Preterminal and terminal axon arborizations in the substantia gelatinosa of cat's spinal cord

Réthelyi, M.

doi:10.1002/cne.901720307

Cited by 143 publications

(51 citation statements)

References 26 publications

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“…The finding that the CI potential was directly proportional to the amplitude of C-fibre nerve volley thus suggests that the CI potential is generated primarily by the synapses between the C afferent fibres and the second-order neurones in lamina II. On the other hand, the non-linear relation between the C-fibre-evoked field potential in lamina V and the C-fibre nerve volley indicates a polysynaptic C-fibre input to lamina V. These conclusions are supported by results from anatomical studies, indicating that cutaneous C fibres terminate mainly, if not exclusively, in laminae I and II of the spinal cord (LaMotte, 1977;Rethelyi, 1977;Ralston & Ralston, 1979, 1982.…”

Section: Discussionsupporting

confidence: 77%

Functional and topographical properties of field potentials evoked in rat dorsal horn by cutaneous C‐fibre stimulation.

Schouenborg¹

1984

The Journal of Physiology

112

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SUMMARY1. Extracellular field potentials in the lumbosacral dorsal horn evoked by stimulation of cutaneous C fibres in the sural nerve were explored in the halothaneanaesthetized rat.2. C-fibre-evoked field potentials were prominent in lamina II and lamina V of the dorsal horn. These potentials had a latency of 80-130 ms and a duration of more than 200 ms. A peak in the C-fibre-evoked field potential, termed the CI potential, with a median latency of 120 ms, range 105-150 ms, was distinguished in lamina II. The time from onset to peak of the CI potential was, on average, 13 ms when all C fibres were activated. The amplitude of the CI potential in lamina II was directly proportional to the amplitude of the C-fibre-evoked nerve volley, whereas the relation between the C-fibre nerve volley and the C-fibre-evoked field potential in lamina V was non-linear. A selective block of A fibres did not influence the amplitude of these field potentials.3. Following stimulation of C afferent fibres in the medial sural nerve, at frequencies higher than 0-1 Hz, the CI potential in lamina II, but not the C-fibre-evoked field potential in lamina V, was increased. There was no concomitant change of the A-fibre-evoked field potentials. The magnitude of the potentiation of the CI potential was dependent both on the frequency and the number of stimuli. Mean percentage potentiation was 200 %, range 150-300 %, after seventy stimulations at a frequency of 1-0 Hz. During the stimulation the CI potential increased monotonically. The decay of the potentiation of the CI potential was well described by two exponentially declining phases. There was a positive correlation between the size of the time constants of the decay and the number of stimuli during conditioning.4. Following noxious radiant heat (temperature 5-55 'C) applied to a restricted part of the skin (area 20-30 mm2) within the receptive field of the medial sural nerve for 10-20 s, the CI potential was potentiated by 50-130%. The duration of this potentiation was 3-15 min. This potentiation was somatotopically organized. By contrast, there was no effect on the amplitude of the CI potential following innocuous skin stimulation (slowly moving contact, brushing the skin, warmth 40 TC). Hence, the potentiation of the CI potential generated during electrical stimulation is probably mainly due to activity in nociceptive afferent fibres. J. SCHO UENBORG 5. A significant increase in the latency of the CI potential (5-10 ms) was observed following noxious radiant heat applied to the skin in four out of five rats. This effect is probably due to a decrease in the conduction velocity of the activated primary non-myelinated afferent fibres generating the CI potential. Hence, it is argued that the CI potential is generated mainly by nociceptive C afferent fibres.6. Isopotential maps of the C-fibre-evoked field potentials and of the Afl-fibreevoked field potentials were constructed in the transverse and in the sagittal planes.The maximal Afl-fibre-evoked field potentials and the C-fibre-evoked fi...

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Section: Discussionsupporting

confidence: 77%

Functional and topographical properties of field potentials evoked in rat dorsal horn by cutaneous C‐fibre stimulation.

