A channelopathy contributes to cerebellar dysfunction in a model of multiple sclerosis

Area of Science:

• Neuroscience
• Immunology
• Channelopathies

Background:

• Cerebellar dysfunction significantly impacts disability in multiple sclerosis (MS), often progressing despite treatments.
• Nav1.8 sodium channels, typically in the peripheral nervous system, are found in cerebellar Purkinje neurons in MS and EAE models.
• The functional role of Nav1.8 in cerebellar dysfunction in MS remains unclear.

Purpose of the Study:

• To test the hypothesis that Nav1.8 upregulation in the cerebellum contributes to MS symptom burden.
• To investigate the functional consequences of Nav1.8 expression in Purkinje neurons.
• To assess the therapeutic potential of Nav1.8 blockade in MS-like deficits.

Main Methods:

• Electrophysiology and behavioral assessments in a transgenic mouse model overexpressing Nav1.8 in Purkinje neurons.
• Evaluation of experimental autoimmune encephalomyelitis (EAE) symptom progression in Nav1.8 knockout mice versus wild-type littermates.
• Administration of a Nav1.8-selective blocker (A803467) to mice with established EAE to assess reversibility of deficits.

Main Results:

• Ectopic Nav1.8 expression in Purkinje neurons altered electrophysiology and disrupted motor behaviors in healthy mice.
• Nav1.8 expression was shown to contribute to symptom development in the EAE model.
• Pharmacological blockade of Nav1.8 partially reversed abnormal Purkinje neuron firing and MS-like motor deficits in EAE.

Conclusions:

• The study provides evidence that a channelopathy involving Nav1.8 contributes to cerebellar dysfunction in MS.
• Nav1.8 channel activity in Purkinje neurons plays a functional role in MS-related motor impairments.
• Nav1.8-specific blockers warrant investigation as a potential therapeutic strategy for MS.