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Updated: Jun 21, 2026

Induction of Paralysis and Visual System Injury in Mice by T Cells Specific for Neuromyelitis Optica Autoantigen Aquaporin-4
Published on: August 21, 2017
Role of n-type voltage-dependent calcium channels in autoimmune optic neuritis
Ivana Gadjanski1, Susann Boretius, Sarah K Williams
1Department of Neurology, Georg-August University, Göttingen, Germany.
Objective:
The aim of this study was to investigate the role of voltage-dependent calcium channels (VDCCs) in axon degeneration during autoimmune optic neuritis.
Methods:
Calcium ion (Ca(2+)) influx into the optic nerve (ON) through VDCCs was investigated in a rat model of optic neuritis using manganese-enhanced magnetic resonance imaging and in vivo calcium imaging. After having identified the most relevant channel subtype (N-type VDCCs), we correlated immunohistochemistry of channel expression with ON histopathology. In the confirmatory part of this work, we performed a treatment study using omega-conotoxin GVIA, an N-type specific blocker.
Results:
We observed that pathological Ca(2+) influx into ONs during optic neuritis is mediated via N-type VDCCs. By analyzing the expression of VDCCs in the inflamed ONs, we detected an upregulation of alpha(1B), the pore-forming subunit of N-type VDCCs, in demyelinated axons. However, high expression levels were also found on macrophages/activated microglia, and lower levels were detected on astrocytes. The relevance of N-type VDCCs for inflammation-induced axonal degeneration and the severity of optic neuritis was corroborated by treatment with omega-conotoxin GVIA. This blocker led to decreased axon and myelin degeneration in the ONs together with a reduced number of macrophages/activated microglia. These protective effects were confirmed by analyzing the spinal cords of the same animals.
Interpretation:
We conclude that N-type VDCCs play an important role in inflammation-induced axon degeneration via two mechanisms: First, they directly mediate toxic Ca(2+) influx into the axons; and second, they contribute to macrophage/microglia function, thereby promoting secondary axonal damage. Ann Neurol 2009;66:81-93.
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