Shao L, Golbaz K, Honer WG, Beasley CL. Deficits in axon-associated proteins in prefrontal white matter in bipolar disorder but not schizophrenia.
Bipolar Disord 2016;
18:342-51. [PMID:
27218831 DOI:
10.1111/bdi.12395]
[Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 01/25/2016] [Accepted: 02/26/2016] [Indexed: 12/24/2022]
Abstract
OBJECTIVES
Brain imaging studies have implicated white matter dysfunction in the pathophysiology of both bipolar disorder (BD) and schizophrenia (SCZ). However, the contribution of axons to white matter pathology in these disorders is not yet understood. Maintenance of neuronal function is dependent on the active transport of biological material, including synaptic proteins, along the axon. In this study, the expression of six proteins associated with axonal transport of synaptic cargoes was quantified in postmortem samples of prefrontal white matter in subjects with BD, those with SCZ, and matched controls, as a measure of axonal dysfunction in these disorders.
METHODS
Levels of the microtubule-associated proteins β-tubulin and microtubule-associated protein 6 (MAP6), the motor and accessory proteins kinesin-1 and disrupted-in-schizophrenia 1 (DISC1), and the synaptic cargoes synaptotagmin and synaptosomal-associated protein-25 (SNAP-25) were quantified in white matter adjacent to the dorsolateral prefrontal cortex in subjects with BD (n = 34), subjects with SCZ (n = 35), and non-psychiatric controls (n = 35) using immunoblotting and an enzyme-linked immunosorbent assay (ELISA).
RESULTS
Protein expression of β-tubulin, kinesin-1, DISC1, synaptotagmin, and SNAP-25 was significantly lower in subjects with BD compared to controls. Levels of axon-associated proteins were also lower in subjects with SCZ, but failed to reach statistical significance.
CONCLUSIONS
These data provide evidence for deficits in axon-associated proteins in prefrontal white matter in BD. Findings are suggestive of decreased axonal density or dysregulation of axonal function in this disorder.
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