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  • 1
    Electronic Resource
    Electronic Resource
    The dopamine D3-receptor: A postsynaptic receptor inhibitory on rat locomotor activity (1993)
    Springer
    Journal of neural transmission 94 (1993), S. 11-19 
    Details
    ISSN: 1435-1463
    Keywords: Dopamine ; release ; D 3 receptor ; locomotor activity ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We report on the pharmacological effects of the 20 fold D 3 vs. D 2 dopamine receptor preferring compound U 99194 A. It is shown that U 99194 A increases rat locomotor activity at doses that do not increase release or utilisation of dopamine in the striatum or the nucleus accumbens significantly. The data do not support any direct agonist action of U 99194 A at dopamine receptors. It is suggested that U 99194 A can antagonise a population of postsynaptic dopamine receptors involved in the suppression of some aspects of psychomotor activity. These postsynaptic receptors presumably belong to the D 3 receptor subtype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01244979
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  • 2
    Electronic Resource
    Electronic Resource
    The adrenal dopamine as an indicator of adrenomedullary hormone biosynthesis (1972)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 275 (1972), S. 347-357 
    Details
    ISSN: 1432-1912
    Keywords: Dopamine ; Adrenomedullary Hormones ; Tyrosine Hydroxylase ; Rat Adrenals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary One pair of rat adrenals was found to contain 100–200 ng of dopamine (DA), the molar concentration ratio of DA to adrenaline + noradrenaline being about 0.005. After inhibition of tyrosine hydroxylase DA decreased exponentially, with a half life of 1.35 h. Insulin and the ganglionic blocking agent chlorisondamine caused within 90 min an increase in adrenal DA which was prevented by a high spinal transection. Chlorisondamine prevented the insulin-induced depletion of adrenaline but the rise in DA persisted. The insulin-induced increase in DA was enhanced by inhibitors of dopamine-β-hydroxylase and monoamine oxidase. The data support the view that neurogenic stimulation of the adrenal medulla activates the rate-limiting synthetic enzyme tyrosine hydroxylase by a mechanism which can be dissociated from the secretory response. Therefore, reduced end-product inhibition does not seem to be a likely explanation of the increased tyrosine hydroxylase activity. The observations suggest that neurogenic short-term activation of tyrosine hydroxylase, like the long-term induction of this enzyme is mediated by special receptors, which can be distinguished from the nicotinic receptors mediating the secretory response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00501124
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of intermittent and continuous cocaine administration on dopamine release and uptake regulation in the striatum: in vitro voltammetric assessment (1996)
    Springer
    Psychopharmacology 126 (1996), S. 331-338 
    Details
    ISSN: 1432-2072
    Keywords: Cocaine ; Dopamine ; Continuous administration ; Caudate nucleus ; Autoreceptors ; Voltammetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Chronic daily injections of cocaine induce behavioral sensitization to subsequent cocaine challenge, while continuous infusion induces tolerance. Following a 7-day withdrawal period, we examined the effects of these two dosing regimens on: (1) baseline dopamine efflux and uptake following single-pulse electrical stimulation, (2) inhibition of uptake by cocaine; and (3) inhibition of efflux by autoreceptor activation. Cocaine (40 mg/kg per day) was administered to rats for 14 days either continuously by osmotic minipumps or intermittently by once-a-day injections. Minipumps containing saline were implanted in the control group. After 7 days of withdrawal, dopamine kinetics in the caudate was examined using in vitro fast-scan cyclic voltammetry. This technique provides very rapid measurements of dopamine in the extracellular space. Thus, when combined with endogenous dopamine efflux evoked by single-pulse, electrical stimulations, it was possible directly to measure the release and uptake components of the efflux. In the absence of pharmacological agents, no group differences were found in the amount of baseline dopamine released or in the uptake kinetics; the potency of bath-applied cocaine (0.03–60 µM) in inhibiting the uptake was also unaltered in either group. In contrast, the potency of quinpirole (an autoreceptor agonist, 5–250 nM) was significantly decreased and increased in the cocaine injection and pump groups, respectively. Thus, the cocaine administration regimen which produces sensitization results in a functional subsensitivity of release-modulating autoreceptors, while the tolerance-producing regimen results in autoreceptor supersensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247384
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of dopamine and serotonin-releasing agents on methamphetamine discrimination and self-administration in rats (1999)
    Springer
    Psychopharmacology 141 (1999), S. 287-296 
    Details
    ISSN: 1432-2072