Schouenborg¹

1984

The Journal of Physiology

112

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“…e.g. Rethelyi, 1977;Light & Perl, 1979;Maxwell & Rethelyi, 1987). The failure of attempts to reveal transganglionic degeneration of C-fibre afferents is puzzling in the light of repeated demonstrations, following peripheral nerve lesions, of the degeneration and permanent loss of small ganglion cells (see e.g.…”

mentioning

confidence: 99%

Pathobiological reactions of C‐fibre primary sensory neurones to peripheral nerve injury

Jancsó

1992

Experimental Physiology

101

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Mammalian primary sensory neurones display profound anatomical and chemical changes in response to injury of their peripheral processes. Peripheral nerve damage results in transganglionic degeneration of central terminals of A‐fibre primary afferent neurones terminating in the deeper layers of the medullary or spinal dorsal horn. The depletion of neuropeptides and other neurone‐specific macromolecules from neurones in sensory ganglia and from the superficial dorsal horn, the known central projection area of C‐fibre primary afferents, is a salient phenomenon commencing after peripheral nerve lesions. A recently devised new experimental procedure, termed the capsaicin‐gap method, permitted evaluation of the transganglionic degenerative phenomena which develop in C‐fibre primary sensory neurones after a lesion is inflicted upon their peripheral branches. The experimental findings indicated that C‐fibre primary afferent terminals underwent transganglionic degeneration following a perineural treatment with capsaicin, and that this was associated with, and probably resulted from, ganglionic cell degeneration. Studies on the effects of peripheral nerve section yielded similar results. It has therefore been suggested that the observed depletion of specific macromolecules, including sensory peptides, specific glycoconjugates and sensory neurone specific acid phosphatase, may be accounted for, at least in part, by an irreversible loss of sensory ganglion neurones. In contrast, many injured neurones express peptides, including vasoactive intestinal polypeptide, peptide histidine‐isoleucine and galanin, which can be demonstrated in only a few neurones under normal conditions. These seem to be involved in dorsal horn regenerative and/or compensatory processes following peripheral nerve damage. There is suggestive evidence that the partial deafferentation caused by the transganglionic degeneration of C‐fibre primary afferents creates favourable circumstances for an anatomical rearrangement of neuronal connections within the spinal cord dorsal horn. These changes may provide a morphological substrate of some of the functional alterations demonstrated after peripheral nerve lesions.

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“…Our previous study (Maxwell et al 1983b) was devoted entirely to the marginal zone (lamina I). In this study we have concentrated on the substantia gelatinosa (lamina II) which contains small nociceptive interneurones (Light, Trevino & Perl, 1979) and receives input from non-myelinated primary afferents (C fibres, Rethelyi, 1977). Such afferents are believed to convey nociceptive information (see Perl, 1980).…”

Section: Introductionmentioning

confidence: 99%

Synaptic Arrangements Formed by Serotonin‐immunoreactive Axons in the Substantia Gelatinosa of the Rat Spinal Cord

1985

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SUMMARYUltrastructural properties of serotonin-immunoreactive axons in the rat's substantia gelatinosa were examined in order to determine the synaptic arrangements that they form in the neuropil. Some immunoreactive varicosities formed synaptic associations with somata or dendrites suggesting that serotoninergic systems are capable of influencing the activity of these structures post-synaptically. No examples of axo-axonic synapses were found. Most varicosities, however, did not form identifiable synaptic junctions, but were closely associated with somata, dendrites or axons. Some of these associations may be functional but morphological evidence for this is lacking.

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Preterminal and terminal axon arborizations in the substantia gelatinosa of cat's spinal cord

Cited by 143 publications

References 26 publications

Functional and topographical properties of field potentials evoked in rat dorsal horn by cutaneous C‐fibre stimulation.

Functional and topographical properties of field potentials evoked in rat dorsal horn by cutaneous C‐fibre stimulation.

Pathobiological reactions of C‐fibre primary sensory neurones to peripheral nerve injury

Synaptic Arrangements Formed by Serotonin‐immunoreactive Axons in the Substantia Gelatinosa of the Rat Spinal Cord

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