A pregnant woman has to feed for two and the surface area of her small intestine increases proportionally, shows a study conducted by Austrian researchers from the University of Vienna. This increase continues during breastfeeding when the mother still has high nutritional needs to produce quality milk.
In pregnant mice, researchers were able to observe that this adaptation results from the slowing down of the intensive renewal of intestinal villi, these folds of approximately 1 mm in height which line the intestinal mucosa of the small intestine. The villi then lengthen in the intestine, grow, and their greater density also slows down the transit of nutrients which are thus better absorbed.
Changes induced by a hormone: prolactin
In addition, the intestinal cells of these villi express more transporters for lipids, amino acids and vitamins. The researchers discovered that this change was induced by a hormone, prolactin, produced during gestation in mammals and already known to cause the development of mammary tissue and its production of milk.
As evidence of the critical role of prolactin, simply removing newborns from their mothers, which causes her blood prolactin level to drop, or directly blocking the action of prolactin with an inhibitor, caused the surface area of their intestine to shrink.
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A condition for the baby's proper development
Using intestinal tissue organoids developed from human cells, the researchers found the same mechanisms for developing the intestinal surface during pregnancy. This transient adaptation to an increased demand for nutrients conditions the proper development of the fetus and then of the baby when it is breastfed.
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Pups born to mice that did not have this increase in intestinal surface area during gestation were smaller and had a higher risk of diabetes as adults, mimicking a consequence already observed in children born to pregnant women during the great famine of 1944 in the Netherlands.
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