Vitamin B12 combined with methylene blue prevents septic shock by regulating KCNMB1 and cGMP-PRKG pathway

Background Septic shock, a severe manifestation of sepsis, is characterized by profound circulatory collapse, microvascular dysfunction, and metabolic derangement, contributing to high mortality and healthcare burden worldwide. Methylene blue (MB) and vitamin B12 (VB12) have independently shown promise in modulating PRKG. However, the synergistic effects and underlying mechanisms of their combined use remain poorly defined. Method A rat model of septic shock was established to evaluate the prophylactic efficacy of MB and VB12 co-administration. Transcriptomic analyses of carotid artery tissues were performed to identify differentially expressed genes and related pathways. The expression levels of KCNMB1, PRKG1, and PRKG2 were validated by immunohistochemistry, Western blotting, and qPCR. Cardiovascular parameters, systemic inflammatory markers, oxidative stress indices, and histological changes in major organs were comprehensively assessed by HE staining, ELISA and biochemical assay. Results Combined MB and VB12 treatment significantly modulated the expression of KCNMB1 and cGMP/PRKG pathway-related genes compared to monotherapies. This co-administration more effectively improved cardiac output, stabilized mean arterial pressure, and reduced systemic NO, H ₂ S, and lactate levels. Histopathological analyses showed attenuated tissue injury and inflammatory cell infiltration in the lungs, liver, kidneys, and vasculature. Moreover, circulating cytokines and oxidative stress markers were markedly decreased with combination therapy. Conclusion Prophylactic co-administration of MB and VB12 confers synergistic protective effects against septic shock by modulating the KCNMB1 and cGMP/PRKG pathways, improving hemodynamic stability, and reducing organ injury.