STRIATAL TYROSINE HYDROXYLASE-POSITIVE NEURONS ARE ASSOCIATED WITH L-DOPA-INDUCED DYSKINESIA IN HEMIPARKINSONIAN MICE

• L-3,4-Dihydroxyphenylalanine (L-DOPA) is the therapeutic gold standard in Parkinson's disease. However, long-term treatment is complicated by the induction of debilitating abnormal involuntary movements termed L-DOPA-induced dyskinesias (LIDs). Until today the underlying mechanisms of LID pathogenesis are not fully understood. The aim of this study was to reveal new factors, which may be involved in the induction of LID. We have focused on the expression of striatal tyrosine hydroxylase-positive (TH+) neurons, which are capable of producing either L-DOPA or dopamine (DA) in target areas of ventral midbrain DAergic neurons. To address this issue, a daily L-DOPA dose was administered over the course of 15 days to mice with unilateral 6-hydroxydopamine-induced lesions of the medial forebrain bundle and LIDs were evaluated. Remarkably, the number of striatal TH+ neurons strongly correlated with both induction and severity of LID as well as Delta FosB expression as an established molecular marker for LID. Furthermore, dyskinetic mice showed a marked augmentation of serotonergic fiber innervation in the striatum, enabling the decarboxylation of L-DOPA to DA. Axial, limb and orolingual dyskinesias were predominantly associated with TH+ neurons in the lateral striatum, whereas medially located TH+ neurons triggered locomotive rotations. In contrast, identified accumbal and cortical TH+ cells did not contribute to the generation of LID. Thus, striatal TH+ cells and serotonergic terminals may cooperatively synthesize DA and subsequently contribute to supraphysiological synaptic DA concentrations, an accepted cause in LID pathogenesis. (C) 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Neurovetenskaper (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Neurosciences (hsv//eng)

Keyword

Parkinson's disease

dopamine

abnormal involuntary movement

striatum

accumbens

TH

PARKINSONS-DISEASE PATIENTS

LEVODOPA-INDUCED DYSKINESIAS

DOPAMINERGIC-NEURONS

NUCLEUS-ACCUMBENS

RAT MODEL

FUNCTIONAL-SIGNIFICANCE

FOSB EXPRESSION

UP-REGULATION

DELTA-FOSB

IMMUNOREACTIVE NEURONS

Neurosciences

INSSEN EPM

1994

JOURNAL OF NEUROSCIENCE

V14

P1555

SHIRO Y

1989

NEUROSCIENCE LETTERS

V97

P6

Publication and Content Type

ref (subject category)

art (subject category)