The Mechanism of Methylmercury Permeation Through the Blood-Brain Barrier using <i>Caenorhabditis elegans</i>

Methylmercury is a neurotoxin present in fish tissues that permeates the blood-brain barrier after consumption. Previous research has shown that methylmercury is harmful to neurons, causing pH alterations, oxidative stress, excitotoxicity, and parenchymal damage. Methylmercury is a known factor of neurological disorders including Alzheimer's and Parkinson's. The method by which methylmercury passes through the blood-brain barrier is largely unknown. According to preliminary studies, one way methylmercury crosses the blood-brain barrier is by creating a complex with L-Cysteine, which facilitates its passage by the LATs system through mimicking another amino acid existing in the body. The human blood-brain barrier was studied using C. elegans as a model organism. It was hypothesized that if methylmercury passes through the blood-brain barrier of C. elegans faster with L-Cysteine present than without L-Cysteine present, the methylmercury's adverse effects (death and locomotive difficulty) will occur sooner. Each of the four experimental groups contained one C. elegans: the control, the L-Cysteine group, the methylmercury group, and the methylmercury and L-Cysteine combination group. The effects of L-Cysteine and methylmercury on C. elegans were studied using three metrics: viability, locomotive disability, and time for locomotive effects to occur. The group that received both methylmercury and L-Cysteine had reduced viability rates and a decreased time for locomotive difficulty to develop, supporting the hypothesis. These findings suggest that L-Cysteine aids methylmercury permeation through the blood-brain barrier. Because the experiment indicates how methylmercury penetrates the blood-brain barrier, these results aid in finding a therapeutic solution to reverse methylmercury neurotoxicity in the brain. Additionally, this study further opens channels into potential therapeutic and preventative measures for dementia, improving morbidity and mortality in neurodegenerative diseases.