ISSN:
1432-2072
Keywords:
DA receptor subtypes
;
Apomorphine
;
Motility
;
Neuroleptics
;
Rat
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract A critical dose of apomorphine (300 μg/kg SC) given immediately before placing rats into a novel environment produced a diphasic motility response (initial sedation followed by enhanced locomotion). Various neuroleptics having different clinical and/or pharmacological profiles were studied by using such a model. (−)-Sulpiride and sultopride preferentially antagonized apomorphine inhibition; haloperidol and tiapride antagonized both phases of apomorphine response at similar doses; chlorpromazine, fluphenazine, thioridazine, metoclopramide and SCH 23390 preferentially antagonized apomorphine stimulation. The results are discussed in terms of the dopamine receptor subtypes involved in the two phases of apomorphine effect. Apomorphine stimulation can be antagonized by D-1 as well as D-2 receptor blockade. A higher affinity for D-2 receptors seems a necessary requisite for the antagonism of apomorphine inhibition; moreover, the ability of neuroleptics to antagonize apomorphine inhibition seems to depend on the ratio of their presynaptic versus postsynaptic D-2 activity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00174356
