The potential role of dexmedetomidine on neuroprotection and its possible mechanisms: Evidence from in vitro and in vivo studies

The alpha2-adrenoceptor agonist clonidine protects against hypoxic-ischemic brain damage in neonatal mice through the Nrf2/NF-κB signaling pathway

Neonatal hypoxic-ischemic brain damage (HIBD) is a severe condition closely associated with neuroinflammation and oxidative stress. Clonidine, a selective α2-adrenergic receptor agonist, is known for its anti-inflammatory and antioxidant properties. Despite these recognized therapeutic benefits, the exact mechanisms by which clonidine exerts its effects in the context of HIBD are not fully understood. This study was designed to thoroughly investigate the impact of clonidine on HIBD-induced neuronal injury and to clarify its underlying mechanism of action. We employed a neonatal mouse model of HIBD to meticulously assess the effects of clonidine on neuronal injury, apoptosis, inflammation, and oxidative stress markers. In addition, we conducted extensive in vitro studies to evaluate the neuroprotective effects of clonidine on primary hippocampal neuronal cells, utilizing advanced techniques such as the Cell Counting Kit-8 (CCK-8), flow cytometry, enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay, and western blotting. Furthermore, we explored the regulatory effects of clonidine on the nuclear factor erythroid 2-related factor (Nrf2)/nuclear factor-κB (NF-κB) signaling pathway through a combination of in vivo and in vitro experiments. The results showed that clonidine significantly reduced cerebral infarction, neuronal damage, and apoptosis in HIBD mice. It also alleviated neuroinflammation and oxidative stress, improved cell viability, and reduced neuronal injury following oxygen-glucose deprivation/reoxygenation (OGD/R). The neuroprotective effects of clonidine were linked to the activation of the Nrf2/heme oxygenase-1 (HO-1) pathway and the inhibition of the NF-κB pathway. Overall, clonidine exhibited neuroprotective properties in HIBD by reducing neuroinflammation and oxidative stress, likely through the modulation of the Nrf2/NF-κB signaling pathway.

Dexmedetomidine decreases cerebral hyperperfusion incidence following carotid stenting: A double-blind, randomized controlled trial

BACKGROUND

Cerebral hyperperfusion syndrome (CHS) is a severe complication after carotid artery stenting (CAS). Dexmedetomidine (Dex) is an α2 adrenoceptor agonist with sedative, analgesic, and neuroprotective properties. This randomized, double-blind, placebo-controlled trial (ChiCTR1900024416) aims to investigate whether prophylactic low-dose Dex decreases CH-induced brain injury following CAS.

METHODS

After obtaining written informed consent, patients aged 18-80 who underwent CAS were enrolled between July 2019 and October 2022. Patients were randomly assigned to receive either intravenous Dex (0.1 μg/kg/h, until post-operative day 3) (n = 80) or placebo (normal saline) (n = 80). The primary endpoint was the incidence of CH and CHS assessed up to the third post-operative day. The secondary endpoints included National Institute of Health Stroke Scale (NIHSS) and Modified Rankin Scale (mRS) scores within 30 days of operation, extubation time, discharge from the hospital within 7 days post-operation, length of hospital stay post-operation, and all-cause 30-day mortality. Blood samples were collected before and after surgery for lipidomics, brain-derived neurotrophic factor (BDNF), and neurofilament light chain (Nfl) measurements. Acceptability, safety, and efficacy were evaluated by Cox model and logistic model.

FINDINGS

CH occurred in 30 (37.5%) of 80 patients who received a placebo compared to 9 (11.2%) of 80 patients given Dex (prevalence: odds ratio [OR]: 0.21, 95% confidence interval [CI]: 0.088-0.467; p < 0.001; incidence: hazard ratio [HR]: 0.27, 95% CI: 0.14-0.50; p < 0.001). CHS was significantly higher in the placebo group (13.75%) than in the Dex group (2.5%) (prevalence: [OR]: 0.161, 95% CI: 0.024-0.626; p = 0.020; incidence: [HR]: 0.17, 95% CI: 0.06-0.52; p = 0.009). Dex significantly upregulated BDNF, decreased Nfl, and uniquely increased lysophosphatidylethanolamine.

