Oxytocin, a messenger chemical that affects the brain as well as the entire body where it acts like a hormone, is also a powerful chemical.
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Oxytocin is a substance that has been shown to be effective in treating certain diseases. “cuddle hormone” A study on lab animals found that the hormone known to be involved in bonding may play a part in delaying early pregnancy.
A new study in mice has shown that this hormone is capable of putting embryos at the very beginning of their development in a state of hibernation. This process is called “diapause,” It is possible for a mouse to postpone a pregnancy when there are limited resources, such as if she’s still caring for a litter of mice pups.
“The fact that oxytocin had an influence on this was a little bit of a surprise,” Live Science spoke with study coauthor Moses Chao, a Neuroscientist from the New York University Grossman School of Medicine.
In general, diapause is somewhat mysterious. This phenomenon occurs naturally in marsupials such as kangaroos, possums and at least 130 different species of mammals including mice and bats.
In rare instances, it may even happen in humans. It’s difficult to monitor in human pregnancy, but scattered reports suggest that in some cases embryos implanted in the uterus can hang around for several weeks. One case from 1996 reported that it took 5 weeks for a pregnancy to start after the embryo was transferred.
Related: Study suggests that pregnancy may accelerate biological aging
Chao says it’s unclear how long diapause lasts, or how embryos can enter this suspended animation state.
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Jessica Minder, the first author of the study, is a graduate medical student from NYU Grossman School of Medicine. She was particularly interested in the role of oxytocin in diapause, as the hormone has been implicated in the development of embryos and in nursing, in both mammals including humans.
Minder, along with his colleagues, began their work by placing male mice in the enclosures that housed female mice who had recently given birth. This allowed the mice to mating while they were still breastfeeding the first litters. Researchers found that pregnancies in female mice who were still nursing lasted a little longer than in those mice not breastfeeding.
This is likely to be a sign of pre-implantation. “pause.” The mouse pregnancy lasts only between 19 and 21 days. This pause is a sign of a delay.
They then began to investigate how the pause could occur.
The team also used optogenetics to stimulate the release of oxytocin in the brains and uteri of mice that were newly pregnant. This technique uses light to activate specific neurons. Researchers timed the stimulation so that it resembled the pulses seen in nursing.
The mice were then removed from the uterus to evaluate embryonic growth. The embryos of five of six mice mothers showed signs of diapause.
In the comparison group of pregnant mice, those who had not been stimulated with oxytocin did not display any diapause symptoms.
The team also treated mouse embryos in laboratory dishes with oxytocin, which caused cellular changes that were consistent with diapause.
Researchers reported in Science Advances on March 5, that the combined evidence indicated that oxytocin caused the embryonic cells’ translation of genes to proteins to be slowed. The multi-step process involves copying DNA instructions into a molecule called RNA, which is then shipped to the cell’s proteins construction sites.
Chao pointed out that even embryos lacking oxytocin can undergo diapause. This means there may be multiple triggers for the pause. But oxytocin appears to be necessary for embryos to endure this arrest.
Researchers found that when they turned off the oxytocin-receptors in mouse embryos only 11 percent survived the diapause compared to 42 percent of embryos with functioning oxytocin-receptors.
Chao explained that this research was an initial exploration of metabolism in early embryos. A better understanding of the mechanisms could eventually reveal why people miscarry early and lead to improved fertility treatments.
Chao stated that more work is needed to better understand the biochemical pathways from oxytocin to diapause.
Chao said that the new results could be useful for understanding cell death more broadly. As an example, the nervous system refines itself before birth and half the embryonic nerve cells die. Many of the developing nerve cells in the womb will last for a lifetime.
“Later on [in development], you don’t want half your cells dying,” Chao said, “so we’re very interested in what keeps those cells going.”
Stephanie Pappas writes for Live Science. She covers topics ranging in scope from archaeology and geosciences to human behavior, brain function and the psychology of humans. Formerly a Senior Writer for Live Science, she is now a Freelance Based in Denver Colorado and contributes regularly to Scientific American, The Monitor and the Monthly Magazine of the American Psychological Association. Stephanie has a Bachelor’s in Psychology from the University of South Carolina, and an advanced certificate in Science Communication from the University of California Santa Cruz.
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