Knockout Corner.

Serotonin (5-hydroxytryptamine, 5-HT) is a neurotransmitter involved in a number of physiological functions including sleep, appetite, pain perception, and sexual activity. Several pathological states such as migraine, depression, and anxiety have been linked to the serotonergic system, and serotonergic drugs have been used to treat these disorders. To date, there are 14 known serotonin receptor subtypes through which serotonin exerts its multiple actions. The classic pharmacological approach to study how these individual receptor subtypes contribute to various behaviours has been to use selective drugs that either block or activate certain receptor subtypes, and then study the effects of these compounds on physiology and behaviour. A complementary genetic approach is the technique of gene targeting. Using this technology, we and others have begun to examine the contribution of several serotonin receptor subtypes to complex behaviours through the generation of knockout mice that lack the genes encoding these receptors. In this review, we will describe what we have learned about the serotonergic system and the function of the 5-HT(1B) receptor by the analysis of 5-HT(1B) receptor knockout mice. Furthermore, we will discuss the implications of these findings and our plans for future studies.