Characterization and comparison of respiratory toxicity induced by sublethal poisoning to two organophosphorus compounds: A pesticide and a sarin structural analog in mice

The chemical risk associated with the use of organophosphorus nerve agents remains a major concern, as highlighted by recent international events (e.g., Syrian conflict, Novichok poisoning incidents) and the tense geopolitical climate. Concurrently, the use of organophosphorus pesticides continues to represent a major global public health challenge, resulting in numerous poisonings and fatalities each year. Organophosphorus compounds exert their toxic effects by irreversibly inhibiting cholinesterase enzymes, disrupting cholinergic signaling within the affected organism. This disruption impairs vital functions and, without appropriate medical intervention, can result in respiratory failure and death. However, whether differences in the molecular and physiological mechanisms underlying organophosphorus compound-induced respiratory failure between pesticides and nerve agents exist remains poorly defined. This study aimed to characterize and compare respiratory toxicity in mice exposed to two sublethal organophosphorus compounds: a pesticide (paraoxon) and a sarin structural analog (NIMP). Respiratory ventilation in mice was monitored using double-chamber plethysmography. Cholinesterase activity and inflammatory biomarkers were quantified in blood and tissues involved in respiration. Both compounds dose-dependently affected ventilatory function of the mice, reducing respiratory rate and minute volume and increasing specific airway resistance. No significant differences were observed between the two organophosphorus compounds in these effects. However, lungs and diaphragm triggered a rapid inflammatory response, depending on the specific organophosphorus compound tested. While NIMP exposure increased IL-6 expression, potentially involving the NF-κB pathway, POX exposure upregulated IL-1ß expression without activating NF-κB. Thus, exposure to POX or NIMP similarly impaired ventilatory function in mice, but distinct signaling pathways appear to be involved.