Scientists from the European Molecular Biology Laboratory in Monterotondo, Italy, genetically modified lab mice to produce low levels of the brain-signalling protein serotonin. After being exposed to slight external temperature changes, the rodents suddenly died because their bodies could not adjust, researchers said.
The results showed the mice suffered drops in heart rate and other symptoms of SIDS, and many of the animals died at an early age. Researchers now believe that low levels of serotonin in the animals' brainstems, which control heartbeat and breathing, may have caused sudden death, researchers said in the July 4 issue of Science.
SIDS or unexplained infant deaths are the leading case of death for children under the age of one, and the third leading cause of infant mortality, according to the Centers for Disease Control and Prevention.
Many SIDS deaths are the result of simple mistakes, such as placing a baby on his or her stomach rather than back, that cause heart rate variability. Over-bundling babies with several pillows or blankets and thus overheating them, or co-sleeping with a parent can increase the risk of babies dying.
Serotonin is a chemical messenger synthesized in the central nervous system that helps the brainstem communicate with nerve cells in the spinal cord and beyond. It is involved in many critical body functions, such as heart rate regulation, breathing, temperature regulation and more.
The animal model can help test the effect of drugs on serotonin system dysfunctions in the brain and help pinpoint biological risks for crib death in humans, researchers say.
SIDS is responsible for roughly 1 death per 2,000 births in the U.S. It is responsible for far fewer deaths than congenital disorders and disorders related to short gestation, though it is the leading cause of death in healthy babies after one month of age.
