Prepubertal methylphenidate leads to sex-dependent differences in probabilistic discounting

Area of Science:

• Neuroscience
• Developmental Psychology
• Pharmacology

Background:

• Methylphenidate (MPH) is a first-line psychostimulant for ADHD, known to improve attention and reduce hyperactivity.
• Preclinical research on MPH's effects on reward and learning primarily focuses on males, with less known about its impact on females.
• Concerns exist regarding the long-term cognitive effects of MPH, particularly in non-ADHD populations.

Purpose of the Study:

• To investigate the sex-dependent, long-term effects of early developmental methylphenidate (MPH) exposure on decision-making and anxiety in adult rats.
• To compare the impact of MPH on risk preference and open field behavior between male and female rats exposed during development.

Main Methods:

• Long-Evans female and male rats received methylphenidate (0, 2.5, or 5 mg/kg) daily for 20 days during early development (postnatal days 10-29).
• In adulthood, rats were assessed for risk preference using a probabilistic discounting task (large-risky vs. small-certain reward).
• Anxiety-like behavior was evaluated using a modified open field test.

Main Results:

• Prepubertal MPH exposure had lasting effects on adult decision-making, with sex-specific outcomes.
• Female rats treated with 2.5 mg/kg MPH showed decreased preference for risky choices, while males showed increased preference.
• MPH treatment (2.5 mg/kg) reduced anxiety-like behavior in both sexes, independent of locomotor activity.

Conclusions:

• Early developmental exposure to methylphenidate (MPH) can induce sex-dependent alterations in adult decision-making and anxiety.
• These findings highlight the importance of considering sex when evaluating the long-term neurodevelopmental impact of psychostimulants.
• The study contributes evidence suggesting MPH's effects on behavior are modulated by developmental timing and sex.