Molecular mechanisms of neuronal plasticity during learning: the role of secondary messengers.

We present published data along with our own results concerning the role of second messengers and their intracellular receptors in molecular mechanisms associated with the plasticity of neurons during learning. The participation of cyclic 3',5'-adenosine monophosphate, cyclic 3',5'-guanosine monophosphate, calcium, calmodulin, and also the metabolic products of inositol phospholipids, inositol-1,4,5-triphosphate, diacylglycerol and the protein kinase C activated by it, arachidonic acid, and the products of its lipoxygenase oxidation during the regulation of neuronal plasticity over the course of prolonged potentiation, sensitization, habituation, and classical associative training are discussed.