Hepatotoxic effects caused by simultaneous exposure to noise and toluene in New Zealand white rabbits: a biochemical and histopathological study

The aim of this experimental study was to investigate hepatotoxicity effects of noise and toluene, and in particular, to study hepatotoxicity effects of simultaneous exposure to noise and toluene by histopathological and biochemical experiments. To experiment hepatotoxicity effects of noise and toluene, 100 dB white noise and 1000 ppm toluene vapors were generated during two consecutive weeks in healthy male New Zealand White rabbits. Non-simultaneous exposure to noise and toluene increased liver enzymes and the serum levels of superoxide dismutase, malondialdehyde, and total antioxidant capacity, and also decreased serum level of glutathione peroxidase. Alanine transaminase, aspartate transaminase, gamma-glutamyl transferase, malondialdehyde, total antioxidant capacity, and superoxide dismutase levels increased by simultaneous exposure to noise and toluene. Furthermore, catalase and alkaline phosphatase level decreased by simultaneous exposure to noise and toluene. The hematoxylin and eosin stain (H&E) experiments indicated significant swelling, lipidosis, eosinophilic cytoplasm, pyknosis, karyorrhexis, and disruption of the cytoplasmic membrane in the liver tissue due to exposure to noise, toluene and simultaneous exposure to them.

     

Toxicopathological Changes Induced By Combined Exposure To Noise and Toluene in New Zealand White Rabbits

Noise and toluene can have significant adverse effects on different systems in the human body, but little is known about their combination. The aim of this study was to see how their combined action reflects on serum levels of inflammatory cytokines tumour necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β), body weight, and pathological changes in the heart, lung, stomach, and spleen tissues. To do that we exposed New Zealand rabbits to 1000 mg/L toluene and 100 dB of white noise in a chamber specifically designed for the purpose over two consecutive weeks. Serum levels of TNF-α and IL-1β were measured with the enzyme-linked immunosorbent assay (ELISA), whereas Bax and Bcl-2 expressions in tissues were determined with real-time polymerase chain reaction (PCR). Noise and toluene changed TNF-α and IL-1β serum levels on different days following the end of exposure and significantly increased the Bax/Bcl-2 ratio in the lung and spleen. In addition, they induced different pathological changes in the heart, lung, spleen, and stomach tissues. This study has confirmed that exposure to noise and toluene can induce a range of toxicopathological changes, probably by inducing inflammatory pathways and apoptosis, but their combined effects look weaker than those of its components, although histopathological findings suggest the opposite.Key words: body weight, environmental exposure, heart, IL-1β, industrial toxicology, apoptosis, lung, spleen, stomach, TNF-α