Anxiety–related Behavioral Alterations Following Repeated Paraoxon Exposure in Rats Moslem Mohammadi,

Background and purpose: Organophosphate (OP) compounds exert toxicity by inhibition of acetylcholinesterase (AChE), leading to the accumulation of acetylcholine in cholinergic synapses and overstimulation of the cholinergic system. Hyperactivity of brain cholinergic system can contribute to the pathophysiology of anxiety. The purpose of this study was to investigate the influence of repeated exposure to paraoxon on behaviors related to anxiety in male adult rats. Materials and methods: Adult male Wistar rats were repeatedly exposed to paraoxon at daily doses of 0.1, 0.2, and 0.3 mg/kg, IP for 14 days. Following a recovery period of 24 hours, the anxiety level was determined using behavioral tests (elevated plus-maze and elevated T-maze). Results: Plasma and brain ChE activity was inhibited in a dose dependent manner by paraoxon. Paraoxon (0.3 mg/kg) increased the percentage of entry in the open arms and the time spent on the open arms in the elevated plus-maze (P<0.05). Results of the elevated T-maze showed that 0.3 mg/kg paraoxon increased escape latency and decreased avoidance latencies (P<0.001). Conclusion: Results showed that repeated exposure to 0.3 mg/kg paraoxon exerts anxiolytic-lik