A team of researchers led by Tamas Horvath, Professor of Comparative Medicine, Neurobiology, and Obstetrics and Gynecology at the Yale School of Medicine, has found that natural birth, not delivery by Caesarian section (C-section), stimulates production of a protein important for brain development.
The discovery was a chance finding for the researchers, who were initially investigating the role that mitochondrial uncoupling protein 2 — or UCP2 — plays in the brain. It is believed that the main role of the protein is to enable cells to metabolize fat, a key process for the adaptability of cells. The researchers were studying this protein in post-natal mice and looked for differences in expression between in utero and ex utero as a control. “What we noticed was that if the animal was naturally born, the expression of the UCP2 was significantly higher than if the pup was taken from C-section,” Horvath explains, “and that’s when the whole thing started to be interesting for us.”
Once the team established the connection between higher levels of UCP2 and natural birth, they turned their attention to the role that UCP2 has on brain development. By inferring the UCP2 expression using chemical methods and genetic suppression, the team discovered that lower UCP2 expression resulted in less connectivity between the neurons in the hippocampus — the part of the brain responsible for developing memory and aiding the learning processes. Additionally, mice with lower levels of UCP2 performed differently in simple tasks associated with the hippocampus region. They exhibited less spatial awareness, moved more slowly, and showed greater anxiety about moving into open areas than did the mice with normal levels of UCP2.
The discovery comes at a time when many women, especially those in the United States, are electing to have C-sections out of convenience rather than medical necessity. Though the World Health Organization recommends that the C-section rate be less than 10 percent to 15 percent, the rate in the U.S. has climbed from 4.5 percent in 1965 to 32 percent in 2007. While Horvath does not think this discovery will halt the trend, he is hopeful that it will lead to a greater understanding of the procedure. “If there is a biological process that makes a difference between C-sections and natural birth, it will at least be good to know and see how [one] can take that into consideration,” he says. Horvath also points to the possibility that future studies could reveal the threshold of medical need for women to have a C-section.
In future studies, Horvath plans to investigate the triggers of UCP2 induction to determine why it occurs with natural birth, which could lead to the development of methods to mimic it through surgical means. He also plans to expand on the original finding with additional studies on surgically and naturally born mice and eventually dogs. This may include following their development and behavior throughout their life, but the long-term goal remains to conduct studies in the human population.