Rat study reveals long-term effects of adolescent amphetamine abuse on the brain

March 30, 2016
Psychology professor Joshua Gulley, left, graduate student Shuo Kang and their colleagues found that amphetamine abuse in young rats led to changes in dopamine signaling in the brain that persisted into adulthood. Credit: L. Brian Stauffer

A study of rats given regular, high doses of amphetamine finds that those exposed to the drug at an age corresponding to human adolescence experience long-term changes in brain function that persist into adulthood.

The study, reported in the journal Neuroscience, found that leads to changes in dopamine signaling. Dopamine is a neurotransmitter that plays a role in memory, attention, learning and feelings of pleasure.

"The dopamine system, which continues to develop throughout adolescence and young adulthood, is a primary target of psychostimulant drugs like amphetamine," said University of Illinois psychology professor Joshua Gulley, who led the new research. "Changes in dopamine function in response to repeated drug exposure are likely to contribute to the behavioral consequences - addiction and relapse, for example - that abusers experience."

Parallels between rat and human development make rats a worthy model for the study of human drug addiction, which often begins in adolescence, Gulley said.

"Rats exhibit many of the characteristics that human do. They tend to be more impulsive than adult rats; they tend to make more risky decisions," he said. They also can engage in "addiction-like behaviors," he said.

"They show increased drug use in response to stress," Gulley said. "And, just as in humans, there is evidence that animals that start using drugs in adolescence are more likely to relapse than animals that start in adulthood."

A limitation of the new study was that, unlike humans, who generally choose whether or not to partake in drug use, "the rats had no say in whether they got amphetamine," Gulley said.

A previous study from Gulley and his colleagues looked at the effects of amphetamine abuse on working memory - the ability to retain information just long enough to use it - in young and .

"In that study, we found that animals that were exposed to the drug during adolescence had much more significant deficits in working memory than those exposed during adulthood," Gulley said.

The researchers hypothesized that drug exposure during adolescence, a time of vast changes in the brain, "somehow influences the normal developmental trajectory," Gulley said. "But how?"

To get at this question, the team focused on the prefrontal cortex, a brain region behind the forehead that is among the last to fully develop during adolescence. The researchers found that repeated exposure to amphetamine - beginning in adulthood or in adolescence - reduced the ability of key cells in the rats' to respond to dopamine. In this part of the brain, dopamine influences "inhibitory tone," telling cells to stop responding to a stimulus, Gulley said.

"Inhibition in the nervous system is just as important as activation," he said. "You need cells that are firing and communicating with one another, but you also need cells to stop communicating with one another at certain times and become quiet.

"Our research suggests that a subtype of dopamine receptor, the D1 receptor, is altered following amphetamine exposure," Gulley said. "It's either not responding to dopamine or there are not as many of these receptors after exposure as there used to be."

This change in signaling persisted for 14 weeks after exposure to amphetamine in the adolescent-exposed , he said.

"That's akin to a change in humans that persists from adolescence until sometime in their 30s, long after drug use stopped," he said.

"Along with other studies, this shows pretty clear evidence that drug use during adolescence, a time when the brain is still developing, has extremely long-lasting consequences that go far beyond the last ," Gulley said.

Explore further: Adolescent amphetamine use linked to permanent changes in brain function and behavior

More information: S. Kang et al. D1 receptor-mediated inhibition of medial prefrontal cortex neurons is disrupted in adult rats exposed to amphetamine in adolescence, Neuroscience (2016). DOI: 10.1016/j.neuroscience.2016.02.064

Related Stories

Adolescent amphetamine use linked to permanent changes in brain function and behavior

November 3, 2011
(Medical Xpress) -- Amphetamine use in adolescence can cause neurobiological imbalances and increase risk-taking behaviour, and these effects can persist into adulthood, even when subjects are drug free. These are the conclusions ...

Connecting alcohol use in adolescence with risky behavior in adulthood

May 1, 2014
A new study conducted in rats offers clues about how teen drinking alters brain chemistry, suggesting early alcohol use has long-term effects on decision making.

Socially isolated rats are more vulnerable to addiction, report researchers

January 23, 2013
Rats that are socially isolated during a critical period of adolescence are more vulnerable to addiction to amphetamine and alcohol, found researchers at The University of Texas at Austin. Amphetamine addiction is also harder ...

Steady relationships reduce amphetamine's rewarding effects

June 1, 2011
Long-term relationships make the commonly abused drug amphetamine less appealing, according to a new animal study in the June 1 issue of The Journal of Neuroscience. The findings suggest that social bonds formed during adulthood ...

Too much sugar during adolescence may alter brain's reward circuits

January 19, 2016
A new study in rats may provide significant insights into the long-term impacts of over-consumption of sugary foods during adolescence.

Recommended for you

The neural codes for body movements

July 21, 2017
A small patch of neurons in the brain can encode the movements of many body parts, according to researchers in the laboratory of Caltech's Richard Andersen, James G. Boswell Professor of Neuroscience, Tianqiao and Chrissy ...

Faulty support cells disrupt communication in brains of people with schizophrenia

July 20, 2017
New research has identified the culprit behind the wiring problems in the brains of people with schizophrenia. When researchers transplanted human brain cells generated from individuals diagnosed with childhood-onset schizophrenia ...

Scientists reveal how patterns of brain activity direct specific body movements

July 20, 2017
New research by Columbia scientists offers fresh insight into how the brain tells the body to move, from simple behaviors like walking, to trained movements that may take years to master. The discovery in mice advances knowledge ...

Scientists discover combined sensory map for heat, humidity in fly brain

July 20, 2017
Northwestern University neuroscientists now can visualize how fruit flies sense and process humidity and temperature together through a "sensory map" within their brains, according to new research.

Team traces masculinization in mice to estrogen receptor in inhibitory neurons

July 20, 2017
Researchers at Cold Spring Harbor Laboratory (CSHL) have opened a black box in the brain whose contents explain one of the remarkable yet mysterious facts of life.

Speech language therapy delivered through the Internet leads to similar improvements as in-person treatment

July 20, 2017
Telerehabilitation helps healthcare professionals reach more patients in need, but some worry it doesn't offer the same quality of care as in-person treatment. This isn't the case, according to recent research by Baycrest.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.