Methomyl induced alteration in mice hepatic-oxidative status

Abstract

Methomyl (S-methyl-1-N (methyl carbamoyl) oxy] thio acetimidate, is a N-methyl carbamate broad spectrum insecticide. The methomyl containing technical formulation the "Lannate" was evaluated for its effects on the liver antioxidant contents, oxidative stress by-products and oxidative stress enzyme activities and histopathology in Swiss albino mice. Normal virgin male Swiss albino mice of 90 days old weighing about 25-30g were used in the experiment. The mice were administered 1, 2, 3, and 4mg/kg body wt methomyl for 30 days and effective dose 4 mg for 5, 10, and 20 days to know the dose and durational effect on liver. The mice were sacrificed on day 31 st or 24 hours after the terminal exposure. Liver dissected out freed from adherent tissue and weighed to nearest milligram. The liver histology, estimations of antioxidant contents, oxidative stress by-products and oxidative stress enzyme activities were carried out. Liver antioxidant contents showed that levels of GSH (Glutathione) and ascorbic acid were decreased significantly in mice treated with 2, 3 and 4mg/kg/day methomyl and 4 mg/ kg/ day for 10 and 20days of methomyl treatment, except the level of ascorbic acid was not changed significantly in mice treated with 2 mg/kg body wt. Liver antioxidant products showed that levels of TBARS (thiobarbaturic acid) and protein carbonyl were increased significantly in mice treated with 2, 3 and 4mg/kg/day methomyl and 4 mg/ kg/ day for 10 and 20days of methomyl treatment, except the level of TBARS was not changed significantly in mice treated with 2 mg/kg body wt of methomyl. Liver oxidative stress enzyme activities showed that levels of CAT (Catalase), SOD (super oxide dismutase) and GST (Glutathione-s-transferase) were decreased significantly in mice treated with 2, 3 and 4mg/kg/day methomyl and 4 mg/ kg/ day for 10 and 20days of methomyl treatment. The Histology of liver of mice treated with 2, 3 and 4 mg / kg/ day methomyl and 4 mg / kg/ day for 10 and 20days of duration showed that dilation of central vein, sinusoids between hypertrophied hepatocytes and cytoplasmic vacuolization with loss of radial arrangement of cells. The result of the present study suggests that chronic exposure to methomyl insecticide has deleterious effect on liver. The study also revealed that the methomyl might have affected cell metabolism and cell membrane permeability and detoxification system in liver.