Researchers examine brain's role in breathing

Much of our knowledge of the brain's role in regulating breathing comes from research with mice and rats. A chemical receptor within the brain stem communicates with the central nervous system to generate the basic pattern of breathing. The next step is applying that information to human tissue to identify these critical components in the human brain and their medical implications.

An article in the current issue of the journal Pediatric and Developmental Pathology builds on our current knowledge of the role of the brain in breathing. Researchers examined postmortem brain stem tissue from 17 fetuses and infants to locate the human retrotrapezoid nucleus (RTN), which serves as the critical central chemoreceptor.

Mutations in the protein expression pattern of PHOX2B can lead to a rare disorder, congenital central hypoventilation syndrome. This condition is responsible for loss of air hunger and complete sleep apnea. The current research can guide scientists toward better understanding of this and related breathing disorders.

By applying immunohistochemical studies similar to those performed in rodent models, scientists sought to identify the RTN in the human brain. Reviews of autopsy records and stained slides from brain stem sections were conducted between 2001 and 2008. Selected cases were evaluated for PHOX2B immunoreactivity in parts of the caudal pons and medulla brain sections of these samples. In essence, researchers followed the PHOX2B pattern to locate the RTN.

In this study, the predictions made from rodent models held true for human tissue. The authors report that the putative human RTN is located ventral to the facial nucleus and lateral to the superior olivary nucleus, where the two brain sections studied meet—the pontomedullary junction. The authors describe this as a "valuable first step toward defining what is likely to be a key site of respiratory regulation."