Reciprocal connections between the medullary dorsal reticular nucleus and the spinal dorsal horn in the rat

• Type: Article in International Scientific Journal
• Date: 2000

Authors

Almeida, A (Author) Other; Isaura Tavares (Author) FMUP; Deolinda Lima (Author) FMUP

Journal

Title: European Journal of Pain

Vol. 4

Pages: 373-387

ISSN: 1090-3801

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 24 Citations

Scopus - 26 Citations

Other information

Authenticus ID: P-001-1FK

DOI: 10.1053/eujp.2000.0193

Abstract (EN): The synaptic architecture of spinal afferents of the dorsal portion (DRtd) of the medullary dorsal reticular nucleus (DRt) is studied. After iontophoretic injections of cholera toxin subunit B (CTb) into the superficial (laminae I-II), deep (laminae IV-V) or entire (laminae IV) dorso-ventral extent of the spinal dorsal horn at the cervico-thoracic or lumbo-sacral levels, axonal boutons of two distinct types were labelled in the DRtd. Type A boutons (82% after cervico-thoracic injections and 92% after lumbo-sacral injections) were roundish. small and presented few mitochondria and small, round synaptic vesicles. Type B boutons (18% after cervicothoracic injections and 8% after lumbo-sacral injections) were elongated, two to three times larger, and exhibited numerous mitochondria and larger round vesicles. Both types of bouton established asymmetrical synaptic contacts with small dendritic profiles and. less frequently, with dendritic trunks and perikarya. Retrograde labelling occurred in the postsynaptic profile of 15-18'%, type A boutons labelled from any injection site. Taken together with previous data on DRt-spinal synaptic contacts at the superficial dorsal horn, the present results point to the occurrence of a reciprocal excitatory loop connecting the dorsal DRt and lamina I, which may be at the basis of the DRt-mediated pain-facilitating effects described recently. (C) 2000 European Federation of Chapters of the International Association for the Study of Pain.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 15