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  • D3 receptor  (2)
  • dopamine autoreceptors  (2)
  • (+)-3PPP  (1)
  • (+)-UH 232 and (+)-AJ 76  (1)
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Keywords
  • 1
    ISSN: 1435-1463
    Keywords: Dopamine ; dopamine autoreceptors ; adrenal medulla ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previous work in this laboratory, as well as observations reported in the literature, indicate that the adrenal medulla contains dopamine (DA) receptors of the D-2 subtype, which among other things are capable of controlling the DA level in rat adrenal glands. To further characterize the DA receptors involved in the control of the adrenal DA level, the effects of 9 DA receptor agonists with various intrinsic activities were compared. After various periods of drug administration the rats were killed by decapitation and the DA content of the adrenal glands and the DOPAC content of the forebrain were measured by high-performance liquid chromatography with electrochemical detection. All the investigated DA receptors agonists caused an increase in adrenal DA level, although statistical significance was not reached in one case /(−)-HW165/. Domperidone, a DA D-2 receptor antagonist which does not readily cross the blood brain barrier, blocked the DA-elevating effects of apomorphine, quinpirole, B-HT 920 and both enantiomers of 3-PPP. For the two ergolines terguride and SDZ 208-920 the blockade by domperidone was not complete, suggesting that their effects are mediated not only through DA, but also through other receptor systems. The dose of domperidone used (3 mg/kg) had but a marginal influence on brain DOPAC levels, supporting the almost exclusively peripheral effect of this agent. Our data indicate that the DA D-2 receptors which control the DA level in the adrenal medulla in rats, have characteristics similar to, though not identical with the autoreceptors in the forebrain.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1106
    Keywords: Dopamine ; Autoreceptor antagonists ; (+)-UH 232 and (+)-AJ 76 ; Nigro-striatal system ; 6-OH-DA lesion ; Rotational behaviour ; In vivo DP-5,6-ADTN binding ; Receptor sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The in vivo dopamine (DA) receptor binding and behavioural properties of the recently characterised putative preferential DA autoreceptor antagonists (+)-AJ 76 and (+)-UH 232 were studied in rats with a unilateral 6-OH-DA lesion of the substantia nigra. The main findings were a) that (+)-UH 232 and (+)-AJ 76 per se failed to produce significant turning behaviour, b) that both agents antagonised contralateral rotation caused by the DA agonist apomorphine, including a change of the characteristic two-peak apomorphine rotation pattern into a single peak, indicating that the DA antagonist properties of (+)-UH 232 and (+)-AJ 76 are retained also at denervation-sensitised postsynaptic DA receptors and — in support of this notion — c) that (+)-UH 232 and (+)-AJ 76 were able to displace the specific in vivo binding of the DA receptor agonist DP-5,6-ADTN in the denervated as well as in the intact striata of the 6-OH-DA-lesioned animals. Interestingly, in this regard (+)-UH 232 was significantly less efficient on the lesioned as compared to the intact side. The DP-5,6-ADTN-displacing effect of (+)-AJ 76 did not, however, differ between the intact and the denervated striatum. The implications of the present findings are discussed with particular reference to DA receptor sensitivity and adaptational phenomena.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-1463
    Keywords: D3 receptor ; conditioned place preference ; intracranial self-stimulation ; 7-OH-DPAT ; (+)-3PPP ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Compounds showing an in vitro binding preference for the dopamine D3 receptor were tested in two models designed to assess positive reinforcement in the rat: intracranial self-stimulation (ICSS) and conditioned place preference (CPP). R-(+)-7-OH-DPAT, a D3 preferring agonist, inhibited ICSS behaviour over a wide dose range. At higher doses, a facilitation of ICSS was seen. In the CPP model, 7-OH-DPAT was inactive except at the highest dose where a significant change in preference was seen. A dose of R-(+)-7-OH-DPAT, that significantly inhibited ICSS behaviour, was combined with a dose of d-amphetamine, that significantly facilitated ICSS behaviour. Surprisingly, this resulted in a significant synergistic facilitation of the amphetamine response. The putative D3 antagonist, U99194A was inactive in the ICSS model but induced significant place preference. The present results suggest that the dopamine D3 receptor, in contrast to the D2 receptor, has an inhibitory influence on reward mechanisms.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 103 (1996), S. 331-341 
    ISSN: 1435-1463
    Keywords: Microinjections ; dopamine D3 ; dopamine autoreceptors ; spreading depression ; multiple regression analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The preferential dopamine autoreceptor, and slightly D3 preferring, antagonist (+)-UH232 (cis-(+)-(1S,2R)-5-methoxy-1-methyl-2-(n-dipropylamino) tetralin) increases locomotor activity and synaptic dopamine release in the nucleus accumbens and striatum after systemic administration to the rat. As shown in this study, (+)-UH232, was unable to produce anincrease in locomotor activity measured for 60 minutes after local administration into the terminal or somato-dendritic regions of the mesolimbic dopamine pathways or into the lateral ventricle. Instead, a dose dependent decrease of spontaneous locomotor activity after local application (0.05–50.0 nmol/ side) of (+)-UH232 into the nucleus accumbens, was seen. A similar reduction in locomotor activity was produced by the classical dopamine antagonist raclopride. Analysis of the dose*time interactions on locomotor activity did, however, indicate that there is a significant dose*time interaction after local application of (+)-UH232 into the lateral ventricle and VTA. Raclopride, on the other hand, produced only a weak time dependent effect in the VTA. The potential problem of Leao's spreading depression in micro-injection experiments were considered, however, spreading depression does not seem to influence the effects of (+)-UH232 locally applied into the nucleus accumbens. In conclusion, both (+)-UH232 and raclopride produced a dose dependent decrease in spontaneous locomotor activity when examined as the total activity count over 60 minutes after local application into the N Acc.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 95 (1994), S. 71-74 
    ISSN: 1435-1463
    Keywords: D3 receptor ; locomotor activity ; dopamine release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The dopamine D3 preferring ligand R-(+)-7-OH-DPAT induced strong hypolocomotion in rats. Doses producing reduction of locomotion failed to affect dopamine release or synthesis rate. These data support the hypothesis that the dopamine D3 receptor is a postsynaptic receptor with an inhibitory influence on rat locomotor activity.
    Type of Medium: Electronic Resource
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