# L-Borneolum Attenuates Ischemic Stroke Through Remodeling BBB Transporter Function via Regulating MFSD2A/Cav-1 Signaling Pathway

## TL;DR

L-borneolum protects against stroke by improving brain barrier function through a specific signaling pathway.

## Contribution

Identifies L-borneolum's neuroprotective mechanism via MFSD2A/Cav-1 signaling in ischemic stroke.

## Key findings

- L-borneolum reduces neurological damage and cerebral infarction in stroke models.
- It enhances BBB integrity and decreases albumin leakage in brain tissue.
- MFSD2A and SREBP1 expression increases, while Cav-1 decreases with treatment.

## Abstract

Objective: This study compares the brain protective effects of L-borneolum and its main components (a combined application of L-borneol and L-camphor) on the rat model of middle cerebral artery occlusion/reperfusion (MCAO/R). It also makes clear the intrinsic regulatory mechanisms that link the neuroprotective effects of these compounds on IS to the blood-brain barrier (BBB), based on network pharmacology predictions. Furthermore, the study investigates the relationship between these compounds and the Major Facilitator Superfamily Domain-containing Protein 2A (MFSD2A)/Caveolin-1 (Cav-1) signaling axis. Methods: The MCAO/R model in rats was established to evaluate the therapeutic effect of L-borneolum (200 mg/kg) and its main components combination of L-borneol and L-camphor (6:4 ratio, 200 mg/kg). Neurological scores, 2,3,5-triphenyl tetrazolium chloride (TTC) staining, hematoxylin-eosin (HE) staining, and Nissl staining were performed to evaluate the neurological damage in the rats. Cerebral blood flow Doppler was applied to monitor the cerebral blood flow changes. Immunofluorescence analysis of albumin leakage and transmission electron microscopy (TEM) were conducted to evaluate blood-brain barrier (BBB) integrity. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the optimal drug concentration. Trans-epithelial electrical resistance (TEER) and horseradish peroxidase (HRP) assays were employed to confirm the successful establishment of an in vitro BBB co-culture model. Network pharmacology was utilized to predict the biological processes, molecular functions, and cellular components involved in the treatment of ischemic stroke (IS) by the main components of L-borneolum (L-borneol and L-camphor). Finally, immunofluorescence, real-time fluorescent quantitative PCR (RT-qPCR) and western blot analyses were performed to detect the expression of Major Facilitator Superfamily Domain Containing 2A (MFSD2A), caveolin-1 (CAV-1), sterol regulatory element-binding protein 1 (SREBP1) in brain tissue and hCMEC/D3 cells. Results: Network pharmacology prediction indicated that L-borneolum and its main components (L-borneol and L-camphor) in the treatment of IS are likely associated with vesicle transport and neuroprotection. Treatment of IS with L-borneolum and its main components significantly decreased neurological function scores and cerebral infarction area, while alleviating pathological morphological changes and increasing the number of Nissl bodies in the hippocampus. Additionally, it improved cerebral blood flow, reduced albumin leakage, and decreased vesicle counts in the brain. The trans-epithelial electrical resistance (TEER) of the co-culture model stabilized on the fifth day after co-culture, and the permeability to horseradish peroxidase (HRP) in the co-culture model was significantly lower than that of the blank chamber at this time. RT-qPCR and Western blot results demonstrated that, compared to the model group, the expression of SREBP1 and MFSD2A significantly increased, while the expression of Cav-1 decreased. Conclusions: L-borneolum and its main components combination (L-borneol/L-camphor, 6:4 ratio) may exert a protective effect in rats with IS by improving BBB transport function through modulation of the MFSD2A/Cav-1 signaling pathway.