Chronic acrylamide exposure induced glia cell activation, NLRP3 infl-ammasome upregulation and cognitive impairment

Acrylamide (ACR), a potential neurotoxin, is present in diet and drinking water. Dietary exposure contributes to cognitive impairment, but relevant mechanism information is limited. Neuroinflammation plays important roles in neurodegenerative disorders. This study aimed to explore whether chronic acrylamide exposure induced neuronal lesions, microglial activation, NLRP3 inflammasome-mediated neuroinflammation and cognitive impairment. For this purpose, 36 Sprague-Dawley (SD) rats were randomly divided into three groups (n = 12/group) and maintained on treated drinking water providing dosages of 0, 0.5, or 5 mg/kg/day ACR for 12 months. Chronic exposure to ACR caused gait abnormality and cognitive dysfunction, which was associated with neuronal lesions, decrease in synapse associated proteins including synapsin I (SYN1), synaptophysin (SYP) and postsynaptic density protein 95 (PSD95), neurogenesis suppression as shown by reduced brain derived neurotrophic factor (BDNF) and doublecortin (DCX) in the hippocampus and frontal cortex. ACR stimulated glial proliferation and microglial activation by increasing GFAP⁺, Iba-1⁺, Iba-1⁺CD68⁺ positive cells. ACR markedly upregulated the protein levels of NLRP3 inflammasome constituents NLRP3, caspase-1 and increased pro-IL-1β and IL-1β. ACR elevated the protein P62 to suppress NLPR3 inflammasome cleavage. Inflammatory cytokines including TNF-α, IL-6 and Cox-2 were also significantly increased after NF-κB pathway activation, which aggravated neuronal lesions and caused memory deficits. This work helped to propose the possible mechanism of chronic exposure of ACR-induced neurotoxicity.