Vesicular neurotransmitter transporters in Huntington's disease: initial observations and comparison with traditional synaptic markers.

Abstract	Markers of identified neuronal populations have previously suggested selective degeneration of projection neurons in Huntington's disease (HD) striatum. Interpretations are, however, limited by effects of compensatory regulation and atrophy. Studies of the vesicular monoamine transporter type-2 (VMAT2) and of the vesicular acetylcholine transporter (VAChT) in experimental animals indicate that they are robust markers of presynaptic integrity and are not subject to regulation. We measured dopamine and acetylcholine vesicular transporters to characterize the selectivity of degeneration in HD striatum. Brains were obtained at autopsy from four HD patients and five controls. Autoradiography was used to quantify radioligand binding to VMAT2, VAChT, the dopamine plasmalemmal transporter (DAT), benzodiazepine (BZ) binding sites, and D2-type dopamine receptors. The activity of choline acetyltransferase (ChAT) was determined as an additional marker of cholinergic neurons. Autoradiograms were analyzed by video-assisted densitometry and assessment of atrophy was made from regional structural areas in the coronal projection. Striatal VMAT2, DAT, and VAChT concentrations were unchanged or increased, while D2 and BZ binding and ChAT activity were decreased in HD. After atrophy correction, all striatal binding sites were decreased. However, the decrease in ChAT activity was 3-fold greater than that of VAChT binding. In addition to degeneration of striatal projection neurons, there are losses of extrinsic nigrostriatal projections and of striatal cholinergic interneurons in HD on the basis of vesicular transporter measures. There is also markedly reduced expression of ChAT by surviving cholinergic striatal interneurons.
Authors	M Suzuki, T J Desmond, R L Albin, K A Frey
Journal	Synapse (New York, N.Y.) (Synapse) Vol. 41 Issue 4 Pg. 329-36 (Sep 15 2001) ISSN: 0887-4476 [Print] United States
PMID	11494403 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
Copyright	Copyright 2001 Wiley-Liss, Inc.
Chemical References	Carrier Proteins Dopamine Plasma Membrane Transport Proteins GABA Modulators Membrane Glycoproteins Membrane Transport Proteins Nerve Tissue Proteins Neuropeptides Receptors, Dopamine D2 Receptors, GABA-A SLC18A2 protein, human SLC18A3 protein, human SLC6A3 protein, human Slc18a2 protein, rat Slc18a3 protein, rat Slc6a3 protein, rat Vesicular Acetylcholine Transport Proteins Vesicular Biogenic Amine Transport Proteins Vesicular Monoamine Transport Proteins Vesicular Transport Proteins Tritium 5-O-methyldihydrotetrabenazine Flumazenil Choline O-Acetyltransferase Tetrabenazine
Topics	Adult Aged Aged, 80 and over Animals Autoradiography Carrier Proteins (analysis, metabolism) Choline O-Acetyltransferase (analysis, metabolism) Cholinergic Fibers (chemistry, enzymology) Corpus Striatum (chemistry, metabolism) Dopamine Plasma Membrane Transport Proteins Female Flumazenil (metabolism, pharmacology) GABA Modulators (metabolism, pharmacology) Humans Huntington Disease (metabolism) Male Membrane Glycoproteins (analysis, metabolism) Membrane Transport Proteins Middle Aged Nerve Tissue Proteins Neuropeptides Postmortem Changes Rats Rats, Sprague-Dawley Receptors, Dopamine D2 (analysis, metabolism) Receptors, GABA-A (analysis, metabolism) Substantia Nigra (chemistry, metabolism) Synapses (chemistry, metabolism) Tetrabenazine (analogs & derivatives) Tritium Vesicular Acetylcholine Transport Proteins Vesicular Biogenic Amine Transport Proteins Vesicular Monoamine Transport Proteins Vesicular Transport Proteins

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