Effect of sumatriptan in different models of pain in rats.
The effect of sumatriptan in two standard algesimetric tests and in a model of cephalalgia was evaluated in rats. The pain threshold was measured by the hot-plate and the writhing tests; cephalalgia was produced by injecting bradykinin (10 microg in a volume of 10 microl) into a common carotid artery. Sumatriptan was subcutaneously (s.c.) injected at the doses of 4, 8, 24 or 42 mg/kg; morphine (5 or 10 mg/kg s.c.) and indomethacin (5 or 10 mg/kg s.c) were used as standard analgesic drugs. Sumatriptan had no analgesic activity either in the hot-plate test or in the writhing test. On the other hand, at 24 and 42 mg/kg it dose-dependently reduced the response to the intracarotid injection of bradykinin (vocalization and tachypnea), this effect being prevented by the 5-HT(1B) receptor antagonist, isamoltane. The 5-HT(1D) receptor antagonist BRL15572 prevented the effect of sumatriptan on bradykinin-induced tachypnea, but not the effect of sumatriptan on bradykinin-induced vocalization. These data demonstrate that sumatriptan is significantly effective in a reliable animal model of cephalalgia, while having no systemic analgesic activity.
Department of Biomedical Sciences, University of Modena and Reggio Emilia, Section of Pharmacology, Via G. Campi 287, 41100 Modena, Italy. alessandraottani@yahoo.it
Alessandra
A
Ottani
Eleonora
E
Ferraris
Daniela
D
Giuliani
Chiara
C
Mioni
Alfio
A
Bertolini
Emilio
E
Sternieri
Anna
A
Ferrari
D000818:Animals; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D008297:Male; D010147:Pain Measurement / Q000187:drug effects* / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D018170:Sumatriptan / Q000494:pharmacology*
D018170:Sumatriptan