Therapeutic potential of calcitriol in cerebral ischemia/reperfusion injury: In vivo and in silico insights into TLR4 and FGFR2 pathways.

BACKGROUND

Cerebral ischemic injury remains a major cause of high mortality, with limited effective treatments available. Inflammatory responses play a critical role in the pathophysiology of cerebral ischemia/reperfusion (I/R) injury. Suppressing inflammation is a key strategy for mitigating cerebral I/R injury, making it a promising therapeutic target for stroke. Vitamin D supplementation has been revealed to exhibit anti-inflammatory and neuroprotective properties during I/R injury; however, the underlying protective mechanisms are not yet fully understood. This study aimed to investigate the effects of post-ischemic calcitriol treatment on ischemic stroke, focusing specifically on the TLR4/MyD88/NF-κB and FGFR2 signaling pathways.

METHODS

Male Wistar rats were divided into three main groups: sham, I/R+ Vehicle, and I/R+ Calcitriol. An experimental I/R model was created by occluding the middle cerebral artery (MCA) for 1 h, followed by a 72-h reperfusion period. Calcitriol (1 μg/kg) was administered intraperitoneally for three consecutive days post-stroke. Neurological deficit scores and infarct size were evaluated 72 h after MCAO. Gene expression levels of TLR4, MyD88, NF-κB, and FGFR2 in the brain cortex were measured using RT-PCR. Additionally, histopathological changes in the cortex were examined with Nissl staining. A molecular docking analysis was performed to investigate the interactions of calcitriol with TLR4 and FGFR2, providing insights into their binding affinities and potential functional implications.

RESULTS

Our findings indicated that calcitriol treatment significantly enhanced neurological function (P < 0.05) and reduced infarct volume (P < 0.001) in cerebral I/R injury. Furthermore, calcitriol decreased the number of damaged neurons while markedly increasing the count of neurons with normal morphology (P < 0.001). Consistent with the results from molecular docking showing that calcitriol antagonizes TLR4 and FGFR2, RT-PCR analysis also revealed that calcitriol significantly suppressed the upregulation of TLR4 (P < 0.05), MyD88 (P < 0.01), NF-κB (P < 0.01), and FGFR2 (P < 0.001) mRNA expression levels.

CONCLUSION

The results demonstrate that calcitriol treatment offers significant neuroprotective benefits following cerebral I/R injury. These protective effects may be mediated, at least in part, by the inhibition of inflammation through the TLR4/MyD88/NF-κB and FGFR2 signaling pathways. This study enhances our understanding of the molecular mechanisms involved in calcitriol's neuroprotective actions.