Cold makes thin offspring



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Activated brown fat cells are small heating plants. They burn more sugar than any other cell in the body and convert energy into heat. So babies have a lot – as protection against the cold. Adults would like more – as protection against obesity. But the amount of brown adipose tissue is different and depends on how much cold we have to endure. Or how cold it was when our parents designed us. A team led by nutritionist Christian Wolfrum of ETH Zurich has now discovered using images of a PET scanner

"In collaboration with the Zurich University Hospital, we conducted a study on humans, where we retrospectively badyze 8400 subjects.And then, quite by chance, we found that there is a very clear correlation between brown adipose tissue and birth time and the timing of conception , that is, people who were conceived in the cold months of October and February, had significantly more brown fat than people conceived during the hottest months. "

"Correlation between brown adipose tissue and the timing of conception"

This coincidence made researchers curious. They wanted to know if the effect of cold on offspring could be actively produced under laboratory conditions. And if so, what exactly happens in the process, that is, for example, if something changes in the activation of certain genes. In a series of experiments, scientists exposed male and female mice at different temperatures for a week and then spawned them, explains Christian Wolfrum

"In mice where fathers had previously lived at eight degrees for a week instead of 23 degrees, you can see the increase of brown fat in the offspring, in male offspring, if you do that with female mice, you do not see anything, so that means that 39 it is clearly transmitted by sperm. "

Why about sperm, but there is only one explanation: the exposed location of the testicles. This is why sperm become much colder than eggs that mature inside the body. Cold temperatures influenced the DNA in the spermatozoa of mouse mice and changed the genes by methylation so that they were read differently. This is the first time that researchers have demonstrated the direct genetic effect of an environmental factor

Cold irritation changes gene activity

Christian Wolfrum : "This is the first time we have a system how cold in the brain signals. This gives us an indication: How are the methylations changed in sperm?"

The researchers also found the Methylation-altered gene activity in the offspring of cold-tested mice.

"These are clearly genes that play a major role in the formation of brown adipocytes and genes involved in neuronal activation, both of which are processes that we need to make brown fat and From the brown fat And when we go back to the mouse, we see just that: you have more brown fat, and that brews The fat is more active, it reacts much faster than a mouse grown at normal temperatures. "

Cold stimuli alter the activity of individual genes and thus provide more brown fat to the offspring. According to Wolfrum, this epigenetic effect could have been beneficial in the evolution. For example at the ice age. Our ancestors had to adjust their metabolism to negative degrees so as not to die of cold. Today, however, we have global warming, thermal underwear and living in overheated rooms.

Those who freeze more often activate their brown fat cells

"Brown fat probably has a few people." Brown fat, when it is not active, nothing or relatively little, you can badume that many more people have inactive brown fat, just because we dress so thermoneutral that we do not feel cold Brown fat is not really active under normal conditions In recent decades, the average room temperature in the home has increased by several degrees, which perfectly matches the development of obesity in the United States. United.

A little more chill in everyday life could help the body regain more starts and protects us from being overweight. And if men consider this advice, their children will probably benefit.

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