NLRP3-GABA signaling pathway contributes to the pathogenesis of impulsive-like behaviors and cognitive deficits in aged mice.

Background: Perioperative neurocognitive disorders (PND), such as delirium and cognitive impairment, are commonly encountered complications in aged patients. The inhibitory neurotransmitter γ-aminobutyric acid (GABA) is aberrantly synthesized from reactive astrocytes following inflammatory stimulation and is implicated in the pathophysiology of neurodegenerative diseases. Additionally, the activation of NOD-like receptor protein 3 (NLRP3) inflammasome is involved in PND. Herein, we aimed to investigate whether the NLRP3-GABA signaling pathway contributes to the pathogenesis of aging mice's PND.

Methods: 24-month-old C57BL/6 and astrocyte-specific NLRP3 knockout male mice were used to establish a PND model via tibial fracture surgery. The monoamine oxidase-B (MAOB) inhibitor selegiline (1 mg/kg) was intraperitoneally administered once a day for 7 days after the surgery. PND, including impulsive-like behaviors and cognitive impairment, was evaluated by open field test, elevated plus maze, and fear conditioning. Thereafter, pathological changes of neurodegeneration were explored by western blot and immunofluorescence assays.

Results: Selegiline administration significantly ameliorated TF-induced impulsive-like behaviors and reduced excessive GABA production in reactive hippocampal astrocytes. Moreover, astrocyte-specific NLRP3 knockout mice reversed TF-induced impulsive-like and cognitive impairment behaviors, decreased GABA levels in reactive astrocytes, ameliorated NLRP3-associated inflammatory responses during the early stage, and restored neuronal degeneration in the hippocampus.

Conclusions: Our findings suggest that anesthesia and surgical procedures trigger neuroinflammation and cognitive deficits, which may be due to NLRP3-GABA activation in the hippocampus of aged mice.