Long-term behavioral changes in rats following organophosphonate exposure

The organophosphorus compound soman irreversibly inhibits cholinesterase in both the central and peripheral nervous systems. High doses of this compound produce seizures and death in animals. Surviving animals exhibit neural lesions and behavioral abnormalities. The behavioral effects of a single exposure to soman were evaluated in rats injected with 50 micrograms/kg or 85 micrograms/kg soman or with saline. Each rat was tested for either activity in an open field or performance in a 14 choice point multiple T-maze. All rats were then tested for reactivity to tactile stimuli. Some rats exposed to soman showed increased activity in the open field, learning deficits in the Stone maze, and increased reactivity to tactile stimuli, while others showed behavior similar to that of controls. An increase in reactivity was correlated with increased open field activity and with poor performance in the Stone maze. Rats which had received soman and were abnormal in behavioral tests were more likely to have abnormal brain pathology than rats which had received soman and were normal in behavioral tests.