Monday , August 2 2021

Toxoplasmosis parasites alter our synapses in the brain

Many people are infected: how the toxoplasmosis parasite transforms synapses in the brain

Pets do a great job for most people. But some of the four-year-old friends can transmit the disease. For example, toxoplasmosis, an infectious disease whose pathogen is often found in cat feces. Researchers have now shown in the study that the toxoplasmosis parasite is restoring synapses in the brain.

One of the most common infectious diseases

A few years ago, American scientists reported that some cats owners had an increased likelihood of aggression and nervousness. For those who were infected with Tokoplasma gondii. World single-celled parasite causes one of the most common infectious diseases, toxoplasmosis.

A simple parasite Tokoplasma gondii infests birds and mammals – including humans. However, his last hosts are cats. For some people, the pathogen can be dangerous. (Image: alho007 /

A single parasite is infested by birds and mammals

A simple parasite Tokoplasma gondii infests birds and mammals – including humans. However, his last hosts are cats.

Researchers at the Otto von Guericke Magdeburg University (OVGU) and the Leibniz Institute of Neurobiology (LIN) at the Institute of Inflammation and Neurodegeneration (LIN) have studied how the parasite affects the metabolism in the brain of their hosts and has shown that there is a change in the molecular composition of the synapse there.

The results of the scientists were published in the journal Neuroinflammatory Journal.

The illness usually goes unnoticed

According to a report published by Informationsdienst Vissenschaft (idv), about 30 to 50 percent of all people have already been infected with toxoplasm during their lifetime. For over 50 years, even takes over 50%.

Most toxoplasmoses are unnoticed and infected do not suspect that they are infected.

"In healthy people, the infection causes short-term symptoms such as chills, fever and pain in the body," explains prof. Dr. Med. Ildiko Rita Dunai, Director of the Institute for Inflammation and Neurodegeneration in OVGU.

"Such an infection can be dangerous for pregnant women or people with a weakened immune system." "There is no therapy to get rid of parasites when the brain is attacked, so when you get infected it will last a lifetime," says an expert.

Another problem is that toxoplasmosis in the newborn often remains undetected, as experts from the Robert Koch Institute (RKI) reported in the journal Scientific Reports.

Parasite is absorbed by humans through digestion

Parasite nests in the muscle tissue of infected animals, but not only:

"The gonorrhea toxins are absorbed by humans by digestion, entering the bloodstream and also migrating to the brain, where it is retained in life in the nervous cells," Dr. Med. Karl-Heinz Small from the Special Laboratory of Molecular Biological Techniques at LIN.

Previous studies by other German researchers have shown that toxoplasmosis can cause serious long-term effects in the brain.

Even Magdeburg's scientists have already found in previous experiments with mice the infection of animals on the gondos toxoplasia with incredible behavioral changes:

"Mice, who were prey cats, lost their natural fear of cats after infection. If the rodents had the smell of the cat's urine, they seemed to have had the advantage of cats," researchers said.

Therefore, in order to explain these behavioral changes, they examined the changes in the mouse brain – especially the molecular composition of the synapse, because these are the basic structures for signal processing in the brain.

In collaboration with the Helmholtz Center for the Investigation of Infection in Braunschweig, they succeeded in proving that in a total of 300 synaptic proteins, levels in the brain changed after infection with toxoplasmosis.

In particular, the proteins are particularly reduced in the excitatory release of the release glutamate. On the other hand, increased levels of proteins involved in the immune response have been found.

Improved immune response

To treat infection with toxoplasmosis, sulphadiazine is often used, which partially prevents the proliferation of toxoplasmens.

Psychiatrist and neuroscientist Bjorn Schott explains: "Now we wanted to find out how the treatment of sulphadiazine affects the molecular changes in the brain caused by the infection."

Result: The protein content of the mouse in the mouse after therapy was comparable to those uninfected.

"All tested proteins, which are responsible for transmitting glutamater signals, are again in the normal range, and inflammatory activity has declined measurably."

It seems that the infection leads to an improved immune response that reduces the proteins involved in the synaptic excitability of glutamate, while sulfadiazine reduces toxoplasma and thereby normalizes the immune response, causing the synaptic protein recovery.

Findings can also be relevant to people

These findings can also be medically relevant to humans.

"They support the suggestion that Tokoplasma gondii is a risk factor for neuropsychiatric disorders," said neuroimunologist Danaj.

"Malfunction of glutamatergic synapses is involved in the causes of depression, schizophrenia, and autism. Also, the components of the immune response indicate these diseases," explains the expert.

"This suggests that the immune response can cause changes in the synapses that can lead to neuropsychiatric disorders." (Ad)

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