CONCLUSIONS

A low prophylactic dose of Dex significantly reduced the incidence of CH and CHS up to 72 h after CAS.

FUNDING

This work was funded by National Natural Science Foundation of China (no. 82271288) and the Henan Provincial Science and Technology Research Project (nos. 242300421192 and JQRC2023004).

TREK-1 channel as a therapeutic target for dexmedetomidine-mediated neuroprotection in cerebral ischemia

Our objective is to explore the protective effect of Dexmedetomidine on brain apoptosis and its mechanism through TREK-1 pathway. Forty male Sprague-Dawley rats were allocated into four groups: Sham, Cerebral Ischemia/Reperfusion Injury (CIRI), 50 µg/kg Dex, and 100 µg/kg Dex. A rat model of middle cerebral artery occlusion (MCAO) was employed to simulate cerebral embolism. Primary cortical neurons were exposed to Dex for 48 h, with some receiving additional treatment with 100 µM yohimbine hydrochloride (YOH) or TREK-1 small interfering RNA (siRNA). Neuronal damage was assessed using hematoxylin and eosin (HE) staining. Cell viability and apoptosis were measured by Cell Counting Kit-8 (CCK8) and flow cytometry, respectively. Protein and gene expression levels of Bcl-2, Bax, and TREK-1 were determined by Western blot and real-time polymerase chain reaction (PCR). Histopathological changes revealed that Dex treatment at both 50 µg/kg and 100 µg/kg significantly mitigated neuronal damage compared to the CIRI group. YOH treatment and Trek1 siRNA significantly reduced cell viability (p < 0.05). The mRNA expression and protein levels of TREK-1 and Bax were remarkably increased, while mRNA expression and protein levels of Bcl-2 was seriously decreased after CIRI modeling. In contrast, Dex treatment at both concentrations led to decreased TREK-1 and Bax expression and increased Bcl-2 expression in primary cortical neurons. Addition of 100 µM YOH and Trek1 siRNA reversed the effects of Dex on apoptosis-related genes (p < 0.05). Dex exerts neuroprotective effects through the TREK-1 pathway in vivo and in vitro.

Application value of dexmedetomidine in anesthesia for elderly patients undergoing radical colon cancer surgery

BACKGROUND

Colon cancer presents a substantial risk to the well-being of elderly people worldwide. With advancements in medical technology, surgical treatment has become the primary approach for managing colon cancer patients. However, due to age-related physiological changes, especially a decline in cognitive function, older patients are more susceptible to the effects of surgery and anesthesia, increasing the relative risk of postoperative cognitive dysfunction (POCD). Therefore, in the surgical treatment of elderly patients with colon cancer, it is of paramount importance to select an appropriate anesthetic approach to reduce the occurrence of POCD, protect brain function, and improve surgical success rates.

AIM

To explore the value of dexmedetomidine (Dex) in anesthesia for elderly patients undergoing radical colon cancer surgery.

METHODS

One hundred and seventeen patients with colon cancer who underwent elective surgery under general anesthesia were selected and divided into two groups: A and B. Group A received Dex before anesthesia induction, and B group received an equivalent amount of normal saline. Changes in the mini-mental state examination, regional cerebral oxygen saturation (rSO2), bispectral index, glucose uptake rate (GluER), lactate production rate (LacPR), serum S100β and neuron-specific enolase (NSE), POCD, and adverse anesthesia reactions were compared between the two groups.

