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

• Tipo: Artigo em Revista Científica Internacional
• Data: 1993

Autores

ALMEIDA, A (Autor) Outra; Isaura Tavares (Autor) FMUP; Deolinda Lima (Autor) FMUP; COIMBRA, A (Autor) Outra

Revista

Título: Neuroscience

Vol. 55

Páginas: 1093-1106

ISSN: 0306-4522

Editora: Elsevier

Indexação

ISI Web of Knowledge - 53 Citações

Scopus - 54 Citações

Outras Informações

ID Authenticus: 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.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 14