Central serotonin and autoresuscitation capability in mammalian neonates

Autoresuscitation is an important cardiorespiratory protective mechanism that allows neonatal mammals to recover from primary apnea. It begins with hypoxia-induced gasping and ends, if successful, with the recovery of rhythmic breathing and normal heart rate. Many factors influence the efficacy of autoresuscitation, including the availability of serotonin (5-HT) in the brain. Since the early 2000's, there has been mounting interest in the role of 5-HT in promoting autoresuscitation, driven in large part by the recognition that both failed autoresuscitation and a deficiency of central 5-HT correlate with Sudden Infant Death Syndrome in humans. Within this timeframe, newly developed animal models with a central 5-HT deficiency have examined experimentally the role of 5-HT in autoresuscitation capability. The purpose of this review is to discuss some of the methodological considerations associated with 5-HT-deficient animal models, to summarize major findings arising from their use, and to highlight several key issues related to 5-HT involvement in gasping and the autoresuscitation response.