Drunk, stoned mice shed light on addiction

Researchers in the US have discovered that the part of the brain that makes it fun to get stoned, also makes it pleasurable to get drunk .

The tests, which were carried out on mice, confirmed that the so-called cannabinoid receptors known as CB1, are also stimulated by drinking alcohol. The CB1 receptors are directly involved in triggering what the researchers call "the reinforcing properties" of both substances.

Panayotis Thanos, lead author of this study, and a neuroscientist at the US Department of Energy’s Brookhaven National Laboratory, said that the results improved the general understanding of the role these receptors play in alcohol abuse. They also shed light on how a person's genes could affect their susceptibility to addiction.

The researchers tested three groups of mice: the control group with a normal set of CB1 receptors, a group with half of the CB1 receptors blocked, and a third group with all the receptors blocked.

The mice were conditioned to expect alcohol in a particular part of their cage, and saline solution in another. The researchers then monitored the amount of time the mice spent hanging around in the alcoholic portion of the cage, effectively looking for a drink, and compared it with how long they spent elsewhere.

The mice with the blocked CB1 receptors showed no particular preference for either the alcohol or the saline solution. The mice with no blockers, on the other hand, clustered in the alcohol chamber like undergraduate students in the local students' union bar. Those with half their CB1s blocked were somewhere in between the other two groups.

"These results support our belief that the cannabinoid system and CB1 receptors play a critical role in mediating the rewarding and pleasurable properties of alcohol, contributing to alcohol dependency and abuse...[and] provide further evidence for a genetic component to alcohol abuse that includes the CB1 gene - the same gene that is important for the behavioural effects of marijuana," Thanos said.

The researchers hope that ultimately, their work will be useful in developing effective treatments for addiction. ®