Acute exposure to abuse-like concentrations of toluene induces inflammation in mouse lungs and brain

Toluene is an aromatic hydrocarbon commonly abused by young adolescents for its central nervous system depressant effects. Although toluene's pharmacological effects at high concentrations are relatively well-known, few studies have assessed toluene's effects on lung and brain tissues. The present study characterized the pathological effects of acute inhaled toluene exposure in the lungs and brains of male Swiss-Webster mice (N = 68). Using a static vapor exposure chamber, mice (PND 28) received a single 30-min toluene administration (0, 1000, 2000, or 4000 ppm). Lung and brain tissues were extracted 24-h post-exposure. Histology results revealed significant changes in the morphology of lung tissue (e.g., irregular cellular architecture) with the 2000- and 4000-ppm exposures expressing greater signs of pathology than control 0-ppm exposure. Markers of immune system activity (F4/80 and Ly-6G) and cellular proliferation (Ki-67) in the lung revealed no significant differences. Additionally, brain tissues were analyzed for changes of astrogliosis (glial fibrillary acidic protein [GFAP]) and oxidative stress (glutathione peroxidase [GPx]). GFAP showed increased astrogliosis in the striatum with 2000-ppm toluene showing significantly higher expression than control (p < 0.05) and a marginal effect in the hippocampus. No other markers showed significant changes. The increased signs of inflammation and cellular damage suggest that exposure to a single high concentration of toluene, typical of abuse, is capable of producing pathology in both lung and brain tissue.