Neurotoxicity of acrylamide has been demonstrated both in humans and animals, while the mechanisms remain largely unknown. We recently reported TNF-α deletion suppressed acrylamide-induced neurotoxicity in mice at low dose. Here we further investigated expression of antioxidant and proinflammatory cytokines to explore roles of TNF-α. Wild type and TNF-α KO mice were exposed to acrylamide at 0/12.5/25 mg/kg bw for 28 days. The results showed that acrylamide significantly decreased body weight at 12.5 and 25 mg/kg bw, but decreased brain weight only at 25 mg/kg bw. TNF-α deletion didn’t alleviate the above effects. Also, TNF-α deletion didn’t alleviate decrease of grip strength at 25 mg/kg bw. Immunohistochemical results showed that TNF-α deletion alleviated noradrenergic axon degeneration in cortex S1FL and S1HL regions at 12.5 mg/kg bw, but not 25 mg/kg bw. Moreover, TNF-α deletion suppressed acrylamide-induced upregulation of TGF-β and NF-κB, but didn’t suppress upregulation of IL-6, suggesting possible roles of IL-6 in acrylamide-induced neurotoxicity, particularly at high concentration. Moreover, this study showed a dipolar effect of TNF-α deletion on oxidative stress pathways, i.e., at 25 mg/kg bw, TNF-α deletion suppressed upregulation of oxidative stress (Keap1/HO-1/Gclc/Gclm/Sod/Cat/Gstm/MT-1); however, at 12.5 mg/kg bw, TNF-α deletion accelerated upregulation of Nqo1/Gclm/Sod1/Cat/Gsr. Taken together, genetic TNF-α ablation, at least partially, alleviated acrylamide neurotoxicity at low concentration. Limited alleviation effects at high concentration generated a hypothesis that this may be due to IL-6 signaling and dipolar regulating effects of TNF-α deletion on oxidative stress pathway. This study provided new insights into acrylamide neurotoxicity and TNF-α-targeting strategy.
Zong et al. (Thu,) studied this question.