The Rat Pack Slot Machine: image via slotzs.comRats who are compulsive gamblers have reason to celebrate today as researchers at the University of British Columbia (UBC) announced the first successful drug to inhibit this compulsive behavior, a dopamine D4 receptor-blocking medication, in its test group. The test of 32 laboratory rats over a 16-month period involved the development and deployment of the only slot machine-style rat casino in North America, a casino built by the UBC Laboratory of Molecular and Behavioral Neuroscience.
While I have presented this development somewhat satirically, indeed the results have very serious implications for humans as, to date, researchers have not found a successful medical treatment for compulsive gambling, an addiction which is becoming a larger public health issue daily. Paul Crocker, lead author of the study, says that observation of the rats "shed new light on the brain processes involved in gambling and gambling addictions."
The rat casino was actually very sophisticated. Rats were given a choice of tapping two levers with their paws, one for cashing out, and the other for rolling again. Three lights signaled a win, and zero, one, or two lights signaled a loss (7 possibilities). Rats got 10 sugar pellets if they won, no pellets if they rolled again. But there was a 10 second penalty on rolling if the rats tried to cash out when they didn't win.
The 'near-misses,' times when the two lights flashed at once, but not a third, caused the rats to tap the cash out lever much of the time, even though they were not rewarded. This, the researchers inferred, indicates the addictive nature of slot machines, as they have more near-misses than other machines, encouraging the reward-seeking behavior, even in the absense of reward.
Researchers chose to focus on the dopamine D4 receptor as it has been linked to several behaviors, particularly novelty seeking behavior. They formulated a D4 receptor-blocker, which they administered to the rats with the results that the rats reduced the reward-seeking behavior (cashing out) when near-misses occured.
The study was the first to show that a D4 receptor-blocker might be able "to reduce the rewarding aspects of near-misses that appear to be important in gambling," said Crocker.
This study is published online in the journal Biological Psychiatry.
source: UBC News