RESULTS

Surgical duration, duration of anesthesia, and intraoperative blood loss were comparable between the two groups (P > 0.05). The overall dosage of anesthetic drugs used in group A, including propofol and remifentanil, was significantly lower than that used in group B (P < 0.05). Group A exhibited higher rSO2 values at the time of endotracheal intubation, 30 min after the start of surgery, and immediately after extubation, higher GluER values and lower LacPR values at the time of endotracheal intubation, 30 min after the start of surgery, immediately after extubation, and 5 min after extubation (P < 0.05). Group A exhibited lower levels of serum S100β and NSE 24 h postoperatively and a lower incidence of cognitive dysfunction on the 1st and 5th postoperative days (P < 0.05).

CONCLUSION

The use of Dex in elderly patients undergoing radical colon cancer surgery helps maintain rSO2 Levels and reduce cerebral metabolic levels and the incidence of anesthesia- and surgery-induced cognitive dysfunction.

Brain protective effect of dexmedetomidine vs propofol for sedation during prolonged mechanical ventilation in non-brain injured patients

BACKGROUND

Dexmedetomidine and propofol are two sedatives used for long-term sedation. It remains unclear whether dexmedetomidine provides superior cerebral protection for patients undergoing long-term mechanical ventilation.

AIM

To compare the neuroprotective effects of dexmedetomidine and propofol for sedation during prolonged mechanical ventilation in patients without brain injury.

METHODS

Patients who underwent mechanical ventilation for > 72 h were randomly assigned to receive sedation with dexmedetomidine or propofol. The Richmond Agitation and Sedation Scale (RASS) was used to evaluate sedation effects, with a target range of -3 to 0. The primary outcomes were serum levels of S100-β and neuron-specific enolase (NSE) every 24 h. The secondary outcomes were remifentanil dosage, the proportion of patients requiring rescue sedation, and the time and frequency of RASS scores within the target range.

RESULTS

A total of 52 and 63 patients were allocated to the dexmedetomidine group and propofol group, respectively. Baseline data were comparable between groups. No significant differences were identified between groups within the median duration of study drug infusion [52.0 (IQR: 36.0-73.5) h vs 53.0 (IQR: 37.0-72.0) h, P = 0.958], the median dose of remifentanil [4.5 (IQR: 4.0-5.0) μg/kg/h vs 4.6 (IQR: 4.0-5.0) μg/kg/h, P = 0.395], the median percentage of time in the target RASS range without rescue sedation [85.6% (IQR: 65.8%-96.6%) vs 86.7% (IQR: 72.3%-95.3), P = 0.592], and the median frequency within the target RASS range without rescue sedation [72.2% (60.8%-91.7%) vs 73.3% (60.0%-100.0%), P = 0.880]. The proportion of patients in the dexmedetomidine group who required rescue sedation was higher than in the propofol group with statistical significance (69.2% vs 50.8%, P = 0.045). Serum S100-β and NSE levels in the propofol group were higher than in the dexmedetomidine group with statistical significance during the first six and five days of mechanical ventilation, respectively (all P < 0.05).

CONCLUSION

Dexmedetomidine demonstrated stronger protective effects on the brain compared to propofol for long-term mechanical ventilation in patients without brain injury.

Dexmedetomidine During Therapeutic Hypothermia: A Multicenter Quality Initiative

OBJECTIVES

Sedation is typically used during neonatal therapeutic hypothermia (TH). This report describes a quality improvement (QI) initiative with the aim of decreasing opioid exposure during TH by implementing dexmedetomidine as the primary sedative agent.

METHODS

This dual-center QI initiative used a multidisciplinary team to create a sedation algorithm for safe implementation of dexmedetomidine as first-line therapy during TH. The primary measure in this initiative was cumulative opioid exposure during TH; balancing measures included safety parameters, primarily the rate of dexmedetomidine discontinuation because of bradycardia. Baseline demographic and clinical data were collected retrospectively for the period before implementation and prospectively during the QI period. Data were analyzed using statistical process control charts to identify change over time.

