ABSTRACT
The mechanisms of the analgesic action of carbamazepine and oxcarbazepine, in particular the role of opioid receptors, have not been established precisely. The systemic effects of naloxone, an opioid receptor antagonist, on the antihyperalgesic effects of carbamazepine and oxcarbazepine were examined in the model of inflammatory hyperalgesia induced by the intraplantar (i.pl.) administration of concanavaline A (Con A, 0.8 mg/paw) into the rat hind paw. Naloxone (3 mg/kg; i.p.) did not alter the antihyperalgesic effects of either carbamazepine or oxcarbazepine. These results indicate that the opioid system of pain modulation does not play a significant role in the antihyperalgesic effects of carbamazepine and oxcarbazepine.
Subject(s)
Analgesics, Non-Narcotic/pharmacology , Carbamazepine/analogs & derivatives , Carbamazepine/pharmacology , Hyperalgesia/drug therapy , Animals , Anticonvulsants/pharmacology , Concanavalin A , Hyperalgesia/chemically induced , Male , Naloxone/pharmacology , Narcotic Antagonists/pharmacology , Oxcarbazepine , Pain/drug therapy , Rats , Rats, WistarABSTRACT
In this study we determined whether oxcarbazepine (OXC) could produce local peripheral antinociceptive effects in a rat model of inflammatory hyperalgesia, and whether adenosine receptors were involved. When coadministered with the pro-inflammatory compound concanavalin A, OXC (1000-3000 nmol/paw) caused a significant dose- and time-dependent anti-hyperalgesia. Caffeine (1000-1500 nmol/paw), a nonselective adenosine receptor antagonist, as well as 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) (10-30 nmol/paw), a selective A1 receptor antagonist, coadministered with OXC, significantly depressed its anti-hyperalgesic effect. Drugs injected into the contralateral hind paw did not produce significant effects. These results indicate that OXC produces local peripheral anti-hyperalgesic effects, which is mediated via peripheral A1 receptors.
