Characterization of a putatively vesicular binding site for [3H]MPP+ in mouse striatal membranes.
[3H] N-Methyl-4-phenylpyridinium ion (MPP+) binds with a fully reversible, high affinity process to a population of sites mainly localized in the mouse striatum (Bmax = 168 +/- 15 fmol/mg protein, KD = 1.4 +/- 0.4 nM). The majority of specifically-bound radioactivity was localized in the synaptosomal fraction. Unilateral, striatal denervation with 6-hydroxydopamine (6-OHDA) markedly (by 65-70%) decreased the number of [3H]MPP+ sites. Besides dopamine, the vesicular markers tyramine, tetrabenazine and reserpine inhibited [3H]MPP+, while mazindol was a poor displacer. Adenosine triphosphate (ATP) and Mg(2+)-ions did not affect [3H]MPP+ binding. It is concluded that these sites may represent a marker of striatal storage vesicles for dopamine.
Del Zompo
M
M
Department of Neuroscience, University of Cagliari, Italy.
Piccardi
M P
MP
Ruiu
S
S
Corsini
G U
GU
Vaccari
A
A
D015655:1-Methyl-4-phenylpyridinium / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051379:Mice; D009928:Organ Specificity; D013347:Subcellular Fractions / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism*; D014316:Tritium
D014316:Tritium; D015655:1-Methyl-4-phenylpyridinium