title: Topography of methylphenidate (ritalin)-induced gene regulation in the striatum: differential effects on c-fos, substance P and opioid peptides.
abstract: Dopamine action alters gene regulation in striatal neurons. Methylphenidate increases extracellular levels of dopamine. We investigated the effects of acute methylphenidate treatment on gene expression in the striatum of adult rats. Molecular changes were mapped in 23 striatal sectors mostly defined by their predominant cortical inputs in order to determine the functional domains affected. Acute administration of 5 and 10 mg/kg (i.p.) of methylphenidate produced robust increases in the expression of the transcription factor c-fos and the neuropeptide substance P. Borderline effects were found with 2 mg/kg, but not with 0.5 mg/kg. For 5 mg/kg, c-fos mRNA levels peaked at 40 min and returned to baseline by 3 h after injection, while substance P mRNA levels peaked at 40-60 min and were back near control levels by 24 h. These molecular changes occurred in most sectors of the caudate-putamen, but were maximal in dorsal sectors that receive sensorimotor and medial agranular cortical inputs, on middle to caudal levels. In rostral and ventral striatal sectors, changes in c-fos and substance P expression were weaker or absent. No effects were seen in the nucleus accumbens, with the exception of c-fos induction in the lateral part of the shell. In contrast to c-fos and substance P, acute methylphenidate treatment had minimal effects on the opioid peptides dynorphin and enkephalin. These results demonstrate that acute methylphenidate alters the expression of c-fos and substance P preferentially in the sensorimotor striatum. These molecular changes are similar, but not identical, to those produced by other psychostimulants.
authors.affiliation: Department of Cellular and Molecular Pharmacology, Rosalind Franklin University of Medicine and Science/The Chicago Medical School, North Chicago, IL 60064, USA.
authors.forename: Motoyo
authors.initials: M
authors.lastname: Yano
authors.forename: Heinz
authors.initials: H
authors.lastname: Steiner
mesh_terms: D000818:Animals; D001345:Autoradiography; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects*; D016762:Genes, fos / Q000235:genetics*; D007091:Image Processing, Computer-Assisted; D017403:In Situ Hybridization; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology*; D017072:Neostriatum / Q000187:drug effects / Q000378:metabolism*; D018847:Opioid Peptides / Q000096:biosynthesis* / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013373:Substance P / Q000096:biosynthesis* / Q000235:genetics*
chemical_list: D000697:Central Nervous System Stimulants; D018847:Opioid Peptides; D008774:Methylphenidate; D013373:Substance P