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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 258 (1975), S. 750-751 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Amphetamine increases the release and prevents re-uptake of both noradrenaline (NA) and dopamine (DA) and could therefore induce stereotypy by its action on any of the brain CA systems8"10. DA seems, however, to play a critical role in amphetamine stereotypy as this drug-induced behaviour is ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 18 (2003), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Central administration of 15 ng interleukin (IL)-1β in the rat significantly enhanced conditioned fear memory assessed by a passive avoidance task, when retested at 24 and 48 h post-training. Pain threshold was unaffected by 15 ng IL-1β administration. IL-1β treatment also increased serum corticosterone. This increase in serum corticosterone was further enhanced in rats given both IL-1β and footshock. Furthermore, the glucocorticoid receptor antagonist mifepristone blocked IL-1β-induced elevation in corticosterone and also attenuated the enhanced conditioned fear memory. Central administration of IL-1β significantly increased prostaglandin E2 and decreased the anti-inflammatory cytokine IL-10 release from whole blood cultures; therefore this treatment appears to be effective in inducing an inflammatory response in both the periphery and the brain. The present study confirms that IL-1β can enhance conditioned fear memory, an effect which is correlated with changes in glucocorticoid function. This facilitation of defensive behaviour could reflect adaptive responses which may enhance survival during sickness.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Chronoamperometric recording techniques were used to monitor extracellular dopamine efflux in the nucleus accumbens associated with unconditioned and conditioned increases in motor activity in rats, following the intravenous administration of either d-amphetamine (0.63 mg/kg) or cocaine (3 mg/kg), or the presentation of a conditioned stimulus paired repeatedly with one of these psychostimulants. Each drug was administered daily for 7 days, either in the home cage or an environment in which a compound stimulus (light offset, odour) was presented. Rats in control groups received saline instead of drug in the distinctive test environment. On day 7 of training, significant increases in unconditioned motor activity were observed in the 30 min session following infusions of either d-amphetamine or cocaine. Associated dopamine oxidation currents in the nucleus accumbens increased immediately following administration of either drug and remained significantly elevated above baseline during the entire 30 min recording period. On the test day, presentation of the conditioned stimulus with vehicle infusions, in the distinct environment, was accompanied by an increase in dopamine oxidation currents and a conditioned increase in motor activity, only in the groups in which these stimuli had been paired with d-amphetamine or cocaine. Neither the magnitude or duration of the conditioned motor activity matched the corresponding change in extracellular dopamine efflux in the nucleus accumbens. Accordingly, it is argued that the increase in dopamine concentration serves as a neurochemical correlate of the unconditioned and conditioned stimuli. The change in motor activity constitutes the unconditioned and conditioned responses that are subserved by the neural systems activated by the initial rise in extracellullar dopamine.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In vivo chronoamperometry was used to monitor changes in dopamine oxidation currents corresponding to dopamine efflux in the nucleus accumbens of rats after presentation of a conditioned light stimulus repeatedly paired with either yoked- or self-administered intravenous injections of the psychostimulant d-amphetamine. Daily conditioning trials began with a non-contingent drug injection, paired with a conditioned stimulus consisting of a 5 s flashing light and 30 s lights out, after which a house light was illuminated during the 3 h session, signalling drug availability. Each subsequent injection of d-amphetamine was paired with the conditioned stimulus. Electrochemical measures were taken on conditioning trials 4–7, and on each trial, intravenous d-amphetamine (0.25 mg/kg per injection) self-administration produced a significant maximal increase in mean dopamine oxidation currents of ≈ 8 nA above baseline. Dopamine oxidation currents in rats receiving yoked d-amphetamine were ≈ 5 nA above baseline by the fourth day of drug administration and reached ≈ 8 nA on the seventh and final day of drug administration. On day 9 the first presentation of the vehicle injection and conditioned stimulus, in combination with illumination of the house lights, induced an immediate increase in nucleus accumbens dopamine oxidation currents in all rats that had previously received d-amphetamine. Subsequent presentations of the conditioned stimulus at 30 min intervals induced further increases in extracellular dopamine oxidation currents in both drug-treated groups. By the end of the 3 h session, both groups had similar maximal conditioned increases in dopamine oxidation currents of ≈ 6 nA. These data are discussed with relation to the neurochemistry of drug craving.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Afferents from the basolateral amygdala and dopamine projections from the ventral tegmental area to the nucleus accumbens have both been implicated in reward-related processes. The present study used in vivo chronoamperometry with stearate-graphite paste electrodes in urethane-anaesthetized rats to determine how basolateral amygdala efferents to the nucleus accumbens synaptically regulate dopamine efflux. Repetitive-pulse (20 Hz for 10 s) electrical stimulation of the basolateral amygdala evoked a complex pattern of changes in monitored dopamine oxidation currents in the nucleus accumbens related to dopamine efflux. These changes were characterized by an initial increase that was time-locked to stimulation, a secondary decrease below baseline, followed by a prolonged increase in the dopamine signal above baseline. The effects of burst-patterned stimulation (100 Hz, 5 pulses/burst, 1-s interburst interval, 40 s) of the basolateral amygdala on the basal accumbens dopamine signal were similar to those evoked by 20 Hz stimulation, with the lack of a secondary suppressive component. Infusions of the ionotropic glutamate receptor antagonists (±)-2-amino-5-phosphonopentanoic acid (APV) or 6,7-dinitroquinoxaline-2,3-dione (DNQX) into the nucleus accumbens dose-dependently blocked or attenuated the initial and prolonged increases in the dopamine signal following 20 Hz or burst-patterned basolateral amygdala stimulation. Infusions of the metabotropic glutamate receptor antagonist (+)-α-methyl-4-carboxyphenylglycine selectively blocked the intermediate suppressive effect of 20 Hz basolateral amygdala stimulation on dopamine oxidation currents. Blockade of glutamate receptors or inhibition of dopamine neuronal activity via infusions of either APV + DNQX, lidocaine or γ-hydroxybutyric acid, respectively, into the ventral tegmental area did not effect the pattern of changes in the accumbens dopamine signal evoked by basolateral amygdala stimulation. These data suggest that the glutamatergic basolateral amygdala inputs to nucleus accumbens dopamine terminals synaptically facilitate or depress dopamine efflux, and these effects are independent of dopamine neuronal firing activity. Moreover, these results imply that changes in nucleus accumbens dopamine levels following presentation of reward-related stimuli may be mediated, in part, by the basolateral amygdala.