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Lab rats are afraid of men - and that's a problem for science


Understand how a new study can cast doubt on decades of research. His body behaves differently depending on who is interacting with him.

Men and mice have a close relationship when it comes to science. After all, the number of rodents used in research each year is impressive - an estimated 25 million lab rats are sold by breeders each year (not to mention the offspring born in the labs themselves). And the animals provide scientists with data about their behavior and their organisms. But now a new study is putting nearly all the research done on pets in check.

According to McGill University research, mice are afraid of men rather than women. And this means that studies conducted by the hands of male researchers may have other results, since being manipulated by men, the mice would be stressed. And the effects of stress can alter both the behavior and the organism of animals.

Cancer studies, for example, which usually begin with rodent testing, may be compromised. "If you are studying a rat's liver cells, the cells came from an animal that was sacrificed by either a man or a woman. Rat stress levels were in very different states depending on the situation," says the author. of the research, Jeffrey Mogil, in an interview with The Verge. "And it could affect how the liver cell will look in the experiment," he concludes.

In the study to reach this conclusion, the researchers used a scale to measure how much pain rats felt when exposed to men, women and their respective smells. The idea is that fear can dampen pain - so when exposed to a man or his smell, the mice analyzed in the survey showed less pain.

It may even seem like a positive effect - after all, the rat does not suffer when it is being injured or killed "by science" in male hands. But if we bring the idea into the human sphere, we can compare this situation with an athlete who is stressed during a match. He suffers an injury, but stress and adrenaline make him feel no pain and he continues to force the injured area, making the situation worse.

Rat pain was not the only indicator of stress considered in the study. Other experiments showed that when exposed to men or their smells, rodents also had high levels of corticosterone, a hormone that appears in stressful situations. And this effect was not only noticed with the scent of human males: the scent of males of other species such as dogs, hamsters and cats also affected them in this way.

Why do rats fear men?
The researchers suggest that the reaction comes from a sense of competition rather than identifying a predator. Male rats are territorial and compete with others when they have the opportunity to mate. And probably mice can't discern the smell of another male rat from the smell of a male of another species.

And the polls? According to scientists, the fear of mice depends not only on the sex of those who interact with them, but also on the situation. For example, if the rat smells both male and female at the same time, it does not have the same stress symptoms. This shows that the threat is a lone male - and there are ways to continue rodent research without compromising the results.

Another factor is how accustomed the mice are to the researcher's presence in the room. If he stays more than 45 minutes in the same environment without hurting the mice, their fear level drops. That is, it is possible to continue the research, as long as these measures are taken not to compromise the results. Researchers also expect future research to list the genre of researchers who interacted with guinea pigs.

"I now hope that fellow scientists realize that the way their guinea pigs were treated, whether by men or not, may explain some mysteries, some results different from those expected in research," says Mogil. It remains to be seen if research authors will resume their studies to see if they have been altered by rat stress - and if they will replicate their experiments.

(//revistagalileu.globo.com/Ciencia/Search/news/2014/04/laboratory-rates-have-fear-of-men-and-a-problem-for-cience.htmll)