Methamphetamine-induced neurotoxicity alters locomotor activity, stereotypic behavior, and stimulated dopamine release in the rat.

Neuroscience Graduate Program, University of Cincinnati, Cincinnati, Ohio 45267, USA.
Journal of Neuroscience (Impact Factor: 6.91). 11/1999; 19(20):9141-8.
Source: PubMed

ABSTRACT The neurochemical evidence of methamphetamine (MA)-induced toxicity to dopaminergic nerve terminals is well documented; however, the functional consequences are not clearly defined. The present study was designed to investigate whether MA-induced dopamine depletions affect locomotor activity, stereotypic behavior, and/or extracellular dopamine concentrations in the neostriatum. Male rats were treated with a neurotoxic regimen of MA (10 mg/kg, i.p., every 2 hr for four injections) or vehicle and tested for functional effects 1 week later. Animals that had received the neurotoxic regimen of MA showed a reduction in both caudate nucleus and nucleus accumbens dopamine contents of 56 and 30%, respectively. Furthermore, MA-treated rats exhibited a significant attenuation in spontaneous activity, as well as a significant diminution in MA (low dose)-stimulated locomotor activity as compared to vehicle-treated rats. However, there were no differences in the MA (low dose)-induced increases in extracellular dopamine concentrations in the caudate nucleus or the nucleus accumbens core of either group. Interestingly, the acute administration of higher doses of MA elicited a significantly augmented stereotypic response and a significantly attenuated increase in the extracellular concentration of dopamine in the caudate nucleus of rats treated with a neurotoxic regimen of MA as compared to vehicle-treated animals. These data indicate that MA-induced neurotoxicity results in abnormal dopamine-mediated behaviors, as well as a brain region-specific impairment in stimulated dopamine release.

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    ABSTRACT: To better understand the neurobiology of methamphetamine (METH) dependence and the cognitive impairments induced by METH use, we compared the effects of extended (12 h) and limited (1 h) access to METH self-administration on locomotor activity and object place recognition, and on extracellular dopamine levels in the nucleus accumbens and caudate-putamen. Rats were trained to self-administer intravenous METH (0.05 mg/kg). One group had progressively extended access up to 12-h sessions. The other group had limited-access 1-h sessions. Microdialysis experiments were conducted during a 12-h and 1-h session, in which the effects of a single METH injection (self-administered, 0.05 mg/kg, i.v.) on extracellular dopamine levels were assessed in the nucleus accumbens and caudate-putamen compared with a drug-naive group. The day after the last 12-h session and the following day experimental groups were assessed for their locomotor activities and in a place recognition procedure, respectively. The microdialysis results revealed tolerance to the METH-induced increases in extracellular dopamine only in the nucleus accumbens, but not in the caudate-putamen in the extended-access group compared with the control and limited-access groups. These effects may be associated with the increased lever-pressing and drug-seeking observed during the first hour of drug exposure in the extended-access group. This increase in drug-seeking leads to higher METH intake and may result in more severe consequences in other structures responsible for the behavioral deficits (memory and locomotor activity) observed in the extended-access group, but not in the limited-access group.
    European Journal of Neuroscience 09/2013; · 3.75 Impact Factor
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    ABSTRACT: Methamphetamine-induced neurotoxicity results in long-lasting depletions of monoamines and changes in basal ganglia function. We previously reported that rats with methamphetamine-induced neurotoxicity no longer engage dorsomedial striatum during a response reversal-learning task, as their performance is insensitive to acute disruption of dorsomedial striatal function by local infusion of an N-methyl-D-aspartate receptor antagonist or an antisense oligonucleotide against the activity-regulated cytoskeleton-associated (Arc) gene. However, methamphetamine-pretreated rats perform the task as well as controls. Therefore, we hypothesized that the neural circuitry involved in the learning had changed in methamphetamine-pretreated rats. To test this hypothesis, rats were pretreated with a neurotoxic regimen of methamphetamine or with saline. Three to five weeks later, rats were trained on the reversal-learning task and in situ hybridization for Arc was performed. A significant correlation between Arc expression and performance on the task was found in nucleus accumbens shell of methamphetamine-, but not saline-, pretreated rats. Consistent with the idea that the correlation between Arc expression in a brain region and behavioral performance implicates that brain region in the learning, infusion of an antisense oligonucleotide against Arc into the shell impaired consolidation of reversal learning in methamphetamine-, but not saline-, pretreated rats. These findings provide novel evidence suggesting that methamphetamine-induced neurotoxicity leads to a shift from dorsal to ventral striatal involvement in the reversal-learning task. Such reorganization of neural circuitry underlying learning and memory processes may contribute to impaired cognitive function in individuals with methamphetamine-induced neurotoxicity or others with striatal dopamine loss, such as patients with Parkinson's disease.Neuropsychopharmacology accepted article preview online, 22 October 2013. doi:10.1038/npp.2013.296.
    Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 10/2013; · 8.68 Impact Factor
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    ABSTRACT: Background Despite the evidence that women world-wide are using methamphetamine (MA) during pregnancy little is known about the neurodevelopment of their children. Design The controlled, prospective longitudinal New Zealand (NZ) Infant Development, Environment and Lifestyle (IDEAL) study was carried out in Auckland, NZ. Participants were 103 children exposed to MA prenatally and 107 not exposed. The Mental Developmental Index (MDI) and the Psychomotor Developmental Index (PDI) of the Bayley Scales of Infant Development, Second Edition (BSID-II) measured cognitive and motor performance at ages 1, 2 and 3, and the Peabody Developmental Motor Scale, Second Edition (PDMS-II) measured gross and fine motor performance at 1 and 3. Measures of the child’s environment included the Home Observation of Measurement of the Environment and the Maternal Lifestyle Interview. The Substance Use Inventory measured maternal drug use. Results After controlling for other drug use and contextual factors, prenatal MA exposure was associated with poorer motor performance at 1 and 2 years on the BSID-II. No differences were observed for cognitive development (MDI). Relative to non-MA exposed children, longitudinal scores on the PDI and the gross motor scale of the PDMS-2 were 4.3 and 3.2 points lower, respectively. Being male and of Maori descent predicted lower cognitive scores (MDI) and being male predicted lower fine motor scores (PDMS-2) Conclusions Prenatal exposure to MA was associated with delayed gross motor development over the first 3 years, but not cognitive development. However, being male and of Maori descent were both associated with poorer cognitive outcomes. Males in general did more poorly on tasks related to fine motor development.
    Neurotoxicology and Teratology 01/2014; · 3.18 Impact Factor

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