MK-801 (dizocilpine): synergist and conditioned stimulus in bromocriptine-induced psychomotor sensitization.
Synapse
; 22(4): 362-8, 1996 Apr.
Article
en En
| MEDLINE
| ID: mdl-8867030
ABSTRACT
Intraperitoneal injections of the D2/D3 dopamine agonist bromocriptine (5.0 mg/kg, IP) induced locomotion that became progressively stronger on successive days of testing. The sensitized response developed twice as rapidly when the non-competitive NMDA antagonist MK-801 (0.25 mg/kg, IP) was given 30 min after bromocriptine (so that the peak effects of the two drugs overlapped). In a second group of animals, MK-801 was given 30 min prior to bromocriptine (the pretreatment regimen typical of studies where MK-801 is reported to block cocaine, amphetamine or morphine sensitization) and locomotion was monitored during the pretreatment period; in this case sensitization to the locomotor-stimulating effects of MK-801 alone (in the pretreatment period) as well as sensitization to the locomotor-stimulating effects of the drug combination (following the second injection) were observed. No sensitization to the effects of MK-801 alone (pretreatment) were seen in animals that received saline rather than bromocriptine as their second injection in this experiment. Thus MK-801 does not block but rather enhances bromocriptine sensitization; it appears to do so by a synergism with the locomotor effects of bromocriptine and by becoming a conditioned stimulus for the sensitized response. These findings confirm the earlier report that NMDA receptor activation is not critical to bromocriptine-induced sensitization, and they illustrate the importance of controls for conditioning and state-dependency phenomena in studies of drug interactions in psychomotor sensitization.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Bromocriptina
/
Maleato de Dizocilpina
/
Condicionamiento Psicológico
/
Locomoción
Límite:
Animals
Idioma:
En
Revista:
Synapse
Asunto de la revista:
NEUROLOGIA
Año:
1996
Tipo del documento:
Article
País de afiliación:
Canadá