Muscle Function Differences between Patients with Bulbar and Spinal Onset Amyotrophic Lateral Sclerosis. Does It Depend on Peripheral Glucose?

Abstract

Background: One of the pathogenic mechanisms of ALS disease is perturbed energy metabolism particularly glucose metabolism. Given the substantial difference in the severity and the prognosis of the disease, depending on whether it has a bulbar or spinal onset, the aim of the study was to determine metabolic differences between both types of ALS, as well as the possible relationship with muscle function. Materials and Methods: A descriptive, analytical, quantitative, and transversal study was carried out in hospitals and Primary Care centers in the region of Valencia, Spain. Fasting glucose and alkaline phosphatase (AP) levels in venous blood, muscle percentage, fat percentage, muscle strength (MRC scale), and functional capacity (Barthel Index) were measured in 31 patients diagnosed with ALS (20 with spinal onset ALS and 11 with bulbar onset ALS). A healthy control of 29 people was included. Results: No significant differences were observed in blood AP and glucose levels between spinal onset and bulbar onset ALS patients. However, a significant positive correlation was observed between the mean values of both substances in patients with spinal onset ALS. Moreover, a lower percentage of muscle mass and a higher percentage of fat mass were also seen in spinal ALS patients, who also presented lower muscle strength and lower functional capacity. Conclusion: The results of this study seem to point to a possible difference in the peripheral use of glucose between patients with bulbar onset ALS and spinal onset ALS, who appear to have possible insulin resistance. These metabolic differences could explain the lower muscle percentage and lower muscular function in spinal onset ALS patients, although further studies are required.

Potential molecular mechanism of exercise reversing insulin resistance and improving neurodegenerative diseases

“…Other researchers have suggested an alternative and potentially more reasonable explanation, where insulin resistance in patients with ALS may be closely linked to their limitations in performing daily activities due to their disease severity ( Harris et al, 1986 ). Certain studies have also proposed that insulin resistance-induced metabolic differences can further exacerbate skeletal muscle atrophy during the disease course ( de la Rubia Ortí et al, 2021 ). Finally, skeletal muscle atrophy and early impairment of insulin secretion may lead to hyperosmolar hyperglycemia in patients with late-stage ALS ( Shimizu et al, 2011 ).…”

Janus kinase inhibitors are potential therapeutics for amyotrophic lateral sclerosis

“…The latter inhibits activity of pyruvate dehydrogenase, thereby preventing the entry of glucose-derived acetylCoA to the Krebs cycle. This reduced glucose utilisation will reduce ATP supply in motor neurons, while in muscle mitochondria it could perhaps explain the relative insulin resistance seen in ALS patients [ 54 ]. JAK inhibition is therefore expected to improve the generation of ATP by the Krebs cycle and oxidative phosphorylation, thereby increasing the provision of ATP to the upper and lower motor neurons and muscle fibres.…”