    Keywords: Key words Methamphetamine ; Dopamine ; Serotonin ; Phentermine ; Fenfluramine ; Drug-discrimination ; Self-administration ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  To analyze the involvement of dopamine (DA) and serotonin (5-HT) release in the stimulus properties of methamphetamine, two amphetamine analogs that selectively release either brain DA (phentermine) or 5-HT (fenfluramine) were tested for their ability to substitute for methamphetamine in rats discriminating methamphetamine (1.0 mg/kg) from saline. They were subsequently tested for their ability to alter IV methamphetamine (0.06 mg/kg per injection) self-administration in the same species when given as a pretreatment. The DA releaser phentermine, like methamphetamine itself, decreased methamphetamine self-administration (to 70% of baseline responding), but only at a dose of 3.0 mg/kg that fully generalized to the methamphetamine stimulus in the discrimination study. The 5-HT releaser fenfluramine attenuated methamphetamine self-administration to a much larger extent than phentermine (to 37% of baseline responding) at a dose of 1.8 mg/kg that did not generalize to methamphetamine and did not decrease rate of responding in the discrimination study. Tolerance developed to the inhibitory effect of 1.8 mg/kg fenfluramine on methamphetamine self-administration when it was given repeatedly over four consecutive daily sessions. The fenfluramine-induced decrease in methamphetamine self-administration was also attenuated when it was given together with the small 1.0 mg/kg dose of phentermine. These results suggest that DA release plays a dominant role in the discriminative stimulus effects of methamphetamine. However, stimulation of 5-HT release can strongly modify methamphetamine self-administration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050836
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  • 5
    Electronic Resource
    Electronic Resource
    Discriminative stimulus properties of the dopamine D3 antagonist PNU-99194A (1998)
    Springer
    Psychopharmacology 138 (1998), S. 40-46 
    Details
    ISSN: 1432-2072
    Keywords: Key words D3 receptors ; Dopamine ; PNU-99194A ; (+)-AJ76 ; ( ; )-DS121 ; PNU-95666E ; Rats ; Drug discrimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  It was recently documented that the relatively selective dopamine D3 receptor antagonist, PNU-99194A, is capable of establishing discriminative stimulus control in rats and that the discriminative cue associated with this compound is not similar to that produced by psychostimulants. The present experiment further characterized the discriminative stimulus properties of PNU-99194A by examining several other dopaminergic agents for stimulus generalization in 23 male Sprague-Dawley rats trained to discriminate 10 mg/kg PNU-99194A (SC, 15 min) from vehicle in a two-choice discrimination procedure under an FR10 schedule of food reinforcement. Rats achieved a criterion of ten consecutive sessions with correct lever choice after a median of 35.5 sessions (range 23–78). In substitution tests, the non-selective D2 receptor antagonist, halo- peridol (0.01– 0.1 mg/kg), and the mixed D2/D3 antagonists, amisulpiride (3.2–32 mg/kg) and sulpiride (32–200 mg/kg), failed to produce stimulus generalization, while the D3-preferring antagonists, (–)-DS121 (1–10 mg/kg) and (+)-AJ76 (3.2–32 mg/kg), produced complete stimulus generalization. Direct and indirect DA agonists, including apomorphine (0.01–0.32 mg/kg) and d-amphetamine (0.1–1 mg/kg), the D1 agonist SKF-38393 (10–100 mg/kg), the D2 selective agonist PNU-95666E (0.32–3.2 mg/kg) and the D3-preferring agonist pramipexole (0.032–1 mg/kg), all produced non-significant amounts of drug-appropriate responding and significantly reduced response rate. It is concluded that PNU-99194A produces a distinctive subjective cue which is probably based on D3 receptor antagonism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050643
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  • 6
    Electronic Resource
    Electronic Resource
    Dopaminergic involvement in the discriminative-stimulus effects of methamphetamine in rats (2000)
    Springer
    Psychopharmacology 148 (2000), S. 209-216 
    Details
    ISSN: 1432-2072
    Keywords: Key words Methamphetamine ; Drug-discrimination ; Dopamine ; Cocaine ; GBR-12909 ; Nomifensine ; Bupropion ; Chloro-PB ; Chloro-APB ; NPA ; 7-OH-DPAT ; SCH-23390 ; Spiperone ; cis-Flupenthixol ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Dopamine plays a major role in the behavioral effects of methamphetamine. Objective: In the present experiments, the effects of different dopaminergic agonists, antagonists, and uptake inhibitors were evaluated in rats discriminating methamphetamine from saline. Methods: In Sprague-Dawley rats trained to discriminate 1.0 mg/kg methamphetamine, i.p., from saline under a fixed-ratio schedule of food delivery, the ability of various dopaminergic agonists and uptake inhibitors to substitute for methamphetamine was evaluated. Subsequently, the ability of various dopaminergic antagonists to block the discriminative-stimulus effects of the training dose of methamphetamine was tested. Results: The dopamine-uptake inhibitors cocaine (10.0 mg/kg), nomifensine (3.0 mg/kg), GBR-12909 (18.0 mg/kg), and bupropion (30.0 mg/kg) fully substituted for the 1.0 mg/kg training dose of methamphetamine. Chloro-APB (SKF-82958), a full agonist at D1 dopamine receptors, produced about 85% methamphetamine-appropriate responding, but the dose required (0.18 mg/kg) markedly decreased rates of responding. Chloro-PB (SKF-81297), another agonist at D1 receptors with a lower intrinsic activity than Chloro-APB, produced only partial generalization (maximum about 55%) at a dose of 1.0 mg/kg. Full substitution for the training dose of methamphetamine was observed with 0.03 mg/kg of the D2 agonist NPA and 0.56 mg/kg of the D3/D2 agonist 7-OH-DPAT. Both NPA and 7-OH-DPAT markedly decreased rates of responding at these doses. The D1 antagonist SCH-23390 (0.056 mg/kg), the D2 antagonist spiperone (0.18 mg/kg), and the mixed D1,D2 antagonist cis-flupenthixol (0.56 mg/kg) all completely blocked the discriminative-stimulus actions of the training dose of methamphetamine. Conclusions: The present findings in rats support previous research findings in other species indicating a major role of dopamine in the discriminative-stimulus effects of methamphetamine. These findings further indicate involvement of dopamine uptake sites as well as D1 and D2 receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050044
