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  • 1
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Pharmacology, Biochemistry and Behavior 47 (1994), S. 345-349 
    ISSN: 0091-3057
    Schlagwort(e): 6-OHDA ; Alcohol preference ; Amphetamine ; Dopamine ; Ethanol ; Nucleus accumbens ; Sensitization ; Ventral striatum
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-2072
    Schlagwort(e): Immobility reaction ; Open field behavior ; Diazepam ; Dopamine ; Apomorphine ; Haloperidol ; Weanling rats
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Weanling rats were treated with diazepam, apomorphine, and haloperidol to study the influence of the dopamine (DA) system on the audiogenic immobility reaction and open field locomotory behavior. Treatment with diazepam (0.025, 0.05, and 0.1 mg/kg) caused a dose-dependent shortening of the duration of the immobility response. Treatment with apomorphine (0.125, 0.25, and 0.50 mg/kg) shortened both the immobility reaction and the latency to leave the spot where the animal was first placed in the open field (latency for first crossing). Locomotor activity increased in a dose-dependent fashion. Both grooming and rearing showed biphasic dose response curves, with a maximum occurring at the 0.125 mg/dose for grooming and at the 0.25 mg/dose for rearing. Haloperidol (0.06 mg/kg) exerted opposite effects to those of apomorphine, but also produced increased running during the auditory stimulation (flight distance). Using the immobility reaction as an expression of fear, we concluded that activation of the DA system decreases while inhibition of the DA system increases fear. It was hypothesized that the DA system exerts an inhibitory function in the expression of fear.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-2072
    Schlagwort(e): Developing rat ; Immobility reaction ; Neurotoxins ; 5,7-Dihydroxytryptamine ; 6-Hydroxydopamine ; Serotonin ; Dopamine ; Noradrenaline ; Open field behavior
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The ontogenetic development of the audiogenic immobility reaction (freezing) was studied in rats given intracisternal injections of the neurotoxins 5,7-dihydroxytryptamine (5,7-DHT), 25 μg, or 6-hydroxydopamine (6-OHDA), 100 μg, neonatally (Day 1). The duration of the freezing response was strongly reduced in the 5,7-DHT-treated rats between 20–30 days of age, when normal animals show very prolonged responses. During the same period increased motor activity was observed in the 6-OHDA-treated rats while only a slight reduction of the freezing response was noted. Biochemical analyses performed on brains from animals 35 days of age showed a selective reduction (about 50%) of whole brain levels of serotonin in the 5,7-DHT-treated rats, while the noradrenaline levels were selectively reduced by about 60% in the 6-OHDA rats. A longitudinal investigation on the effects of neonatal treatment with 5,7-DHT showed a persistent selective reduction of the whole brain level of serotonin up to at least 90 days of age. Since 5,7-DHT mainly affects the serotonergic pathways, the results suggest that the disturbances noted in the ontogeny of the freezing response may be due to interference with the developing serotonergic system.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 295 (1976), S. 203-209 
    ISSN: 1432-1912
    Schlagwort(e): Ethanol ; Locomotor activity ; Dopamine ; GABA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ethanol (2.4 g/kg) was given intraperitoneally to mice and was found to cause a marked increase in spontaneous locomotor activity. When mice were pretreated with low doses of agents which mimic or augment the action of GABA (γ-hydroxybutyric acid, baclophen, or aminooxyacetic acid) the ethanol-induced locomotor stimulation was completely eliminated. Baclophen (10 mg/kg) was found to cause an initial increase followed by a later decrease in synthesis of catecholamines, as measured by the accumulation of dopa after inhibition of central aromatic l-amino acid decarboxylase, in dopamine-rich areas of rat brain. These data are consistent with previous findings that baclophen, as well as other agents which enhance the activity of GABA systems, reduce the firing of dopamine neurons, thus causing enhanced synthesis of dopamine via feedback mechanisms. These findings also indicate a potential interaction between GABA-like drugs and alcohol in man, and may be of heuristic value in the treatment of chronic alcoholism. The possibility that the mechanism of the inhibition of ethanol-induced locomotor stimulation by GABA-like drugs may be due to a selective interference with ethanol-induced dopamine release is discussed.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1432-2072
