Volltext verfügbar nach Anmeldung bzw. im Campus-Netz.
Segmental disinhibition suppresses C-fiber inputs to the rat superficial medullary dorsal horn via the activation of GABA<subscript>B</subscript> receptors.
In: European Journal of Neuroscience, Jg. 37 (2013-02-01), Heft 3, S. 417-428
Online
academicJournal
Zugriff:
Specialized primary afferents, although they terminate in different laminae within the dorsal horn ( DH), are known to interact through local circuit excitatory and inhibitory neurons. That a loss of segmental inhibition probably contributes to persistent pain hypersensitivity during chronic pain raises the question as to how disinhibition-induced changes in cross-modal interactions account for chronic pain symptoms. We sought to characterize how pharmacological blockade of glycine and gamma-aminobutyric acid ( GABA) receptors modifies synaptic transmission between primary afferent fibers and second-order neurons by recording field potentials in the superficial medullary dorsal horn ( MDH) of anesthetized rats. Transcutaneous electrical stimulation evokes three negative field potentials elicited by, from earliest to latest, Aβ-, Aδ- and C-fiber primary afferents. Blocking segmental glycine and/or GABAA receptors, with strychnine and bicuculline, respectively, strongly facilitates Aβ- and Aδ-fiber-evoked polysynaptic field potentials but, conversely, inhibits, or even abolishes, the whole C-fiber field potential. Blocking segmental GABAB receptors, with phaclofen, reverses such suppression of C-fiber field potentials. Interestingly, it also potentiates C-fiber field potentials under control conditions. Finally, activation of segmental GABAB receptors, with baclofen, preferentially inhibits C-fiber field potentials. Our results suggest that activation of A-fiber primary afferents inhibits C-fiber inputs to the MDH by the way of polysynaptic excitatory pathways, last-order GABAergic interneurons and presynaptic GABAB receptors on C-fiber primary afferents. Under physiological conditions, activation of such local DH circuits is closely controlled by segmental inhibition but it might contribute to paradoxically reduced pain hypersensitivity under pathological disinhibition. [ABSTRACT FROM AUTHOR]
Titel: |
Segmental disinhibition suppresses C-fiber inputs to the rat superficial medullary dorsal horn via the activation of GABA<subscript>B</subscript> receptors.
|
---|---|
Autor/in / Beteiligte Person: | Melin, Céline ; Jacquot, Florian ; Dallel, Radhouane ; Artola, Alain |
Link: | |
Zeitschrift: | European Journal of Neuroscience, Jg. 37 (2013-02-01), Heft 3, S. 417-428 |
Veröffentlichung: | 2013 |
Medientyp: | academicJournal |
ISSN: | 0953-816X (print) |
DOI: | 10.1111/ejn.12048 |
Schlagwort: |
|
Sonstiges: |
|