Chemical phenotype of calretinin interneurons in the human striatum.
We recently reported the existence of a new class of aspiny interneurons characterized by their immunoreactivity for the calcium-binding protein calretinin (CR) in human striatum. This group is composed of numerous medium-sized (10-20 microm) neurons with poorly branched dendrites and a smaller number of large-sized (24-42 microm) neurons with highly ramified dendrites. We further demonstrated the selective sparing of the medium-sized, but not all the large-sized, CR+ striatal neurons in Huntington's disease. In the present study, we applied a double-antigen localization method to postmortem striatal tissue obtained from normal individuals to further characterize the chemical phenotype of these two subsets of CR+ neurons. Our results reveal that in the medium-sized neurons, CR is not colocalized with any of the following current markers of striatal neurons: calbindin, parvalbumin, beta-nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d), or choline acetyltransferase (ChAT). Furthermore, quantitative estimates show that the medium-sized CR+ neurons are by far the most abundant type of interneurons in the human striatum. In contrast, CR is colocalized with ChAT in about 80% of the large-sized CR+ neurons. Thus, the medium-sized CR+ neurons appear to form a distinct class of striatal interneurons, whereas most of the large-sized CR+ neurons belong to the population of giant cholinergic neurons. This study has provided the first exhaustive characterization of the chemical phenotype of the CR + neurons in the human striatum.
Centre de Recherche Université Laval Robert-Giffard, Beauport, QC, Canada.
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D000328:Adult; D015415:Biomarkers; D064032:Calbindin 2; D064026:Calbindins; D002795:Choline O-Acetyltransferase / Q000032:analysis; D003342:Corpus Striatum / Q000166:cytology* / Q000378:metabolism / Q000473:pathology; D003712:Dendrites / Q000648:ultrastructure; D005260:Female; D006801:Humans; D006816:Huntington Disease / Q000473:pathology; D007395:Interneurons / Q000166:cytology* / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D008875:Middle Aged; D009252:NADPH Dehydrogenase / Q000032:analysis; D009419:Nerve Tissue Proteins; D010320:Parvalbumins / Q000032:analysis; D010641:Phenotype; D064030:S100 Calcium Binding Protein G / Q000032:analysis*
D015415:Biomarkers; C576764:CALB2 protein, human; D064032:Calbindin 2; D064026:Calbindins; D009419:Nerve Tissue Proteins; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G; D009252:NADPH Dehydrogenase; D002795:Choline O-Acetyltransferase