Memory Disorders Related to Hippocampal Function: The Interest of 5-HT(4)Rs Targeting

The hippocampus has long been considered as a key structure for memory processes. Multilevel alterations of hippocampal function have been identified as a common denominator of memory impairments in a number of psychiatric and neurodegenerative diseases. For many years, the glutamatergic and cholinergic systems have been the main targets of therapeutic treatments against these symptoms. However, the high rate of drug development failures has left memory impairments on the sideline of current therapeutic strategies. This underscores the urgent need to focus on new therapeutic targets for memory disorders, such as type 4 serotonin receptors (5-HT(4)Rs). Ever since the discovery of their expression in the hippocampus, 5-HT(4)Rs have gained growing interest for potential use in the treatment of learning and memory impairments. To date, much of the researched information gathered by scientists from both animal models and humans converge on pro-mnesic and anti-amnesic properties of 5-HT(4)Rs activation, although the mechanisms at work require more work to be fully understood. This review addresses a fundamental, yet poorly understood set of evidence of the potential of 5-HT(4)Rs to re-establish or limit hippocampal alterations related to neurological diseases. Most importantly, the potential of 5-HT(4)Rs is translated by refining hypotheses regarding the benefits of their activation in memory disorders at the hippocampal level.