Immunohistochemical and biochemical investigation of experimental acute toluene toxicity on the prefrontal cortex, hippocampus, entorhinal cortex, hypothalamus and substantia nigra regions of the rabbit brain

Toluene is a volatile substance that is widely used in the industry and has adverse health effects. This study aimed to investigate the histopathological and biochemical effect of high dose Toluene on brain cortex in acute period of treated rabbits. Seventeen adult female New Zelland rabbits (Oryctolagus cuniculus) were divided into 2 groups. Group I was used as a control group (n=7), while Group II was administered to high dose of Toluene (876 mg/kg/ip) (n=10). After the 3 hours experimental exposure, blood samples for biochemistry analyses and brain tissues for histopathological analyses were fined from sacrificed animals and fixed in %10 neutral formalin, then, embedded in paraffin and sectioned (5 μm). Histological examinations were performed using H&E, Crystal violet staining Bax and Caspase-3 immunohistochemical staining. In addition, NGF, TNF alpha, Dopamine, GFAP, Na, K, GSH, MDA and NO tests were performed on serum and plasma to determine the level of biochemical damage. Histopathologically, focal vacuolar degeneration (abscesses), gliosis, perivascular demyelination, numerous picnic cells and necrosis areas were observed in the prefrontal and entorinal brain cortex in toluene-administered rabbits. In the hypothalamus and hippocampus regions, excessive dilatation of blood vessels, degeneration in the compen- sation between cells, scattered cell boundaries and amyloid plaque formation have been observed. There was a significant increase in Na, K, MDA levels in the toluene group, but a significant decrease in GSH and NO levels was observed. In our study, in the biochemical evaluation of the prefrontal cortex, hippocampus, hypothalamus, substantia nigra and entorhinal cortex, the TNF alpha levels in the brain were found significantly higher than the control group. Levels of dopamine, secreted from substantia nigra, NGF developed from the hippocampal neurons, and GFAP, secreted from astrocyte cells were detected significantly lower in the Toluene-receiving group than the control group (p<0.05). Toluene group was found to show a serious invrease in immunreactivity against Bax and Caspase-3. Furthermore, Toluene was found to cause a serious increase in immunreactivity against Bax and caspase-3 in cell cytoplasms of brain cortex. As a result of this study, it was shown that high doses of Toluene could cause serious damage in acute phase in different regions of the brain.