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  • Ethanol  (4)
  • Blood-brain barrier  (2)
  • (−)-Propranolol  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 314 (1980), S. 47-50 
    ISSN: 1432-1912
    Keywords: Ethanol ; Blood-brain barrier ; Carrier transport ; Tyrosine ; Tryptophan ; 5-Hydroxytryptophan ; α-Methyldopa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ethanol 2 g kg−1 i.p. to rat increased the concentrations in the brain of administered large neutral amino acids (tyrosine, tryptophan, 5-hydroxytryptophan and α-methyldopa). We have previously found a similar effect of ethanol on administered l-Dopa, resulting in increased brain/plasma ratios of dopa. Since large neutral amino acids are known to compete with each other for the carrier-mediated transport into the brain we suggest that the increased concentrations of the administered amino acids in the brain are at least partly the consequence of the ethanol-induced decrease in plasma amino acids observed previously.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 59 (1978), S. 91-94 
    ISSN: 1432-2072
    Keywords: GABA ; Locomotor activity ; Ethanol ; Aminooxyacetic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Gammaaminobutyric acid (GABA) was injected intraperitoneally (i.p.) into mice at doses from 25–2000 mg/kg, and spontaneous locomotor activity was recorded for the following 20 min. A slight but significant decrease in the spontaneous locomotor activity was noted only with the highest dose. The stimulation of motor activity induced by ethanol (2.4 g/kg i.p.) was significantly counteracted by GABA (100 mg/kg i.p. and upwards). A further suppression of ethanol-induced hyperactivity was reached by pretreatment with aminooxyacetic acid (AOAA, 15 mg/kg i.p.). The stimulation of motor activity induced by morphine (10 mg/kg i.p.) remained unaffected by even high doses of i.p. GABA. Motility produced by activation of postsynaptic catecholamine receptors, i.e., by apomorphine (3 mg/kg i.p.) and clonidine (3 mg/kg i.p.) following reserpine (10 mg/kg i.p.) and α-methyltyrosine (250 mg/kg i.p.) pretreatment, was not affected by i.p. GABA injections, whereas hypomotility caused by a low dose of haloperidol (150 μg/kg i.p.) was enhanced. In conjunction with earlier biochemical data, these results suggest a certain access of blood-borne GABA to the CNS, leading to inhibition of dopaminergic neurons involved in motility regulation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 77 (1982), S. 98-100 
    ISSN: 1432-2072
    Keywords: l-dopa ; Tryptophan ; Brain concentration ; Isoprenaline ; Carrier transport ; Blood-brain barrier ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A small dose of isoprenaline or saline was administered intraperitoneally to rats 20 min before the administration of one of the amino acids l-dopa or l-tryptophan. Isoprenaline caused a marked increase in the brain concentration of the administered amino acid. Isoprenaline has previously been shown to cause a decrease in at least some of those plasma amino acids which compete with l-dopa and tryptophan for carrier-mediated transport into the brain. The effect of isoprenaline on the concentrations of dopa and tryptophan in the brain is suggested to be at least partly caused by a change in the relationship between endogeneous and administered amino acids. It is also possible that a direct effect of isoprenaline on the blood-brain barrier transport system contributes to the effect. The reported finding might be of clinical interest in view of the therapeutic importance of aromatic amino acids with a central site of action.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1912
    Keywords: Ethanol ; Apomorphine ; ET 495 ; Locomotor Activity ; Dopamine Receptors ; Dopamine Synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ethanol, 2.2 g/kg was given intraperitoneally to mice, grouped 3 by 3, alone or together with either of the dopamine-receptor stimulating agents apomorphine, 2.5 mg/kg, or ET 495, 5 mg/kg. Control animals received saline injections. Locomotor activity was then recorded every 5 min for 60 min, starting 5–7 min after the injection. Apomorphine and ET 495, which had no marked effect on the locomotor activity, both inhibited the locomotor stimulation induced by ethanol. Other animals received ethanol, 4 g/kg, alone or together with either apomorphine or ET 495, and at various time intervals thereafter, 3H-labelled tyrosine. Control animals received 3H-tyrosine alone. The net yield of 3H-dopamine and 3H-noradrenaline in the brain as well as the specific activity of 3H-tyrosine in plasma 10 min after the 3H-tyrosine injection were measured. Apomorphine and ET 495, 2.5 and 5 mg/kg, respectively, did not change the net yield of 3H-dopamine and 3H-noradrenaline. However, both of them inhibited the ethanol-induced increase in net yield of 3H-dopamine. This effect of apomorphine and ET 495 could not be ascribed to changes in the specific activity of 3H-tyrosine in the plasma. Apomorphine had no effect on the blood level of ethanol as measured 1 h after the administration of ethanol. The possibility that the inhibitory effects of the dopamine-agonists on the ethanol-induced stimulation of the dopamine synthesis and locomotor activity may be mediated by stimulation of presynaptic, inhibitory receptors is discussed.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1912
    Keywords: Ethanol ; Plasma amino acids ; Adrenalectomy ; Hypophysectomy ; (−)-Propranolol ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In previous studies we have demonstrated that an acute dose of ethanol cause an immediate decrease in most plasma amino acids in both man and rat. This effect of ethanol is partly inhibited by the β-adrenergic antagonist (−)-propranolol, partly by adrenalectomy or hypophysectomy and almost completely by a combination of adrenalectomy with (−)-propranolol. This finding suggests an involvement of both β-adrenergic mechanisms and steroids from the adrenal cortex in the ethanol-induced decrease in plasma amino acids.
    Type of Medium: Electronic Resource
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