title: Dopamine modulation of membrane excitability in striatal spiny neurons is altered in DARPP-32 knockout mice.
abstract: The phosphoprotein DARPP-32 (dopamine and cAMP-regulated phosphoprotein 32 kDa) plays a central role in mediating the actions of a variety of neurotransmitters in medium spiny neurons of the striatum (Greengard, 1990; Fienberg et al., 1998). This study examines D1 and D2 dopamine (DA) agonist effects on the membrane properties of identified striatal neurons recorded in slices obtained from wild-type and DARPP-32-knockout mice. In wild-type spiny cells, DA D1 receptor activation decreased cell excitability, causing a 58.8 +/- 13.5% increase in rheobase current required to evoke spike discharge. In contrast, D1 agonist administration did not alter cell excitability when applied to spiny cells in slices prepared from the DARPP-32 knockout mice. D2 agonist administration decreased cell excitability in both wild-type and knockout mice. The response produced by combined D1 and D2 agonist stimulation was dependent on the sequence of agonist administration. Thus, the D1 agonist-induced decrease in excitability was reversed to a facilitation of spiking upon subsequent D2 agonist administration. In contrast, D2 agonist applied simultaneously with the D1 agonist only produced a reduction in excitability. This type of D1-dependent modulation was not present in slices from the DARPP-32 knockout mice.
authors.affiliation: Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA. shao-pii.onn@drexel.edu
authors.forename: Shao-Pii
authors.initials: SP
authors.lastname: Onn
authors.forename: Allen A
authors.initials: AA
authors.lastname: Fienberg
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Grace
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D003342:Corpus Striatum / Q000166:cytology; D004298:Dopamine / Q000378:metabolism*; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D010750:Phosphoproteins / Q000172:deficiency* / Q000235:genetics; D017447:Receptors, Dopamine D1 / Q000819:agonists; D017448:Receptors, Dopamine D2 / Q000819:agonists
chemical_list: D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D004298:Dopamine