Co-administration of digoxin and trans-2-decenoic acid ethyl ester improves motor learning performance in mice

Neural circuit formation through synaptogenesis plays a crucial role in learning, memory, and the recovery of neural function following brain dysfunction. We previously reported that administering the low-dose cardiac glycoside digoxin, which activates brain Na/K-ATPase, promotes dendritic spine formation and improves motor learning. On the other hand, brain-derived neurotrophic factor (BDNF) is also involved in axon elongation, branching, attraction, and the maturation of dendritic spines. Since trans-2-decenoic acid ethyl ester (DAEE), an ester of medium-chain fatty acid with ten carbons, activates the signaling pathway downstream of BDNF-TrkB, co-administration of digoxin and DAEE could further improve motor learning. This study compared the effects of digoxin, DAEE, or both on motor learning performance and locomotor activity in mice. Digoxin improved early performance in the rotarod test without changing locomotor activity, but did not affect final performance. DAEE increased activity in the open-field test but had no effect on the running wheel and did not influence motor learning in the rotarod test. On the other hand, the combination of digoxin and DAEE improved performance on the rotarod test later in the study. These data indicate that combining digoxin with DAEE delays the peak effects of motor learning compared to digoxin monotherapy, a temporal shift that may offer therapeutic advantages in rehabilitation outcomes.