Effect of creatine supplementation on metabolite levels in ALS motor cortices

Mitochondrial pathology is an early observation in motor neurons and skeletal muscle of patients with amyotrophic lateral sclerosis (ALS). To clarify the relevance of this finding, we determined the effects of a 1-month oral administration of creatine on (1)H NMR-visible metabolites in the motor cortices of 15 controls and 15 patients with sporadic ALS, most of whom had mitochondrial pathology in skeletal muscle. In the motor cortex of the ALS group the N-acetylaspartate (NAA)/creatine (Cr(t)) metabolite ratio was lower than in our control group, indicating NAA loss. Upon creatine supplementation we observed in the controls a decline in the NAA/Cr(t), NAA/choline (Cho), glutamate + glutamine (Glx)/Cr(t), and Glx/Cho metabolite ratios. In contrast, in the ALS patient group the NAA/Cr(t) and the NAA/Cho metabolite ratios remained unchanged, while the Glx/Cr(t) and Glx/Cho metabolite ratios decreased. These data are compatible with the interpretation that creatine supplementation causes an increase in the diminished NAA levels in ALS motor cortex as well as an increase of choline levels in both ALS and control motor cortices. Because NAA is synthesized by mitochondria in an energy-dependent manner and the NAA/Cho metabolite ratios in the ALS motor cortices were found to be correlated to the degree of mitochondrial pathology in ALS skeletal muscle, our results can be explained by a deficiency of enzymes of mitochondrial respiratory chain in the ALS motor cortex which might affect motor neuron survival.