Mercury in fish may affect brain function

In studying the chronic exposure of rats to low dosage of methyl-mercury, an environmental contaminant commonly found in seafood, Professor Samuel Lo and his team concluded that the cerebellum accumulated the highest amount of mercury, followed by the visual cortex, then the motor cortex and somatosensory cortex.

The study also found that apart from methyl-mercury, the brain also accumulated other forms of mercury. In cases of acute mercury poisoning as seen in Minamata disease, the neuro-sensory pathway seems to be affected first.

Hence the PolyU team studied protein expression in the somatosensory cortices of rats intoxicated with low-dose methyl-mercury using advanced proteomic techniques. They found that expression of 104 out of 973 proteins was decreased by at least 50% after exposure to mercury contaminants.

Among these down-regulated proteins, 18% were related to cytoskeleton, 26% related to energy metabolism, 18% related to protein metabolism and 20% related to neurotransmitter release and signal transduction. The combined effects of these down-regulated proteins will suppress normal neuronal functions enormously, including the brain’s ability to repair itself. This inevitably means that chronic exposure to low dose methyl-mercury may increase the risk of having neurodegenerative diseases.

Professor Samuel Lo will speak on the chronic exposure to mercury and its impact on the brain at the fifth International Functional Food Symposium being hosted by The Hong Kong Polytechnic University from 10 to 11 March 2011.