    Schlagwort(e): Acoustic startle response ; Prepulse inhibition ; Schizophrenia ; Mesocorticolimbic DA system ; Dopamine ; Serotonin ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effect of local injection of pertussis toxin (PTX) into the ventral tegmental area (VTA) on acoustic startle in rats was investigated. The PTX treatment caused only minor effects of its own on the acoustic startle response (ASR) or prepulse inhibition (PPI) of acoustic startle. However, systemic treatment with the indirect DA receptor agonist, amphetamine (2 mg/kg, SC) caused a significant increase in ASR magnitude and a significant disruption of PPI in PTX-treated rats while no such effects were observed in sham-treated rats. Treatment with the direct DA receptor agonist, apomorphine (2 mg/kg, SC), caused a significant disruption of PPI, an effect that was observed in both PTX-and sham-treated rats. Treatment with the 5-HT1A receptor agonist, 8-OH-DPAT (0.5 mg/kg, SC), did not affect PPI in either group but caused a marked increase in ASR magnitude in sham-treated rats. Interestingly, this effect was blocked in PTX-treated rats. The present results suggest that local injection of PTX into the VTA causes an increased sensitivity to the behavioural effects of psychostimulants on acoustic startle and may also suggest that intact midbrain 5-HT1A receptors are essential for the effect of 5-HT1A agonists on acoustic startle.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 149 (2000), S. 181-188 
    ISSN: 1432-2072
    Schlagwort(e): Key words Acoustic startle response ; Prepulse inhibition ; Sensorimotor gating ; Schizophrenia ; Dopamine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Rationale: Prepulse inhibition of acoustic startle is the reduction in startle response to an intense auditory stimulus when this stimulus is immediately preceded by a weaker prestimulus. Prepulse inhibition occurs normally in humans and experimental animals, but schizophrenic persons often exhibit a marked impairment in this measure. Previous studies have shown that dopamine (DA)-dependent neuronal mechanisms are involved in the modulation of prepulse inhibition. Objective: Experiments were conducted in rats to elucidate further the involvement of DA-ergic mechanisms in prepulse inhibition. Results: In line with previous studies, the indirect DA agonist, amphetamine, was shown to decrease prepulse inhibition. A close reverse relationship over time between DA overflow in the nucleus accumbens and prepulse inhibition was obtained using a technique allowing concomitant measurement of these parameters in awake, freely moving rats. This effect was more pronounced in amphetamine-treated rats compared to rats treated with equimolar doses of cocaine, which increased DA overflow without affecting prepulse inhibition. In other experiments, the combined treatment with subthreshold doses of the selective DA D1 agonist, SKF 38393, and the selective DA D2 agonist, quinpirole, was also shown to decrease prepulse inhibition. Finally, the selective DA D2 antagonist, raclopride, was shown to enhance prepulse inhibition. Conclusions: In line with previous studies, it is concluded that DA neurotransmission is involved in the modulation of prepulse inhibition and that the ventral part of the mesostriatal DA system may serve an important role in this modulation. Furthermore, the possibility is discussed that the discrepant results on prepulse inhibition obtained with amphetamine and cocaine may disclose functionally relevant differences in their mechanisms of action, and that the enhancement of prepulse inhibition induced by some antipsychotics in rats may reflect their propensity to induce adverse mental effects in humans.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 13 (1968), S. 140-144 
    ISSN: 1432-2072
    Schlagwort(e): Electroshock ; Dopamine ; Homovanillic Acid
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A single electroshock stimulation (EST) by means of a conventional clinical EST apparatus was administered to 40 rats. Ten minutes after the start of general convulsions the animals were sacrificed. Corpus striatum was analyzed for dopamine (DA) and homovanillic acid (HVA). A statistically not significant increase of DA and a highly significant increase of HVA was noted in the EST group compared to the control animals. The data indicate an acceleration of the DA synthesis induced by EST. The results are discussed in relation to the action of antidepressive drugs on the monoaminergic neurons and a supposed biochemical correlate of endogenous depression.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1432-2072
