Micro-Doses of DNP Preserve Motor and Muscle Function with a Period of Functional Recovery in Amyotrophic Lateral Sclerosis Mice

Mitochondrial dysfunction is one of the earliest pathological events observed in amyotrophic lateral sclerosis (ALS). The aim of this study is to evaluate the therapeutic efficacy of 2,4-dinitrophenol (DNP), a mild mitochondrial uncoupler, in an ALS mouse model to provide preclinical proof-of-concept evidence of using DNP as a potential therapeutic drug for ALS. hSOD1 mice were treated with 0.5-1.0 mg/kg DNP through daily oral gavage from presymptomatic stage or disease onset until 18 weeks old. Longitudinal behavioral studies were performed weekly or biweekly from 6 to 18 weeks old. In situ muscle contraction measurements in extensor digitorum longus muscles were conducted to evaluate the preservation of contractile force and motor unit numbers in hSOD1 mice following DNP treatment. Muscle innervation and inflammatory markers were assessed using immunostaining. Extent of protein oxidation and activation of Akt pathway were also examined. DNP delayed disease onset; improved motor coordination and muscle performance in vivo; preserved muscle contractile function, neuromuscular junction morphology, and muscle innervation; and reduced inflammation and protein oxidation at 18 weeks old in hSOD1 mice. Strikingly, symptomatic hSOD1 mice exhibited a period of recovery in running ability at 20 cm/s several weeks after 2,4-dinitrophenol treatment started at disease onset, offering the first observation in disease phenotype reversal using a small molecule. Our results strongly support that micro-dose DNP may be used as a potential novel treatment for ALS patients, with a possibility for recovery, when used at optimal doses and time of intervention. ANN NEUROL 2024.