RESULTS

One-hundred and fifty-four neonates in the 2-year pre-QI period were compared with 135 neonates in the 2 years after guideline implementation. Guideline compliance with dexmedetomidine initiation was 99% and compliance with initial dosing increased from 70% to 91% during the QI period. The cumulative dose of opioid during TH decreased by >90% by the end of the QI period. Dexmedetomidine was discontinued for transient bradycardia in 9.6% of the study population. No other adverse effects were observed.

CONCLUSIONS

Dexmedetomidine may be used as the primary sedative during neonatal TH with a low incidence of adverse effects. Clinical trials evaluating the impact of sedation during TH on neurologic outcomes are needed.

The effects of dexmedetomidine on trauma-induced secondary injury in rat brain

BACKGROUND

The objective of this study was to investigate the effect of dexmedetomidine (Dex), a sedative drug with little or no depressant effect on respiratory centers, on secondary injury in rat brain tissue by means of the Na+/K+ ATPase enzyme, which maintains the cell membrane ion gradient; malondialdehyde, an indicator of membrane lipid peroxidation; glutathione, an indicator of antioxidant capacity; and histopathological analyses.

METHODS

Eighteen rats were randomized into three groups: the trauma group received anesthesia, followed by head trauma with a Mild Traumatic Brain Injury Apparatus; the Trauma+Dex group received an additional treatment of 100 µg/kg intraperitoneal dexmedetomidine daily for three days; the Control group received anesthesia only.

RESULTS

The highest MDA levels compared to the Control group were found in the Trauma group. Mean levels in the Trauma+Dex group were lower, albeit still significantly high compared to the Control group. Glutathione levels were similar in all groups. Na/K-ATPase levels were significantly lower in the Trauma group compared to both the Control group and the Trauma+Dex group. Histopathologic findings of tissue degeneration including edema, vascular congestion and neuronal injury, and cleaved caspase-3 levels were lower in the Trauma+Dex group compared with the Trauma group.

CONCLUSIONS

Dexmedetomidine administered during the early stage of traumatic brain injury may inhibit caspase-3 cleavageHowever, the mechanism does not seem to be related to the improvement of MDA or GSH levels.

Analgesia and sedation strategies in neonates undergoing whole-body therapeutic hypothermia: A scoping review

BACKGROUND

Therapeutic hypothermia (TH) is a widely practiced neuroprotective strategy for neonates with hypoxic-ischemic encephalopathy. Induced hypothermia is associated with shivering, cold pain, agitation, and distress.

OBJECTIVE

This scoping review determines the breadth of research undertaken for pain and stress management in neonates undergoing hypothermia therapy, the pharmacokinetics of analgesic and sedative medications during hypothermia and the effect of such medication on short- and long-term neurological outcomes.

METHODS

We searched the following online databases namely, (i) MEDLINE, (ii) Web of Science, (iii) Cochrane Library, (iv) Scopus, (v) CINAHL, and (vi) EMBASE to identify published original articles between January 2005 and December 2022. We included only English full-text articles on neonates treated with TH and reported the sedation/analgesia strategy used. We excluded articles that reported TH on transport or extracorporeal membrane oxygenation, did not report the intervention strategies for sedation/analgesia, and reported hypoxic-ischemic encephalopathy in which hypothermia was not applied.

RESULTS

The eligible publications (n = 97) included cohort studies (n = 72), non-randomized experimental studies (n = 2), pharmacokinetic studies (n = 4), dose escalation feasibility trial (n = 1), cross-sectional surveys (n = 5), and randomized control trials (n = 13). Neonatal Pain, Agitation, and Sedation Scale (NPASS) is the most frequently used pain assessment tool in this cohort. The most frequently used pharmacological agents are opioids (Morphine, Fentanyl), benzodiazepine (Midazolam) and Alpha2 agonists (Dexmedetomidine). The proportion of neonates receiving routine sedation-analgesia during TH is center-specific and varies from 40-100% worldwide. TH alters most drugs' metabolic rate and clearance, except for Midazolam. Dexmedetomidine has additional benefits of thermal tolerance, neuroprotection, faster recovery, and less likelihood of seizures. There is a wide inter-individual variability in serum drug levels due to the impact of temperature, end-organ dysfunction, postnatal age, and body weight on drug metabolism.

