ORIGINAL ABSTRACT

Glyphosate is reported to compromise the central nervous system and induce behavioral disorders in mammals. However, evidence is deficient with respect to the potential mechanisms involved. In this study, C57BL/6 mice were orally exposed to glyphosate at doses ranging from 0 to 200 mg/kg/day for 16 weeks. The results of behavioral tests showed that glyphosate decreased time spent and distance traveled within the central area of open field test, decreased the retention time and number of entries into the open arms, and increased the retention time and number of entries into the close arms of elevated plus maze test. The expressions of anxiety-related genes htr5, htr6, and tmem132d were also significantly upregulated by glyphosate. This behavioral phenotype was linked to the permeation of glyphosate into the brain via disrupting the functional tight junctions of blood-brain barrier (BBB). As a result, glyphosate directly compromised the morphological structure of neurons, increased the number of IBA-1 microglia, and activated the expression of NLRP3-mediated pyroptosis pathway (NLRP3, Caspase-1, GSDMD, and IL-18) in the hippocampus of mice. Moreover, the glyphosate-induced activation of NLRP3 pathway in microglia was markedly reversed by NLRP3 inhibitor MCC950. The conditional mediums from glyphosate-treated BV2 cells aggravated the cytotoxicity of HT-22 neurons, which was also rescued by MCC950. In conclusion, this work demonstrated that microglia-mediated activation of NLRP3 pyroptosis pathway plays a detrimental role in glyphosate-behavioral disorders and neuron damage. These findings provide novel evidence for glyphosate-induced neurotoxicity and support the growing association between glyphosate exposure and neurobehavioral disorders in humans.