Antidepressant treatment can normalize adult behavioral deficits induced by early-life exposure to methylphenidate.
BACKGROUND
Methylphenidate (MPH) is prescribed for the treatment of attention-deficit/hyperactivity disorder. Exposure to MPH before adulthood causes behavioral deficits later in life, including anxiety- and depression-like behaviors and decreased responding to natural and drug rewards. We examined the ability of fluoxetine (FLX), a selective serotonin reuptake blocker, to normalize these MPH-induced behavioral deficits.


METHODS
Male rats received MPH (2.0 mg/kg) or saline (VEH) during preadolescence (postnatal day [PD] 20-35). When adults, rats were divided into groups receiving no treatment, acute or chronic FLX, and behavioral reactivity to several emotion-eliciting stimuli were assessed.


RESULTS
The MPH-treated rats were significantly less responsive to natural (i.e., sucrose) and drug (i.e., morphine) rewards and more sensitive to stress- and anxiety-eliciting situations. These MPH-induced deficits were reversed by exposure to FLX.


CONCLUSIONS
These results indicate that exposure to MPH during preadolescence leads to behavioral alterations that endure into adulthood and that these behavioral deficits can be normalized by antidepressant treatment. These results highlight the need for further research to better understand the effects of stimulants on the developing nervous system and the potential enduring effects resulting from early-life drug exposure.
Bolaños
Carlos A
CA
Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306-4301, USA. bolanos@psy.fsu.edu
Willey
Matthew D
MD
Maffeo
Melissa L
ML
Powers
Kyle D
KD
Kinka
Daniel W
DW
Grausam
Katie B
KB
Henderson
Ross P
RP
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D000928:Antidepressive Agents / Q000627:therapeutic use*; D001522:Behavior, Animal / Q000187:drug effects*; D003216:Conditioning, Operant / Q000187:drug effects; D005473:Fluoxetine / Q000627:therapeutic use*; D005518:Food Preferences / Q000187:drug effects; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D001523:Mental Disorders / Q000139:chemically induced* / Q000188:drug therapy*; D008774:Methylphenidate; D051381:Rats; D017207:Rats, Sprague-Dawley; D013550:Swimming
D000928:Antidepressive Agents; D005473:Fluoxetine; D008774:Methylphenidate