Cholinesterase Effects of Pesticides in Rabbit Embryos and their Potential for Use in Hazard Assessment

Kasim Sakran Abass,Kamal Ali Salih

doi:10.4172/2157-7579.1000401

Abstract

Cholinesterase are often taken as biomarkers of exposure and effect. Then acetylhydrolase isozymes and acylcholine acylhydrolase were examined for their suitability as biomarkers of pesticide exposure. The study of effects of embryos of the rabbit is already an accepted tool in monitor food waste levels, but effects of various groups of substances to the rabbit embryo remain to be studied. A 43% inhibition of acetylhydrolase enzyme activities was reached by 250 mg/kg malathion, while 35% inhibition of acylcholine acylhydrolase enzyme activities was reached by 500 mg/kg malathion indicating the possible use of these enzymes as biomarkers of exposure. There are found some significant specific activities of the acetylhydrolase ranged from 1.5-7.1 U mg−1 protein. The specific activity of acylcholine acylhydrolase in the range of 0.9-4.5 U mg−1 protein in the respective developmental stages. Substratespecificity was analyzed using specific inhibitors (iso-OMPA and BW284c51). The results showed that the observed cholinesterase’s activities in the whole embryo may be attributed mainly to acetylhydrolase with a partial capability to use butyrylthiocholine (BuSCh) as an additional substrate.

Highlights

Several major classes of insecticides are applied in the field as inactive esters which are hydrolyzed within rabbit tissues to release the alcohol or phytotoxic acid [1]
Acylcholine acylhydrolase assay was included in the enzyme analysis to examine if acylcholine acylhydrolase might be a more sensitive biomarker of exposure to insecticides than the cholinesterase isozymes
The results indicate that acetylhydrolase is the dominant cholinesterases enzyme of rabbit embryos

Summary

Introduction

Several major classes of insecticides are applied in the field as inactive esters which are hydrolyzed within rabbit tissues to release the alcohol or phytotoxic acid [1]. The OP (Malathion) is the metabolically activated metabolite the parent substance malaoxon and was chosen as model test substance [2]. It is an OP which forms covalent chemical bonds with the isozymes of the cholinesterases type (acetylhydrolase and acylcholine acylhydrolase) thereby inhibiting it. Acylcholine acylhydrolase assay was included in the enzyme analysis to examine if acylcholine acylhydrolase might be a more sensitive biomarker of exposure to insecticides (malathion a descriptive in this study) than the cholinesterase isozymes. The acetylhydrolase and acylcholine acylhydrolase of the rabbit in the first five days postfertilization of development and the effects of malathion on the cholinesterase isozymes activities were analyzed

Methods

Results

Discussion

Conclusion