Cholinergic modulation of tonic immobility and nociception in the NRM of guinea pig.
Physiol Behav
; 87(4): 821-7, 2006 Apr 15.
Article
em En
| MEDLINE
| ID: mdl-16545845
Tonic immobility (TI) is an inborn defensive behavior characterized by a temporary state of profound and reversible motor inhibition elicited by some forms of physical restraint. It is known that endogenous antinociceptive systems are activated during the emission of defensive behaviors including TI. The nucleus raphe magnus (NRM) is related to the modulation of nociceptive and behavioral responses. In the present study, we investigated the role of the cholinergic system of the NRM in the modulation of TI and nociception in guinea pigs. Microinjection of the cholinergic agonist carbachol (0.5 microg/0.2 microl) into the NRM promoted a reduction in the duration of TI episodes and nociception, the latter measured by the vocalization test in guinea pigs. The effect of microinjection of carbachol on TI reduction and antinociception was blocked by the previous microinjection of the cholinergic antagonist atropine (0.5 microg/0.2 microl and 1 microg/0.2 microl, respectively), demonstrating the participation of muscarinic receptors in the modulation of these responses. Microinjection of atropine per se did not interfere with the duration of TI episodes. In summary, the present results demonstrate that cholinergic stimulation of the NRM promoted analgesia and a reduction in the duration of TI in guinea pigs. These data indicate that the NRM possibly contributes to the modulation of defensive and nociceptive behavioral responses, probably by modulating the activity of neurons in the ventral and dorsal horn of the spinal cord, respectively.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Núcleos da Rafe
/
Fibras Colinérgicas
/
Limiar da Dor
/
Resposta de Imobilidade Tônica
Limite:
Animals
Idioma:
En
Revista:
Physiol Behav
Ano de publicação:
2006
Tipo de documento:
Article
País de afiliação:
Brasil
País de publicação:
Estados Unidos