Long-Term Changes in Basal Ganglia Function after a Neurotoxic Regimen of Methamphetamine

• Published in: The Journal of pharmacology and experimental therapeutics 2001-02, Vol.296 (2), p.520
• Main Authors: Chapman, D E, Hanson, G R, Kesner, R P, Keefe, K A
• Format: Article
• Language: English
• Subjects: Animals; Basal Ganglia - drug effects; Basal Ganglia - metabolism; Basal Ganglia - pathology; Behavior, Animal - drug effects; Central Nervous System Stimulants - administration & dosage; Central Nervous System Stimulants - toxicity; Dopamine - metabolism; Electron Transport Complex IV - metabolism; Gene Expression Regulation - drug effects; In Situ Hybridization; Male; Methamphetamine - administration & dosage; Methamphetamine - toxicity; Neural Pathways - drug effects; Neural Pathways - physiopathology; Neuropeptides - biosynthesis; Neuropeptides - genetics; Neurotoxicity Syndromes - metabolism; Neurotoxicity Syndromes - physiopathology; Neurotoxicity Syndromes - psychology; Rats; Rats, Sprague-Dawley; Serial Learning - drug effects; Substance P - biosynthesis; Substance P - genetics; Substantia Nigra - drug effects; Substantia Nigra - physiopathology
• ISSN: 0022-3565; 1521-0103

The abuse of psychostimulants, such as methamphetamine (METH), can cause long-lasting deficits in the dopamine (DA) innervation of the striatum. Although the consequences of large DA depletions on basal ganglia function have been well characterized, less is known about the alterations associated with smaller depletions, such as those produced by high doses of METH. The purpose of this study was to assess the long-term consequences of METH-induced DA depletion on basal ganglia function. Three weeks after rats were given multiple administrations of METH (5–10 mg/kg, four times at 2-h intervals), dose-related decreases in DA tissue content in striatum and tyrosine hydroxylase mRNA in the substantia nigra pars compacta were observed. In situ hybridization histochemistry revealed a selective decrease in preprotachykinin mRNA in striatum, predominately at the highest dose of METH, and no change in striatal preprodynorphin, preproenkephalin, or neurotensin/neuromedin N mRNAs. Cytochrome oxidase activity was significantly elevated in the entopeduncular nucleus and substantia nigra pars reticulata of METH-treated rats, but not in the striatum, globus pallidus, or subthalamic nucleus, consistent with a selective decrease in striatonigral, but not striatopallidal, neuron function. Additionally, rats treated with a neurotoxic regimen of METH were impaired on a radial maze sequential learning task when tested 3 weeks following METH administration. These data indicate that exposure to a neurotoxic regimen of METH results in long-term changes in striatonigral, but not striatopallidal neuron function and, consequently, altered basal ganglia function.