Author(s):
Almeida, Armando 
; Cobos, Angeles ; Tavares, Isaura ; Lima, Deolinda
Date: 2002
Persistent ID: http://hdl.handle.net/1822/1655
Origin: RepositóriUM - Universidade do Minho
Subject(s): Amygdala; Antinociceptive system; Extrapyramidal system; Hypothalamus; Pain modulation; Prefrontal cortex; Sensorimotor cortex; Pronociceptive system
Description
The medullary dorsal reticular nucleus (DRt) was recently shown to belong to the supraspinal pain control system; neurons within
this nucleus give origin to a descending projection that increases spinal nociceptive transmission and facilitates pain perception
[Almeida et al. (1999), Eur. J. Neurosci., 11, 110-122]. In the present study, the areas of the brain that may modulate the activity
of DRt neurons were investigated by using of tract-tracing techniques. Injection of a retrograde tracer into the DRt resulted in
labelling in multiple areas of the brain. In the contralateral orbital, prelimbic, infralimbic, insular, motor and somatosensory
cortices labelling was prominent, but a smaller ipsilateral projection from these same areas was also detected. Strong labelling
was also noted in the central amygdaloid nucleus, bed nucleus of stria terminalis and substantia innominata. Labelled
diencephalic areas were mainly confined to the hypothalamus, namely its lateral and posterior areas as well as the
paraventricular nucleus. In the mesencephalon, the periaqueductal grey, red nucleus and deep mesencephalic nucleus were
strongly labelled, whereas, in the brainstem, the parabrachial nuclei, rostroventromedial medulla, nucleus tractus solitarius, spinal
trigeminal nucleus, and the parvocellular, dorsal, lateral and ventral reticular nuclei were the most densely labelled regions. All
deep cerebellar nuclei were labelled bilaterally. These data suggest that the DRt integrates information from the somatosensory,
antinociceptive, autonomic, limbic, pyramidal and extrapyramidal systems while triggering its descending facilitating action upon
the spinal nociceptive transmission.
