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Metzger JM, Matsoff HN, Zinnen AD, Fleddermann RA, Bondarenko V, Simmons HA, Mejia A, Moore CF, Emborg ME. Post mortem evaluation of inflammation, oxidative stress, and PPARγ activation in a nonhuman primate model of cardiac sympathetic neurodegeneration. PLoS One 2020; 15:e0226999. [PMID: 31910209 PMCID: PMC6946159 DOI: 10.1371/journal.pone.0226999] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 12/09/2019] [Indexed: 12/21/2022] Open
Abstract
Cardiac dysautonomia is a common nonmotor symptom of Parkinson’s disease (PD) associated with loss of sympathetic innervation to the heart and decreased plasma catecholamines. Disease-modifying strategies for PD cardiac neurodegeneration are not available, and biomarkers of target engagement are lacking. Systemic administration of the catecholaminergic neurotoxin 6-hydroxydopamine (6-OHDA) recapitulates PD cardiac dysautonomia pathology. We recently used positron emission tomography (PET) to visualize and quantify cardiac sympathetic innervation, oxidative stress, and inflammation in adult male rhesus macaques (Macaca mulatta; n = 10) challenged with 6-OHDA (50mg/kg; i.v.). Twenty-four hours post-intoxication, the animals were blindly and randomly assigned to receive daily doses of the peroxisome proliferator-activated receptor gamma (PPARγ) agonist pioglitazone (n = 5; 5mg/kg p.o.) or placebo (n = 5). Quantification of PET radioligand uptake showed increased oxidative stress and inflammation one week after 6-OHDA which resolved to baseline levels by twelve weeks, at which time pioglitazone-treated animals showed regionally preserved sympathetic innervation. Here we report post mortem characterization of heart and adrenal tissue in these animals compared to age and sex matched normal controls (n = 5). In the heart, 6-OHDA-treated animals showed a significant loss of sympathetic nerve fibers density (tyrosine hydroxylase (TH)-positive fibers). The anatomical distribution of markers of sympathetic innervation (TH) and inflammation (HLA-DR) significantly correlated with respective in vivo PET findings across left ventricle levels and regions. No changes were found in alpha-synuclein immunoreactivity. Additionally, CD36 protein expression was increased at the cardiomyocyte intercalated discs following PPARγ-activation compared to placebo and control groups. Systemic 6-OHDA decreased adrenal medulla expression of catecholamine producing enzymes (TH and aromatic L-amino acid decarboxylase) and circulating levels of norepinephrine, which were attenuated by PPARγ-activation. Overall, these results validate in vivo PET findings of cardiac sympathetic innervation, oxidative stress, and inflammation and illustrate cardiomyocyte CD36 upregulation as a marker of PPARγ target engagement.
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Affiliation(s)
- Jeanette M. Metzger
- Wisconsin National Primate Research Center, University of Wisconsin–Madison, Madison, WI, United States of America
- Cellular and Molecular Pathology Graduate Program, University of Wisconsin–Madison, Madison, WI, United States of America
| | - Helen N. Matsoff
- Wisconsin National Primate Research Center, University of Wisconsin–Madison, Madison, WI, United States of America
| | - Alexandra D. Zinnen
- Wisconsin National Primate Research Center, University of Wisconsin–Madison, Madison, WI, United States of America
| | - Rachel A. Fleddermann
- Wisconsin National Primate Research Center, University of Wisconsin–Madison, Madison, WI, United States of America
| | - Viktoriya Bondarenko
- Wisconsin National Primate Research Center, University of Wisconsin–Madison, Madison, WI, United States of America
| | - Heather A. Simmons
- Wisconsin National Primate Research Center, University of Wisconsin–Madison, Madison, WI, United States of America
| | - Andres Mejia
- Wisconsin National Primate Research Center, University of Wisconsin–Madison, Madison, WI, United States of America
| | - Colleen F. Moore
- Department of Psychology, University of Wisconsin–Madison, Madison, WI, United States of America
| | - Marina E. Emborg
- Wisconsin National Primate Research Center, University of Wisconsin–Madison, Madison, WI, United States of America
- Cellular and Molecular Pathology Graduate Program, University of Wisconsin–Madison, Madison, WI, United States of America
- Department of Medical Physics, University of Wisconsin–Madison, Madison, WI, United States of America
- * E-mail:
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