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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 48 (1987), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Concentrations of dopamine, serotonin, and some of their metabolites were analyzed by means of HPLC in brain samples obtained from rats operantly conditioned to turn in circles to obtain water reinforcement. In experiment 1 using Wistar rats, no differences in the levels of transmitters or metabolites were detected between brain samples (frontal cortex, ventral striatum, dorsal striatum, septum, amygdala, substantia nigra) from the hemispheres located ipsi- and contralateral to the direction of turning. A higher dopamine metabolism (indicated by higher metabolite/transmitter ratios) in ventral striatum, dorsal striatum, and amygdala was found after 15 min than after 5 min of turning in both hemispheres. A higher dopamine metabolism was found in water-deprived rats compared to nondeprived rats independently of whether or not deprived rats were trained to turn for water reinforcement. In two additional experiments, no differences in dopamine metabolism were found between the ipsi- and contralateral striatum of Wistar rats after 25 min and Sprague-Dawley rats after 10 min of operantly conditioned turning. The present results confirm that dopamine metabolism can change with different behavioral or physiological states; they do not support the hypothesis that conditioned turning is correlated with asymmetrical changes in the metabolism of dopamine or serotonin in the brain.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The effectiveness of intranasal drug administration to stimulate central neuronal systems is well known from drug addiction and has also been considered as an alternative pharmacokinetic approach to treat brain disorders such as Parkinson's disease. In the present study, the possible neurochemical effects of intranasal administration of the psychostimulants cocaine and amphetamine and of the antiparkinsonian drug l-DOPA were analyzed. By using in vivo microdialysis in the urethane-anesthetized rat, it was found that unilateral intranasal administration of either of the psychostimulants led to huge and rapid increases of extracellular dopamine levels in the neostriatum followed by decreases of its metabolites dihydroxyphenylacetic acid and homovanillic acid. Furthermore, intranasal administration of l-DOPA, but not of the saline vehicle, also led to increased extracellular levels of neostriatal dopamine and to increases of its metabolites. Because the effect of intranasal l-DOPA on neostriatal dopamine was observed only ipsilaterally but not contralaterally to the side of intranasal drug administration, it can be hypothesized that l-DOPA was not effective via passage through the circulation but may have acted through a neuronal or an extraneuronal route. These data provide neurochemical evidence that the intranasal route may not only be efficient in drug abuse, but may also be useful to target the brain therapeutically, as in the case of neurodegenerative brain disorders.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 525 (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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  • 4
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Histamine has been implicated, inter alia, in mechanisms underlying arousal, exploratory behaviour and emotionality. Here, we investigated behavioural and neurochemical parameters related to these concepts, including open-field activity, rotarod performance and anxiety, as well as brain acetylcholine and 5-HT concentrations of mice deficient for the histidine decarboxylase (HDC) gene. These mice are unable to synthesize histamine from its precursor histidine. The HDC-knockout mice showed reduced exploratory activity in an open-field, but normal habituation to a novel environment. They behaved more anxious than the controls, as assessed by the height–fear task and the graded anxiety test, a modified elevated plus-maze. Furthermore, motor coordination on the rotarod was superior to controls. Biochemical assessments revealed that the HDC-knockout mice had higher acetylcholine concentrations and a significantly higher 5-HT turnover in the frontal cortex, but reduced acetylcholine levels in the neostriatum. These results are suggestive of important interactions between neuronal histamine and these site-specific neurotransmitters, which may be related to the behavioural changes found in the HDC-deficient animals.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Striatal parameters were assessed for their relevance to age-related behavioural decline. Forty aged rats (28–30 months) were tested in the water maze and open field. Of these, seven superior and seven inferior learners were compared with each other in terms of levels of in vitro short- and long-term potentiation (STP and LTP), and gene expression of choline acetyltransferase (ChAT) as well as of the NMDA-NR2A-C subunits assessed by quantitative RT-PCR. Results revealed that the superior as compared with the inferior learners had higher levels of ChAT mRNA in the striatum. For the superior group, ChAT mRNA was correlated with escape on to the cued platform in the water maze, whereas level of LTP was predictive of place learning in the water maze and rearing activity in the open field. For the inferior group, expression of NR2A and NR2B was positively correlated with place learning and probe trial performance in the water maze. The results show that individual differences in various behaviours of aged rats were accounted for by variability in striatal parameters, i.e. LTP, ChAT and NMDA-NR2 subunit mRNA. Notably, the correlations found were heterogeneous amid the groups, e.g. variability in place learning was explained by variability in levels of LTP in the superior learners, but in levels of NR2A-B mRNA in the inferior group.