WILBERT

Wildauer Bücher+E-Medien Recherche-Tool

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 70 (1980), S. 173-177 
    ISSN: 1432-2072
    Keywords: Endogenous opiates ; Beta-endorphin ; Amnesic effects ; Amnesic mechanisms ; Memory consolidation ; Non-associative factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The endogenous opiate peptide, beta-endorphin (0.4, 1.0, 2.0, and 10.0 μg/kg) was injected IP into rats immediately after training in a shuttle avoidance task, and its effect on memory retention was evaluated in test sessions carried out 24 h later. The drug was found to cause retrograde amnesia, the ED50 being 1.0 μg/kg. Beta-endorphin immunoreactivity was measured in the hypothalamus and rest of the brain of rats submitted to training, or test sessions of shuttle avoidance learning, pseudoconditioning in the shuttle-box, tones alone, or foot-shocks alone. After training in any of the four paradigms, there was a marked (46–60%) depletion of beta-endorphin immunoreactivity in the rest of the brain. No changes were detected in the hypothalamus or after test sessions. The loss of beta-endorphin immunoreactivity may be attributed to release of this substance caused by the stimuli used for training. From the present findings, as well as previous observations on the memory-facilitating influence of the opiate receptor antagonist, naloxone, it is concluded that there is a physiological amnesic mechanism mediated by beta-endorphin (and perhaps other opoid peptides as well), which is triggered by the non-associative factors present in the various forms of learning.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 80 (1983), S. 181-183 
    ISSN: 1432-2072
    Keywords: Memory ; Adrenaline ; Tyramine ; α1 Receptors ; α2 Receptors ; Epinephrine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The posttraining IP administration of adrenaline (epinephrine) HCl (5.0 μg/kg) or tyramine HCl (1.0 mg/kg) causes retrograde amnesia for a one-way step-down inhibitory avoidance task in rats. The effect is cancelled by the simultaneous injection of the α2-adrenergic receptor antagonist yohimbine HCl (2.0 mg/kg), but not by that of the α1 antagonist prazosin HCl (2.0 mg/kg) or of the β1−β2 blocker propranolol HCl (2.0 mg/kg). The amnestic effect of posttraining adrenaline or tyramine is counteracted by the administration of adrenaline or tyramine prior to testing: each drug has a greater antiamnestic effect against itself than against the other drug. The antiamnestic effect of tyramine and adrenaline is antagonized by the simultaneous administration of prazosin or yohimbine, but not by that of propranolol. We conlcude that the posttraining amnestic effect of adrenaline and tyramine is mediated by α2 receptors (probably postsynaptic) and that it doesnot reflect a storage deficit, since memory can be restored by an appropriate treatment given before the test session. The antiamnestic effect of adrenaline and tyramine is mediated both by α1 and by α2 receptors, and probably reflects the dependency of mechanisms that make stored information available for retrieval on circulating catecholamines. The present findings provide no clue as to the anatomical distribution of the adrenergic receptors involved in the amnestic or antiamnestic actions of adrenaline and tyramine.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 129 (1993), S. 47-55 
    ISSN: 1573-4919
    Keywords: ATP diphosphohydrolase ; apyrase ; platelets ; rat blood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In the present report we describe an apyrase (ATP diphosphohydrolase, EC 3.6.1.5) in rat blood platelets. The enzyme hydrolyses almost identically quite different nucleoside di- and triphosphates. The calcium dependence and pH requirement were the same for the hydrolysis of ATP and ADP and the apparent Km values were similar for both Ca2+-ATP and Ca2+-ADP as substrates. Ca2+-ATP and Ca2+-ADP hydrolysis could not be attributed to the combined action of different enzymes because adenylate kinase, inorganic pyrophosphatase and nonspecific phosphatases were not detected under our assay conditions. The Ca2+-ATPase and Ca2+-ADPase activity was insensitive to ATPase, adenylate kinase and alkaline phosphatase classical inhibitors, thus excluding these enzymes as contaminants. The results demonstrate that rat blood platelets contain an ATP diphosphohydrolase involved in the hydrolysis of ATP and ADP which are vasoactive and platelet active adenine nucleotides.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Neurochemical research 16 (1991), S. 1303-1310 
    ISSN: 1573-6903
    Keywords: ATP diphosphohydrolase ; apyrase ; ATPase ; ADPase ; neurotransmission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Data from the literature have demonstrated that synaptosomal preparations from various sources can hydrolyze externally added ATP. Various authors characterized this activity as an ecto-ATPase. In the present report, we demonstrate that synaptosomal preparations obtained from the cerebral cortex of rats show ATPase activity that could not be dissociated from ADPase activity, suggesting that an ATP-diphosphohydrolase is involved in ATP and ADP hydrolysis. Furthermore, the ATP and ADP hydrolysis could not be attributed to associations of enzymes that could mimic an ATP-diphosphohydrolase because none of the following activities were detected in our assay conditions inorganic pyrophosphatase, adenylate kinase, or nonspecific phosphatases. A possible association between an ATPase and an ADPase was excluded on the basis of both the kinetics and much additional data on inhibitors, ion dependence, pH, etc. The present results demonstrate that in synaptosomal preparations from cerebral cortex an ATP-diphosphohydrolase is involved, at least in part, in ATP and ADP hydrolysis.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...