Cholera toxin effects on body temperature changes induced by morphine.
Pharmacol Biochem Behav
; 56(3): 499-505, 1997 Mar.
Article
en En
| MEDLINE
| ID: mdl-9077589
ABSTRACT
The present study evaluates the influence of cholera toxin and its B-subunit on thermic responses to morphine in the rats. The holotoxin (1 microg/rat) and the B-subunit (5 microg) were administered ICV and three days later rats were challenged ICV with morphine and tested for changes of body temperature. Cholera toxin, but not its B-subunit, modified the time course of the hyperthermic response induced by a low dose of morphine (2.5 microg), converted the hypothermia due to a higher dose of morphine (18 microg) to a consistent hyperthermia and only partially reduced the greater hypothermia induced by 36 microg of morphine. Cholera toxin-induced modifications of thermic responses to morphine were paralleled with a decreased Gs(alpha) immunoreactivity and a reduced ability for the toxin to catalyse the "in vitro" ADP-ribosylation of Gs(alpha) in hypothalamic membranes. In contrast, at the same time when morphine-induced effects on body temperature were assessed, no changes in pertussis toxin-mediated ADP-ribosylation of Gi(alpha)/Go(alpha), or basal adenylate cyclase activity, or binding of mu-opioid receptor selective ligand [3H]-DAMGO were observed in hypothalamic areas from rats treated with cholera toxin. These findings suggest that adaptative events secondary to prolonged activation of Gs(alpha) play a role in the modifications of thermic responses to morphine induced by CTX.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Regulación de la Temperatura Corporal
/
Toxina del Cólera
/
Analgésicos Opioides
/
Morfina
Límite:
Animals
Idioma:
En
Revista:
Pharmacol Biochem Behav
Año:
1997
Tipo del documento:
Article
País de afiliación:
Italia