ABSTRACT
Introduction ............................................................................................................................................ 348 Melatonin .......................................................................................................................................... 348
Physiology and Pharmacology of Endogenous Melatonin .................................................................... 348 Exogenous Melatonin ............................................................................................................................ 349 Endogenous and Exogenous Melatonin and the Brain .......................................................................... 350 Melatonin and Neurobehavior ................................................................................................................351 Melatonin and Exploratory Behavior ......................................................................................................351 Melatonin, Learning and Memory ..........................................................................................................353 Conclusion ............................................................................................................................................. 354 References .............................................................................................................................................. 354
ABSTRACT Melatonin, an indoleamine found in both plants and animals, is a pleiotropic signaling molecule. In animals, it plays an important role in the maintenance of the circadian rhythm and, to date, debates are still ongoing on its other functions and possible uses. Administered melatonin has effects on many behavioral processes, with animal models demonstrating its anticonvulsant, anxiolytic, antidepressant, and locomotor-suppressant and memory-modulating effects. Presently, melatonin research is looking at new horizons, where its role in the etiology and management of clinical conditions such as schizophrenia and dementia is being deeply examined. In this chapter, the sequence of melatonin metabolism and the relationship between melatonin, brain, and neurobehavior is discussed. The implications of exogenous administration of daytime melatonin and its effect on novelty-induced behaviors, learning, and memory are presented.
