Anterior pretectal nucleus facilitation of superficial dorsal horn neurones and modulation of deafferentation pain in the rat.
AUTOR(ES)
Rees, H
RESUMO
1. Functional relationships between the anterior pretectal nucleus (APTN) and nociceptive dorsal horn neurones were investigated electrophysiologically in the anaesthetized rat. The effects of APTN lesions were assessed behaviourally in a model of deafferentation pain. 2. Cells in the dorsal and rostral parts of the APTN were excited orthodromically by electrical stimulation of the ipsilateral dorsolateral funiculus or the contralateral dorsal columns, and by noxious and innocuous cutaneous stimuli. 3. Electrical stimulation of the APTN excited nociceptive lamina I spinal neurones. These cells all projected rostrally in the contralateral dorsolateral funiculus. Identical APTN stimulation also inhibited multireceptive spinal neurones which lay deep in the dorsal horn. These particular cells were shown to project to the brain in the ventrolateral funiculus. 4. It is proposed that noxious stimuli excite spinal lamina I projection neurones which send excitatory axons to the brain, including the APTN. The APTN inhibits deep multireceptive neurones, to reduce the perception of noxious stimuli. The discharge of spinal lamina I neurones, however, will be sustained by the noxious stimulus and by facilitation from the APTN. A sustained descending inhibition of this nature would reduce responses to prolonged injury. 5. The involvement of the APTN in responses to a chronic pain state was examined by comparing the behaviour of animals with bilateral lesions of the APTN with normal controls. Lesions of the APTN strongly enhanced the autotomy behaviour triggered by sectioning of the dorsal roots. 6. These observations support the suggestion that the APTN reduces the debilitating effects of prolonged injury.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1156800Documentos Relacionados
- Anterior pretectal stimulation alters the responses of spinal dorsal horn neurones to cutaneous stimulation in the rat.
- Activation of cells in the anterior pretectal nucleus by dorsal column stimulation in the rat.
- Long-lasting synaptic facilitation induced by serotonin in superficial dorsal horn neurones of the rat spinal cord.
- Antinociceptive effects of dorsal column stimulation in the rat: involvement of the anterior pretectal nucleus.
- Primary afferents with TRPM8 and TRPA1 profiles target distinct subpopulations of rat superficial dorsal horn neurones