Organophosphorus insecticide, monocrotophos, possesses the propensity to induce insulin resistance in rats on chronic exposure.

Background: Our earlier studies had shown that monocrotophos (MCP), an
organophosphorus insecticide (OPI), has the propensity to augment the secondary
complications associated with type-1 diabetes. The present study investigates
whether rats exposed for prolonged periods to monocrotophos would
develop insulin resistance mediated by alteration in glucose homeostasis.
Methods: Male rats were administered sublethal doses of monocrotophos
daily for 180 days. Interim blood samples were collected to measure alteration
in blood glucose and lipid profile. Rats were also subjected to glucose and
insulin tolerance test and fasting blood glucose and insulin levels were measured
to calculate insulin resistance by HOMA-IR method. After 180 days,
the rats were also evaluated for pancreatic histology and activities of hepatic
gluconeogenetic enzymes.
Results: Monocrotophos elicited a gradual and sustained increase in blood
glucose and insulin resistance in rats with concomitant glucose intolerance
and reduced insulin sensitivity. MCP exposure was also associated with
increase in weights of key white adipose pads, activities of gluconeogenesis
enzymes and increase in pancreatic islet diameter, all of which led to hyperglycemia,
hyperinsulinemia and dyslipidaemia.
Conclusion: Long-term exposure of rats to MCP resulted in glucose intolerance
with hyperinsulinemia, a hallmark of insulin resistance. Our data suggest
that chronic exposure to low doses of monocrotophos, might lead to development
of insulin resistance by altering lipid profile and glucose homeostasis