Subacute cholinesterase inhibition and behavioral effects of chlorpyrifos experimentally supplied via drinking water in chicks

Banan Al-Baggou
unpublished
Objective: Chlorpyrifos is a chlorinated organophosphate insecticide that might contaminate the water. The purpose of the study was to assess plasma and tissue cholinesterase inhibition and behavioral effects of chlorpyrifos in young chick model after exposure via the drinking water. Methods: Two-day old chicks were allocated randomly into two groups of 33 birds each. The control group was given free access to tap water, whereas the second group had free access to chlorpyrifos solution prepared
more » ... s solution prepared in tap water (100 ppm) from the age of two days to the age of 27 days. At the ages of 8, 14 and 28 days, chicks of the control and chlorpyrifos groups (n=11/age group) were subjected to measurements of body weight, 3-min open-field activity, tonic immobility, followed by measurement of brain and liver weights as well as determination of plasma, brain and liver cholinesterase activities using an electrometric method. Results: chlorpyrifos did not significantly affect the growth and body weight of the chicks until the age of 28 days. In the chlorpyrifos group, the brain weight significantly increased on day 8, whereas liver weight significantly decreased on day 14 in comparison with respective control values. In the open-field behavioral paradigm, chicks exposed to chlorpyrifos in the drinking water showed significantly decreased locomotor activity at the age of 8 days as well as lower pecking score at the age of 28 days in comparison with respective control values. Significant prolongation of tonic immobility occurred in the chlorpyrifos group at the age of 28 days. Chlorpyrifos decreased cholinesterase activities in the plasma, brain and liver of the chicks at ages of 8, 14 and 28 in comparison with respective age-matched control values by 3-57%. Conclusion: the present findings suggest the sensitivity of the young chick model to examine subtle adverse effects of chlorpyrifos when given in the drinking water. These were expressed in the chicks behaviorally as decreased locomotion and increased tonic immobility and biochemically in the form of decreased cholinesterase activity in the plasma, brain and liver. Citation Al-Baggou BK. Subacute cholinesterase inhibition and behavioral effects of chlorpyrifos experimentally supplied via drinking water in chicks. HVM Bioflux 2014;6(2):70-75.
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