Most parasites will draw nutrients directly from the host, but some parasites can control the host's brain and force it to make some dangerous moves, and this is how toxoplasma gondii controls the behavior of mice, as for the reason for this, the original toxoplasma can only complete sexual reproduction in the cat's body to produce eggs.
Rats for the cat's fear, is directly burned in the genes, if a few drops of cat urine near the bun, the mouse will only consider this bun when making a choice before starvation, at this time the mouse will instinctively secrete adrenaline, improve the vigilance of the surrounding environment, while the body's pain will be reduced, so those rats who are played with by the cat's claw, most of them have been "scared to death" because of excessive tension before the fatal blow.
However, mice infected with toxoplasma gondii will not make the above avoidance actions, and even some mice will be attracted by the smell of cats, they will swagger to the cat, this is not the mouse to find the cat "single-handed", but the mouse's behavior is no longer controlled by their own instincts, what is going on?
<h1 class="pgc-h-arrow-right" > one of the most "successful" parasites</h1>
Toxoplasma gondii, also known as Toxoplasma gondii, is praised by scientists as one of the most "successful" parasites, because this parasite can live in almost all thermostatic animals, and is an opportunistic pathogen, scientists have discovered this parasite as early as 100 years ago, according to statistics, about 30% of humans in the world have been infected with Toxoplasma gondii, but Toxoplasma can not reproduce sexually in the human body, coupled with the control of the immune system, the vast majority of infected people do not have any feeling.
Mention toxoplasmosis, it has to be said that cats, one of the most intimate animals of human beings, have a very complex life history and require two hosts:
Intermediate host: In the body of thermostatic animals such as humans, mice, birds, etc., Toxoplasma gondii develops outside the intestinal wall, and then enters various tissues and organs through the blood and lymphatic circulatory system, and any nucleated cells other than red blood cells may be parasitic, and asexual reproduction increases in these cells, but does not produce eggs.
Terminal host: Toxoplasma gondii can only complete enteral development in cats and felines, perform sexual reproduction and produce oocysts that are discharged into the environment with feces, which only take 2-3 days to mature in the environment and produce infectious capacity, posing a threat to other animals that come into contact.
Therefore, in all animals except cats, even if infected will not produce eggs and then cause a wider range of transmission, such harsh developmental conditions for Toxoplasma gondii is very unfavorable to the reproduction of the race, scientists in the study of infected mice, found the ability of Toxoplasma to control the mouse brain, so that infected mice can actively approach the cat, its series of complex mechanisms can not help but make scientists feel the success of Toxoplasma gondii.
<h1 class="pgc-h-arrow-right" > mechanism that controls the brains of mice</h1>
When the scientists studied mice infected with Toxoplasma gondii, they found that not only was they no longer afraid of the cat's smell, but some individuals were interested, a strange behavior not because Toxoplasma toxoplasma destroyed the mouse's olfactory central nervous system, but more complex neurotransmitters and physiological mechanisms.
In the brains of infected mice, many toxoplasma gondii cysts are produced, and these toxoplasma gondii have two important effects on the brain:
Promotes the secretion of more dopamine. Dopamine we are very familiar with, this is a neurotransmitter closely related to reward and pleasure, but also affect the brain's motivation and guiding behavior, these Toxoplasma cysts contain a large amount of dopamine, in response to this phenomenon, scientists in vitro let the nerve cells that synthesize dopamine infected Toxoplasma gondii, found that nerve cells secreted more dopamine, obviously Toxoplasma toxoplasma infection and dopamine regulatory changes have a certain association.
Produces inhibitory neurotransmitters. When the scientists studied the effects of Toxoplasma gondii on dendritic cells in the brains of mice, they found an abnormal increase in the secretion of γ-aminobutyric acid in the brains γ of mice, which is an important inhibitory neurotransmitter that has the effect of alleviating fear and anxiety.
The abnormal increase in dopamine and γ-aminobutyric acid caused the mice to become more excited and fearless.
The above-mentioned "head-to-head" behavior of liking to find cats can be more accurately understood as the behavior driven by the increase in desire to explore and curiosity, and some studies have further shown that rats not only become bold to cats, but also show strong curiosity about animals such as foxes and guinea pigs, and these behaviors begin to become more and more obvious as the number of cysts in the brain of mice increases.
For Toxoplasma gondii, this not only promotes the success rate of cats to kill mice, but also increases the number of protozoa entering the cat's body, which is conducive to the reproduction of Toxoplasma gondii.
<h1 class= "pgc-h-arrow-right" > the effects of toxoplasma gondii infection on humans</h1>
Although about 30% of people in the world have been infected with Toxoplasma gondii, Toxoplasma gondii is very suppressed by the immune system in the human body, Toxoplasma toxoplasma gondii will directly hide in the cell after entering the human body, and its brady protozoan can effectively inhibit the apoptosis of cells, so that it can lurk in the host for many years, which is why the impact of Toxoplasma gondii on humans is positively related to the immune system.
In recent years, however, a growing body of research has begun to reveal an association between Toxoplasma gondii and human behavioral abnormalities and mental problems.
In a foreign survey published in 2002 on traffic accidents, 146 people who had traffic accidents were compared with locals, and found that the proportion of positive toxoplasma gondii in this group of people who had traffic accidents was significantly higher than that of locals. The survey also calculated that people infected with Toxoplasma gondii were 2.65 times more likely to have a traffic accident than untouched, and although the causes of traffic accidents were diverse, the survey found that infected drivers did take longer to react than healthy drivers and were more likely to behave in a manner that did not follow traffic rules.
Following this survey, a 2003 questionnaire based on modern psychobiology, which tested 857 conscripts, found that those who were positive for Toxoplasma toxoplasma scored on impulsivity, profligacy, and disorder, which were generally lower than those in healthy people and had different degrees of low IQ.
Toxoplasma gondii in the host body, has a stronger infectivity to the nervous system, toxoplasma in the brain to produce cysts are randomly grown in any area of the entire brain, but preferentially concentrated in the cerebral cortex, hippocampus, amygdala, cerebellum, brainstem and other neuronal dense areas, and once the function of specific areas is affected, behavioral changes may occur. A 2007 study published in the Journal of the National Academy of Sciences suggested that toxoplasmosis cysts in the amygdala may be key to influencing behavioral abnormalities.
< h1 class="pgc-h-arrow-right" > concluding remarks</h1>
At present, there are many unsolved mysteries waiting for scientists to solve, in view of the wide range of infection routes of Toxoplasma gondii, we need to prevent toxoplasmosis in life is very many aspects, we eat beef infection rate in 0.2% -43.0%, pork infection rate in 4.0% ~ 71.4%, these two meats are important sources of infection, fortunately, Toxoplasma toxoplasma toxoplasma survive between -20 ° C -70 ° C, general processing methods can kill Toxoplasma gondii.
And for cat lovers, there is no need to "beat to death" because of toxoplasmosis and cat behavior, scientific cat raising and regular quarantine is the key, as for the behavior of liking cats is affected by parasites, of course, it is impossible, the mechanism of toxoplasmosis to affect behavior is placed there, it is impossible to control human specific like cats, toxoplasma to control human bridge section is only the plot of the movie.