Dexmedetomidine Pretreatment Improves Lipopolysaccharide-induced Iron Homeostasis Disorder in Aged Mice

Dexmedetomidine for the treatment of sepsis-associated encephalopathy: Mechanism and prospects

Sepsis-associated encephalopathy (SAE) is a severe central nervous system complication that is secondary to sepsis and is characterized by a poor prognosis, high mortality, and multiple systemic manifestations. Although the specific etiology remains incompletely understood, SAE typically presents with varying degrees of neurological dysfunction. The complex mechanisms underlying SAE significantly influence patient outcomes. Recent studies have emphasized the roles of bloodbrain barrier (BBB) disruption, microglial activation, mitochondrial dysfunction, apoptosis, inflammatory responses, and oxidative stress in the development and progression of SAE. Dexmedetomidine, a highly selective α2-adrenergic receptor agonist initially employed as an anesthetic adjunct, has attracted increasing attention for its therapeutic potential in SAE. Its notable pharmacological properties include anti-inflammatory activity, modulation of microglial responses, regulation of immune function, stabilization of mitochondrial activity, inhibition of apoptosis, and maintenance of hemodynamic stability in patients with sepsis. In addition, dexmedetomidine supports gastrointestinal homeostasis and offers multiorgan protection. This review consolidates current findings regarding the protective mechanisms of dexmedetomidine in sepsis-induced brain injury and provides insight into its potential clinical applications in the management of SAE.

Propofol and Dexmedetomidine Ameliorate Endotoxemia-Associated Encephalopathy via Inhibiting Ferroptosis

Background

Sepsis is recognized as a multiorgan and systemic damage caused by dysregulated host response to infection. Its acute systemic inflammatory response highly resembles that of lipopolysaccharide (LPS)-induced endotoxemia. Propofol and dexmedetomidine are two commonly used sedatives for mechanical ventilation in critically ill patients and have been reported to alleviate cognitive impairment in many diseases. In this study, we aimed to explore and compare the effects of propofol and dexmedetomidine on the encephalopathy induced by endotoxemia and to investigate whether ferroptosis is involved, finally providing experimental evidence for multi-drug combination in septic sedation.

Methods

A total of 218 C57BL/6J male mice (20-25 g, 6-8 weeks) were used. Morris water maze (MWM) tests were performed to evaluate whether propofol and dexmedetomidine attenuated LPS-induced cognitive deficits. Brain injury was evaluated using Nissl and Fluoro-Jade C (FJC) staining. Neuroinflammation was assessed by dihydroethidium (DHE) and DCFH-DA staining and by measuring the levels of three cytokines. The number of Iba1+ and GFAP+ cells was used to detect the activation of microglia and astrocytes. To explore the involvement of ferroptosis, the levels of ptgs2 and chac1; the content of iron, malondialdehyde (MDA), and glutathione (GSH); and the expression of ferroptosis-related proteins were investigated.

Conclusion

The single use of propofol and dexmedetomidine mitigated LPS-induced cognitive impairment, while the combination showed poor performance. In alleviating endotoxemic neural loss and degeneration, the united sedative group exhibited the most potent capability. Both propofol and dexmedetomidine inhibited neuroinflammation, while propofol's effect was slightly weaker. All sedative groups reduced the neural apoptosis, inhibited the activation of microglia and astrocytes, and relieved neurologic ferroptosis. The combined group was most prominent in combating genetic and biochemical alterations of ferroptosis. Fpn1 may be at the core of endotoxemia-related ferroptosis activation.

Inhibition of SET domain-containing (lysine methyltransferase) 7 alleviates cognitive impairment through suppressing the activation of NOD-like receptor protein 3 inflammasome in isoflurane-induced aged mice

BACKGROUND

As a common postoperative complication to elderly patients, postoperative cognitive dysfunction (POCD) is a central nervous system complication, often taking place after anesthesia and surgery. (Su(var)3-9, enhancer-of-zeste, and trithorax) domain-containing protein 7 (SETD7) plays important roles in metabolic-related diseases, viral infections, tumor formation, and some inflammatory reactions. However, the role and mechanism of SETD7 in POCD have not been previously studied.

METHODS

RT-PCR and Western blot were performed to evaluate the efficiency of knockdown of SETD7. The pathological changes of hippocampal neurons in isoflurane-anesthetized mice were detected by HE staining, and the Morris water maze experiment was performed to evaluate the learning and memory abilities of mice. The effect of SETD7 on the hippocampus in isoflurane-induced aged mice was examined by Western blot and TUNEL assay. Then ELISA assay was applied to determine the expression of some inflammatory cytokines, followed by the detection of expression of NOD-like receptor protein 3 (NLRP3) inflammasome through Western blot.

RESULTS

The data of this research revealed that SETD7 knockdown improved cognitive impairment in isoflurane-anesthetized mice, ameliorated cell pyroptosis, inhibited the release of inflammatory cytokines, and suppressed the activation of NLRP3 inflammasome in the hippocampus in isoflurane-induced aged mice.

CONCLUSION

Collectively, these results provided evidence that the inhibition of SETD7 could alleviate neuroinflammation, pyroptosis, and cognitive impairment by suppressing the activation of the NLRP3 inflammasome in isoflurane-induced aged mice.