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Those who have a lot of brown adipose tissue are lucky: this tissue, which is found in some people below the tongue, in the clavicle and spine area, helps to use the surplus of energy. The more tissue you have and the more active it is, the lower the risk of being overweight or developing metabolic diseases.
An international team of researchers led by Professor Christian Wolfrum of ETH Zurich showed that a central decision-making process was taking place before conception: if the father stays cold before being conceived , the offspring will have more active brown adipose tissue. This means nothing more than an environmental influence, which exposes the father, transfers to his offspring.
Tomographic images were analyzed
This finding attracts study researchers on mice – where a relationship between temperature in the generation and brown fat is also manifested in humans: In collaboration with colleagues from the Zurich University Hospital, ETH scientists analyzed CT images of 8400 adult patients. He showed that people who have their birthdays from July to November (and were thus conceived during the winter semester) have significantly more active brown adipose tissue than people with birthdays from January to June (and the time of a generation during the summer).
Mice, researchers studied this relationship. They kept the animals at moderate (23 degrees Celsius) or cool (8 degrees) temperatures and allowed them to reproduce. The analyzes in the offspring showed that the temperature of the mother before and after conception had no effect on fat adipose tissue, but that of the fathers: the offspring of males who lived in a cool environment for several days prior to conception had more active brown adipose tissue like that of males that were at temperate temperatures. In addition, the offspring of males in cold weather was better protected against obesity – it became less oily in high fat diets – and metabolic disorders.
Epigenetic changes in spermatozoa
Thanks to in vitro fertilization and sperm analysis, researchers have finally been able to show that information on the temperature of the father's residence is passed on to the offspring by epigenetic imprint of the spermatozoon. This refers to a change in the pattern that forms certain chemical markers (methylations) on the genetic material.
The fact that certain environmental influences can modify the epigenetic profile of sperm has been known for several years. However, scientists have now shown for the first time that ambient temperature can also lead to epigenetic changes.
Brown fat cells produce body heat by burning energy. Mice with more brown adipose tissue can therefore better regulate their body temperature at low temperatures. "This can protect them from the freezing cold, which could explain why this epigenetic mechanism has prevailed in the history of evolution," says Professor Wolfrum of the EPF
. Consistent with previous observations, people in cold regions have extra brown fat. "Previously, we thought it had to do with temperatures during his life," said Wolfrum. "Our observations suggest that it could also be influenced by the temperature before conception."
The ETH professor points out another context: The average temperature in inland areas has increased over the last few decades, at least in the United States where this has been studied. In addition, there are studies that show a relationship between the temperature of life and obesity. "In our work, we show a possible mechanism for this," says Wolfrum
Should couples considering family planning now guess that the man would swim in a cold lake or frolic in the snow before the # 39; act? "Before we can give such advice, we need to better understand the context in humans," says Wolfrum. "Probably, however, a longer exposure to cold weather is necessary for epigenetic impression.A jump in cool water or a short rest on a block of ice may not be enough." Scientists are now planning a study in which they want to compare the epigenetic characteristics of human sperm in summer and winter.
Reference
Sun W et al .: Cold-induced epigenetic programming of sperm enhancements in the progeny of the spermatozoa. brown adipose tissue activity, Nature Medicine, July 9, 2018, doi: 10.1038 / s41591-018-0102-y [19659016] idw 2018/07
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