Toluene Induces Depression-Like Behaviors in Adult Mice

It has been clinically reported that toluene causes mental depression in humans. However, the detrimental effects of toluene exposure on brain function and the relation between features of mental depression and toluene exposure are poorly understood. This study evaluated depression-like behaviors in adult C57BL/6 mice after administration of toluene, and elucidated the effects of classical antidepressants on the depression-like behaviors. For the estimation of depression-like behaviors, tail suspension test (TST) and forcedswim test (FST) were performed 1, 4 and 16 days after toluene (0~1000 mg/kg bw) treatment. In addition, classical antidepressants such as fluoxetine (FLX, 20 mg/kg bw) and imipramine (IMI, 40 mg/kg bw) were administered 12 h and 1 h before the tests. In the TST and FST, toluene-treated mice exhibited a longer duration of immobility than vehicle-treated mice 1 and 4 days after toluene treatment. The depression-like behaviors were significantly reversed by FLX and IMI. The weight of the adrenal gland and the size of adrenocortical cells were significantly higher in toluene-treated mice compared to vehicle-treated controls. It is suggested that acute toluene exposure of adult mice is sufficiently detrimental to induce depression. In addition, this study has established a mouse model for a depressive state induced by toluene treatment.