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  • Recurrent Inhibition  (3)
  • Dezerebrierungsstarre  (2)
  • Microglia  (2)
  • β-amyloid  (2)
  • 1
    ISSN: 1432-0533
    Keywords: Amyloid precursor protein ; β-amyloid ; Quinolinic acid ; Astrocytes ; Microglia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Clinical and experimental data have indicated an up-regulation of amyloid precursor protein (APP) after various types of CNS injury. In the present study the cellular source of lesion-induced APP has been investigated an a neurotoxic CNS model. Quinolinic acid injection into the striatum results in neuronal degeneration, while glial cells survive. APP immunoreactivity was detected in glial cells starting at postoperative day 3 and persisted until day 21, the last time point studied. Double immunocytochemistry identified the majority of APP-immunoreactive cells as glial fibrillary acidic protein-immunoreactive astrocytes. There was no evidence of amyloid fibril deposition during this time. It is concluded that following excitotoxic neuronal degneration APP is mainly produced by reactive astrocytes in the lesioned area.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Key words     Amyloid precursor protein ; β-amyloid ; Quinolinic acid ; Astrocytes ; Microglia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract      Clinical and experimental data have indicated an up-regulation of amyloid precursor protein (APP) after various types of CNS injury. In the present study the cellular source of lesion-induced APP has been investigated in a neurotoxic CNS model. Quinolinic acid injection into the striatum results in neuronal degeneration, while glial cells survive. APP immunoreactivity was detected in glial cells starting at postoperative day 3 and persisted until day 21, the last time point studied. Double immunocytochemistry identified the majority of APP-immunoreactive cells as glial fibrillary acidic protein-immunoreactive astrocytes. There was no evidence of amyloid fibril deposition during this time. It is concluded that following excitotoxic neuronal degneration APP is mainly produced by reactive astrocytes in the lesioned area.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2013
    Keywords: Primary Muscle Spindle Endings ; Static and Dynamic Sensitivities ; Decerebrate State ; Spinalization ; Deefferentation ; Primäre Muskelspindelendigungen ; Statische und dynamische Empfindlichkeiten ; Dezerebrierungsstarre ; Spinalisierung ; Deefferentierung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Primäre Spindelafferenzen, die bei anaesthesierten Katzen (Fluothane- oder Äther-Stickoxydul-Sauerstoffgemisch) rampenförmige Muskeldehnungen statisch und dynamisch gut beantworten, verlieren nach intercolliculärer Dezerebrierung sowohl an statischer als auch an dynamischer Aktivität. Sofern diese Afferenzen aus Extensoren stammen, führen Spinalisierung und Deefferentierung eine zusätzliche Aktivitätsminderung herbei. 2. Handelt es sich hingegen um primäre Spindelafferenzen, die bei anaesthesierten Katzen ansteigende Muskeldehnungen statisch schlecht oder gar nicht messen, dann nimmt deren Aktivität nach intercolliculärer Dezerebrierung zu, ist allerdings erst nach Deefferentierung maximal. 3. Aus den Ergebnissen wird geschlossen, daß die intercolliculäre Dezerebrierung fusimotorische Spindelsysteme nicht enthemmt.
    Notes: Summary 1. In cats, anesthetized either with mixtures of Fluothane and nitrous oxide or ether and nitrous oxide, primary spindle afferents lose to some extent their static and dynamic responsiveness after intercollicular decerebration, provided that they responded before decerebration quite well to ramp-like muscle extension. If this type of afferents originate from extensor muscles, an additional reduction of their activity is caused by sectioning the spinal cord at Th XII and by deefferentation. 2. In contrast, the static activity of primary endings increases after intercollicular decerebration and spinalization, if their static responsiveness to muscle extension was insufficient before decerebration. In this case, however, maximum activity is not reached until the ventral roots are cut. 3. It is concluded that the intercollicular decerebration does not enhance the activity of primary spindle afferents by release of fusimotor activity.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 329 (1971), S. 23-33 
    ISSN: 1432-2013
    Keywords: Extensor γ-Motoneurones ; Recurrent Inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The antidromic effect of ventral root or muscle nerve stimulation has been studied on functionally isolated γ-efferents to the medial gastrocnemius muscle in the intercollicular decerebrate cat. Tetanic stimulation of the ventral root at levels below the threshold for the investigated γ-efferents decreases the activity of 10 out of 19 γ-motoneurones. This effect is greater in cats with intact contralateral dorsal roots. Tetanic stimulation of synergic muscular nerves inhibits some of the investigated γ-motoneurones, whereas tetanic stimulation of antagonistic muscular nerves fails to have any inhibitory effect. It is suggested that the recurrent inhibition of γ-motoneurones is mediated via at least one additional interneuron between the Renshaw cell and the γ-motoneuron.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 346 (1974), S. 251-262 
    ISSN: 1432-2013
    Keywords: Extensor γ-Motoneurones ; Autogenetic Inhibition ; Recurrent Inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of stretching the triceps surae muscle on the resting discharge of functionally isolated and identified γ-efferents in the medial gastrocnemius nerve were studied in intercollicular decerebrate cats. Extension of the muscle decreases the activity of 9 out of 25 γ-motoneurones. This inhibition becomes apparent at about 8 mm muscle length and increases with increasing extension. Only those γ-efferents exhibiting this length-dependent inhibition are found to be inhibited by repetitive antidromic stimulation of the ventral root or the homonymous muscle nerve. We suggest that inhibition of fusimotor neurones by muscle stretch is at least partly mediated by the recurrent collaterals of the α-motoneurones activated by the stretch. 11 γ-motoneurones were predominantly excited by muscle stretch applied to the detached Achilles tendon as well as by squeezing the tendon. Nociceptors within the tendon or surrounding fascia are probably responsible.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 311 (1969), S. 148-158 
    ISSN: 1432-2013
    Keywords: Decerebrate State ; Extensor Motoneurones ; Recurrent Inhibition ; Disinhibition ; Schlüsselwörter ; Dezerebrierungsstarre ; Extensor-Motoneurone ; Recurrente Inhibition ; Disinhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Trotz kontinuierlicher Anaesthesie und Unterbrechung der Gamma-Spindelschleife löst die natürliche oder elektrische Reizung homonymer Ia-Afferenzen mit konstanter Stärke nach intercolliculärer Dezerebrierung an Extensor-Motoneuronen regelmäßigere Antworten, Verkürzung der Reflexzeit, Zunahme der Entladungsfrequenz, Verstärkung der post-tetanischen Potenzierung und Rekrutierung aus. Da der Grad der recurrenten Hemmung abnimmt, schließen wir, daß die gesteigerte Erregbarkeit der Extensor-Motoneurone im Zustand der Dezerebrierung mit Disinhibition verbunden ist. Die mit einem konstanten Quantum reflexwirksamer Afferenzen erhaltenen Resultate sprechen für unsere Annahme, daß Spastizität nicht hauptsächlich auf fusimotorischer Enthemmung beruht.
    Notes: Summary Even with continued anesthesia and interrupted gamma-loop intercollicular decerebration leads in extensor motoneurones (excited by electrical or natural stimulation of homonymous Ia-afferents with constant strength) to the following phenomona: more regular responses, shortening of reflex time, increase of discharge frequency, enhancement of post-tetanic potentiation, and recruitment. Because the degree of recurrent inhibition is diminished we conclude that the higher excitability of extensor motoneurones in the decerebrate state is correlated with disinhibition. Furthermore the results obtained with the afferent input for motoneurones kept constant favour our assumption that spasticity is not based merely on the release of fusimotor activity.
    Type of Medium: Electronic Resource
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