Diosgenin is an exogenous activator of 1,25D ₃-MARRS/Pdia3/ERp57 and improves Alzheimer's disease pathologies in 5XFAD mice

The aim of this study was to investigate the effects and the mechanism of diosgenin, a famous plant-derived steroidal sapogenin, on memory deficits in Alzheimer's disease (AD) model mice. Diosgenin-treated 5XFAD mice exhibited significantly improved performance of object recognition memory. Diosgenin treatment significantly reduced amyloid plaques and neurofibrillary tangles in the cerebral cortex and hippocampus. Degenerated axons and presynaptic terminals that were only observed in regions closely associated with amyloid plaques were significantly reduced by diosgenin treatment. The 1,25D ₃-membrane- associated, rapid response steroid-binding protein (1,25D ₃-MARRS) was shown to be a target of diosgenin. 1,25D ₃-MARRS knockdown completely inhibited diosgenin-induced axonal growth in cortical neurons. Treatment with a neutralizing antibody against 1,25D ₃-MARRS diminished the axonal regeneration effect of diosgenin in Aβ(1-42)-induced axonal atrophy. This is the first study to demonstrate that the exogenous stimulator diosgenin activates the 1,25D ₃-MARRS pathway, which may be a very critical signaling target for anti-AD therapy.