Open-field behaviors and pain reaction time of naive rats before and after acute lacquer thinner exposure

Abstract

Experiments were carried out on naive Wistar rats to determine the effects of 3-days exposure to lacquer thinner (30.9 mg/l of air, 1 hr a day). During the period of sham exposure two major groups of open-field behaviours (RAB) and slowly adapting behaviours (SAB). The RAB consisted of sniffing, exploring, rearing and motor activity. The SAB consisted of grooming and gnawing + licking. The frequency of RAB decreased rapidly after sham exposure compared with before. In contrast, the SAB did not show significant decrease in frequency after sham exposure. The frequency of SAB was generally less than that of the RAB. Immediately after thinner exposure, the frequency of some RAB (sniffing and motor activity) increased but that of some RAB (exploring and rearing) and SAB was unchanged. The tail-flick pain reaction time showed a significant decrease on the 1(st) day of sham exposure, but not further significant changes on subsequent 5 days of sham and thinner exposure. The rapid decrease of RAB during control period may be due to hemeostatic mechanisms to save metabolic energy. Comparisons of the acute and chronic effects of thinner on animal open-field behaviours and tail-flick pain reaction open-field behaviours and tail-flick pain reaction time indicate some differences between acute and chronic toxicity of thinner on nervous system function.