Mice are not afraid of cats? They may have been "controlled" by Toxoplasma gondii

Source: Science and Technology Daily

Mice are not afraid of cats? They may have been "controlled" by Toxoplasma gondii

Toxoplasma gondii is a parasite commonly found in cats, and previous studies have suggested that toxoplasma gondii targeted mice to stop being afraid of felines, making it easier for them to be eaten by the latter, helping to spread toxoplasma through cat droppings. According to a new study published in the Cell Report, Toxoplasma gondii did not specifically reduce the fear of cats in infected mice, but generally reduced their anxiety and perception of risk.

In the experiment, the infected mice's curiosity about the smell of cats and non-predators did not differ significantly, but they were all greater than those of the uninfected mice. This behavioral change is mainly related to parasite-induced brain tissue cysts and chronic neuroinflammation, rather than direct interference with specific neurons.

According to the study, the reason for this change is that toxoplasma gondii invades mice, causes a short-term infection, and can create cysts in the brains of mice. But it is not yet known why this persistent change occurred after a brief infection, and the cyst did not continue to develop and did not produce encephalitis.

It is important to note that even though Toxoplasma gondii has been largely or completely eliminated after infection, this persistent behavior of change persists. A single transient infection can cause permanent changes in host biology, and scientists don't know the mechanisms that cause this long-term behavioral change, but there are two speculations. The first possibility is that the parasite may disrupt the olfactory area of the rat's brain, preventing the rats from smelling the cat's scent and triggering fear. Another possibility is that the parasite directly modifies the brain cells of mice involved in memory and learning functions.

Toxoplasma gondii is found all over the globe and has infected many mammals, including humans. However, this pathogen can only breed in cats and mice, and eventually causes mice to lose their fear of cats. According to some studies, this infected mouse also became interested in the taste of cat urine, resulting in a greater increase in the risk of rats infected with this parasite being eaten by cats, eventually transmitting to cats and exacerbating the spread.

The parasite, which has been found in one-third to one-half of humans, can cause suicidal tendencies if present behind the brain and can cause other mental illnesses. One study showed that people infected with this parasite were more likely to be nervous.

Source: Global Science