Watch CBSN Live

Endorphins Play Role in Alcohol's Effects

Light to moderate drinking triggers "feel good"
chemicals in the brain that can reduce anxiety, but heavier doses don't, a new
study shows.

Drinking's allegedly good and bad effects have been enumerated in many
studies, but scientists in Canada say they've found that while low and moderate
doses of alcohol produce a general feeling of well-being, having just a tad too
much might reinforce the desire for more, or trigger depression or feelings of

Christina Gianoulakis, PhD a professor of psychiatry and physiology at
McGill University, and colleagues published the findings in the journal
Alcoholism: Clinical and Experimental Research.

They performed experiments using rats, and say they confirmed for the first
time that low to moderate levels of alcohol alter beta-endorphin release in a
region of the brain linked to drug and alcohol addiction , producing "the
pleasant effects that likely reinforce alcohol consumption."

Gianoulakis tells WebMD that researchers don't know the mechanisms
responsible for the fact "that some people can stop after one-two drinks
while others cannot."

"One way that alcohol may influence brain function is by increasing or
decreasing the release of a number of neurotransmitters, among which are the
endogenous opioid peptides, in distinct brain regions important for drug
addiction," she tells WebMD.

But conditions other than drinking, such as exercise , also could increase
endorphin release, reduce anxiety, and induce a general feeling of well-being,
says Gianoulakis.

"In the best of my knowledge we do not know the exact mechanisms that
make some people stop drinking after one-two drinks and not others," she
says in emailed responses to questions from WebMD. "Many scientists are
working to find the answer to that question, looking for genetic differences in
the response to alcohol among individuals with and without a family history of

The researchers tested male rats with either injected saline or alcohol in
various doses, then tracked the response of endorphins and other natural
opioids at the midbrain area.

"We found that low to moderate but not high doses of alcohol increase
the release of beta-endorphin in the VTA, one of the brain regions shown to be
important for mediating the reward effect of alcohol," Gianoulakis says in
a news release. "This supports a role of beta-endorphin in mediating some
of the rewarding effects of alcohol."

"Readers should understand that drinking only low amounts of alcohol
will increase endorphin release and produce pleasant effects," Gianoulakis
says. "Thus, if after consumption of about two drinks of alcohol an
individual does not experience the pleasant effects ... he or she should stop

"The psychological state of a person when he/she stars drinking may play
a significant role on the behavioral effects of alcohol," she tells

By Bill Hendrick
Reviewed by Louise Chang
©2005-2008 WebMD, LLC. All rights reserved

View CBS News In
CBS News App Open
Chrome Safari Continue