<abstract xmlns="http://www.w3.org/1999/xhtml">We have earlier demonstrated the potential of monocrotophos (MCP), a highly toxic organophosphorus insecticide (OPI), to elicit insulin resistance in rats after chronic exposure. Given the understanding of role of paraoxonase1 (PON1) in OPI toxicity and diabetes pathology, this study was envisaged to understand the effect of duration of exposure to MCP on plasma PON1 activity in rats. Rats were administered MCP <italic>per os</italic> at 1/20 and 1/10th LD50 as daily doses for 180 days. Interim blood samples were collected at 15, 30, 45, 90 and 180 d for analysis of plasma parameters. Exposure to MCP for 45 resulted in persistent trend of hyperinsulinemia, while significant increase in fasting glucose levels was observed after 180 days. MCP caused suppression of plasma cholinesterase activity though the study period, albeit extent of inhibition was more severe during the early phase of the study. Exposure to MCP for 180 d resulted in hypertriglyceridemia and marginal decrease in HDL-C levels. MCP failed to modulate PON1 activity in plasma during the early phase of the study (up to 45 d). However, prolonged exposure resulted in significant increase in the plasma PON1 activity. This suggests that manifestation of insulin resistance in rats subjected to chronic exposure to MCP is associated with increase in PON1 activity. Our work provides rationale for studying whether the increase in PON1 activity observed in the present study serves to counter the deleterious effect of long term exposure to organophosphorus insecticides on metabolic homeostasis.</abstract>

We have earlier demonstrated the potential of monocrotophos (MCP), a highly toxic organophosphorus insecticide (OPI), to elicit insulin resistance in rats after chronic exposure. Given the understanding of role of paraoxonase1 (PON1) in OPI toxicity and diabetes pathology, this study was envisaged to understand the effect of duration of exposure to MCP on plasma PON1 activity in rats. Rats were administered MCP per os at 1/20 and 1/10th LD50 as daily doses for 180 days. Interim blood samples were collected at 15, 30, 45, 90 and 180 d for analysis of plasma parameters. Exposure to MCP for 45 resulted in persistent trend of hyperinsulinemia, while significant increase in fasting glucose levels was observed after 180 days. MCP caused suppression of plasma cholinesterase activity though the study period, albeit extent of inhibition was more severe during the early phase of the study. Exposure to MCP for 180 d resulted in hypertriglyceridemia and marginal decrease in HDL-C levels. MCP failed to modulate PON1 activity in plasma during the early phase of the study (up to 45 d). However, prolonged exposure resulted in significant increase in the plasma PON1 activity. This suggests that manifestation of insulin resistance in rats subjected to chronic exposure to MCP is associated with increase in PON1 activity. Our work provides rationale for studying whether the increase in PON1 activity observed in the present study serves to counter the deleterious effect of long term exposure to organophosphorus insecticides on metabolic homeostasis.

Plasma paraoxonase1 activity in rats treated with monocrotophos: a study of the effect of duration of exposure

Food Protectants and Infestation Control Department, CSIR- Central Food Technological Research Institute

Occupational Biochemistry, Regional Occupational Health Centre

Interdisciplinary Toxicology

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

We have earlier demonstrated the potential of monocrotophos (MCP), a highly toxic organophosphorus insecticide (OPI), to elicit insulin resistance in rats...

Plasma paraoxonase1 activity in rats treated with monocrotophos: a study of the effect of duration of exposure

Published Online: Feb 20, 2020

Page range: 129 - 135

Received: Nov 13, 2018

Accepted: Jul 22, 2019

DOI: https://doi.org/10.2478/intox-2019-0015

Keywords
paroxonase1 activity, monocrotophos, organophosphorus insecticide, insulin resistance, chronic exposure, metabolic homeostasis

© 2019 Raju Nagaraju et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Plasma paraoxonase1 activity in rats treated with monocrotophos: a study of the effect of duration of exposure

Published Online: Feb 20, 2020

Page range: 129 - 135

Received: Nov 13, 2018

Accepted: Jul 22, 2019

DOI: https://doi.org/10.2478/intox-2019-0015

Keywordsparoxonase1 activity, monocrotophos, organophosphorus insecticide, insulin resistance, chronic exposure, metabolic homeostasis

© 2019 Raju Nagaraju et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
paroxonase1 activity, monocrotophos, organophosphorus insecticide, insulin resistance, chronic exposure, metabolic homeostasis