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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 175 (1987), S. 289-301 
    ISSN: 1432-0568
    Keywords: Dura mater encephali ; Sensory receptors ; Nerve fibres ; Vascular bed ; Lymphatic vessel ; Nociception ; Headache
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The dura mater encephali of the rat is richly supplied by myelinated (A-axons) and unmyelinated (C-axons) nerve fibres. For the supratentorial part the main nerve supply stems from all three branches of the trigeminal nerve. Finally, 250 myelinated and 800 unmyelinated nerve fibres innervate one side of the supratentorial part. The vascular bed of the dura mater exhibits long postcapillary venules up to 200 μm in length with segments of endothelial fenestration. Lymphatic vessels occur within the dura mater. They leave the cranial cavity through the openings of the cribriform plate, rostral to the bulla tympani together with the transverse sinus, and the middle meningeal artery. The perineural sheath builds up a tube-like net containing the A- and C-axons. It is spacious in the parietal dura mater and dense at the sagittal sinus along its extension from rostral to caudal and at the confluence of sinuses. Terminals of both the A- and C-axons are of the unencapsulated type. Unencapsulated Ruffini-like receptors stemming from A-axons are found in the dural connective tissue at sites where superficial cerebral veins enter the sagittal sinus and at the confluence of sinuses. The terminations of single A-axons together with C-fibre bundles mix up in their final course in one Schwann cell to build up multiaxonal units or terminations (up to 15 axonal profiles). A morphological differentiation is made due to the topography of these terminations; firstly, in different segments of the vascular bed: postcapillary venule, venule, the sinus wall, lymphatic vessel wall, and secondly, within the dura mater: inner periosteal layer, collagenous fibre bundles of the meningeal layer and at the mesothelial cell layer of the subdural space.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 92 (1993), S. 391-398 
    ISSN: 1432-1106
    Keywords: Joint afferents ; Nociception ; Transduction ; Phorbol esters ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of β -phorbol 12, 13-dibutyrate (PDBu) on the discharge properties of slowly conducting knee joint afferents (group III and group IV fibers) were studied to determine the role of protein kinase C in nociception. Extracellular single unit recordings were made from small filaments dissected from the medial articular nerve in cats anesthetized with alphachloralose. PDBu was applied intra-arterially close to the joint in concentrations of 10-6 up to 10-4 M. The afferents were classified as low-threshold and high-threshold units with regard to their sensitivity to passive noxious and innocuous movements of the knee joint. Following PDBu application, an excitation occurred in 28% of the group III and in 40% of the group IV fibers. An enhancement of responses to passive movements of the joint (sensitization) occurred in 37% of group III and 19% of group IV afferents. In summary, 37.5% of the low-threshold and 50% of the high-threshold fibers proved to be sensitive to PDBu. Most of the PDBu-positive units responded also to bradykinin, whereas only a few PDBu-positive units were sensitive to prostaglandin I2 and E2. We conclude from these results that, in a distinct population of slowly conducting joint afferents, protein kinase C is likely to be involved in the process of transduction. Thus, pain and hyperalgesia may be mediated at least partly by intracellular mechanisms that are linked to protein kinase C.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 101 (1994), S. 452-464 
    ISSN: 1432-1106
    Keywords: Somatosensory thalamus ; Knee joint ; Nociception ; Bradykinin ; Capsaicin ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to gain insight into the representation of articular pain of the knee at the supraspinal level, recordings were made from lateral thalamic neurons receiving input from afferent fibres of the knee joint in chloralose-anaesthetized cats. Dorsoventral penetrations were made through the ventral posterior lateral nucleus (VPL) using high intensity electrical stimulation of the medial articular nerve (MAN), which contains a high proportion (80%) of Aδ and C afferent fibres. All recording sites were verified histologically. Close retrograde injections (300 μl over 6 s) into geniculate artery of KCl (2 × isotonic), bradykinin (BK, 2.6 or 26 μg) and capsaicin (200 μM) were used to test the response properties of thalamic neurons. Of the 50 MAN-positive units tested, 20 showed a response to intra-arterial KCl; of these 20, 12 had a response