Adolescent morphine exposure induces immediate and long-term increases in impulsive behavior

Area of Science:

• Neuroscience
• Developmental Psychology
• Pharmacology

Background:

• Adolescence is a critical period marked by increased risk-taking and drug use.
• Adolescent brain development is vulnerable to drug exposure, potentially leading to loss of control over intake.
• Impulsivity, acting prematurely without foresight, is a key cognitive change associated with adolescence and drug abuse.

Purpose of the Study:

• To investigate the long-term effects of subchronic morphine administration on impulsive behavior in adolescent rats compared to young adults and adults.
• To determine the time-dependent impact of morphine exposure on impulse control during and after the adolescent developmental stage.

Main Methods:

• Adult, young adult, and adolescent rats received daily subcutaneous injections of morphine or saline for five days.
• Impulsive behavior was assessed using the five-choice serial reaction time task (5-CSRTT) at 24 hours and 25 days after the last morphine injection.

Main Results:

• Subchronic morphine increased premature responding (impulsivity) 24 hours post-injection in all age groups, without affecting motor activity.
• Motivation was significantly altered in adult and young adult rats, but not adolescents, at the 24-hour mark.
• Adolescent rats showed a significant long-term increase in premature responses after 25 days of abstinence, unlike adult and young adult rats.

Conclusions:

• Adolescent morphine exposure has a lasting and profound impact on motor impulsive behavior into adulthood.
• Findings suggest heightened caution is necessary regarding opioid consumption and prescription in adolescents due to enduring effects on impulse control.