It is known that women have heart problems on average later than men. That shows woman heart is stronger than man. The first thought that suggests itself here is that it is all about female sex hormones that affect not only the reproductive system, but the whole organism.
However, as researchers at the University of Guelph write in Cardiovascular Research, the matter is not only in hormones of man and woman heart, but also in circadian rhythms.
Earlier, Tami Martino and her colleagues in experiments on mice showed that in males, the consequences of a heart attack are much harder if the attack happened during sleep. Every phenomenon that depends on the time of day is related to a biological clock.
To understand where the biological clock is, the authors of the work introduced mutations into the clock gene, which is one of the main genes that control circadian rhythms. The protein encoded by clock includes the gene of another protein per, which is considered the clock spring of daily rhythms (we recall that for decoding the mechanism of work per this year they gave the Nobel Prize in medicine and physiology).
A mutation in the clock gene breaks the internal clock – figuratively speaking, their spring continues to contract and unclench, but without any clear rhythm. And it turned out that a spoiled biological clock is more dangerous for a male heart than for a spontaneous one. With age, male mice that had a clock mutation had heart disease more often than females with exactly the same mutation.
Moreover, it was found that males and females have different heart cells. In the male heart, glucose metabolism and, in general, energy metabolism were impaired – obviously, the problems started because the heart could not provide itself with energy properly. Moreover, a special kind of cardiolipins appeared in the heart cells of males, which are peculiar to a sick heart.
Cardiolipins are lipids that are found in abundance in the membranes of mitochondria – cell organelles involved in the production of metabolic energy. The reactions in which energy is produced occur just on the mitochondrial membranes, and the efficiency of mitochondria strongly depends on what they have with the membranes. Therefore, it is not surprising that changes in the composition of cardiolipins can affect the condition of the whole heart.
As for the females, in spite of the mutation in the “clock” gene, their cardiolipins were healthy, and everything was more or less in order with the metabolism. Actually, the biological clock is favorable for woman heart.
But where does the hormones that we talked about at the very beginning? It turned out that when the ovaries were removed in females with a mutation in clock, their hearts began to deteriorate as quickly as in males. That is, the female sex hormones synthesized in the ovary somehow protect the heart, even when problems begin in the biological clock.
In relation to people, we can say that with age, most likely, both men and women upset their biological rhythms equally, but women heart have an additional hormonal preservative for such a case, but the male heart remains defenseless.
In the future, it remains to be seen how exactly “hourly” defects affect the lipid composition of heart cells, and which female sex hormones help mitigate the breakdown in the circadian rhythm, and how they do it, and whether female sex hormones (or their analogues) can be helped the male body does not hurt the heart.
Undoubtedly, the results obtained should be very useful in clinical medicine – because in order for our internal clocks to break, we do not need a mutation, it is enough to bring down the daily regimen. The researchers themselves say that the mutation that they introduced into the clock gene gives the same effect as a variety of shift work, like “day after three”, when a person is awake, day or night.
Now they say a lot about the fact that a downed biological clock can lead to very serious health problems, and the above study once again confirms this.
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Melisa Marzettis a freelance writer who is currently writing for editing services and enjoys her life traveling. There are many things she likes doing apart from writing and traveling, which are cooking, shopping, playing with her nephews when she comes home, handmade and sports. She is a very active person, a movie enthusiast and a nature lover.