to BK; 8 of these 12 units were additionally tested with capsaicin and all responded. KCl and capsaicin injections had similar mean response latencies (4.5 and 6.8 s), whereas BK had a longer mean latency (18.6 s). The mean peak response was greatest for capsaicin (168 impulses/s), then KCl (87.5 imp/s) and least with BK (36.4 imp/s). The mean response duration was longest with capsaicin (118 s), followed by BK (67.5 s) and least with KCl (27.9 s). Most of these were convergent wide dynamic range (WDR) neurons with a deep receptive field in the knee joint and hindlimb muscle and/or cutaneous distal hind limb digit, located to the dorsal or ventral periphery of the lateral division of the VPL, the VPLl. In addition, 8 neurons showed inhibitory responses to KCl and/or BK injections. The background activity of the VPLl neurons activated by saphenous nerve stimulation was inhibited by the nociceptive articular stimulus with a magnitude and time course which mirrored the excitatory responses in the periphery of VPLl. These results support the concept that the lateral thalamus plays an important role in mediating discriminative aspects of joint pain.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1106
    Keywords: [K+]0 Spinal cord ; Posterior articular nerve ; Knee joint ; Inflammation ; Pain ; Arthritis ; Nociception ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In 20 cats anaesthetized with alpha-chloralose and spinalized at the thoracolumbar junction we investigated the role of stimulation induced accumulation of extracellular potassium in the spinal cord in the processing of nociceptive discharges from the knee joint. For that we electrically stimulated the posterior articular nerve of the knee. We further performed innocuous and noxious stimulation of the knee and of other parts of the leg and studied the effect of an acute inflammation of the knee on [K+]0 in the spinal cord. Innocuous stimulation of the skin (brushing or touching) and innocuous movements in the knee joint all induced rises in [K+]0 which were maximal at recording depths of 1500 to 2200 μm below the surface of the cord dorsum. Peak increases were 0.4 mM for touching the leg and 1.7 mM during rhythmic flexion/ extension of the knee joint. Noxious stimulation of the skin, the paw, the tendon and noxious movements of the knee joint also produced rises in [K+]0, which were somewhat larger for the individual types of stimuli than those produced by innocuous intensities. Electrical stimulation of the posterior articular nerve induced rises in [K+]0 by up to 0.6 mM. Stimulus intensities sufficient to activate unmyelinated group IV fibers were only slightly effective in raising [K+]0 above the levels reached during stimulation of myelinated group II and III fibers. During development of an acute inflammation of the knee joint (induced by kaolin and carrageenan), increases in [K+]0 and associated field potentials became larger by about 25%. We assume that this reflects an increase in neuronal responses. In conclusion, changes in [K+]0 in the spinal cord are some-what larger during noxious stimulation than during innocuous stimulation. The absolute level reached depended more on the site and type of stimulation than on the actual stimulus intensity itself. Hence a critical role of spinal K+ accumulation for nociception is unlikely.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1106
    Keywords: Pain ; Inflammation ; Descending inhibition ; Nociception ; Spinal cord ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In ten cats, single unit electrical activity was recorded in the lumbosacral spinal cord from neurones driven by stimulation of afferent fibres from the ipsilateral knee joint. Tonic descending inhibition (TDI) on the responses of these cells was measured as increases in resting and evoked activity of the neurones following reversible spinalization of the animals with a cold block at upper lumbar level. Acute inflammation of the knee joint was induced in five of the cats by the injection of kaolin and carrageenan into the joint. TDI was observed in 25 of 33 neurones recorded in normal animals (76%) and in 36 of 40 (90%) neurones recorded in animals with acute knee joint inflammation. In both kinds of preparation TDI was more pronounced in neurones recorded in the deep dorsal horn and in the ventral horn than in those recorded in the superficial dorsal horn. There was a tendency in the whole sample for TDI to be greater in neurones with input from inflamed knees. We conclude that the spinal processing of afferent information from joints is under tonic descending influences and that the amount of TDI can be altered during acute arthritis.
    Type of Medium: Electronic Resource
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