Methylphenidate exposure induces dopamine neuron loss and activation of microglia in the basal ganglia of mice

ABSTRACT: Background: Methylphenidate (MPH) a psychostimulant prescribed to manage ADHD symptoms, has been increasingly prescribed to children not meeting the strict criteria for ADHD. It has also been misused as a “cognitive enhancer” and as an alternative to other psychostimulants. Here, we investigate whether chronic or acute administration of methylphenidate in mice at either 1mg/kg or 10mg/kg dosing, affects cell number and gene expression in the basal ganglion. Methodology/Principal findings: Through the use of stereological counting methods, we observed a significant reduction (~20%) in dopamine neuron numbers in the substantia nigra pars compacta (SNpc) following chronic administration of 10mg/kg MPH. This dosage of MPH also induced a significant increase in the number of morphologically-activated SNpc microglia. Additionally, exposure to either 1mg/kg or 10 mg/kg MPH increased the sensitivity of SNpc dopamine neurons to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced oxidative stress. Unbiased gene screening employing Affymetrix GeneChip® HT MG-430 PM revealed changes in 115 and 54 genes in the substantia nigra (SN) of mice exposed to 1mg/kg and 10mg/kg MPH doses, respectively. Decreases in the mRNA levels of gdnf, dat1, vmat2 and th in the substantia nigra (SN) was observed with both acute and chronic dosing of 10mg/kg MPH. We also found an increase in mRNA levels of the pro-inflammatory genes il-6 and tnf-α in the striatum; although these were seen only at an acute dose of 10mg/kg and not following chronic dosing. Conclusion: Collectively our results suggest that chronic MPH usage in mice, especially at prolonged higher doses, has long-term neurodegenerative consequences. drug treatment: 3 control, 3 low dose treatment, 3 high dose treatment

ORGANISM(S): Mus musculus

SUBMITTER: Chunxu Qu 

PROVIDER: E-GEOD-33619 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress