Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Caffeine-amphetamine interactions were studied to determine whether attenuation of amphetamine-induced activity by caffeine pretreatment (30 mg/kg) is the result of increased or decreased sensitivity to amphetamine. Caffeine pretreatment attenuated amphetamine activity in the rats without producing a horizontal shift in the dose-response curve. Results support a reduction in sensitivity to amphetamine. A cross-tolerance design revealed an asymmetrical interaction between caffeine and amphetamine. Multiple caffeine treatments (30 mg/kg) produced tolerance and attenuation of subsequent amphetamine activity (1.5 mg/kg). Amphetamine did not produce tolerance or affect subsequent caffeine-induced activity.
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PMID:Caffeine reduces amphetamine-induced activity in asymmetrical interaction. 670 74

The human striatum is functionally organized into limbic, associative, and sensorimotor subdivisions, which process information related to emotional, cognitive, and motor function. Dopamine projections ascending from the midbrain provide important modulatory input to these striatal subregions. The aim of this study was to compare activation of dopamine D2 receptors after amphetamine administration in the functional subdivisions of the human striatum. D2 receptor availability (V3") was measured with positron emission tomography and [11C]raclopride in 14 healthy volunteers under control conditions and after the intravenous administration of amphetamine (0.3 mg/kg). For each condition, [11C]raclopride was administered as a priming bolus followed by constant infusion, and measurements of D2 receptor availability were obtained under sustained binding equilibrium conditions. Amphetamine induced a significantly larger reduction in D2 receptor availability (DeltaV3") in limbic (ventral striatum, -15.3 +/- 11.8%) and sensorimotor (postcommissural putamen, -16.1 +/- 9.6%) regions compared with associative regions (caudate and precommissural putamen, -8.1 +/- 7.2%). Results of this region-of-interest analysis were confirmed by a voxel-based analysis. Correction for the partial volume effect showed even greater differences in DeltaV3" between limbic (-17.8 +/- 13.8%), sensorimotor (-16.6 +/- 9.9%), and associative regions (-7.5 +/- 7.5%). The increase in euphoria reported by subjects after amphetamine was associated with larger DeltaV3" in the limbic and sensorimotor regions, but not in the associative regions. These results show significant differences in the dopamine response to amphetamine between the functional subdivisions of the human striatum. The mechanisms potentially accounting for these regional differences in amphetamine-induced dopamine release within the striatum remain to be elucidated, but may be related to the asymmetrical feed-forward influences mediating the integration of limbic, cognitive, and sensorimotor striatal function via dopamine cell territories in the ventral midbrain.
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PMID:Imaging human mesolimbic dopamine transmission with positron emission tomography. Part II: amphetamine-induced dopamine release in the functional subdivisions of the striatum. 1262 4

Behavioural economic models of substance choice describe the relationship between changes in unit price and consumption. As the majority of UK non-dependent substance misusers are polysubstance misusers, we investigated the influence of price upon hypothetical purchases of alcohol, amphetamine, cocaine and ecstasy. Forty-three current polysubstance misusers (25 males, 18 females; mean age 21.3 +/- 2.8) were recruited into the study. As the price of alcohol rose, demand was inelastic. Amphetamine was a substitute for alcohol, cocaine was a compliment drug and ecstasy was independent. Demand for amphetamine was elastic as its price rose, but only alcohol was identified as a substitute drug and other drug purchases were independent of amphetamine price. As the price of cocaine increased, demand was elastic. Alcohol and ecstasy were substitute drugs but amphetamine purchase was independent, indicating asymmetrical substitution of alcohol and cocaine. Finally, demand for ecstasy was also elastic, but only cocaine substituted as ecstasy price rose. These results extend previous findings in substance dependent populations using behavioural economic models and support the opinion that purchasing substances is a complex process, involving both socio-economic and psychopharmacological factors. Whilst subjects expressed a preference for ecstasy, these behavioural findings indicated that alcohol was their drug of choice when economic considerations were brought into play. Self-reported drug preference, although facilitating between subjects experimental design, may therefore not accurately represent real world polysubstance misuse.
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PMID:A behavioural economic analysis of alcohol, amphetamine, cocaine and ecstasy purchases by polysubstance misusers. 1538 Feb 93