Dynamic interplay between H-current and M-current controls motoneuron hyperexcitability in amyotrophic lateral...

Area of Science:

• Neuroscience
• Genetics
• Physiology

Background:

• Amyotrophic lateral sclerosis (ALS), a motor neuron disease (MND), involves progressive motor function loss due to motoneuron degeneration.
• Neuronal hyperexcitability, an exaggerated neuronal response, is implicated in motoneuron loss but poorly understood during disease progression.
• Previous studies primarily examined hyperexcitability in pre-symptomatic stages, limiting understanding of its role throughout disease development.

Purpose of the Study:

• To investigate upper motoneuron excitability, focusing on oscillatory behavior and repetitive firing capabilities during ALS disease progression.
• To elucidate the cellular and ionic mechanisms underlying age-related motoneuron hyperexcitability in the context of ALS.
• To explore the correlation between disease progression and the expression of specific ion channel genes.

Main Methods:

• Assessment of upper motoneuron excitability in SOD1^G93A ALS mice and wild-type controls across different disease stages.
• Analysis of gene expression levels for HCN and KCNQ channels.
• Examination of H-current and M-current dynamics.

Main Results:

• Increased motoneuron intrinsic excitability is a general aging phenomenon.
• Cellular mechanisms driving hyperexcitability differ between SOD1^G93A ALS mice and controls.
• Alterations in HCN and KCNQ channel gene expression influence H-current and M-current, correlating negatively with disease onset and progression.

Conclusions:

• Age-related increases in motoneuron excitability are influenced by distinct molecular pathways in ALS.
• Dysregulation of HCN and KCNQ channels contributes to motoneuron hyperexcitability and vulnerability in aging ALS models.
• Findings offer insights into the mechanisms underlying motoneuron degeneration in ALS, particularly concerning aging.