Posted by JohnX2 on March 25, 2002, at 1:55:10
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9083792&dopt=Abstract
: Eur J Pharmacol 1997 Feb 19;321(1):105-11 Related Articles, Books, LinkOut
Aripiprazole, a novel antipsychotic drug, inhibits quinpirole-evoked GTPase activity but does not up-regulate dopamine D2 receptor following repeated treatment in the rat striatum.Inoue A, Miki S, Seto M, Kikuchi T, Morita S, Ueda H, Misu Y, Nakata Y.
Department of Pharmacology, Hiroshima University School of Medicine, Japan.
Aripiprazole, a quinolinone derivative, is a new dopaminergic agent which has been recently developed and demonstrated to be clinically useful as an antipsychotic drug with reduced extrapyramidal motor side effects. Here, we found that aripiprazole competed [3H]spiperone binding with a 100-fold higher affinity than [3H]SCH23390 binding, and inhibited the quinpirole-induced facilitation of high-affinity GTPase activity in rat striatal membranes. The effects of chronic administration of aripiprazole and haloperidol on dopamine D2 receptor binding and mRNA level in rat striata were examined by a [3H]spiperone binding assay and a ribonuclease protection assay. Haloperidol induced a significant rise in Bmax of [3H]spiperone binding at 1 mg/kg and in the level of dopamine D2L receptor mRNA at 4 mg/kg. A high dose of aripiprazole (100 mg/kg) only tended to increase the Bmax of [3H]spiperone binding non-significantly, and had no effect on the level of dopamine D2L receptor mRNA. These results indicated that aripiprazole had an antagonistic activity to dopamine D2 receptors with a high affinity, but that the potency of aripiprazole to up-regulate dopamine D2 receptors in the striatum was much smaller than that of haloperidol. This small up-regulation may be related to the ability to aripiprazole to act without side effects including tardive dyskinesia.
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