A new study by the researchers at the University of Illinois published in the British Journal of Nutrition, has discovered the genetic processes that show the link between insufficient protein intake during pregnancy with the development of muscle problems in mothers and their male offspring. The study also reveals the metabolic pathway through which these genetic changes are transferred to the fetus, thereby triggering the development of chronic health problems in adulthood such as obesity, cardiovascular disease, and Type 2 diabetes.
The study has a huge significance said Huan Wang, the principal investigator on the study. During the course of pregnancy, women must consume an additional 25 grams of protein every day If insufficiency of protein intake is detected during the early stages of pregnancy, the consequences can be averted by treating it through dietary changes or other strategies,. It can significantly avert many serious health conditions in the next generation.
Wang carried out her study in rats, but evidences from prior research show that the implications are similar for humans. During the study, Wang found that inadequate protein intake during pregnancy activates the amino acid response (AAR) pathway, triggering cell destruction – a process called autophagy or atrophy, which simply means wasting, of the mother’s skeletal muscles.
Under stress conditions, cell resorts to autophagy – a survival mechanism whereby cells degrade unnecessary or dysfunctional components to maintain homeostasis in the body. These genetic changes get transferred through the placenta and are “memorized” in the skeletal muscles of the fetus, which can result in low birth weight and stunted growth in male offspring.
Wang conducted the research while completing her doctorate in food science and human nutrition at Illinois. She says that it is the link that scientists have been seeking for years, which shows transduction from the mom through the placenta to the child. She points out that it should be noted that there is a gender specificity as the cell autophagy is activated in the skeletal muscles of the male offspring only. It seems the female offspring have more resistance to low-protein exposure during gestation and to cell autophagy.
For this study, Wang experimented on 2 groups of pregnant rats one group consumed food that contained 8 or 9 percent protein, while the other one consumed about two times of it – 18 to 20 percent. After delivery, all of the rats consumed the control diet during lactation, so did their pups after weaning. The body weights and food intake of the rats were recorded every other day. It was found that the mother rats on the low-protein diet gained significantly less weight during pregnancy, and their babies were smaller at birth. It was also found that the rats on low protein diet had lower levels of threonine and histidine, and higher levels of alanine, lysine and serine, which suggests of potential disturbances in their protein metabolism.
When the skeletal muscles of the mother rats were examined after delivery, evidence of muscle atrophy, such as smaller fiber size, greater variation in fiber diameter and split fibers were found by Wang.
Among other findings of the study were increased activation of several AAR pathway downstream genes in both the mothers’ with low protein intake and their male pups’ skeletal muscles. Surprisingly, it was found that their other tissues – and those of the female pups – were unaffected. It was also discovered that rats on the low-protein diet showed higher expression of the ATF4 gene, a key regulatory protein within the AAR pathway known to play a critical role in muscle dystrophy caused by fasting. ATF4 is also linked with cell autophagy.
The study confirms a molecular link between the activation of the AAR signal and the autophagy pathway, Wang said. It is understood that the AAR- and autophagy-related genes remained activated in the skeletal muscles of the male pups, signifying that the amino acid limitation signal within the pregnant mothers’ skeletal muscles was transferred to the offspring through the placenta.
The findings stresses on the importance of adequate protein intake in women during pregnancy to protect the health of their children.
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