Messengers in Opioid Dependence

Opioid drugs are powerful therapeutic agents that have been used for a thousand years to relieve various pathological situations. At the present time, morphine and its derivatives still remain the most potent class of analgesics, and they have clear therapeutic indications despite a considerable number of adverse side effects. However, some opioid compounds also represent an important public health problem because heroin, a diacetylated morphine derivative, is one of the most prominent illicit drugs of abuse. Most of the mechanisms involved in acute opioid responses have been well clarified now. Nevertheless, the neurobiological processes underlying opioid addiction are still poorly understood and remain a field of intense research activity.