title: The effect of striatal pre-enkephalin overexpression in the basal ganglia of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mouse model of Parkinson's disease.
abstract: The midbrain dopamine (DA) cell death underlying Parkinson's disease (PD) is associated with upregulation of pre-enkephalin (pENK) in striatopallidal neurons. Our previous results obtained with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) parkinsonian monkeys suggest that increased striatal expression of pENK mRNA is a compensatory mechanism to alleviate PD-related motor symptoms. In this study, we tested the hypothesis that increased pENK expression in the striatum protects against the neurotoxic insults of MPTP in mice. To this end, recombinant adeno-associated virus serotype 2 also containing green fluorescent protein was used to overexpress pENK prior to DA depletion. Our results showed that overexpression of pENK in the striatum of MPTP mice induced: (i) increased levels of the opioid peptide enkephalin (ENK) in the striatum; (ii) higher densities of ENK-positive fibers in both the globus pallidus (GP) and the substantia nigra; (iii) higher locomotor activity; and (iv) a higher density of striatal tyrosine hydroxylase-positive fibers in the striatum. In addition, striatal overexpression of pENK in MPTP -treated mice led to 52 and 43% higher DA concentrations and DA turnover, respectively, in the GP compared to sham-treated MPTP mice. These observations are in agreement with the idea that increased expression of pENK at an early stage of disease can improve PD symptoms.
authors.affiliation: Axe Neurosciences, Centre de recherche du CHU de Québec, CHUL, 2705, boul. Laurier, Québec, QC, G1V 4G2, Canada.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Bissonnette
authors.forename: Sophie
authors.initials: S
authors.lastname: Muratot
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vernoux
authors.forename: François
authors.initials: F
authors.lastname: Bezeau
authors.forename: Frédéric
authors.initials: F
authors.lastname: Calon
authors.forename: Sébastien S
authors.initials: SS
authors.lastname: Hébert
authors.forename: Pershia
authors.initials: P
authors.lastname: Samadi
mesh_terms: D000818:Animals; D004298:Dopamine / Q000378:metabolism; D004745:Enkephalins / Q000235:genetics / Q000378:metabolism*; D005917:Globus Pallidus / Q000378:metabolism*; D008124:Locomotion; D020267:MPTP Poisoning / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013378:Substantia Nigra / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics / Q000378:metabolism
chemical_list: D004745:Enkephalins; D011498:Protein Precursors; D012333:RNA, Messenger; C033660:preproenkephalin; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine
keywords: dopamine; globus pallidus; neurodegeneration; opioid; striatum