Motor neuron degeneration correlates with respiratory dysfunction in SCA1

Area of Science:

• Neuroscience
• Genetics
• Pathology

Background:

• Spinocerebellar ataxia type 1 (SCA1) is a neurodegenerative disorder causing progressive loss of motor coordination.
• Bulbar dysfunction, including impaired airway clearance, is a severe complication leading to mortality in SCA1 patients.

Purpose of the Study:

• To investigate if motor neuron degeneration underlies bulbar dysfunction in SCA1.
• To validate the *Atxn1* knock-in mouse as a model for studying SCA1-related motor neuron pathology and bulbar dysfunction.

Main Methods:

• Assessment of spinal cord and brainstem motor neurons in *Atxn1* mice at multiple ages.
• Evaluation of breathing physiology, diaphragm histology and electromyography.
• Histological and immunohistochemical analysis of motor neurons, including Atxn1 aggregate detection.

Main Results:

• *Atxn1* mice exhibited progressive neuromuscular respiratory abnormalities and neurogenic diaphragm changes.
• Motor neuron degeneration was observed in the spinal cord and brainstem, accompanied by astrocytosis and Atxn1 aggregates.
• Findings in the mouse model correlated with observations in SCA1 patient tissues.

Conclusions:

• Motor neuron degeneration is the cause of bulbar dysfunction in SCA1, as demonstrated in the *Atxn1* mouse model.
• The *Atxn1* mouse is a valid model for studying SCA1 pathogenesis and potentially other motor neuron diseases.
• Pulmonary function tests and non-invasive ventilation may benefit SCA1 patients, with physiological tests serving as potential biomarkers.