Dopaminergic neurons intrinsic to the primate striatum

• Type of Material: Article
• Authors: Ranjita Betarbet, Emory University; Robert Turner, Emory University; Vijay Chockkan, Emory University; Mahlon R DeLong, Emory University; Kelly A. Allers, Emory University; Judith Walters, National Institute of Neurological Disorders and Stroke; Allan I Levey, Emory University; J. Timothy Greenamyre, Emory University
• Language: English
• Date: 1997-09-01
• Publisher: Lippincott, Williams & Wilkins
• Publication Version: Final Published Version
• Copyright Statement: Copyright © 1997 Society for Neuroscience
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1523/JNEUROSCI.17-17-06761.1997
• Title of Journal or Parent Work: Journal of Neuroscience Nursing
• ISSN: 0888-0395
• Volume: 17
• Issue: 17
• Start Page: 6761
• End Page: 6768
• Grant/Funding Information: This work was supported by United States Public Health Service Grants NS33779 (J.T.G.) and NS31937 (A.I.L. and M.R.D.); and a Mallinckrodt Scholar Award (J.T.G.).
• Keywords: Neurosciences & Neurology; Neurosciences; DENDRODENDRITIC SYNAPTIC INTERACTIONS; OLFACTORY-BULB; glutamic acid decarboxylase; dopamine transporter; parvalbumin; CHOLINERGIC NEURONS; ELECTRON-MICROSCOPY; Parkinson's disease-treated monkeys; calbindin; Science & Technology; IMMUNOREACTIVE NEURONS; HIPPOCAMPAL PYRAMIDAL CELLS; TYROSINE HYDROXYLASE-LIKE; NADPH-DIAPHORASE; BASAL GANGLIA; striatum; dopaminergic cells; RAT NEOSTRIATUM; Life Sciences & Biomedicine
• Research Categories: Biology, Neuroscience; Health Sciences, Pharmacology

Abstract

Intrinsic, striatal tyrosine hydroxylase-immunoreactive (TH-i) cells have received little consideration. In this study we have characterized these neurons and their regulatory response to nigrostriatal dopaminergic deafferentation. TH-i cells were observed in the striatum of both control and 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP)-treated monkeys; TH-i cell counts, however, were 3.5-fold higher in the striatum of MPTP-lesioned monkeys. To establish the dopaminergic nature of the TH-i cells, sections were double-labeled with antibodies to dopamine transporter (DAT). Immunofluorescence studies demonstrated that nearly all TH-i cells were double-labeled with DAT, suggesting that they contain the machinery to be functional dopaminergic neurons. Two types of TH-i cells were identified in the striatum: small, aspiny, bipolar cells with varicose dendrites and larger spiny, multipolar cells. The aspiny cells, which were more prevalent, corresponded morphologically to the GABAergic interneurons of the striatum. Double-label immunofluorescence studies using antibodies to TH and glutamate decarboxylase (GAD67), the synthetic enzyme for GABA, showed that 99% of the TH-i cells were GAD67-positive. Very few (<1%) of the TH-i cells, however, were immunoreactive for the calcium-binding proteins calbindin and parvalbumin. In summary, these results demonstrate that the dopaminergic cell population of the striatum responds to dopamine denervation by increasing in number, apparently to compensate for loss of extrinsic dopaminergic innervation. Moreover, this population of cells corresponds largely with the intrinsic GABAergic cells of the striatum. This study also suggests that the adult primate striatum does retain some intrinsic capacity to compensate for dopaminergic cell loss.