The mechanism behind placental transport of mercury has been unveiled by a group of scientists from Karl Landsteiner University of Health Sciences (Austria) and Medical University of Vienna. Mercury, which is one of the toxic heavy metal was found to enter the bloodstream of unborn babies through placenta by camouflaging with an amino acid.
“Mercury is present in a form that is structurally similar to an amino acid which the placenta absorbs from the mother’s blood. So the mercury disguises itself and deceives the system” explains Prof. Claudia Gundacker, who led the research team.
The amino acid like cysteine which contains sulphur can easily bond with mercuric neurotoxicant like methylmercury. This compound of mercury which is similar to the amino acid methionine is taken up by placenta using a specific mechanism known as system L.
Placenta effectively blocks metals such as cadmium and lead but fails to stop mercury from entering it. Thus, mercury enters the foetus’s circulatory system from mothers blood efficiently.
Prof. Gundackers team revealed for the first time that system L transports methylmercury like an amino acid demonstrating the placental transport mechanism which pump mercury into the unborn. The research was performed in cell cultures resembling the in vivo conditions of placenta. The study also shows that foetuses have a higher concentration of mercury in their blood than mothers.
The findings were published in the journal Toxicology and the International Journal of Molecular Sciences.
The inter-university team is now looking forward on exploring the transport of iron which is a very essential element often found insufficient in expectant mother and their unborn foetus.
Prof. Hans Salzer of KL Krems commented: “Now we are also looking at the uptake of iron into the placenta. In contrast to mercury, foetuses need iron. But unfortunately, iron deficiency is common among pregnant women and newborns, even in highly developed countries. We can only address this problem effectively if we have a better understanding of how it is transported.”
In view of the placenta’s importance for the health of unborn children and expectant mothers, the gaps in our understanding of its transport methods are staggering and need to be explored.