title: Acute reserpine treatment induces down regulation of D-1 dopamine receptor associated adenylyl cyclase activity in rat striatum.
abstract: Behavioural studies suggest a functional interaction between D-1 and D-2 systems in normal rat striatum to alter motor behaviour and which is disrupted by dopamine depletion induced by acute reserpine treatment. Consequently, we have investigated the effect of acute reserpine treatment on the biochemical interaction between D-1 and D-2 receptors present in rat striatal slices. Twenty-four hours following the administration of reserpine (5 mg/kg i.p.), striatal dopamine content was depleted by more than 73%; the density (B(max)) of D-1 receptor sites measured by the in vitro binding of [3H]SCH 23390 to striatal membranes was increased while the binding of [3H]spiperone to D-2 receptor sites was unaltered. Reserpine treatment had no effect on the affinity (Kd) of [3H]SCH 23390 or [3H]spiperone for D-1 and D-2 sites. Basal levels of cyclic AMP accumulation in striatal slices prepared from reserpine-treated rats were lower than those observed in control slices. In striatal slices prepared from normal rats, dopamine (10-320 microM) and the D-1 agonist SKF 38393 (0.1-3.2 microM) induced concentration-dependent increases in cyclic AMP accumulation. The D-1 antagonist SCH 23390 (10 microM) abolished the accumulation of cyclic AMP produced by dopamine or SKF 38393. The D-2 antagonist (+/-)-sulpiride (50 microM) enhanced the response to dopamine (10-320 microM) while the D-2 agonist quinpirole (10 microM) abolished the response to SKF 38393 (0.1-3.2 microM). However, 24 hr after reserpine treatment the ability of dopamine (10-320 microM) and SKF 38393 (0.1-3.2 microM) to elicit an increase in cyclic AMP accumulation was markedly reduced in striatal slices. SCH 23390 (10 microM) did not enhance the trend for an increase in cyclic AMP accumulation produced by dopamine. Also, quinpirole (10 microM) did not affect the response to SKF 38393 (0.1-3.2 microM) in striatal slices from reserpine pretreated rats. The data confirm the positive linkage between D-1 receptors and adenylyl cyclase and the inhibitory coupling to D-2 sites in striatal slices from normal, rats. Acute reserpine treatment appears to cause an uncoupling of D-1 receptors associated with adenylyl cyclase.
authors.affiliation: Parkinson's Disease Society Experimental Research Laboratories, King's College London, U.K.
authors.forename: K L
authors.initials: KL
authors.lastname: Thomas
authors.forename: S
authors.initials: S
authors.lastname: Rose
authors.forename: P
authors.initials: P
authors.lastname: Jenner
authors.forename: C D
authors.initials: CD
authors.lastname: Marsden
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001552:Benzazepines / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D000242:Cyclic AMP / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects* / Q000378:metabolism; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D012110:Reserpine / Q000494:pharmacology*; D013134:Spiperone / Q000378:metabolism
chemical_list: D001552:Benzazepines; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D013134:Spiperone; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D012110:Reserpine; D000242:Cyclic AMP; D000262:Adenylyl Cyclases