Brain Advance Access published online on April 17, 2007
Brain, doi:10.1093/brain/awm061
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Modification of the number and phenotype of striatal dopaminergic cells by carotid body graft
1Laboratory of Regenerative Therapy, 2Animal Services Unit, Center for Applied Medical Research (CIMA) and 3Department of Neurology and Neurosurgery, Clínica Universitaria de Navarra, University of Navarra, Avenida de Pío XII, 55 Pamplona Navarra, Spain
Correspondence to:
M. Rosario Luquin, Laboratory of Regenerative Therapy, Center for Applied Medical Research (CIMA), University of Navarra, Avenida de Pío XII, 55, Pamplona, Navarra, Spain E-mail: rluquin{at}unav.es
In non-human primates, striatal tyrosine hydroxylase-immunoreactive (TH-ir) cells are increased in number after dopamine depletion and in response to trophic factor delivery. As carotid body cells contain the dopaminotrophic glial cell line-derived neurotrophic factor (GDNF), we evaluated the number, morphology and neurochemistry of these TH-ir cells, in the anterior and posterior striatum of five monkeys treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) which received a graft of carotid body cell aggregates (CBCA) (n = 3) or sham surgery (n = 2), and six MPTP-monkeys that were sacrificed 6 months and 3 years after the last MPTP dose [MPTP I (n = 3) and MPTP II (n = 3), respectively]. Three intact monkeys served as controls. A disability rating scale was used for the assessment of parkinsonism in all lesioned animals, both before and after surgery. For the neurochemical examination, tissue sections were double-labelled with antibodies to TH, dopamine transporter, dopa decarboxylase-67, vesicular monoamine transporter 2, glutamic acid decarboxylase –67, calbindin, parvalbumin, calretinin, neuronal nitric oxide synthase and GDNF. Only animals receiving CBCA graft showed a moderate but significant recovery of parkinsonism that persisted 12 months after the graft. The grafted striatum contained the greatest TH-ir cell density (120.4 ± 10.3 cells/100 mm2), while the control striatum displayed the lowest (15.4 ± 6.8 cells/100 mm2), and MPTP I, MPTP II and sham-operated monkeys showed a similar intermediate value (66.1 ± 6.2, 58.3 ± 17.2 and 57.7 ± 7.0 cells/100 mm2, respectively). In addition, in the post-commissural striatum, only CBCA graft induced a significant increase in the TH-ir cell density compared to control animals (47.9 ± 15.9 and 7.9 ± 3.2, respectively). Phenotypically, TH-ir cells were striatal dopaminergic interneurons. However, in the grafted animals, the phenotype was different from that in control, MPTP and sham-operated monkeys, with the appearance of TH/GDNF-ir cells and the emergence of two TH-ir subpopulations of different size as the two main differentiating features. Our data confirm and extend previous studies demonstrating that striatal CBCA grafts produce a long-lasting motor recovery of MPTP-monkeys along with an increase in the number and phenotype changes of the striatal TH-ir interneurons, probably by the action of the trophic factors contained in carotid body cells. The increased number of striatal TH-ir cells observed in the grafted striatum may contribute to the improvement of parkinsonism observed after the graft.
Key Words: striatum; Parkinson's disease; dopaminergic cells; carotid body graft; Macaca fascicularis
Abbreviations: BDNF, brain derived neurotrophic factor; CaBP, calbindin-28kD; CB, carotid body; CBCA, carotid body cell aggregates; CR, calretinin; DA, dopamine; DAT, dopamine transporter; DDC, dopamine decarboxylase; GABA, gamma-aminobutyric acid; GAD67, glutamic acid decarboxylase 67; GDNF, glial cell line-derived neurotrophic factor; IF, immunofluorescence; MPTP, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; NGF, nerve growth factor; nNOS, neuronal nitric oxide synthase; 6-OHDA, 6-hydroxydopamine; PBS, phosphate buffer saline; PD, Parkinson's disease; PV, parvalbumin; SVZ, subventricular zone; TH, tyrosine hydroxylase; TH-ir, tyrosine hydroxylase-immunoreactive; VMAT2, vesicular monoamine transporter 2
Received November 18, 2006. Revised February 16, 2007. Accepted March 6, 2007.