Autor(es):
Cobos, Angeles 
; Lima, Deolinda ; Almeida, Armando ; Tavares, Isaura
Data: 2003
Identificador Persistente: http://hdl.handle.net/1822/1663
Origem: RepositóriUM - Universidade do Minho
Assunto(s): Pain modulation; Motor control; Cardiovascular regulation; Cholera toxin subunit B; Biotinylated dextran amine
Descrição
The ventrolateral medulla (VLM) modulates autonomic
functions, motor reactions and pain responses. The
lateralmost part of the caudal VLM (VLMlat) was recently
shown to be the VLM area responsible for pain modulation. In
the present study, the brain sources of VLMlat afferent fibers
were determined by tract-tracing techniques. Following injection
of cholera toxin subunit B into the VLMlat, retrogradely
labeled neurons in the forebrain occurred at the somatosensory,
insular, motor, limbic and infralimbic cortices, and at
the central amygdaloid nucleus. Retrogradely labeled neurons
in diencephalic regions were observed in the lateral
hypothalamus, posterior hypothalamus and paraventricular
nucleus. In the brainstem, retrograde labeling occurred at the
periaqueductal gray, red nucleus, parabrachial area, nucleus
raphe magnus, nucleus tractus solitarii, lateral reticular nucleus
and dorsal and ventral medullary reticular formation. In
the cerebellum, retrogradely labeled neurons occurred at the
lateral nucleus. Following injections of the anterograde tracer
biotinylated dextran amine (BDA) into the lateral hypothalamus
or paraventricular nucleus, anterogradely labeled fibers
were mainly observed in the VLMlat. Injections of BDA into
the periaqueductal gray, red nucleus or lateral nucleus of the
cerebellum resulted in anterograde labeling in the VLMlat and
lateral reticular nucleus.
The present study gives an account of the brain regions
putatively involved in triggering the modulatory actions elicited
from the VLMlat. These include areas committed to somatosensory
processing, autonomic control, somatic and
visceral motor activity and affective reactions. The findings
suggest that the VLMlat may play a major homeostatic role in
the integration of nociception with other brain functions.
