Review of research on alcohol dependence in a model of mice selected for high and low stress-induced analgesia

Decades of studies on alcohol dependence showed that it is a very complex and multifactorial disorder. Several receptor systems are involved in development and susceptibility to alcohol abuse; however, there are some which play a crucial role in its pathogenesis, e.g. dopaminergic or opioid system. In this paper, an effort is made to explain the role of endogenous opioid system activity in alcohol dependence. To achieve the goal, we use a unique model is used which shows mice lines that are divergently selected for high (HA) and low (LA) stress-induced analgesia. This process allowed for selecting individuals characterised by hyperactive (HA) or hypoactive (LA) opioid system. Basing on the performed experiments, we proved that delta opioid receptors play a critical role in the development of addiction. The most notable achievement is an unspecific reaction of mice with the hyperactive opioid system to naloxone – an unspecific opioid system antagonist, which is currently approved in the pharmacotherapy of dependent patients.