# Danggui-Shaoyao-San modulates sphingolipid metabolism to promote oligodendrocyte differentiation and maturation in vascular dementia rats

## TL;DR

This study shows that Danggui-Shaoyao-San improves cognitive function in vascular dementia rats by promoting myelin repair through sphingolipid metabolism.

## Contribution

The study reveals a novel mechanism by which Danggui-Shaoyao-San activates the SPHK2/S1P/S1PR5 pathway to promote myelin regeneration in vascular dementia.

## Key findings

- DSS treatment improved cognitive function and reduced hippocampal and white matter damage in VaD rats.
- DSS activated the SPHK2/S1P/S1PR5 pathway, ameliorated sphingolipid metabolic disorders, and increased S1P levels.
- Albiflorin and Gallic acid from DSS formed stable interactions with SPHK2, as shown by molecular simulations.

## Abstract

Vascular dementia (VaD) is a neurodegenerative disease primarily characterized by white matter injury and myelin degeneration, and currently, there is a lack of effective treatment options. This study aims to investigate the effects of the traditional Chinese medicine formula Danggui Shaoyao San (DSS) on cognitive function and myelin repair in VaD rats and to elucidate its underlying mechanisms.

The VaD rat model was established using the bilateral common carotid artery ligation (2VO) method. The effects of DSS on cognitive function, myelin regeneration, sphingolipid metabolism, and SPHK2/S1P/S1PR5 pathway was conducted using behavioral tests, histological staining, Western blot, lipidomics, qPCR, immunofluorescence, LC–MS/MS, and 16S rRNA sequencing. Besides, molecular docking and molecular dynamics simulation were carried out.

DSS treatment significantly improved learning and memory abilities in VaD rats, reduced structural damage in the hippocampus and white matter, and promoted the differentiation of oligodendrocyte precursor cells (OPCs) into mature oligodendrocytes (OLs). Lipidomics and molecular biological experiments indicated that DSS activated the SPHK2/S1P/S1PR5 pathway, ameliorated sphingolipid metabolic disorders and increased S1P levels, thereby promoting myelin repair. The specific SPHK2 inhibitor ABC294640 significantly weakened the neuroprotective effects of DSS, further confirming the central role of SPHK2/S1P/S1PR5 pathway. Antibiotic depletion experiments confirmed that the gut microbiota was not a key mediator of the therapeutic effects of DSS. Finally, molecular docking and molecular dynamics simulations indicated that the DSS components Albiflorin and Gallic acid form tighter and more stable interactions with SPHK2.

DSS improved VaD cognitive impairment by modulating sphingolipid metabolism and promote myelin regeneration via activating the SPHK2/S1P/S1PR5 signaling pathway. This study provides important experimental evidence for the clinical application of DSS in VaD.