Electrophysiological changes induced by different doses of 1-bromopropane and 2-bromopropane

To ascertain the neurotoxicity of 2-bromopropane and 1-bromopropane, three doses of 2-bromopropane (1.1, 3.7 and 11.0 mmol/kg), two doses of 1-bromopropane (3.7 and 11.0 mmol/kg), and a dose of 2,5-hexanedione (2,5-HD) as a positive reference (2.6 mmol/kg) dissolved in olive oil were subcutaneously injected into rats once a day, 5 d/wk for 4 weeks. A control group were injected with olive oil alone. The maximum motor conduction velocity (MCV) and the motor latency (ML) in rat tail nerve, as indexes of the electrophysiological changes, were investigated for 4 weeks. From 2 weeks after the injections, the MCV in the 1-bromopropane and 2-bromopropane-treated groups began to decrease in a dose-dependent fashion. These dose-related decreases continued, and the MCV in the groups injected with 1-bromopropane (11.0 mmol/kg) and 2-bromopropane (3.7 and 11.0 mmol/kg) decreased significantly compared with that in the control group. The ML in the 1-bromopropane and 2-bromopropane-treated groups increased in reverse correlation with the MCV decreases. The changes in ML occurred earlier than the MCV changes in the 1-bromopropane and 2-bromopropane-treated groups. The potency of the peripheral neurotoxic changes induced by 1-bromopropane and 2-bromopropane at the doses used in the present study was weaker than that observed in the positive reference 2,5-HD (2.6 mmol/kg) group.