The Oxidative Brain Damage Induced By Subthreshold Dose Of Chlorpyrifos On Postnatal Rats

Objective: To explore the oxidative damage effects on postnatal rats exposed to subthreshold doses of chlorpyrifos and the mechanisms of CPF caused development neurotoxicity.Methods: Postnatal 11 days SD rats (n = 108) were randomly divided in to CPF group (n = 36) and control group (n = 72).The control group were then further divided into dimethysulfoxide (DMSO, n = 36) group and normal saline group (NS, n = 36). Postnatal 11-14 days rats were injected with CPF at subthreshold doses for overt systemic toxicity (5 mg/kg/day). The control groups were injected the same doses of DMSO or saline instead. The animals were sacrificed respectively at 12 h, 24 h and 72 h after the final injection and the brains were collected immediately. The Acute organophosphorus pesticide intoxication symptom of the rats was monitored at the above three time points. The superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in the rat brain homogenate were detected by spectrophotometry. Immunohistochemistry assay and Western Blotting assay were taken to detect the expression of protein carbonyl. All data were expressed as the mean±SEM. All data were analyzed using statistic software SPSS v12.0.Results:1. Exposed to subthreshold doses of CPF did not produce any acute organophosphorus pesticide intoxication symptoms.2. The content of MDA in the rat brain homogenate was changed. The CPF group had more MDA than the control groups (p<0.05).3. The content of SOD in the rat brain homogenate was changed. The CPF group had less SOD than the control groups (p<0.05).4. The CPF group had more protein carbonyl than the control group, especially in the hypothalamus detected by the Immunohistochemistry assay. There was significant difference (p<0.05).Conclusions: 1. Exposed to subthreshold doses of chlorpyrifos on postnatal rats can cause oxidative damage;2. Oxidative stress is one of the mechanisms of CPF caused development neurotoxicity.