Vitamin B12 combined with methylene blue alleviates experimental septic shock and is associated with modulation of KCNMB1 and the cGMP-PRKG pathway.

Abstract

Septic shock is characterized by severe circulatory failure, microvascular dysfunction, and metabolic derangement. Methylene blue (MB) and vitamin B12 (VB12) have each shown potential benefit in vasodilatory shock, but the biological effects of their combined use remain unclear. A rat model of LPS-induced septic shock was used to evaluate the effects of combined MB and VB12 pretreatment. Transcriptomic analysis of carotid artery tissue was performed to identify treatment-responsive genes and pathways. Expression of KCNMB1, PRKG1, and PRKG2 was assessed by immunohistochemistry, western blotting, and RT-qPCR. Hemodynamic parameters, circulating injury markers, inflammatory cytokines, oxidative stress indices, and histological changes in major organs were also evaluated. Combined MB and VB12 treatment was associated with lower expression of KCNMB1, PRKG1, and PRKG2 and reduced cGMP levels compared with the model group. The combined treatment also partially improved hemodynamic abnormalities, reduced NO, H2S, and lactate levels, and attenuated inflammatory and oxidative stress responses. Histological injury in the lung, liver, kidney, and carotid artery was also alleviated. In this experimental model, combined MB and VB12 pretreatment attenuated multiple features of septic shock and was accompanied by modulation of KCNMB1 and cGMP-PRKG pathway-related markers. These findings support a potential protective role of the combined regimen, although the causal mechanistic relationship requires further investigation.