Motor neuron diseases (MNDs), which includes amyotrophic lateral sclerosis (ALS), can cause progressive motor neuron loss, leading to tongue weakness, swallowing difficulties, airway dysfunction, and respiratory failure. Obstructive sleep apnea (OSA) is common in patients with MND and associated with shorter survival in patients with ALS. Hypoglossal (XII) motor neuron degeneration contributes to upper airway dysfunction by weakening tongue muscles involved in maintaining open airways.
Researchers used intralingual injections of our CTB-SAP in adult rats to create the animal model. They investigated whether high-repetition, low-resistance tongue exercise could improve hypoglossal motor neuron survival, nerve structure, glial responses, and motor output following CTB-SAP-induced degeneration.
What they saw was that tongue exercise did not improve motor neuron survival or prevent degenerative changes in the hypoglossal nerve.
Tongue exercise increased microglial area and density in the hypoglossal motor nucleus, suggesting an effect on glial activity, although the exact role of microglia remains unclear. Tongue exercise improved hypoglossal motor output even though motor neuron damage remained.
In CTB-SAP-treated rats, exercise reduced motor output deficits, suggesting that the brain and nervous system may adapt to help maintain upper airway function. These findings support further research into tongue exercise as a potential treatment for people with MNDs or OSA.
