Dihydroetorphine-induced place preference was mediated by dopamine D1 receptors in rats.
Abstract
AIM:
To study the influence of dopamine (DA) receptor antagonists upon the rewarding property of dihydroetorphine (DHE).
METHODS:
Conditioned place preference (CPP) paradigm was used to characterize the rewarding effect of DHE. DA receptor antagonists were injected administered subcutaneously or peritoneally and microinjected into nucleus accumbens (NAcc).
RESULTS:
DHE (0.05, 0.5, and 5.0 micrograms.kg-1, s.c.) produced place preference (P < 0.01). Both the DA receptor antagonist haloperidol and the selective D1 receptor antagonist Sch-23390 attenuated the place preference produced by DHE (0.5 microgram.kg-1, s.c.). l-Sulpiride and spiperone, selective D2 receptor antagonists, had no such effects.
CONCLUSION:
The D1 (but not D2) receptors in NAcc are crucial in the mediation of the rewarding effect of DHE.
Keywords:
To study the influence of dopamine (DA) receptor antagonists upon the rewarding property of dihydroetorphine (DHE).
METHODS:
Conditioned place preference (CPP) paradigm was used to characterize the rewarding effect of DHE. DA receptor antagonists were injected administered subcutaneously or peritoneally and microinjected into nucleus accumbens (NAcc).
RESULTS:
DHE (0.05, 0.5, and 5.0 micrograms.kg-1, s.c.) produced place preference (P < 0.01). Both the DA receptor antagonist haloperidol and the selective D1 receptor antagonist Sch-23390 attenuated the place preference produced by DHE (0.5 microgram.kg-1, s.c.). l-Sulpiride and spiperone, selective D2 receptor antagonists, had no such effects.
CONCLUSION:
The D1 (but not D2) receptors in NAcc are crucial in the mediation of the rewarding effect of DHE.