Mitochondria as a target for neuroprotection: role of methylene blue and photobiomodulation

Methylene blue reduces incidence of early postoperative cognitive disorders in elderly patients undergoing major non-cardiac surgery: An open-label randomized controlled clinical trial

STUDY OBJECTIVE

The purpose of the present study was to investigate whether methylene blue (MB) could reduce the incidences of postoperative delirium (POD) and early postoperative cognitive dysfunction (POCD) in elderly patients undergoing major non-cardiac surgery.

DESIGN

Prospective, randomized, open-label clinical trial.

SETTING

University-affiliated hospital.

PATIENTS

Two hundred and forty-eight elderly patients scheduled for non-cardiac surgery.

INTERVENTIONS

Elderly patients undergoing non-cardiac major surgery were randomly assigned to MB group (n = 124), who receiving intravenous infusion of 2 mg/kg MB within 60 min immediately after anesthetic induction, or control group (n = 124), who receiving equal volume saline in the same way.

MEASUREMENTS

All patients were evaluated with delirium and neuropsychological batteries before and after surgery, as well as perioperative adverse events. Two plasma biomarkers superoxide dismutase (SOD) and homocysteine (HCY) were measured pre- and post-operatively.

MAIN RESULTS

There were total 39 cases(15.7%)experienced POD. The incidence of POD in MB group was significantly less than that in control group (7.3% vs. 24.2%, OR = 0.24, 95%CI: 0.11-0.53, p < 0.001). The incidence of early POCD at postoperative 7th day in MB group was also less than that in control group (16.1% vs. 40.2%, OR = 0.30, 95% CI: 0.16-0.57, p < 0.001). The adverse events were comparable in both groups. In addition, there was no significant correlation between POD/POCD and levels of SOD or HCY.

CONCLUSION

We conclude that intraoperative intravenous 2 mg/kg MB could significantly reduce the incidences of POD and early POCD in elderly surgical patients, while not remarkably increase incidence of perioperative adverse events, suggesting MB may be clinically effective and safe for prevention of early postoperative neurocognitive disorders.

FK866 alleviates cerebral pyroptosis and inflammation mediated by Drp1 in a rat cardiopulmonary resuscitation model

OBJECTIVES

Dynamin-related protein 1 (Drp1) mediates mitochondrial fission and triggers NLRP3 inflammasome activation. FK866 (a NAMPT inhibitor) exerts a neuroprotective effect in ischemia/reperfusion injury through the suppression of mitochondrial dysfunction. We explored the effects of FK866 on pyroptosis and inflammation mediated by Drp1 in a cardiac arrest/cardiopulmonary resuscitation (CA/CPR) rat model.

METHODS

Healthy male Sprague-Dawley rats were subjected to 7 min CA by trans-esophageal electrical stimulation followed by CPR. The surviving rats were treated with FK866 (a selective inhibitor of NAMPT), Mdivi-1 (Drp1 inhibitor), FK866 + Mdivi-1, or vehicle and then underwent 24 h reperfusion. Hematoxylin and eosin staining and immunohistochemistry (to detect NSE) were used to evaluate brain injury. We performed immunofluorescent staining to analyze NLRP3 and GSDMD expression in microglia or astrocytes and western blot to determine expression of NLRP3, IL-1β, GSDMD, Drp1, and Mfn2. Transmission electron microscopy was used to observe mitochondria.

RESULTS

FK866 significantly decreased pathological damage to brain tissue, inhibited the activation of NLRP3 in microglia or astrocytes, downregulated the expression of NLRP3, IL-1β, GSDMD, p-Drp1 protein, upregulated Mfn2 and improve mitochondrial morphology.

CONCLUSIONS

Our results demonstrated that FK866 protects the brain against ischemia-reperfusion injury in rats after CA/CPR by inhibiting pyroptosis and inflammation mediated by Drp1.