Buyang Huanwu decoction improves motor function by enhancing internal capsule reorganization through inhibiting Notch...

Buyang Huanwu Decoction (BHD) is a common traditional Chinese medicine formula that has been used for the treating post-stroke disability for centuries. Nevertheless, the impact of BHD on internal capsule injury following stroke remains unknown and warrants further investigation.

This study aimed to assess the efficacy of BHD on post-stroke internal capsule integrity by using an in vivo magnetic resonance imaging (MRI) technique and further explore the potential mechanisms by which BHD facilitates internal capsule reorganization after ischemic stroke.

Male Sprague-Dawley rats were subjected to permanent occlusion of the middle cerebral artery (MCAO) to induce focal cerebral ischemia. BHD was intragastrically administered at doses of 16.6 g/kg and 8.3 g/kg to rats once daily for 30 consecutive days. Subsequently, an automated Digi gait system was utilized to assess the motor function. MRI examinations, including T2 relaxometry mapping and diffusion tensor imaging (DTI), were conducted to detect structural alterations in the internal capsule. Moreover, diffusion tractography was performed to evaluate internal capsule remodeling. Pearson correlation analysis was conducted between the gait and MRI parameters. Additionally, luxol fast blue (LFB) staining was performed for pathological assessment of the internal capsule. Double immunofluorescence staining was carried out to evaluate remyelination and Notch signaling activation in the injured internal capsule.

The gait analysis revealed that BHD treatment significantly decreased stance time while elevating swing time, stride length, and paw area of the MCAO rats. T2 mapping indicated obvious infarction and an elevated T2 value, and DTI detected reduced fractional anisotropy but increased radial diffusivity in the internal capsule following MCAO. LFB staining further confirmed demyelination in the injured internal capsule. However, BHD interventions effectively reversed these MRI abnormalities and demyelination, and improved fiber density and length of the internal capsule. Notably, the gait performances were strongly correlated to the T2 value, fiber density, and fiber length of the internal capsule. Particularly, BHD treatments facilitated oligodendrogenesis in the internal capsule by elevating the numbers of Ki67/NG2, Ki67/Oligo2, and Ki67/CNPase positive cells. Furthermore, BHD effectively inhibited the activation of Notch signaling in the oligodendrocyte precursor cells (OPCs), as evidenced by reduced numbers of NG2/Notch1, NG2/NICD, and NG2/Hes5 positive cells.

The present study demonstrated that BHD could promote post-stroke motor recovery by alleviating structural damage to the internal capsule and facilitating internal capsule reorganization. Notably, BHD treatment enhanced oligodendrogenesis and subsequent remyelination by inhibiting Notch signaling activation in the OPCs.