Neurochemical characterization of dopaminergic neurons in human striatum.

Publication Type:

Journal Article

Authors:

Cossette, Martine; Lévesque, Daniel; André Parent

Source:

Parkinsonism Relat Disord, Volume 11, Issue 5, p.277-86 (2005)

Keywords:

Adolescent, Adult, Biomarkers, Calbindin 2, Corpus Striatum, DNA-Binding Proteins, Dopamine, Dopamine Plasma Membrane Transport Proteins, Female, Glutamate Decarboxylase, Humans, Interneurons, Isoenzymes, Male, Membrane Glycoproteins, Membrane Transport Proteins, Microtubule-Associated Proteins, Middle Aged, Nerve Tissue Proteins, Neural Pathways, Nuclear Receptor Subfamily 4, Group A, Member 2, Parvalbumins, Phenotype, RNA, Messenger, S100 Calcium Binding Protein G, Somatostatin, Transcription Factors, Tyrosine 3-Monooxygenase

Abstract:

<p>We examined the neurochemical phenotype of striatal neurons expressing tyrosine hydroxylase (TH) mRNA to determine if they form a distinct class of neurons within the human striatum. Double in situ hybridization (ISH) and immunohistochemical (IHC) procedures were used to know if TH mRNA-positive striatal neurons express molecular markers of mature neurons (MAP2 and NeuN), dopaminergic neurons (DAT and Nurr1) or immature neurons (TuJ1). All TH mRNA-labeled neurons were found to express NeuN, DAT and Nurr1, whereas about 80% of them exhibited MAP2, confirming their neuronal and dopaminergic nature. Only about 30% of TH mRNA-labeled neurons expressed TuJ1, suggesting that this ectopic dopaminergic neuronal population is principally composed of mature neurons. The same double ISH/IHC approach was then used to know if these dopamine neurons display markers of well-established classes of striatal projection neurons (GAD65 and calbindin) or local circuit neurons (GAD65, calretinin, somatostatin and parvalbumin). Virtually all TH-labeled neurons expressed GAD65 mRNA, about 30% of them exhibited calretinin, but none stained for the other striatal neuron markers. These results suggest that the majority of TH-positive neurons intrinsic to the human striatum belong to a distinct subpopulation of striatal interneurons characterized by their ability to produce dopamine and GABA.</p>