Philadelphia, PA, May 22, 2014 The list of brain receptor targets for opiates reads like a fraternity: Mu Delta Kappa. The mu opioid receptor is the primary target for morphine and endogenous opioids like endorphin, whereas the delta opioid receptor shows the highest affinity for endogenous enkephalins. The kappa opioid receptor (KOR) is very interesting, but the least understood of the opiate receptor family.
Until now, the mu opioid receptor received the most attention in alcoholism research. Naltrexone, a drug approved by the U.S. Food and Drug Administration for the treatment of alcoholism, acts by blocking opiate action at brain receptors and is most potent at the mu opioid receptor. In addition, research has suggested that a variant of the gene that codes for the mu opioid receptor (OPRM1) may be associated with the risk for alcoholism and the response to naltrexone treatment.
However, naltrexone also acts at the kappa opioid receptor and it has not been clear whether this effect of naltrexone is relevant to alcoholism treatment.
A growing body of research in animals implicates the KOR in alcoholism. Stimulation of the KOR, which occurs with alcohol intake, is thought to produce unpleasant and aversive effects. This receptor is hypothesized to play a role in alcohol dependence, at least in part, by promoting negative reinforcement processes. In other words, the theory postulates that during development of alcohol dependence, the KOR system becomes overstimulated, producing dysphoria and anhedonia, which then leads to further alcohol seeking and escalation of alcohol intake that serves to self-medicate those negative symptoms.
A new study in Biological Psychiatry, led by Dr. Brendan Walker at Washington State University, used a rat model of alcohol dependence to directly investigate the KOR system following chronic alcohol exposure and withdrawal.
They found that the KOR system is dysregulated in the amy
|Contact: Rhiannon Bugno|