Learning and memory in 5-HT1A-receptor mutant mice

The serotonin 1A (5-HT1A)-receptor is involved in a wide range of physiological functions, but has also been implicated in the pathophysiology of anxiety disorders and depression. Although the 5-HT1A-receptor is one of the best described receptor subtypes of the serotonergic system. its complex distribution pattern, pre- and postsynaptic localisation, and its impact on various neurotransmitters aggravate the attribution of 5-HT1A-agonistic effects to behavioural outcomes. The role of 5-HT1A-receptors for cognitive processes seems undisputed. However, the exact involvement of pre- and postsynaptic sites remains unexplained. Genetically modified animals are a complementary approach to pharmacological studies for further investigations of the role of the 5-HT1A-receptor. Next to 5-HT1A-receptor knockout mice, two transgenic mouse lines exist that either overexpress the 5-HT1A-receptor transiently or permanently. The latter mouse line stands out due to the fact that a distinct overexpression is primarily found in the outer cortical layers and hippocampus, both projection areas of serotonergic neurons. Here, we discuss the findings obtained from 5-HTIA-receptor knockout and overexpressing mice concerning their learning and memory abilities. (C) 2008 Elsevier B.V. All rights reserved.