Spinal processing of noxious and innocuous cold information: differential modulation by the periaqueductal gray.
J Neurosci
; 30(14): 4933-42, 2010 Apr 07.
Article
em En
| MEDLINE
| ID: mdl-20371814
ABSTRACT
In addition to cold being an important behavioral drive, altered cold sensation frequently accompanies pathological pain states. However, in contrast to peripheral mechanisms, central processing of cold sensory input has received relatively little attention. The present study characterized spinal responses to noxious and innocuous intensities of cold stimulation in vivo and established the extent to which they are modulated by descending control originating from the periaqueductal gray (PAG), a major determinant of acute and chronic pain. In lightly anesthetized rats, hindpaw cooling with ethyl chloride, but not acetone, was sufficiently noxious to evoke withdrawal reflexes, which were powerfully inhibited by ventrolateral (VL)-PAG stimulation. In a second series of experiments, subsets of spinal dorsal horn neurons were found to respond to innocuous and/or noxious cold. Descending control from the VL-PAG distinguished between activity in nociceptive versus non-nociceptive spinal circuits in that innocuous cold information transmitted by non-nociceptive class 1 and wide-dynamic-range class 2 neurons remained unaltered. In contrast, noxious cold information transmitted by class 2 neurons and all cold-evoked activity in nociceptive-specific class 3 neurons was significantly depressed. We therefore demonstrate that spinal responses to cold can be powerfully modulated by descending control systems originating in the PAG, and that this control selectively modulates transmission of noxious versus innocuous information. This has important implications for central processing of cold somatosensation and, given that chronic pain states are dependent on dynamic alterations in descending control, will help elucidate mechanisms underlying aberrant cold sensations that accompany pathological pain states.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Medula Espinal
/
Medição da Dor
/
Substância Cinzenta Periaquedutal
/
Temperatura Baixa
Limite:
Animals
Idioma:
En
Revista:
J Neurosci
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Reino Unido