    Schlagwort(e): Key words Acoustic startle response ; Prepulse inhibition ; Schizophrenia ; Dopamine ; Serotonin ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The β-adrenoceptor antagonist as well as serotonin 5-HT1 receptor antagonist, (−)alprenolol, was found to potentiate the disrupting effect of the non-competitive NMDA receptor antagonist, dizocilpine, on prepulse inhibition (PPI) of the acoustic startle response (ASR) in the rat. The facilitating effect of dizocilpine on ASR amplitude was also potentiated by (−)alprenolol. (−)Alprenolol by itself did not affect either of these measures. These effects did not seem to be related to the unselective β-adrenoceptor antagonist property of (−)alprenolol, since combined pretreatment with the β1- and β2-adrenoceptor antagonists, metoprolol and ICI 118551, did not alter the effects of dizocilpine on startle behaviour. However, a serotonergic influence was suggested by the fact that a facilitating effect of dizocilpine on ASR amplitude was also obtained by pretreatment with the 5-HT precursor, L-5-HTP, in benserazide-pretreated rats. Furthermore, pretreatment with the 5-HT2 selective receptor antagonist, MDL 100907, significantly reduced the (−)alprenolol-induced potentiation of the effects of dizocilpine on startle behaviour, while the 5-HT3 selective receptor antagonist, ondansetron, failed to do that. Finally, the (−)alprenolol-induced potentiation of the effects of dizocilpine was significantly reduced by pretreatment with the atypical antipsychotic, clozapine, and by the potential antipsychotic and selective dopamine D2 receptor antagonist, raclopride. This study suggests that altered 5-HT activity may influence the effects of psychotomimetic drugs such as dizocilpine on sensorimotor function, and this observation may have implications for the pharmacological treatment of schizophrenia in humans.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1432-2072
    Schlagwort(e): Key words Acoustic startle response ; Prepulse inhibition ; Schizophrenia ; Sensitisation ; Amphetamine ; Dopamine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Male Sprague-Dawley rats were repeatedly treated with amphetamine (AMP, 1 mg/kg, SC) at 3- day intervals for 15 days and tested for prepulse inhibition of acoustic startle after each treatment. This treatment regimen induced sensitisation in the animals as evidenced by a progressive increase in the disruptive effect of AMP on prepulse inhibition. Persistent changes in brain function was indicated, since an increase in disruptive effect was observed in sensitised animals also after a 22-day-long drug- and test-free period. The development of sensitisation was blocked by pretreatment with haloperidol (HPD, 0.1 mg/kg, SC), which suggests that sensitisation to the disruptive effect of AMP was dependent on dopamine (DA) D2 receptor activation. Furthermore, the development of sensitisation was blocked by adrenalectomy, which suggests that sensitisation was dependent also on circulating adrenal hormones. Increased DA-ergic activity has been implicated in the pathophysiology of schizophrenia and AMP-induced sensitisation to the neuronal functions that modulate prepulse inhibition may be an experimental model to investigate this hypothesis.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1432-2072
    Schlagwort(e): Benzodiazepines ; Brain reward systems ; Dependence-producing drugs ; Diazepam ; Dopamine ; Locomotor activity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract It is well known that benzodiazepines produce dependence in humans and locomotor stimulation in experimental animals. In this study the possible involvement of catecholamines in the diazepam-induced locomotor stimulation in mice were investigated. Diazepam was found to have a biphasic effect; increasing locomotor activity at a low dose (0.25 mg/kg), while decreasing it at higher doses (〉0.5 mg/kg). The locomotor stimulating effect of diazepam was effectively blocked by pretreatment with the benzodiazepine receptor antagonist flumazenil, as well as with the catecholamine synthesis inhibitor α-methyltyrosine and the dopamine receptor antagonists haloperidol, spiperone and SCH 23390. Taken together, these data indicate that the locomotor stimulating effect observed after low doses of diazepam is due to activation of brain dopaminergic systems involved in locomotor activity. The observations are discussed in relation to the hypothesis that dependence-producing drugs activate specific brain reward systems.
    Materialart: Digitale Medien
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