Tetrandrine enhances cognition in SAH rats via gut microbiota CYP51 and TLR4 signaling

Subarachnoid hemorrhage (SAH) is a common cerebrovascular disease that can lead to cognitive impairment. Although tetrandrine (Tet) has been proposed as a potential therapeutic agent, its efficacy in the treatment of SAH has not been fully explored. To investigate Tet effects on SAH, a rat model was established and divided into an SAH + vehicle and an SAH + Tet group. Cognitive function and behavioral performance were assessed using the Morris water maze and open field tests. Inflammatory cytokine levels were measured by ELISA, and hippocampal injury was evaluated by hematoxylin-eosin (HE) staining. Neuronal loss was quantified using Nissl staining, while neuronal density was assessed via immunofluorescence. The expression of the TLR4/NF-κB signaling pathway related-proteins was examined by Western blotting, and 16 S rRNA sequencing was conducted to determine differences in gut microbiota composition across the groups. Tet treatment significantly reduced mNSS and SAH assessment scores in SAH rats, suggesting an improvement in neurological and cognitive function. Behavioral analysis demonstrated that Tet increased escape latency, movement speed, and total distance in the Morris water maze. Histological staining revealed attenuated hippocampal damage and decreased neuronal death in the Tet-treated group. These neuroprotective effects were accompanied by reduced expression of TLR4 and NF-κB pathway components, as well as decreased secretion of LPS, TNF-α, IL-1β, and IL-6. Notably, Tet modulated the gut microbiota, restoring microbial diversity and abundance, and this modulation was associated with changes in the CYP51 metabolic pathway. Tet improves cognitive function and reduces neuronal injury in SAH rats by regulating the gut microbiota and its associated CYP51 metabolic pathway, thereby suppressing activation of the TLR4/NF-κB signaling cascade.