How the menstrual cycle is regulated: science factors to an inside clock of the physique and attenuates the affect of the lunar phases | Health & Wellness | EUROtoday

The first day of menstruation is the place to begin of a really advanced important course of that science nonetheless doesn’t totally perceive: the ovarian cycle. The first section of this phenomenon begins with the interval, which often lasts about 28 days, and which additionally entails, aside from menstrual bleeding, the expansion of the ovarian follicles till a mature egg is discovered that’s launched into the fallopian tubes and the degradation of the endometrium earlier than the beginning of a brand new menstruation. All of this occurs periodically throughout a girl's fertile life at a kind of fixed fee, however scientists nonetheless have no idea what determines the timing of those cycles and why every section lasts so long as it does. Due to the temporal similarities, some consultants have discovered a hyperlink between this phenomenon and the lunar cycle, however this concept, with restricted and contradictory outcomes, has at all times generated nice controversy among the many scientific group. New analysis, printed this Wednesday within the journal Science Advances, furthers the understanding of this course of and means that, greater than the lunar phases or every other exterior variable, it’s in all probability an inside clock of the organism, just like the circadian chronometer that marks the rhythm of life, that regulates the ovarian cycle.

According to Claude Gronfier, a scientist on the Neuroscience Research Center in Lyon (France) and writer of the research, the normal rationalization for why the menstrual cycle has a interval of 28 days “is that it results from a fine balance between endocrine processes” that result in the completely different phases of this phenomenon. His colleague and first writer of the analysis, René Ecochard, from the University Hospital of Lyon, illustrates the phases of this cycle, beginning with a primary section of latency, which lasts a few week and begins with the primary day of bleeding: “The The main process that takes place during this period is the selection of a follicle that will then lead to ovulation. Then, there is another stage, which is “the fertile window,” which additionally lasts a few week wherein “the growth of the follicle takes place until ovulation, as well as the secretion of liquid mucus in the cervix to receive the sperm.” . The third a part of the cycle, referred to as the “postovulatory phase,” notes Ecochard, extends over about two weeks, from the day after ovulation to the day earlier than the beginning of the following menstrual interval. “Interestingly, and surprisingly, there has never been a consensus explanation as to why these different phases, added together, last approximately 28 days, in addition to the fact that each of them also has a certain duration,” Gronfier explains in an e mail response.

After analyzing almost 27,000 menstrual cycles from 2,300 European ladies and one other 4,800 from 721 North Americans, the authors of the research discovered proof that “it is more than likely” that the rhythmic traits of the menstrual cycle are defined by an inside mechanism of the physique much like the clock. circadian, which is that central timekeeper, positioned within the hypothalamus, that tells the time to the remainder of the physique. This molecular gadget, which is synchronized with the sunshine and darkness of the day, is accountable, along with the small impartial timers of the tissues, of anticipating and making ready the cells for what’s to return, reminiscent of consuming at noon or leaving. to sleep at evening.

“What our article shows is that these processes do not simply follow one another, in such a way that each one begins when the previous one ends. “Our results strongly suggest that a clock-like mechanism drives the rhythmicity of the menstrual cycle, such that its periodicity remains within a certain range and oscillates around the intrinsic rhythmicity of the cycle (which varies between women),” explains Gronfier. Thus, this synchronizing mechanism may even appropriate the fluctuations that happen in a selected cycle, in the identical approach that it takes a couple of days to repair the circadian imbalance that happens after an intercontinental journey, for instance. “If the cycle [ovárico] If it gets longer, for whatever reason, this clock-based process adapts to shorten it quickly, and if it gets shorter, this clock-based process also adapts to lengthen it,” the writer provides.

Gronfier and his group's speculation doesn’t come out of nowhere. In the article they are saying that there’s already “some evidence” that the phases of menstrual cycles can be below the affect of circadian rhythms and that an alteration of this important rhythm can also be related to dysfunctions in menstrual operate. Juan Antonio Madrid, professor of Physiology and director of the Chronobiology and Sleep Laboratory on the University of Murcia, factors out that there’s a connection between the circadian clock and menstrual cycles, however with nuances: “Women with irregular cycles tend to have worse rhythms. daily circadian rhythms and poorer sleep quality. Sleep and good circadian rhythms regulate the menstrual cycle and, in turn, the menstrual cycle influences sleep. If we divide the ovarian cycle in half and place ovulation in the middle, we see that the hormones change in each phase and there are also temperature changes.” But that doesn’t imply, the chronobiologist factors out, that it’s the circadian clock that modulates the menstrual cycle. “In the article, they believe that there is an internal clock similar to the circadian clock that we have in the brain, but they do not identify what it is or where it is. We cannot say that the circadian clock is controlling the menstrual cycle,” says Madrid, who didn’t take part on this research.

