Pain, Opiates and Addiction
|Stephen P Hunt|
|Department of Anatomy and Cell Biology, UCL , UK|
Over the years there has been a paradigm shift away from the belief that the use of opiates for the relief of chronic pain would inevitably lead to addiction to the more interesting proposition that chronic pain in some way prevents the development of opiate addiction. In my presentation I want to explore how this might come about. It is known that both pain systems and areas of the brain concerned with reward and motivation are closely related and that most drugs of abuse also generate some form of analgesia. Also sites in the brain that support electrical self-stimulation behaviour largely overlap those known to produce analgesia either through direct stimulation or by microinjection of opioid drugs. Practically, of course, motivational systems have to compute a cost-benefit analysis and regulate the level of any on-going pain in relation to the value of a specific goal such as food or water. To understand how pain and addiction intersect it is necessary to ask how addiction, a chronic relapsing disease characterised by compulsive drug seeking, is established at the neurobiological level and then to review how pain signals might modulate the long term changes in synaptic plasticity that are thought to predispose recovering addicts to relapse. Ultimately, it might be worth asking whether pain research can contribute to our understanding of the molecular mechanisms that drive regular drug taking into the compulsive addicted state.