A variant of a gene involved in communication among brain cells has a direct influence on alcohol consumption in mice, according to scientists. They caution that it is unknown whether a similar gene variant with a similar effect on alcohol consumption exists in humans.
Known as Grm7, the gene encodes a receptor subtype that inhibits the release of glutamate and other neurotransmitter molecules. The investigators identified a polymorphism that reduces the abundance of Grm7 mRNA in brain tissue.
Mice that possess this gene variant drink more alcohol than do mice with higher brain levels of Grm7 mRNA, according to the research team.
“Our findings support emerging evidence of the critical role that the brain’s glutamate pathways play in addiction,” notes first author Csaba Vadasz, Ph.D., professor of psychiatric research in the department of psychiatry at New York University School of Medicine. “While dopamine has traditionally been cast as a central actor in the neurochemistry of substance use and abuse, recent studies indicate that glutamate systems play an important role in reinforcement and addiction.”
Scientists have long believed that genes account for a significant proportion of the risk for alcoholism. Interactions between multiple genes as well as genes and environmental factors have, however, hampered studies to isolate individual genes.
To overcome these difficulties, Dr. Vadasz and colleagues applied a variety of genetic and analytic techniques to animals having nearly identical genetic background but differing in their preference for alcohol.
The research team also included investigators at Nathan S. Kline Institute for Psychiatric Research, Debrecen University School of Medicine in Hungary, Bayer Hungaria also in Hungary, and VA Medical Center in Kansas City, MO. The study was supported by the National Institute on Alcohol Abuse and Alcoholism. The results are published online and in the December issue of in Genomics.