Endocannabinoid Enhancement via MAGL Inhibition in CDKL5 Deficiency: Selective Cellular Benefits and Domain-Specific Functional Effects in Adult Cdkl5 KO Mice.

CDKL5 Deficiency Disorder (CDD) is a severe neurodevelopmental encephalopathy characterized by early disruptions of synaptic maturation and network stability, leading to persistent motor, cognitive, and behavioral impairments. Given the role of the endocannabinoid system in synaptic development, neuroinflammation, and neuronal resilience, we investigated whether the sustained enhancement of endogenous 2-arachidonoylglycerol (2-AG) signaling via monoacylglycerol lipase (MAGL) inhibition could mitigate key pathological features in adult Cdkl5 knockout (KO) mice. Using an intermittent 6-week treatment, the MAGL inhibitor JZL184 robustly increased plasma 2-AG levels, reduced MAGL protein levels, and activated CB1-AKT signaling without evidence of receptor desensitization. Despite this clear pharmacodynamic efficacy, behavioral effects were domain-specific: neither dose ameliorated core behavioral deficits, although the higher dose selectively reduced stereotypic jumping and modestly improved cue-dependent associative memory. At the cellular level, JZL184 induced biologically meaningful effects, partially restoring dendritic spine maturation in the primary somatosensory cortex and increasing neuronal survival in the vulnerable CA1 hippocampal region. In contrast, microglial responses were dose-dependent and divergent, with the lower dose exerting anti-inflammatory effects, while the higher dose increased cortical microglial density and Allograft Inflammatory Factor-1 (AIF-1) expression, suggesting engagement of compensatory or off-target mechanisms. Overall, these findings show that MAGL inhibition activates neuroprotective pathways and ameliorates select structural deficits in adult Cdkl5 KO mice, but is insufficient to produce broad behavioral recovery, highlighting the domain-specific effects of selective 2-AG enhancement via MAGL inhibition and the need for developmentally informed or multimodal therapeutic strategies in CDD.