Rat study suggests pleasurable endorphin release ends as drinking gets heavier
THURSDAY, March 19 (HealthDay News) -- New research suggests that when it comes to getting pleasure from alcohol, less may be more.
Experiments in rats suggest that a low or moderate amount of drinking releases "feel-good" brain chemicals called beta-endorphins, but this activity tapers off with heavier drinking.
"Drinking the low amounts of alcohol is associated with mild euphoria, decreased anxiety and a general feeling of well-being, while drinking high amounts of alcohol is associated with sedative, hypnotic effects and often with increased anxiety," said study author Christina Gianoulakis, a professor of psychiatry and physiology at McGill University and Douglas Mental Health University Institute, in Montreal.
The bottom line: "If after consumption of about two drinks of alcohol an individual does not experience the pleasant effects of alcohol, he or she should stop drinking," Gianoulakis said.
In the study, researchers injected male laboratory rats with saline or alcohol and tracked levels of opioid brain chemicals such as endorphins, enkephalins and dynorphins.
Rodents given low to moderate levels of alcohol showed increased levels of beta-endorphins, which produce a feeling of well-being in humans, while those given higher levels of alcohol did not. The same doses did not alter levels of the other the two other opioids, enkephalins and dynorphins.
Higher doses of alcohol failed to trigger the same release of beta-endorphins, the team found.
The study results were published online March 19 in the journal Alcoholism: Clinical & Experimental Research and will be available in the journal's June print issue.
Besides helping to explain the "buzz" that comes with light, social drinking, the research may have implications for the treatment of alcoholism, experts said.
"We're always looking for medications that can be used with the alcoholic to cut back on craving and dependency," noted Dr. Marc Galanter, director of the division of alcoholism and drug abuse in the department of psychiatry at New York University School of Medicine in New York City. "That's why this whole neurotransmitter system is one area where we may find useful medications."
While medications that curb alcoholism by acting on brain chemicals are already prescribed today, Gianoulakis speculated that future research may lead to even more targeted therapies.
"Among the current treatments of alcoholism is administration of substances that block the activity of opioid peptides in a non-specific fashion [all opioid peptides in all brain regions]," she explained. "Our findings suggest that a more targeted approach may be developed by blocking the activity of beta-endorphin in the [brain's] ventral tegmental area."
But researchers say additional research is needed to better understand the relationship between alcohol and endorphins and to further develop treatments to treat the disease, beginning with studies involving human beings who actually consume alcohol.
"This is a laboratory study, so it's not easy to extrapolate from this study into specific effects on people in real-life situations," Galanter said. "But it does illustrate how that whole domain is important in research for alcoholism treatment."
Until definitive conclusions are drawn, addiction specialists and physicians continue to advocate that healthy adults consume alcohol in moderation.
"Consumption of high amounts of alcohol not only will fail to increase the release of endorphins and produce a feeling of well-being, but may stimulate other systems in the brain that may lead to the development of anxiety and depression," said Gianoulakis. "My advice to everyone is to drink less alcohol, because more is not necessarily better."
To learn more about alcohol abuse, visit the U.S.National Institute for Alcohol Abuse and Alcoholism .
SOURCES: Christina Gianoulakis, Ph.D., professor, psychiatry and physiology, McGill University and Douglas Mental Health University Institute, Montreal; Marc Galanter, M.D., director, division of alcoholism and drug abuse, department of psychiatry, New York University School of Medicine, New York City; June 2009 Alcoholism: Clinical & Experimental Research
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