The ventrolateral medulla of the rat is connected with the spinal cord dorsal horn by an indirect descending pathway relayed in the A(5) noradrenergic cell group

• Type: Article in International Scientific Journal
• Date: 1996

Authors

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

Journal

Title: Journal of Comparative Neurology

Vol. 374

Pages: 84-95

ISSN: 0021-9967

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 33 Citations

Scopus - 39 Citations

Other information

Authenticus ID: P-001-DHK

DOI: 10.1002/(sici)1096-9861(19961007)374:1<84::aid-cne6>3.0.co;2-j

Abstract (EN): The pathway conveying the descending inhibitory noradrenergic input elicited from the caudal ventrolateral medulla (VLM) onto the spinal cord dorsal horn was studied in the rat. Retrograde labeling with cholera toxin subunit B (CTb) injected into the dorsal horn was combined with immunostaining for dopamine-beta-hydroxylase (DBH) in the VLM and other brainstem nuclei containing noradrenergic cells. CTb-labeled neurons occurred in the lateral part of the VLM (VLMlat), located ventrolaterally to the DBH-immunoreactive cells of the A(1) noradrenergic cell group. Neuronal profiles stained for CTb and DBH (double labeled) occurred in the A(5) (31%), A(6) (57%), and A(7) (12%) noradrenergic cell groups. To ascertain whether noradrenergic cells targeting the spinal cord in those groups received projections from the VLMlat, this area was injected with the anterograde tracer biotinylated dextran amine (BDA). Labeled terminal fibers with boutons en passant were apposed to numerous double-stained neurons in the A(5) cell group. Similar appositions occurred in small amounts in the ventral subcoerulear component of the A(6). Correlated light and electron microscopic analyses of the labeled appositions revealed that the BDA-labeled axonal boutons contained spherical vesicles and were presynaptic at asymmetrical contacts to somata and dendritic profiles of the double-stained A(5) neurons. These data indicate the occurrence of an indirect dysynaptic pathway connecting the VLM to the spinal cord, with a relay In the A(5) cells. This pathway may convey the antinociceptive effects mediated by alpha(2)-adrenoreceptors, which have been previously observed in the spinal cord following VLM stimulation. (C) 1996 Wiley-Liss, Inc.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12