Scientists have identified possible causes of malrotation of the intestine; A common but little-known condition in which the intestine does not rotate properly during development at birth.
Researchers in the United States have found that exposure to the herbicide atrazine disrupts the intestinal rotation of frog embryos, which have similar visceral development to humans.
Nanette Nascone Yoder, a molecular biomedical scientist at North Carolina State University, said, "Our findings provide a new avenue to explore the root cause of this pervasive birth anomaly. ”。
Because frog embryos develop in just a few days and are experimentally readily available, they allow us to quickly test new hypotheses about how and why development goes wrong during poor rotation. ”
During the development of the digestive system, the intestinal tract of vertebrates grows longer. This extra length fits into a relatively small space in the body, as it is a process called intestinal rotation, which tightly winds the "tube" into a compact coil.
In humans, this rotation is thought to be the result of a revolution in the embryonic gut, although the exact mechanism is unknown.
"As vertebrates, frogs and humans share a common ancestor and share many similar anatomical features, including a intestine that rotates in a counterclockwise direction," Nascone Yoder says. ”。
About 1 in 500 newborns fail in the rotation process, resulting in intestinal displacement, known as malrotation. This malrotation can lead to serious complications such as intestinal obstruction caused by the intestinal self-circulation that requires surgery in early infancy.
Genetic and environmental factors are thought to play a role in malrotation, but its complex process is not well understood. This may seem surprising given the high incidence of this condition, and the researchers believe that this is partly due to limited knowledge of how rotation occurs in normal development.
The research team focused their attention on Art.
Razin is a potential cause, as laboratory experiments in frogs have found that the herbicide significantly increases the frequency of intestinal rotation in the wrong direction.
"Frog embryos develop in petri dishes and are transparent when the intestine develops, so they can be exposed to drugs or environmental chemicals to screen for substances that produce spin badly," Nascone Yoder explains. ”。
Atrazine is one of the most widely used agricultural herbicides in the United States, Canada and Australia, but the European Union banned its use in 2004 due to concerns about groundwater contamination. It has been linked to a number of health problems in mice and humans, but the evidence is complex and more research is needed to draw definitive conclusions.
Exposure to atrazine under laboratory conditions causes a metabolic imbalance in frog embryos, preventing cells from normal**, growing, or rearranging, disrupting several cellular processes in the gut. The tissue becomes more difficult to stretch properly, which makes the bowel shorter.
"The resulting shortening of the length of the intestinal tube prevents the key hairpin loops of the intestine from reaching their normal anatomical position, forcing the intestine to coil in the opposite direction," the study authors wrote. ”。
According to the team, these intestinal developmental problems appear to stem from atrazine's throwing the body's redox response out of balance. An imbalance between the cell's oxidants and antioxidants may play a role in the disease. Before frogs are exposed to atrazine, using antioxidants** they can prevent their intestines from twisting.
It is important to note that frog embryos were exposed to 1000 times the normal level in the environment, and these results do not prove that exposure to atrazine causes poor rotation in humans.
That said, these findings highlight the importance of metabolic pathways in gut development and highlight possible causes of intestinal malrotation, although much remains to be learned.
"For example, interfering with the same cellular metabolic processes affected by atrazine may result in malrotation of the human gut by exposure to other chemicals in the environment and/or genetic variants that affect metabolism," Nascone Yoder said. ”。
We are now beginning to delve into the cellular events that orchestrate the complex processes of intestinal elongation and rotation. ”
The study has been published in the journal Development.