DESCENDING PROJECTIONS FROM THE MEDULLARY DORSAL RETICULAR NUCLEUS MAKE SYNAPTIC CONTACTS WITH SPINAL-CORD LAMINA-I CELLS PROJECTING TO THAT NUCLEUS - AN ELECTRON-MICROSCOPIC TRACER STUDY IN THE RAT

• Type: Article in International Scientific Journal
• Date: 1993

Authors

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

Journal

Title: Neuroscience

Vol. 55

Pages: 1093-1106

ISSN: 0306-4522

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 53 Citations

Scopus - 54 Citations

Other information

Authenticus ID: P-001-MV0

DOI: 10.1016/0306-4522(93)90323-8

Abstract (EN): An ultrastructural study is made of the synaptic contacts occurring between structures labelled anterogradely and retrogradely in the superficial dorsal horn following injections of cholera toxin subunit B or horseradish peroxidase in the dorsal reticular nucleus of the medulla oblongata of the rat. Both tracers revealed labelled axonal boutons in lamina I with round synaptic vesicles and a few large granular vesicles making asymmetrical synaptic contacts upon labelled somata and dendrites. After injections of Phaseolus vulgaris leucoagglutinin in the dorsal reticular nucleus, labelled boutons identical to those revealed by the two other tracers were presynaptic to unlabelled somata and dendrites. In addition, dorsoreticular neurons were labelled retrogradely following injections of cholera toxin subunit B into the superficial dorsal horn of the cervical enlargement. These observations show the occurrence of a reciprocal connection between dorsal reticular and lamina I neurons. Considering the putative excitatory nature of the axodendritic contacts in lamina I, a positive feedback circuit is suggested, whereby the nociceptive signals transmitted to the dorsal medullary reticular formation by marginal neurons are intensified.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 14