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  • 7
    Electronic Resource
    Electronic Resource
    Recovery of dopamine in peripheral adrenergic nerves after reserpine treatment (1976)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 292 (1976), S. 133-136 
    Details
    ISSN: 1432-1912
    Keywords: Dopamine ; Dopamine β-hydroxylase ; Monoamine oxidase ; Rat salivary glands ; Reserpine ; Tyrosine hydroxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The endogenous levels of dopamine (DA) in the rat heart and submaxillary gland after a single, large dose of reserpine (10 mg/kg i.p.) were reduced to near zero within 1 h and were restored to normal within 48 h, while the noradrenaline (NA) levels reacted much more slowly. The data suggest that newly formed DA is rapidly taken up by the reserpine-sensitive mechanism of the amine storage granules. The more rapid restoration of DA than of NA levels may be due to preferential release of newly formed NA by the nerve impulse. Electrical stimulation of the cervical sympathetic with 5 Hz for 30 min 4 h after the administration of reserpine increased the DA level of the submaxillary gland of the stimulated side, suggesting an increased tyrosine hydroxylase activity during stimulation, also in nerve terminals affected by reserpine. The use of an inhibitor of monoamine oxidase (pargyline) and/or an inhibitor of dopamine β-hydroxylase (FLA-63) did not significantly alter the increase of DA following nerve stimulation, suggesting that DA was protected by granular uptake. The stimulation-induced increase in DA was, however, much less in reserpine-treated than in normal animals, demonstrating the importance of the reserpine-sensitive uptake mechanisms for preserving newly formed DA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00498583
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  • 8
    Electronic Resource
    Electronic Resource
    Optimum synthesis of linkages with autocorrelation concept (modified least squares technique) (1983)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 19 (1983), S. 1537-1547 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Correlation is a measure of similarity between two functions. When two functions are exactly similar and equal, the correlation between them is maximum. The correlation concept can be used for system design, e.g. the four-bar mechanism, the slider crank mechanism, etc. The motion generated by four-bar linkage can be expressed as a function of link dimensions, input and output angles. The product of generated function and desired function gives correlation. The best possible design would be when the deviation of actual correlation from its maximum value (i.e. 100 per cent correlation) is least. This concept, in fact, leads to a modified least squares approach and based on this an objective function is formulated and minimized to give link dimensions. The results obtained are better than the least squares technique, and this is illustrated through different numerical examples.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620191011
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  • 9
    Electronic Resource
    Electronic Resource
    A posteriori error analysis and adaptive processes in the finite element method: Part II - adaptive mesh refinement (1983)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 19 (1983), S. 1621-1656 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This is a paper presented in two parts dealing respectively with error analysis and adaptive processes applied to finite element calculations. Part I contains the basic theory and methods of deriving error estimates for second-order problems. Part II of the paper deals with the strategy for adaptive refinement and concentrates again on the p-convergent methods. It is shown that an extremely high rate of convergence is reached in practical problems using such procedures. Applications to realistic stress analysis and potential problems are presented.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620191104
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  • 10
    Electronic Resource
    Electronic Resource
    A posteriori error analysis and adaptive processes in the finite element method: Part I - error analysis (1983)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 19 (1983), S. 1593-1619 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This is a paper presented in two parts dealing respectively with error analysis and adaptive processes applied to finite element calculations. Part I contains the basic theory and methods of deriving error estimates for second-order problems. Part II of the paper deals with the strategy for adaptive refinement and concentrates on the p-convergent methods. It is shown that an extremely high rate of convergence is reached in practical problems using such procedures. Applications to realistic stress analysis and potential problems are presented.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620191103
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