Immediate and Persisting Effect of Toluene Chronic Exposure on Hippocampal Cell Loss, Learning and Memory in Adolescent and Adult Rats

摘要

The present study has been undertaken to determine whether toluene chronic exposure provokes immediate and/or persistent effect on the structure of hippocampus, learning and memory in adolescent and adult rats. We exposed male Wistar rats at ages P 28-32 (adolescents) and P 70-75 (adults) to 2000 ppm inhaled toluene for 40 days. The immediate and persisting effects of toluene misuse (immediately after the end of toluene chronic inhalation and 90-day after the end of toluene chronic inhalation, correspondingly) on (i) pyramidal cell loss in the CA1 and CA3 of the hippocampus, (ii) exploratory behavior and recognition memory in the open field and (iii) behavior in multi-branch maze were evaluated. The results reveal that toluene chronic exposure affects the structure of the hippocampus, the behavior in multi-branch maze, exploratory activity and recognition memory in the open field in adolescent and adult rats. In all cases the effect is age-dependent. In particular: in adolescent rats the more significant structural and behavioral alterations were observed immediately after toluene chronic exposure, while in adult rats the most considerable was persisting effect (90 days after withdrawal). Such data indicate that character of alterations depends upon the postnatal age of testing of the animals. The results are also additional evidence that hippocampus-the neural substrate of learning and memory, may contribute to die pathophysiology of toluene abuse in organisms of different age.