Inhalation of 1-bromopropane causes excitation in the central nervous system of male F344 rats

The present study investigates the effects of 1-bromopropane (IBP) on animal behavior to determine the extent of toxicity to the central nervous system (CNS). We measured the spontaneous locomotor activity (SLA) of rats before and after 3 weeks of exposure to IBP for 8 h per day. In control and 10 ppm groups, the SLA values were similar to pre-exposure levels on post-exposure Day 1 and thereafter. However, the SLA values in the 50 and 200 ppm groups were higher than pre-exposure levels. Open-field behavior was evaluated after exposure and freezing time decreased with exposure to increasing concentrations of IBP Ambulation and rearing scores in the exposed groups were higher than control values, particularly in the 50 and 200 ppm groups. The frequency of defecation and urination decreased almost dose-dependently. Exposure to 50-1000 ppm of IBP did not effect passive avoidance behavior examined using a step-through type apparatus. The amount of time swimming in the water maze test was not affected in the controls, or groups exposed to 50 and 200 ppm IBP, but that in the 1000 ppm group was increased compared with control. Exposure at 50-1000 ppm dose-dependently decreased the traction performance of rats, indicating decreased muscle strength. We found that 10-200 ppm of IBP exposure did not effect motor coordination determined by rota-rod performance. The increased SLA values and open-field activity support the notion that IBP has excitatory effects on the CNS of F344 male rats. In addition, IBP reduced the grip or muscle strength of the rats. Memory function was not disordered and the motor coordination of all four limbs remained normal. (C) 2003 Elsevier Inc. All rights reserved.