The effect of organophosphate exposure on neuronal function and its role in mood disorders

Exposure to organophosphate pesticides has been associated with mood disorders however the biological mechanisms underpinning this remain unclear. In this study we aim to establish an invertebrate model to investigate the effect of the chronic organophosphate exposure that has been associated with mood disorders on neuronal function.

Background to research

Previous research has reported a link between exposure to organophosphate pesticides (OPs), mood disorder and suicidal behaviour. They are the most widely used group of pesticides in the world and are considered by the World Health Organisation (WHO) to be one of the most hazardous pesticides to vertebrate animals, responsible for many cases of poisoning worldwide, particularly in developing countries where protective measures are lacking.

The neurotoxic effects of high-level acute poisoning are well established and involve inhibition of the enzyme acetylcholinesterase (AChE). However, the mechanism through which OP exposure may result in mood disorders is unclear.

Research conducted

Previous studies have demonstrated the relevance of Caenorhabditis elegans as a model for mammalian neurotoxicity to acute OP exposure. In this study we are determining the effect of the chronic OP exposure that has been associated with mood disorders on C. elegans neuronal function.

C. elegans neuronal function can be assessed by studying simple behaviours such as locomotion. We have established a C. elegans model of chronic OP exposure by exposing adult worms to low doses of chlorpyrifos (an OP used in crop spraying) and examining the locomotion behaviour of exposed and control animals using automated tracking software.

Research findings

A plausible mechanism for action for low level OP exposure is currently lacking. These behavioural studies provide the basis for genetic experiments to identify the molecular targets of OP exposure that will help to build a more thorough understanding of how OP exposure contributes to mood disorders.