Histological changes in liver and lungs of rats exposed to dichlorvos before and after vitamin supplementation

This study evaluated the effect of vitamins with antioxidant activity on the effect of Dichlorvos (2, 2-dichlorovinyl dimethyl phosphate), an organophosphorus compound used in pest control on mammalian organs. Literature is scanty on the histopathological effects of inhalationally administered dichlorvos, especially of the formulations used in Nigeria. The objective of the study is to evaluate these effects on vital organs, with a view to proffering solutions to ameliorate the effects. Fifty Wistar male rats were divided into 10 groups of 5 rats each. A group served as control, while the other groups were exposed to dichlorvos for between 1-6 weeks in a poorly ventilated compartment. The last three groups in addition to dichlorvos exposure received supplementation with vitamin C, E or red palm oil (RPO). Exposure to dichlorvos was done for 4 hours daily. At completion of exposure, animal tissue was processed by the routine method for paraffin wax and stained sections were examined under the light microscope. Histopathological studies of the lung showed extension in the width of bronchial associated lymphoid tissue (BALT), mild generalized congestion of the peri-bronchiolar and inter-alveolar septum as compared with the control. These observations were much reduced in the vitamin-treated groups. Similarly, histopathological studies of the liver showed diffuse vacuolar degeneration of hepatocytes with peri-portal cellular infiltration by mononuclear cells, vacuolar degeneration and necrosis of hepatocytes when compared with the normal. These changes were significantly reduced in the vitamin-supplemented groups. In conclusion, inhalationally absorbed dichlorvos caused histopathological changes in the lung and liver of rats, but these were ameliorated by co-treatment with vitamin supplementation. The changes provide the histological basis for further work and counselling on careful use of dichlorvos for domestic and agriculture, especially in enclosed areas (AU)

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Effect of neferine on toxicodynamics of dichlorvos for inhibiting rabbit cholinesterase.

AIM: To study the effect of neferine (Nef) on toxicodynamics of dichlorvos (DDVP) for inhibiting the rabbit cholinesterase (ChE) and search the relativity between in vivo and in vitro reactivating effect of Nef. METHODS: Calorimetric method was used to determine the blood concentraiton of DDVP, and 3P97 software was used to calculate the parameters of toxicokinetics. Ellman's method was used to determine the ChE activity in plasma. The toxicodynamics curve in vivo and the concentration-effect curve in vitro were drawn to compare the effects of Nef on these two curves. RESULTS: In the rabbit poisoned by ig DDVP 12.5 mg/kg there was almost no effect of Nef on the toxicokinetics of DDVP. The slope of toxicodynamics curves for depressed ChE increased about 3 times after treatment with Nef 7.5 mg/kg and pyratoxime methylchloride (2-PAM Cl) 50 mg/kg, compared with the untreated group, there was a higher significant difference (P<0.01). In vitro Nef shifted the cumulative concentration-effect curve of DDVP on ChE to the right and decreased the maximal inhibitory effect obviously. The shift tendency of concentration-effect curve for DDVP in vitro was similar to that of the curve in vivo, difference between their value b was not significant (P>0.05). CONCLUSION: Nef reactivates the ChE depressed by DDVP. The experiment in vitro may be used as a preliminary index to observe the reactivation of ChE inhibited by anticholinesterases.

Malathion and dichlorvos toxicokinetics after the oral administration of malathion and trichlorfon.

We studied the distribution and persistence of malathion and dichlorvos in the Wistar rat and established their toxicokinetics with the help of the PCNONLIN software program.