Gronfier additionally admits that they have no idea how circadian rhythms decide the size of menstrual cycles. “We don't know yet, but we believe that the circadian synchronization system—well known for its regulatory role in a large number of physiological rhythmicities, such as the sleep-wake cycle, cognition, memory, metabolism, temperature and cell cycle, just to name a few—is involved, as it is involved in another well-known rhythmic process that we call seasonality or annual rhythmicity (which exists not only in animal species that reproduce seasonally, but also in humans). Therefore, the almost monthly rhythm could also originate from the circadian oscillation.”

Controversial moon effect

The authors also analyze the potential effect of the lunar cycle (it lasts 29.5 days) and do not rule out this theory, but specify that the links found are “weak.” In a context of contradictory scientific literature – there are studies that show a more frequent appearance of menstruation after the new moon and others, on the contrary, point out data in favor of the appearance of the period when the moon is brighter or just before and after the full moon—the authors of this research see that the menstrual cycle began more frequently on a crescent moon in Europe, while in North America it occurred on a full moon. “We do not have an explanation for this difference between the continents, but we believe that a more in-depth study of this issue is justified,” they point out in the article, although some hypotheses are proposed.

One of them, Gronfier recalls, looks towards a potential evolutionary footprint. “There is the possibility that our ancestors, the animal species, the A wise man and others, have developed a synchronization with the lunar cycle, which, especially during the full moon, provides a lot of light at night. Our monkey cousins ​​and felines also have nocturnal behaviors that follow the lunar cycle and we see these behaviors that have been maintained through evolution as examples of other behaviors and physiological processes that have been maintained because those lunar rhythmicities used to have a purpose. Our species, as well as most others now, has lost access to the lunar cycle (in terms of night light) with the invention of artificial light, not long ago in terms of evolution. Of course, all of this is hypothetical and needs to be supported by scientific studies and results before we can present them as real,” the scientist points out.

Madrid, on the other hand, is more reticent about proposals about the influence of the lunar cycle: “It was a very nice hypothesis, but if it were truly a synchronizer and not a mere coincidence, it is difficult to understand biologically that a different synchronization mechanism exists. among women in North America and Europe. There is a slight increase in menstruation, but it does not coincide in different places and the statistical evidence is very weak.”

The authors admit that more work and studies in larger populations are needed to test their hypotheses “and unravel the mechanisms” behind this potential internal clock, but their findings open the door to studying chronobiological approaches to address, for example, dysfunctions. in the ovarian cycle. “We are trying to determine the precise mechanisms involved in the rhythmicity of the menstrual cycle, so that we can manipulate them when they are dysfunctional. For example, if the circadian clock is indeed involved, then we can investigate whether improving circadian timing or advancing or delaying the circadian phase (with phototherapy, for example, or other chronobiological approaches) could improve fertility. There is a lot of work ahead,” Gronfier assumes.

An atlas of the ovary

There are still many unknowns surrounding the most basic reproductive physiology of half the planet and the ovaries continue to be, to a large extent, an enigma for the scientific community. In this context, another research from the University of Michigan has now taken a leap in knowledge of the female sexual organs by publishing last week in the journal Science Advances, a cellular atlas of the ovary. The detailed analysis of the population of cells that populate these organs illuminates the way to expand, in the future, the margins of fertility.

The atlas has revealed, for example, what factors make a follicle (where eggs are gestated) mature correctly, since most of them wither before releasing hormones or eggs. “Now that we know which genes are expressed in oocytes, we can test whether affecting these genes could result in the creation of a functional follicle. This can be used to create an artificial ovary that could eventually be transplanted back into the body,” Ariella Shikanov, professor of biomedical engineering at the University of Michigan and author of the study, said in a statement.

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