CONCLUSIONS

No multidimensional pain scale has been tested for reliability and construct validity in hypothermic encephalopathic neonates. There is an increasing trend towards using routine sedation/analgesia during TH worldwide. Wide variability in the type of medication used, administration (bolus versus infusion), and dose ranges used emphasizes the urgent need for standardized practice recommendations and guidelines. There is insufficient data on the long-term neurological outcomes of exposure to these medications, adjusted for underlying brain injury and severity of encephalopathy. Future studies will need to develop framework tools to enable precise control of sedation/analgesia drug exposure customized to individual patient needs.

Dexmedetomidine compared to low-dose ketamine better protected not only the brain but also the lungs in acute ischemic stroke

BACKGROUND

Dexmedetomidine (DEX) and low-dose ketamine (KET) present neuroprotective effects in acute ischemic stroke (AIS); however, to date, no studies have evaluated which has better protective effects not only on the brain but also lungs in AIS.

METHODS

AIS-induced Wistar rats (390 ± 30 g) were randomized after 24-h, receiving dexmedetomidine (STROKE-DEX, n = 10) or low-dose S(+)-ketamine (STROKE-KET, n = 10). After 1-h protective ventilation, perilesional brain tissue and lungs were removed for histologic and molecular biology analysis. STROKE animals (n = 5), receiving sodium thiopental but not ventilated, had brain and lungs removed for molecular biology analysis. Effects of DEX and KET mean plasma concentrations on alveolar macrophages, neutrophils, and lung endothelial cells, extracted primarily 24-h after AIS, were evaluated.

RESULTS

In perilesional brain tissue, apoptosis did not differ between groups. In STROKE-DEX, compared to STROKE-KET, tumor necrosis factor (TNF)-α and vascular cell adhesion molecule-1 (VCAM-1) expressions were reduced, but no changes in nuclear factor erythroid 2-related factor-2 (Nrf2) and super oxide dismutase (SOD)-1 were observed. In lungs, TNF-α and VCAM-1 were reduced, whereas Nrf2 and SOD-1 were increased in STROKE-DEX. In alveolar macrophages, TNF-α and inducible nitric oxide synthase (M1 macrophage phenotype) were lower and arginase and transforming growth factor-β (M2 macrophage phenotype) higher in STROKE-DEX. In lung neutrophils, CXC chemokine receptors (CXCR2 and CXCR4) were higher in STROKE-DEX. In lung endothelial cells, E-selectin and VCAM-1 were lower in STROKE-DEX.

CONCLUSIONS

In the current AIS model, dexmedetomidine compared to low-dose ketamine reduced inflammation and endothelial cell damage in both brain and lung, suggesting greater protection.

Dexmedetomidine in the Treatment of Depression: An Up-to-date Narrative Review

Depressive disorders (DD) are common, and their prevalence is expected to rise over the next decade. Depressive disorders are linked to significant morbidity and mortality. The clinical conundrum of depressive disorders lies in the heterogeneity of their phenomenology and etiology. Further, the currently available antidepressants have several limitations, including a delayed onset of action, limited efficacy, and an unfavorable side effect profile. In this review, Dexmedetomidine (DEX), a highly selective and potent α2-adrenergic receptor (α2-AR) agonist, is proposed as a potentially novel antidepressant with multiple mechanisms of action targeting various depression pathophysiological processes. These mechanisms include modulation of the noradrenergic system, regulation of neuroinflammation and oxidative stress, influence on the Brain-Derived Neurotrophic Factor (BDNF) levels, and modulation of neurotransmitter systems, such as glutamate. The review begins with an introduction before moving on to a discussion of DEX's pharmacological features. The pathophysiological and phenomenological targets of DD are also explored, along with the review of the existing preclinical and clinical evidence for DEX's putative anti-depressant effects. Finally, the review ends by presenting the pertinent conclusions and future directions.

