Neurotoxicity of anthracene and benz[a]anthracene involves oxidative stress-induced neuronal damage, cholinergic dysfunction and disruption of monoaminergic and purinergic enzymes.

In this study, the modulatory effects of anthracene (ANT) and benz[a]anthracene (BEN) on biochemical markers associated with neurodegeneration were assessed in mouse hippocampal neuronal cells (HT-22). Neuronal cells were cultured and exposed to ANT and BEN (25-125 µM) for 5 days, and the cell viability was determined via MTT assay. Morphological characteristics of the cells were assessed using a compound microscope. Biochemical parameters such as acetylcholinesterase (AChE), monoamine oxidase (MAO) and adenosine deaminase (ADA) activities as well as oxidative stress biomarkers (catalase [CAT], glutathione -S- transferase [GST] activities and Glutathione [GSH] levels) and nitric oxide [NO] levels were assessed after cells were treated with ANT and BEN for two days. The results showed that cell viability reduced with an increase in exposure time. After the fifth day of treatment, BEN and ANT (125 µM) reduced percentage viability to 41 and 38.1%, respectively. Light micrographs showed shrinkage of cells, neuronal injury and cell death in cells treated with higher concentrations of BEN and ANT (50 and 125 µM). Furthermore, AChE and MAO activities reduced significantly after treatment for 48 h with ANT and BEN. A significant decrease in CAT and GST activities and low GSH levels were observed after treatment with BEN and ANT. However, both polycyclic aromatic hydrocarbons caused a significant increase in ADA activity and NO levels. These results suggest that ANT and BEN may induce neurodegeneration in neuronal cells via oxidative stress-induced-neuronal injury, disruption of cholinergic, monoaminergic and purinergic transmission, and increased nitric oxide levels.