Curcumin Mitigates Mercury-induced Memory Impairment and Neurotoxicity: Insights from the Drosophila melanogaster Model

Mercury-containing products, such as dental amalgam used for dental filling in dentistry, have been heavily criticised due to their associated toxicity. Nevertheless, it is still in use in low-income countries due to it being relatively affordable. Therefore, in this study, we evaluate the neurotoxic effects of mercury (Hg) and the possible ameliorative effects of polyphenol-curcumin using the fruit fly (Drosophila melanogaster) model. Male and female D. melanogaster, aged 3 to 5 days, were categorized into six groups, each consisting of 40 flies. To evaluate the impact of Hg exposure and the potential protective effects of curcumin, we conducted measurements on multiple parameters. These included assessing the survival rate, determining the memory index using an aversive phototaxis suppression assay, evaluating locomotor performance through negative geotaxis, and analysing various biochemical parameters associated with antioxidant status and neuronal function-related enzymes. Our findings indicate that dietary exposure to Hg resulted in a decreased survival rate and impaired locomotor performance in D. melanogaster. However, we observed a notable improvement in the antioxidant system among D. melanogaster exposed to Hg toxicity when they were fed a diet supplemented with curcumin. This improvement was evident through enhanced catalase activity, improved memory index, and modulation of acetylcholinesterase and monoamine oxidase activities. These effects were observed in comparison to D. melanogaster solely exposed to HgCl2 without curcumin supplementation. Collectively, these data showed that curcumin could mitigate the neurotoxicity associated with Hg and thus could serve as a substitute for Hg-containing products like dental amalgam.