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Investigations on pesticide-induced endocrine disruption with special reference to biochemical alterations in adrenal cortex and their consequences

Apurva Kumar, R. J. (2010) Investigations on pesticide-induced endocrine disruption with special reference to biochemical alterations in adrenal cortex and their consequences. PhD thesis, University of Mysore.

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Abstract

The present work was carried out to investigate (a) the impact of organophosphorus insecticides (OPI) (acephate and monocrotophos) and organochlorine insecticide (hexachlorocyclohexane; HCH) on adrenocortical functions in rats by assessment of their effects on circulating levels of steroid hormones and associated change in adrenals (b) consequences of their effects on adrenocortical functions (c) toxic effects of OPI (those with potential to alter adrenocortical functions in rats) against the nematode, Caenorhabditis elegans. Our results clearly demonstrated that both OPI and HCH have the propensity to modulate adrenocortical functions. OPI were found to cause hyperactivation of adrenocortical functions characterized by hypercorticosteronemia and depletion of adrenal cholesterol. HCH treatment caused decrease in circulating levels of corticosterone. Under these experimental conditions, OPI elicited hyperglycemia in rats with concomitant increase in liver gluconeogenesis enzymes. Contrastingly, HCH caused decrease in blood glucose levels and decrease in activities of key liver gluconeogenesis enzymes. Stressogenic and hyperglycemic potential of monocrotophos were found to manifest as simultaneous and independent consequences of AChE inhibition. Further studies revealed that physiological significance of hypercorticosteronemia in monocrotophos-treated rats was restricted to induction of liver tyrosine aminotransferase, and not hyperglycemia. Our work shows that monocrotophos-induced hyperglycemia is mediated by adrenergic mechanisms and may involve assimilation of lactate in to glucose. Exposure of C. elegans to sublethal concentrations of monocrotophos was associated with AChE inhibition, paralysis and decrease in brood size. Pralidoxime and atropine were able to rescue worms from paralyzing effects of monocrotophos, indicating role of AChE inhibition in paralysis. Our work clearly demonstrated the effects of OPI and HCH on adrenocortical functions and glucose homeostasis. Further, it is clear that monocrotophos-induced hyperactivation of adrenal cortex and hyperglycemia in rats and paralysis in C. elegans is mediated by AChE inhibition.

Item Type: Thesis (PhD)
Uncontrolled Keywords: organophosphorus insecticides, acephate,organochlorine insecticide, monocrotophos, toxic effects, adrenocortical functions
Subjects: 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 26 Pesticide Chemistry
600 Technology > 01 Medical sciences > 17 Toxicology
Divisions: Food Protectants and Infestation Control
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 14 May 2012 09:31
Last Modified: 18 Nov 2016 08:13
URI: http://ir.cftri.com/id/eprint/10737

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