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In 28- to 30-month-old rats, in vitro short-term and long-term potentiation (STP and LTP) were measured in area CA1 of the hippocampus in seven superior and seven inferior learners, that were selected from a pool of 40 rats based on water maze escape performance over a period of 9 days. The aim was to examine whether levels of STP and LTP could account for group differences in learning of water maze escape, spatial preference and wall (thigmotaxis)-avoidance and in short-term retention of an inhibitory avoidance task. There was no significant group difference in open-field exploration, i.e. the number of rearings. In contrast to expectation, the superior and inferior learners did not differ significantly from each other in levels of STP and LTP. However, variability in escape and spatial learning, but not thigmotaxis-avoidance learning, was significantly predicted by variability in STP and LTP in the superior group. Also, open-field exploratory rearings were significantly correlated with STP and LTP as well as with maze escape learning in the superior group. The results show that, in the aged superior group, levels of CA1 STP and LTP coincided with residual water maze escape and spatial preference learning as well as open-field exploration, i.e. behavioural expressions known to be related to hippocampal functioning, but not with learning to avoid thigmotaxis in the maze. The lack of such correlations in the inferior group may be due to the severe impairment in escape and spatial preference learning and/or the influence of yet unknown third variables on these relationships.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Gap-junction channels in the brain, formed by connexin (Cx) proteins with a distinct regional/cell-type distribution, allow intercellular electrical and metabolic communication. In astrocytes, mainly the connexins 43, 26 and 30 are expressed. In addition, connexin30 is expressed in ependymal and leptomeningeal cells, as well as in skin and cochlea. The functional implications of the astrocytic gap-junctional network are not well understood and evidence regarding their behavioural relevance is lacking. Thus, we have tested groups of Cx30−/−, Cx30+/−, and Cx30+/+ mice in the open-field, an object exploration task, in the graded anxiety test and on the rotarod. The Cx30−/− mice showed reduced exploratory activity in terms of rearings but not locomotion in the open-field and object exploration task. Furthermore, Cx30−/− mice exhibited anxiogenic behaviour as shown by higher open-field centre avoidance and corner preference. Graded anxiety test and rotarod performance was similar across groups. The Cx30−/− mice had elevated choline levels in the ventral striatum, possibly related to their aberrant behavioural phenotypes. The Cx30+/− mice had lower dopamine and metabolite levels in the amygdala and ventral striatum and lower hippocampal 5-hydroxyindole acid (5-HIAA) concentrations relative to Cx30+/+ mice. Furthermore, the Cx30+/− mice had lower acetylcholine concentrations in the ventral striatum and higher choline levels in the neostriatum, relative to Cx30+/+ mice. Our data suggest that the elimination of connexin30 can alter the reactivity to novel environments, pointing to the importance of gap-junctional signalling in behavioural processes.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd/Inc
    Journal of fish biology 63 (2003), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Fishes, in general, have several advantages as vertebrate models for basic brain function. They are phylogenetically closer than mammals to the basic vertebrate blueprint and thus allow behavioural and neurological studies of fundamental brain systems without the interaction of more recently evolved functions. Further, the absence of a highly developed telencephalon allows ready access to many structures without cerebral interference. A disadvantage of working with most fishes is, however, the relatively small size of the brain that often hinders or precludes the use of many standard neurological techniques. In contrast, a group of chondrichthians, the stingrays, Dasyatoidea, has a brain size rivaling mammalian rodent models. Of particular interest to our research, stingrays, like mammals, have a large, complex, three-lobed cerebellum. However, in the yellow stingray these lobes are completely separated. Thus, the lobes can be individually manipulated to examine behavioural correlates of specific lobes. For example, ablation of the centre lobe (also known as anterior caudal lobule) causes a fixed-pattern hyperactivity. Yellow stingrays are abundant in many areas, they are hardy, and tolerate anaesthesia and the surgical procedures well. A more complete elucidation of cerebellar function awaits further physical and pharmacological ablative studies but the potential for these animals as vertebrate models of cerebellar-controlled behaviour is clear.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 28 (1972), S. 1455-1455 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung γ-butyrolacton (400 mg/kg i.p.) bewirkt bei der Ratte eine triphasische Änderung der Körpertemperatur mit einer hyperthermen Komponente. Diese für ein Narkosemittel ungewöhnliche Hyperthermie kann nicht durch eine Erhöhung der Dopaminkonzentration im Gehirn erklärt werden, da sie nach Hemmung der Katecholaminsynthese immer noch vorhanden ist.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 30 (1974), S. 1038-1040 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Unter Verwendung einer passiven Vermeidungsreaktion mit Futterbelohnung nach verschiedenen Zeitintervallen zwischen 0 und 120 sec konnte gezeigt werden, dass belohnung 20, 30 und 50 sec nach dem Fusschock signifikant verbessertes Lernen bewirkt. Diese Daten unterstützen die Hypothese, dass Gedächtnisprozesse-konzeptionell als operante Reaktion aufgefasst-durch Belohnung modiiizierbar sind.
    Type of Medium: Electronic Resource
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