[Pain regulation and plasticity].

The pathophysiology of chronic pain is not well understood. To try to explain why pain may become long-lasting or chronic, it is necessary to understand the plasticity of the neuronal circuits involved in nociception. It seems that mechanisms of learning and memory are involved in this process. Interactions between peptide and nonpeptide neurotransmitters may be important. Other significant factors appear to be changes in gene induction and transcription, and cell injury and destruction as a result of excitation. Through these mechanisms, painful states may induce changes in the nervous system which lead to greater pain, making adequate prevention and treatment of nociceptive pain essential.