MicroRNA-323-5p Involved in Dexmedetomidine Preconditioning Impart Neuroprotection

Background and Objectives: Cerebral ischemia is one of the major preoperative complications. Dexmedetomidine is a well-known sedative-hypnotic agent that has potential organ-protective effects. We examine the miRNAs associated with preconditioning effects of dexmedetomidine in cerebral ischemia. Materials and Methods: Transient infarcts were induced in mice via reperfusion after temporary occlusion of one side of the middle cerebral artery. A subset of these mice was exposed to dexmedetomidine prior to cerebral infarction and miRNA profiling of the whole brain was performed. We administered dexmedetomidine and miRNA-323-5p mimic/inhibitor to oxygen-glucose deprivation/reoxygenation astrocytes. Additionally, we administered miR-323-5p mimic and inhibitor to mice via intracerebroventricular injection 2 h prior to induction of middle cerebral artery occlusion. Results: The infarct volume was significantly lower in the dexmedetomidine-preconditioned mice. Analysis of brain samples revealed an increased expression of five miRNAs and decreased expression of three miRNAs in the dexmedetomidine-pretreated group. The viability of cells significantly increased and expression of miR-323-5p was attenuated in the dexmedetomidine-treated oxygen-glucose deprivation/reoxygenation groups. Transfection with anti-miR-323-5p contributed to increased astrocyte viability. When miRNA-323-5p was injected intraventricularly, infarct volume was significantly reduced when preconditioned with the miR-323-5p inhibitor compared with mimic and negative control. Conclusions: Dexmedetomidine has a protective effect against transient neuronal ischemia-reperfusion injury and eight specific miRNAs were profiled. Also, miRNA-323-5p downregulation has a cell protective effect under ischemic conditions both in vivo and in vitro. Our findings suggest the potential of the miR-323-5p inhibitor as a therapeutic agent against cerebral infarction.

Sedation Therapy in Intensive Care Units: Harnessing the Power of Antioxidants to Combat Oxidative Stress

In critically ill patients requiring intensive care, increased oxidative stress plays an important role in pathogenesis. Sedatives are widely used for sedation in many of these patients. Some sedatives are known antioxidants. However, no studies have evaluated the direct scavenging activity of various sedative agents on different free radicals. This study aimed to determine whether common sedatives (propofol, thiopental, and dexmedetomidine (DEX)) have direct free radical scavenging activity against various free radicals using in vitro electron spin resonance. Superoxide, hydroxyl radical, singlet oxygen, and nitric oxide (NO) direct scavenging activities were measured. All sedatives scavenged different types of free radicals. DEX, a new sedative, also scavenged hydroxyl radicals. Thiopental scavenged all types of free radicals, including NO, whereas propofol did not scavenge superoxide radicals. In this retrospective analysis, we observed changes in oxidative antioxidant markers following the administration of thiopental in patients with severe head trauma. We identified the direct radical-scavenging activity of various sedatives used in clinical settings. Furthermore, we reported a representative case of traumatic brain injury wherein thiopental administration dramatically affected oxidative-stress-related biomarkers. This study suggests that, in the future, sedatives containing thiopental may be redeveloped as an antioxidant therapy through further clinical research.

