ISSN:
1420-9071
Keywords:
Catalepsy
;
Madopar
;
tolcapone
;
3-O-methyldopa
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract Orally administered Madopar (levodopa/benserazide 4∶1) dose-dependently antagonized haloperidol-induced (1 mg/kg s.c.) catalepsy in MPP+-lesioned mice. Pretreatment with a new selective catechol-O-methyltransferase (COMT) inhibitor, tolcapone (30 mg/kg p.o.), slightly potentiated the antagonistic effect of Madopar (15 mg/kg p.o.) on haloperidol-induced catalepsy. The ability of tolcapone to increase the Madopar effect was significantly attenuated by high doses of 3-O-methyldopa (3-OMD) (800 mg/kg i.p.). This might suggest a competitive blockade of the active transport of levodopa through the blood-brain barrier. In conclusion, the inhibitory effect of tolcapone on the O-methylation of levodopa to 3-OMD by COMT is largely due to improved levodopa and dopamine availability in the brain, and to the reduced formation of 3-OMD.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01923483
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