Methamidophos, an Organophosphorus Insecticide, Induces Pro-aggressive Behaviour in Mice

Abstract

Although evidence indicates that exposure to organophosphorus (OP) pesticides induces neurobehavioral disorders, little is known about the effects of OP on aggressive behaviour. Our study investigated the effects of repeated exposure to an OP pesticide, methamidophos, on the isolation-induced aggressive behaviour in mice. Forty seven male mice were individually housed for a month. Socially isolated animals were then confronted with a standard non-isolated opponent for 15 minutes (pre-treatment trial), and the latency and frequency of aggressive and general exploratory behaviours were recorded. Based on the presence of attack behaviour in the pre-treatment trial, mice were classified as isolation-induced aggressive and non-aggressive. All mice were then treated for seven days with methamidophos (3.5 mg/kg/day, n=22, ip) or saline (1 mL/kg/day, control group, n=25, ip) and a second trial performed. Repeated exposure to methamidophos induced attack behaviour in non-aggressive mice. The treatment with methamidophos also decreased plasma butyrylcholinesterase and brain acetylcholinesterase activity. These results suggest that methamidophos has a pro-aggressive effect on socially isolated mice.

Neuroreflex control of cardiovascular function is impaired after acute poisoning with chlorpyrifos, an organophosphorus insecticide: Possible short and long term clinical implications

“…The effectiveness of poisoning was also confirmed by the reduction in plasma BuChE activity, when compared to the pre-poisoning condition and with control animals. The assay of the BuChE cholinesterase activity is a proven sensitive method for monitoring exposure to OP compounds (Do Nascimento et al, 2017;Eddleston et al, 2008;Maretto et al, 2012a;Oliveira-Silva et al, 2000;Pohanka, 2013). Interestingly, the measurement of BuChE has been proposed as a potential marker for predicting cardiovascular risk (Sulzgruber et al, 2015;Sun et al, 2016), which further reinforces the importance of measuring this enzyme activity in studies involving OP exposure and cardiovascular effects.…”

Paraoxonasa 1 y su relación con factores de riesgo en fumigadores del estado de Guerrero: estudio preliminar

“…Los síntomas más frecuentes referidos por la población de estudio fueron irritación de la mucosa nasal y bucal, debilidad/fatiga, dolor de cabeza y mareo, síntomas que han sido reportados en otros estudios (Do Nascimento et al 2017, Muñoz-Quezada et al 2017, Hutter et al 2021. Desde el punto de vista biológico, esto es plausible debido a que el mecanismo de acción de los plaguicidas de tipo OF y carbamato consiste en la inhibición de la acetilcolinesterasa (Nagaraju et al 2014), lo que altera los receptores muscarínicos y nicotínicos responsables de la sintomatología aguda que se presenta en casos de intoxicación aguda (Virú-Loza 2015).…”

Hepatic and Renal Toxicity of Methamidophos in Male Domestic Rabbits: Physiological Aspect

“…Pesticide exposure causes liver damage and leakage of cytosolic enzymes from hepatocytes into blood [39,40]. In contrast, ChE was significantly inhibited and such inhibition was previously reported [42]. It is known that organophosphorus pesticides such as methamidophos cause irreversible inhibition of ChE leading to the accumulation of acetylcholine and over activation of acetylcholine receptors at the neuromuscular junction and in the autonomic and central nervous system.…”