Dexmedetomidine Improves Anxiety-like Behaviors in Sleep-Deprived Mice by Inhibiting the p38/MSK1/NFκB Pathway and Reducing Inflammation and Oxidative Stress

(1) Background: Sleep deprivation (SD) triggers a range of neuroinflammatory responses. Dexmedetomidine can improve sleep deprivation-induced anxiety by reducing neuroinflammatory response but the mechanism is unclear; (2) Methods: The sleep deprivation model was established by using an interference rod device. An open field test and an elevated plus maze test were used to detect the emotional behavior of mice. Mouse cortical tissues were subjected to RNA sequence (RNA-seq) analysis. Western blotting and immunofluorescence were used to detect the expression of p38/p-p38, MSK1/p-MSK1, and NFκBp65/p- NFκBp65. Inflammatory cytokines were detected using enzyme-linked immunosorbent assay (ELISA); (3) Results: SD triggered anxiety-like behaviors in mice and was closely associated with inflammatory responses and the MAPK pathway (as demonstrated by transcriptome analysis). SD led to increased expression levels of p-p38, p-MSK1, and p-NFκB. P38 inhibitor SB203580 was used to confirm the important role of the p38/MSK1/NFκB pathway in SD-induced neuroinflammation. Dexmedetomidine (Dex) effectively improves emotional behavior in sleep-deprived mice by attenuating SD-induced inflammatory responses and oxidative stress in the cerebral cortex, mainly by inhibiting the activation of the p38/MSK1/NFκB pathway; (4) Conclusions: Dex inhibits the activation of the p38/MSK1/NFκB pathway, thus attenuating SD-induced inflammatory responses and oxidative stress in the cerebral cortex of mice.

Effect of perioperative application of dexmedetomidine on post-operative stress reaction, pain and prognostic adverse effects in patients undergoing gynaecological laparoscopy

Introduction

The aim of this study was to analyse the effect of perioperative dexmedetomidine (DEX) application on stress response, post-operative pain and prognosis in patients undergoing gynaecologic laparoscopy.

Patients and Methods

One hundred and sixty-eight patients admitted for gynaecologic laparoscopic surgery from May 2020 to November 2022 were included in the study. The patients were randomly divided into pre-operative DEX group (n = 56), intraoperative DEX group (n = 56) and post-operative DEX group (n = 56) according to the application of DEX in the perioperative period. The visual analogue scale (VAS), time awake, extubation time, pneumoperitoneum time, post-anaesthesia care unit (PACU) stay time and Richmond agitation-sedation scale score (RASS) were recorded.

Results

Patients in both the pre-operative and intraoperative DEX groups had substantially shorter wakeup and extubation times than those in the post-operative DEX group. Patients in the pre-operative DEX group had considerably shorter wakeup and extubation times than those in the intraoperative DEX group, and their pneumoperitoneum time was significantly shorter than that of the post-operative DEX group (P < 0.001). The RASS scores of the pre-operative DEX group and intraoperative DEX group were significantly lower than those of the post-operative DEX group at 1 h, 6 h and 12 h after surgery. Meanwhile, at all time periods, the RASS scores of patients in the pre-operative DEX group were considerably lower than those in the intraoperative DEX group (P < 0.01). The VAS scores of patients in the pre-operative DEX group and intraoperative DEX group were evidently lower than those in the post-operative DEX group at 0.5 h, 2 h and 12 h postoperatively, and the VAS scores of patients in the pre-operative DEX group were markedly lower than those in the intraoperative DEX group (P < 0.001). The incidence of nausea and vomiting was significantly lower in the pre-operative DEX group than in the intraoperative DEX group and the post-operative DEX group at 0-2 h, >2-12 h and >12-24 h postoperatively (P < 0.001). The incidence of nausea and vomiting in the intraoperative DEX group was significantly lower than that in the post-operative DEX group from 0 to 2 h after surgery (P < 0.05). The incidence of adverse reactions was not significantly different amongst the three groups of patients (P > 0.05).

Conclusion

Pre-operative and intraoperative application of DEX can help reduce post-operative pain and stress responses, help patients recover quickly after surgery and improve patient prognosis, especially the pre-operative application of DEX.

