CYTOTOXIC, CARCINOGENIC AND GENOTOXIC EFFECTS OF CARBOSULFAN IN CULTURED MAMMALIAN CELLS
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Date
2021-12-30
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR
Abstract
Carbosulfan a carbamate class of insecticide, is commonly used in
agricultural practices for soil, foliar and seed treatment. There is a paucity of data
about the cytotoxic, carcinogenic and genotoxic effects of carbosulfan. The data
so obtained could be useful in elucidating the various health hazards in humans
and animals due to the environmental exposure to carbosulfan. Hence the present
study was envisaged to evaluate the cytotoxic, carcinogenic and genotoxic effects
of carbosulfan in cultured mammalian cells. The cytotoxic effect was evaluated
using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay
in CHO-K1 cells. The mean cell viability per cent of carbosulfan at 12.5, 25, 50,
100, 250 and 500 µg/mL was found to be 96.93 ± 2.40, 95.66 ± 3.36, 91.89 ±
5.31, 73.28 ± 3.08, 34.24 ± 1.67 which proved carbosulfan to be cytotoxic.
Carbosulfan treatment at 100, 250 and 500 µg/mL showed loss of basic
cytoskeletal structure and cellular contact with reduction in cell density, cell
shrinkage, cell detachment and debris formation. Carbosulfan treatment showed
induction of oxidative stress as revealed by significant (p ≤ 0.001) increase in the
intracellular reactive oxygen species (ROS) generation in CHO-K1 cells. The
DNA fragmentation studies showed significant (p ≤ 0.001) concentration
dependent increase in the per cent of DNA fragments in carbosulfan treated CHO K1 cells. It was observed to produce significant (p ≤ 0.001) DNA damage in
comet assay as evident by significant (p ≤ 0.001) increase in tail length, tail
moment and olive tail moment. Carbosulfan treatment at 50 µg/mL showed time
dependent carcinogenicity in BALB/c 3T3 clone A31 cells using cell
transformation assay revealing the carcinogenic potential of carbosulfan.
Genotoxicity measured using in vitro chromosomal aberration test revealed that
carbosulfan treatment induced significant (p ≤ 0.001) concentration and time
dependent chromosomal aberrations like breaks, gaps and exchange in chromatid,
breaks, gaps and exchange in chromosome, chromosome fragments, dicentric
chromosome, centromeric disruption, ring formation, pulverised chromosome and
multiple aberrations. In vitro micronucleus formation test also showed significant
(p ≤ 0.001) concentration and time dependent increase in the number of binucleate
cells with micronuclei (BNMN). The above results proved carbosulfan to be
genotoxic. Hence the present study concluded that carbosulfan produced
cytotoxicity, carcinogenicity and genotoxicity in cultured mammalian cells due to
the ROS mediated oxidative stress.
Description
Thesis Submitted in partial fulfilment of the requirement for the degree of Master of Veterinary Science in Veterinary Pharmacology and Toxicology