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Bohnen NI, Barr J, Vangel R, Roytman S, Paalanen R, Frey KA, Scott PJH, Kanel P. GABA A Receptor Benzodiazepine Binding Sites and Motor Impairments in Parkinson's Disease. Brain Sci 2023; 13:1711. [PMID: 38137159 PMCID: PMC10741877 DOI: 10.3390/brainsci13121711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 12/03/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023] Open
Abstract
Flumazenil is an allosteric modulator of the γ-aminobutyric acid-A receptor (GABAAR) benzodiazepine binding site that could normalize neuronal signaling and improve motor impairments in Parkinson's disease (PD). Little is known about how regional GABAAR availability affects motor symptoms. We investigated the relationship between regional availability of GABAAR benzodiazepine binding sites and motor impairments in PD. Methods: A total of 11 Patients with PD (males; mean age 69.0 ± 4.6 years; Hoehn and Yahr stages 2-3) underwent [11C]flumazenil GABAAR benzodiazepine binding site and [11C]dihydrotetrabenazine vesicular monoamine transporter type-2 (VMAT2) PET imaging and clinical assessment. Stepwise regression analysis was used to predict regional cerebral correlates of the four cardinal UPDRS motor scores using cortical, striatal, thalamic, and cerebellar flumazenil binding estimates. Thalamic GABAAR availability was selectively associated with axial motor scores (R2 = 0.55, F = 11.0, β = -6.4, p = 0.0009). Multi-ligand analysis demonstrated significant axial motor predictor effects by both thalamic GABAAR availability (R2 = 0.47, β = -5.2, F = 7.2, p = 0.028) and striatal VMAT2 binding (R2 = 0.30, β = -3.9, F = 9.1, p = 0.019; total model: R2 = 0.77, F = 11.9, p = 0.0056). Post hoc analysis demonstrated that thalamic [11C]methyl-4-piperidinyl propionate cholinesterase PET and K1 flow delivery findings were not significant confounders. Findings suggest that reduced thalamic GABAAR availability correlates with worsened axial motor impairments in PD, independent of nigrostriatal degeneration. These findings may augur novel non-dopaminergic approaches to treating axial motor impairments in PD.
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Affiliation(s)
- Nicolaas I. Bohnen
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA; (J.B.); (R.V.); (S.R.); (K.A.F.); (P.J.H.S.); (P.K.)
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA;
- Morris K. Udall Center of Excellence for Parkinson’s Disease Research, University of Michigan, Ann Arbor, MI 48109, USA
- Neurology Service and GRECC, VA Ann Arbor Healthcare System, Ann Arbor, MI 48105, USA
| | - Jaimie Barr
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA; (J.B.); (R.V.); (S.R.); (K.A.F.); (P.J.H.S.); (P.K.)
- Neurology Service and GRECC, VA Ann Arbor Healthcare System, Ann Arbor, MI 48105, USA
| | - Robert Vangel
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA; (J.B.); (R.V.); (S.R.); (K.A.F.); (P.J.H.S.); (P.K.)
| | - Stiven Roytman
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA; (J.B.); (R.V.); (S.R.); (K.A.F.); (P.J.H.S.); (P.K.)
| | - Rebecca Paalanen
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA;
- Morris K. Udall Center of Excellence for Parkinson’s Disease Research, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kirk A. Frey
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA; (J.B.); (R.V.); (S.R.); (K.A.F.); (P.J.H.S.); (P.K.)
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA;
| | - Peter J. H. Scott
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA; (J.B.); (R.V.); (S.R.); (K.A.F.); (P.J.H.S.); (P.K.)
| | - Prabesh Kanel
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA; (J.B.); (R.V.); (S.R.); (K.A.F.); (P.J.H.S.); (P.K.)
- Morris K. Udall Center of Excellence for Parkinson’s Disease Research, University of Michigan, Ann Arbor, MI 48109, USA
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