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Post-weaning social isolation-rearing of rats leads to behavioural and neurochemical sequelae that model aspects of schizophrenia, and it may be useful to test hypotheses related to putative molecular mechanisms of the illness. In humans, the presynaptic protein CDCrel-1 represents an interesting candidate molecule for the mechanism and aetiology of schizophrenia. CDCrel-1 modulates dopamine neurotransmission, binds to the SNARE protein syntaxin and maps onto a region of chromosome 22q11 deleted in velo-cardio–facial and DiGeorge syndromes, which are associated with increased prevalence of schizophrenia. Using the isolation-rearing model, we measured immunoreactivity of the synaptic proteins CDCrel-1, synaptophysin and syntaxin. Male, Sprague–Dawley rats were raised in groups or in isolation for 12 weeks from weaning. Synaptic protein immunoreactivities were measured in striatal and hippocampal homogenates, using a sensitive enzyme-linked immunoadsorbent assay with monoclonal antibodies. Isolation-rearing produced region- and protein-specific effects. CDCrel-1 immunoreactivity was significantly lower in the striatum and marginally higher in the hippocampus of isolation-reared compared with socially reared animals. There were no statistically significant differences in synaptophysin immunoreactivity in either region. Confocal microscopy demonstrated a high degree of colocalization between the two presynaptic proteins. In striatum, a robust relationship between CDCrel-1 and syntaxin immunoreactivities was observed in socially reared rats, this was lost in the isolation-reared animals. Altered levels of the septin CDCrel-1 in isolation-reared rats may contribute to changes in neuronal connectivity and neurotransmission, and suggest a potential role for CDCrel-1 in schizophrenia related to chromosome 22q11 deletion syndrome.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The effects of electrical stimulation of the ventral subiculum/CA1 region of the hippocampus on changes in dopamine oxidation current (corresponding to dopamine efflux) in the nucleus accumbens were examined using in vivo chronoamperometry with stearate-graphite paste electrodes in urethane-anaesthetized rats. Burst-patterned monophasic pulses (10–100 Hz/burst delivered at 0.84 Hz) evoked a three-component change in dopamine efflux in the nucleus accumbens with an initial transient increase in the dopamine signal above baseline, followed by an immediate decrease below baseline, and thereafter by a prolonged increase in the dopamine signal above baseline. 6–Hydroxydopamine lesions of the mesoaccumbens dopamine pathway or transection of the fimbria-fornix blocked all of the evoked changes in the dopamine signal. Both the first and third components of enhanced dopamine efflux were blocked by microinfusion into the nucleus accumbens of the ionotropic glutamate receptor antagonists (±)-2-amino-5-phosphonopentanoic acid, 6,7-dinitroquinoxaline-2,3-dione and kynurenate. Burst stimulation-evoked decreases in the dopamine signal were abolished following microinfusions into the nucleus accumbens of the metabotropic glutamate receptor antagonist (+)-α-methyl-4-carboxyphenylglycine. These results suggest that ventral subiculum/CA1 glutamatergic inputs to the nucleus accumbens may presynaptically modulate dopamine efflux by synaptic activation of both ionotropic and metabotropic glutamate receptors in the nucleus accumbens. These glutamate-dopamine interactions may constitute part of the mechanisms by which hippocampal signals are integrated through selective modulation of dopamine release in the nucleus accumbens in both physiological and pathological conditions.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 20 (2004), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abnormal activity in corticolimbic circuits during development may be a predisposing factor for schizophrenia. Permanent or temporary lesions of limbic structures such as the ventral hippocampus and basolateral amygdala in rats on postnatal day (PND) 7 result in functional changes similar to some behavioural and cognitive signs of schizophrenia. The present experiments tested whether transient increases in the neural activity of corticolimbic circuits on PND 7 would result in similar behavioural changes. Long-Evans rats were treated with either kainic acid (KA, 1.5 mg/kg, i.p.) or saline on PND 7 and tested for prepulse inhibition (PPI) of the acoustic startle response and spontaneous locomotor activity both in a novel environment and following amphetamine treatment before puberty (PND 35) and in early adulthood (PND 56). In subgroups of animals PPI was also measured following apomorphine administration (0.2 mg/kg) and spatial learning and memory were tested in the water maze. Rats treated with KA were indistinguishable from saline-treated animals on PND 35. However, on PND 56, KA-treated animals showed a subtle consistent decrease in PPI relative to control animals, but did not show increased sensitivity to the disruptive effects of a low dose of apomorphine on PPI. Locomotor responses to novelty or amphetamine were not reliably altered in the KA-treated animals. KA- and saline-treated animals performed similarly in the water maze. These results support the hypothesis that neural hyperactivity on PND 7 in rats causes behavioural changes in early adulthood that resemble some symptoms of schizophrenia. These pharmacological data suggest that the changes are not mediated by postsynaptic alterations in mesolimbic dopamine transmission.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 537 (1988), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 537 (1988), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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