Effects of chronic lacquer thinner inhalation on the open-field behaviors and pain reaction time in rats

Abstract

Open-field stereotype behaviours, motor activity and tail-flick pain reaction time of rats chronically exposed to lacquer thinner (30.9 mg/l of air for 1 hr a day, 5 days per week for 2 months) were quantified both before and after thinner exposure. The frequency of gnawing + licking was found to be lower and the tail-flick pain reaction time was found to be higher in rats chronically exposed to thinner immediately before thinner exposure. There were significant reductions in the frequency of sniffing and exploring and increases in tail-flick pain reaction time in chronically exposed rats after thinner exposure as compared with the pre-exposure period. There were no significant changes in the structure of the brain, kidney, adrenal gland, liver, spleen, lung and the heart of rats exposed to thinner for 2 to 5 months. The changes in behaviours in these rats indicate damages to neuronal functions caused by the mixed solvents. The increase in the tail-flick pain reaction time in the chronically exposed rats correlates well with the increase in pain threshold in human lacquer thinner addicts in Thailand.