July 29, 2011

Mice Help Explain SIDS?

(Ivanhoe Newswire) -- New research may pave the way for understanding sudden infant death syndrome (SIDS). Scientists have developed a strain of mice with a built-in off "switch" that can shut down serotonin-producing cells in the animals. These cells make up a brain network that controls breathing, temperature regulation and mood.

SIDS has been linked to low serotonin levels and is thought to involve breathing abnormalities and problems with temperature control. According to the National Center for Health Statistics, SIDS is the third leading cause of infant death.

Researchers developed mice with a unique molecule, or receptor, on the surface of their serotonin-producing brain cells, or neurons. Typically, cells communicate through chemicals that bind to receptors on their surfaces. The researchers added this special receptor to the animal's serotonin-producing neurons using a genetic manipulation technique. Rather than binding to a naturally occurring brain chemical, the receptor binds to a chemical compound manufactured in a lab -- called clozapine-N-oxide (CNO).

The scientists say when CNO binds with the receptor, it deactivates only the serotonin cells, switching off all communications in the serotonin network. When the researchers powered down the animals' serotonin cells, the animals failed to step up their breathing to compensate for an increase of carbon dioxide in the air, and their body temperatures dropped to match the surrounding temperature.

Researchers hypothesize that infants who die of SIDS may not be able to respond to breathing challenges, such as low levels of oxygen or high levels of carbon dioxide. The ability to regulate body temperature is also thought to play a role in SIDS.

"The single most effective way to reduce the risk of SIDS is to always place infants on their backs for sleep," Marian Willinger, Ph.D., special assistant for SIDS at the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development, which provided major funding for the study, was quoted as saying. "This new animal model of the serotonin-producing system holds the promise of helping us to understand the biological processes contributing to SIDS, which is critical for the development of tests and interventions to prevent these deaths.'

The investigators also say they believe their research may provide insights into depressive disorders, which also involve serotonin metabolism.

SOURCE: Science, July 28, 2011