"We've not looked at behavioural changes in people infected with toxoplasma, as that's been dealt with by previous studies," says Dr Barragan. "Instead, we've shown for the first time how the parasite behaves in the body of its host, by which I mean how it enters the brain and manipulates the host by taking over one of the brain's neurotransmitters."
In one laboratory experiment, human dendritic cells were infected with toxoplasma. After infection, the cells, which are a key component of the immune defence, started secreting the signal substance GABA. In another experiment on live mice, the team was able to trace the movement of infected dendritic cells in the body after introducing the parasite into the brain, from where it spread and continued to affect the GABA system.
GABA is a signal substance that, amongst other effects, inhibits the sensation of fear and anxiety. Disturbances of the GABA system are seen in people with depression, schizophrenia, bipolar diseases, anxiety syndrome and other mental diseases.
"For toxoplasma to make cells in the immune defence secrete GABA was as surprising as it was unexpected, and is very clever of the parasite," says Dr Barragan. "It would now be worth studying the links that exist between toxoplasmosis, the GABA systems and major public health threats."
|Contact: The Press Office|