointly contribute to 2-AG-mediated neuroprotection, attenuating neuroinflammation, preserving synaptic integrity, and reducing post-seizure behavioral deficits in this KA-induced SE model.