Funding agencies: This study was supported by the Dean's New Staff Award (to S.H.F.) and Krembil Neuroscience Fund (to J.M.B. and S.H.F.). Philippe Huot held a fellowship from the Edmond J. Safra Philanthropic Foundation, the Parkinson Society Canada, and the Canadian Institutes of Health Research.
Version of Record online: 14 MAR 2012
Copyright © 2012 Movement Disorder Society
Volume 27, Issue 6, pages 735–742, May 2012
How to Cite
Huot, P., Johnston, T. H., Visanji, N. P., Darr, T., Pires, D., Hazrati, L.-N., Brotchie, J. M. and Fox, S. H. (2012), Increased levels of 5-HT1A receptor binding in ventral visual pathways in Parkinson's disease. Mov. Disord., 27: 735–742. doi: 10.1002/mds.24964
Relevant conflicts of interest/financial disclosures: Nothing to report.
Full financial disclosures and author roles may be found in the online version of this article.
- Issue online: 30 MAY 2012
- Version of Record online: 14 MAR 2012
- Manuscript Accepted: 9 FEB 2012
- Manuscript Revised: 27 JAN 2012
- Manuscript Received: 3 NOV 2011
- Parkinson's disease;
- 5-HT1A receptors;
- visual hallucinations
Visual hallucinations are common in advanced Parkinson's disease (PD). The pathophysiology of visual hallucinations may involve enhanced serotonergic neurotransmission. The atypical antipsychotics clozapine and quetiapine, which have affinity for 5-HT2A and 5-HT1A receptors, are effective against visual hallucinations in PD. 5-HT2A receptors are increased in ventral visual pathways in PD patients with visual hallucinations, and we hypothesized that 5-HT1A receptors were also involved in visual hallucinations in PD. Autoradiographic binding using [3H]-WAY-100,635 and NAN-190 was performed in brain sections from 6 PD patients with visual hallucinations, 6 PD patients without visual hallucinations, and 5 age-matched controls. All PD subjects had been treated with L-dopa. Brain areas studied were the orbitofrontal, inferolateral temporal, and motor cortices, as well as the striatum, globus pallidus, substantia nigra, and thalamus. 5-HT1A-binding levels were dramatically increased in the ventral visual pathways of all PD patients compared with controls (0 vs 11 and 0 vs 100 nmol/mg, respectively; both P < .05). There was no significant difference in 5-HT1A-binding levels in PD patients with visual hallucinations compared with PD patients without visual hallucinations or with controls in any of the brain areas studied (P > .05). Gross abnormalities in 5-HT1A levels in ventral visual areas occurred in all PD patients exposed to L-dopa. However, as there was no difference in 5-HT1A-binding levels between hallucinators and nonhallucinators, alterations in 5-HT1A receptor levels may not contribute specifically to visual hallucinations in PD. However, the discrete anatomical distribution of rises to the ventral visual areas suggests some role in predisposing to visual hallucinations. © 2012 Movement Disorder Society