Differential effect of repeated treatment with L-dopa on dopamine-D1 or -D2 receptors.
Unilateral degeneration of the nigro-striatal dopaminergic pathway with 6-hydroxydopamine induced contralateral rotations to apomorphine injection, increased [3H]-spiroperidol binding and enhanced sensitivity of adenylate cyclase to dopamine stimulation in lesioned striata. Prolonged L-DOPA administration counteracted the increased density of [3H]-spiroperidol binding sites but further enhanced the hypersensitivity of adenylate cyclase to dopamine. Also apomorphine-induced contralateral rotations were potentiated. This effect was antagonized by SCH-23390. These results suggest that dopaminergic D1 and D2 receptors are differently affected by prolonged L-DOPA treatment.
Parenti
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M
Flauto
C
C
Parati
E
E
Vescovi
A
A
Groppetti
A
A
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology; D001058:Apomorphine / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology; D006892:Hydroxydopamines / Q000494:pharmacology; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D013134:Spiperone / Q000378:metabolism
D014150:Antipsychotic Agents; D001552:Benzazepines; D006892:Hydroxydopamines; D011954:Receptors, Dopamine; D007980:Levodopa; D013134:Spiperone; D016627:Oxidopamine; D000262:Adenylyl Cyclases; D001058:Apomorphine