Effects of intermittent chlorpyrifos exposure on autonomic and behavioral responses to contextual fear conditioning

Repeated exposure to organophosphorus (OP) compounds may induce widespread health problems, such as neurological, psychiatric, and cardiovascular abnormalities. OP compounds inhibit acetylcholinesterase (AChE) peripherally and centrally, leading to cholinergic overstimulation. Previously, our group found that repeated and intermittent treatment with the OP chlorpyrifos (CPF), which simulates occupational exposure, impairs the cardiorespiratory reflexes and causes cardiac hypertrophy. Contextual fear conditioning (CFC) is a translational tool used to investigate the processing of associative fear memory, which can be monitored by behavioural (freezing levels) and autonomic responses (mean arterial pressure/heart rate [MAP/HR]).