Source: Lancet, The (UK) Contact: http://www.thelancet.com/ Copyright: The Lancet Ltd Pubdate: 12 Dec 1998 Author: Jane Bradbury MORE ON SEROTONIN SYSTEM The serotonin system is thought to regulate most, if not all, complex behaviours, but it has been hard for researchers to get a handle on the system which involves at least 14 distinct types of serotonin receptors. This week, US scientists report that genetically engineered mice lacking the 5-HT1A inhibitory serotonin receptor are more anxious than their normal littermates and that they behave like mice that have been given antidepressants. "Our speculation", says senior author, Laurence Tecott (University of California, San Francisco, CA, USA) "is that both these abnormalities--anxiety and antidepressive responses--can be accounted for by disinhibition of serotonin system activity". The mutant mice "have potential as a model for investigating mechanisms through which serotonergic systems modulate affective state and mediate the actions of psychiatric drugs", conclude the authors (Proc Natl Acad Sci USA 1998; 95: 15049-54). - --- Checked-by: Pat Dolan