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Am J Neurodegener Dis 2013;2(3):221-227

Original Article
Dopaminergic innervation of the human subventricular zone: a
comparison between Huntington’s chorea and Parkinson’s disease

Martin Parent, C Bédard, E Pourcher

Centre de recherche de l’Institut universitaire en santé mentale de Québec, Department of Psychiatry and
Neuroscience, Faculty of Medicine, Université Laval, Quebec City, QC, Canada; Gladstone Institute of Neurological
Disease, UCSF, San Francisco, CA 94158, USA; Quebec Memory and Skills Disorders Research Center, Clinique
Sainte-Anne, Quebec City, QC, Canada

Received June 26, 2013; Accepted August 1, 2013; Epub September 18, 2013; Published September 30, 2013

Abstract: The subventricular zone retains its neurogenic capacity throughout life and, as such, is often considered a
potential source for endogenous repair in neurodegenerative disorders. Because dopamine is believed to stimulate
adult neurogenesis, we looked for possible variations in the dopaminergic innervation of the subventricular zone
between cases of Huntington’s chorea and Parkinson’s diseases. Antibodies against tyrosine hydroxylase (TH) and
proliferating cell nuclear antigen (PCNA) were used as specific markers of dopaminergic axons and cell proliferating
activity, respectively. The immunohistochemical approach was applied to postmortem tissue from 2 Parkinson’s
disease cases, 4 Huntington’s disease cases, along with age-matched controls. The immunostaining was revealed
with either diaminobenzidine or fluorescent-conjugated secondary antibodies. Optical density measurements were
made along the entire dorso-ventral extent of the caudate nucleus. An intense TH+ zone was detected along the
ventricular border of the caudate nucleus in Huntington’s disease cases, but not in patients with Parkinson’s disease
or age-matched controls. This thin (287±38 µm) paraventricular zone was composed of numerous small and densely
packed dopamine axon varicosities and overlapped the deep layers of the subventricular zone. Its immunoreactivity
was 47±8% more intense than that of adjacent striatal areas. The dopamine innervation of the subventricular zone is
strikingly massive in Huntington’s chorea compared to Parkinson’s disease, a finding that concurs with the marked
increase in neurogenesis noted in the subventricular zone of Huntington’s disease patients. This finding suggests that
dopamine plays a crucial role in mechanisms designed to compensate for the massive striatal neuronal losses that
occur in Huntington’s disease. (AJND1306005).

Keywords: Stem cells, adult neurogenesis, basal ganglia, Parkinson’s disease, Huntington’s chorea, subventricular
zone, neurodegenerative disorders, human striatum

Address correspondence to: Dr. Martin Parent, Centre de recherche de l’Institut universitaire en santé mentale de
Québec, 2601, Canardière, Room F-6500, Quebec City, QC, Canada, G1J 2G3. Tel: 418-663-5747; Fax: 418-663-8756;
E-mail: Martin.Parent@crulrg.ulaval.ca