MRI scans: Alcohol-drinking mice that lacked dopamine receptors had lower overall brain volume and reduced volume in the cerebral cortex (blue) and thalamus (purple) compared with mice drinking water
Brain scans of mice given significant quantities of alcohol has revealed serious shrinkage in some regions of the brain.
But the effect only occurred in mice lacking a particular type of receptor for dopamine, a chemical with a key role in setting moods.
The study, conducted at the U.S. Department of Energy’s Brookhaven National Laboratory provides new evidence that these dopamine receptors, known as DRD2, may play a protective role against alcohol-induced brain damage.
Coauthor of the paper and Brookhaven/NIAA neuroscientist Peter Thanos said: ‘These studies should help us better understand the role of genetic variability in alcoholism and alcohol-induced brain damage in people, and point the way to more effective prevention and treatment strategies.’
The study specifically explored how alcohol consumption affects brain volume – overall and region-by-region – in normal mice and a strain of mice that lack the gene for dopamine D2 receptors.
Half of each group drank plain water while the other half drank a 20 per cent ethanol solution for six months.
Then scientists performed MRI scans on all the mice and compared the scans of those drinking alcohol with those from the water drinkers in each group.
The scans showed that chronic alcohol drinking induced significant overall brain deterioration and shrinkage of the cerebral cortex in the mice that lacked dopamine D2 receptors, but not in mice with normal receptor levels.
Mice in both groups drank the same amount of alcohol.
Half of the mice in the test drank plain water while the other half drank a 20 per cent ethanol solution for six months
‘This pattern of brain damage mimics a unique aspect of brain pathology observed in human alcoholics, so this research extends the validity of using these mice as a model for studying human alcoholism,’ Thanos said.
In humans, these brain regions are critically important for processing speech, sensory information, and motor signals, and for forming long-term memories. So this research helps explain why alcohol damage can be so widespread and detrimental.
‘The fact that only mice that lacked dopamine D2 receptors experienced brain damage in this study suggests that DRD2 may be protective against brain atrophy from chronic alcohol exposure,’ Thanos said.
‘Conversely, the findings imply that lower-than-normal levels of DRD2 may make individuals more vulnerable to the damaging effects of alcohol.’