A lot of incredible things happen in the newborn body at birth. The respiratory and circulatory systems have to flip like a switch as the baby starts to breathe on their own, for the first time getting oxygen from the air instead of through the placenta. And the truth is, we don’t know a lot about the biology that makes this happen.
We do know that new connections need to form in the brain stem to make a stable and robust command centre that makes breathing automatic throughout our lives.
Researchers from the University of Virginia, the University of Alberta, and Harvard University have now pinpointed a specific gene that is activated at birth in a cluster of neurons in the brain stem that control breathing. Their study was published in Nature.
The gene contains instructions for a neurotransmitter called PACAP that relays messages between neurons. At birth, this special cluster of neurons immediately begins to release PACAP. It’s the first signalling molecule that has been demonstrated to suddenly and specifically activate at birth by the breathing network.
Initially, the neural connections are fragile and immature, and breathing can be unstable. PACAP seems to play a key role not only because it turns on in the right region of the brain, but also because mice that lack PACAP in the relevant neurons are more prone to potentially dangerous pauses in breathing called apneas. They also don’t react as strongly with faster, deeper breathing when CO2 levels get too high in the blood.
It’s possible that problems with PACAP expression or activity could contribute to increased risk of sudden infant death syndrome (SIDS), when infants die suddenly and without explanation before their first birthday. SIDS is the leading cause of infant mortality in western countries.
The team hopes that further research on the changes that happen in the body at birth may illuminate other infant vulnerabilities that could drive early interventions.