Effect of PON1 on dichlorvos toxicokinetics

OBJECTIVES: To provide toxicokinetic and clinical evidence of the hydrolytic effect of paraoxonase-1 (PON1) on acute organophosphate poisoning in rats. METHODS: 40 male Wistar rats were randomised into four equal groups. Dichlorvos administration group (A group) underwent dichlorvos injection (dissolved in corn oil) using intraperitoneal (ip) dose of 10 mg/kg. PON1 pretreatment group (B group) was injected with PON1 in the tail vein (intravenous), dose 9600 U/kg, 30 min prior to dichlorvos administration. In the treatment group (C group), atropine 0.05 mg/kg and pyraloxime chloride (PAM-CI) 120 mg/kg were injected intravenously within 2 min after dichlorvos administration. Finally, in the co-treatment group (D group), PON1 was injected intravenously with a dose of 9000 U/kg 30 min prior to dichlorvos administration; atropine 0.05 mg/kg and PAM-CI 120 mg/kg were injected intravenously within 2 min after dichlorvos administration. Blood was collected after administration. Plasma dichlorvos concentration was detected by liquid chromatography-mass spectra (LC-MS) method and clinical signs were observed. Toxicokinetic parameters were calculated in a statistical moment model. RESULTS: AUC (0→∞) in group B was statistically different from that in groups A and C (p<0.05), while it was not different from group D (p>0.05); there was no statistical difference between group A and group C (p>0.05). The statistical results of Cmax were the same as those of AUC (0→∞). There were no differences of MRT between four groups (p>0.05). Clinical signs can be improved by PON1 and atropine + PAM-CI, and co-treatment can relieve signs more effectively. CONCLUSION: PON1 can decrease the amount of dichlorvos that entered the blood, lowered the peak concentration and relieved clinical signs.