Adolescent rats help prove that early alcohol exposure alcohol can quickly lead to heavy drinking

• While adolescence is a vulnerable time for alcohol and drug experimentation, not all adolescents develop problems.
• A new study using rodents has found that drinking patterns can emerge quickly among adolescents.
• These findings suggest that humans who consume large quantities of alcohol during early exposure are those most likely to later become heavy drinkers

No one can become alcohol dependent (AD) without repeatedly drinking alcohol, but not everyone who does so will become AD. Certain characteristics – adolescence, novelty seeking, reaction to stress, and response to first alcohol exposure – are believed to influence the vulnerability of developing AD. A new study using adolescent rats has found that early exposure to alcohol during adolescence can quickly lead to heavy drinking patterns.

Results are published in the May issue of Alcoholism: Clinical & Experimental Research.

“We know that adolescence is a vulnerable time,” explained Nicole L. Schramm-Sapyta, research associate in the department of pharmacology and cancer biology at Duke University Medical Center.

“People who start drinking the earliest tend to be the most likely to develop drinking problems,” said Schramm-Sapyta. “But we also know that not all adolescents get into trouble with alcohol and other drugs. We wanted to examine, within an adolescent population, whether these early ‘big drinkers’ were different in some way ... if they had individual characteristics that were responsible for the drinking. We chose to examine novelty seeking and stress because these are two characteristics we see in some populations that develop problem drinking.” Schramm-Sapyta is the study’s first author.

Researchers examined 48 male Sprague-Dawley rats that were 28 days old – the equivalent of rodent adolescence. The rats were exposed to an elevated-plus maze (to measure anxiety) as well as open-field locomotion and novel-object exploration (to measure response to novelty), and also had their blood collected after the maze (to measure stress hormone levels). After testing, the researchers measured how much each rat drank in special lickometer cages. The rats were habituated to the cages with water, which was then switched to an alcohol (10% v/v) solution for three nights, followed by a choice between the water or alcohol solutions for 10 consecutive nights. After two nights of abstinence, the rats were once again given a day’s choice between the water or alcohol solutions in order to measure relapse-like behavior.

“Our key finding is that drinking patterns may be established after only a few exposures to alcohol,” said Schramm-Sapyta. “Rats that demonstrated a ‘taste’ for alcohol after only three nights of drinking were very likely to be the biggest drinkers after longer-term exposure to alcohol.”