Dexmedetomidine Alters the Inflammatory Profile of Rat Microglia In Vitro

BACKGROUND

Microglia are a primary mediator of the neuroinflammatory response to neurologic injury, such as that in traumatic brain injury. Their response includes changes to their cytokine expression, metabolic profile, and immunophenotype. Dexmedetomidine (DEX) is an α2 adrenergic agonist used as a sedative in critically ill patients, such as those with traumatic brain injury. Given its pharmacologic properties, DEX may alter the phenotype of inflammatory microglia.

METHODS

Primary microglia were isolated from Sprague-Dawley rats and cultured. Microglia were activated using multiple mediators: lipopolysaccharide (LPS), polyinosinic-polycytidylic acid (Poly I:C), and traumatic brain injury damage-associated molecular patterns (DAMP) from a rat that sustained a prior controlled cortical impact injury. After activation, cultures were treated with DEX. At the 24-h interval, the cell supernatant and cells were collected for the following studies: cytokine expression (tumor necrosis factor-α [TNFα], interleukin-10 [IL-10]) via enzyme-linked immunosorbent assay, 6-phosphofructokinase enzyme activity assay, and immunophenotype profiling with flow cytometry. Cytokine expression and metabolic enzyme activity data were analyzed using two-way analysis of variance. Cell surface marker expression was analyzed using FlowJo software.

RESULTS

In LPS-treated cultures, DEX treatment decreased the expression of TNFα from microglia (mean difference = 121.5 ± 15.96 pg/mL; p < 0.0001). Overall, DEX-treated cultures had a lower expression of IL-10 than nontreated cultures (mean difference = 39.33 ± 14.50 pg/mL, p < 0.0001). DEX decreased IL-10 expression in LPS-stimulated microglia (mean difference = 74.93 ± 12.50 pg/mL, p = 0.0039) and Poly I:C-stimulated microglia (mean difference = 23.27 ± 6.405 pg/mL, p = 0.0221). In DAMP-stimulated microglia, DEX decreased the activity of 6-phosphofructokinase (mean difference = 18.79 ± 6.508 units/mL; p = 0.0421). The microglial immunophenotype was altered to varying degrees with different inflammatory stimuli and DEX treatment.

CONCLUSIONS

DEX may alter the neuroinflammatory response of microglia. By altering the microglial profile, DEX may affect the progression of neurologic injury.

Application of dexmedetomidine combined with ultrasound-guided transverse abdominal fascia block during radical colorectal cancer surgery under general anesthesia

BACKGROUND

Radical surgery is the main treatment for colorectal cancer, and effective anaesthesia is required in the perioperative period to ensure a smooth operation. Dexmedetomidine is a commonly used anaesthetic drug, but the optimal dose for general anaesthesia in radical colorectal cancer surgery is still unknown.

AIM

To investigate the application of different doses of dexmede-tomidine combined with ultrasound-guided transverse abdominal fascial block in radical colorectal cancer surgery under general anesthesia.

METHODS

Two hundred patients proposed for radical colorectal cancer surgery under general anesthesia at our hospital from October 2017 to September 2022 were selected and divided into three groups (A, B, and C) using the random number table method. Sixty-seven patients in group A were given 0.5 μg/kg dexmedetomidine, 67 patients in group B were given 0.25 μg/kg dexmedetomidine, and 66 patients in group C were given an equal dose of saline. The vital signs [heart rate (HR), oxygen saturation (SaO₂), and mean arterial pressure (MAP)] before induction of anesthesia (T0), after dexmedetomidine injection (T1), 1 h after the start of surgery (T2), and immediately after the end of surgery (T3), the visual analog scale (VAS) scores at 6 h, 12 h, and 24 h after surgery, the number of analgesic pump compressions at 24 h after surgery, the number of times of remedial analgesia, the levels of immune cytokines [tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), and interleukin-10 (IL-10)], serum neurotransmitter [serum S100B protein (S100B), serum neuron-specific enolase (NSE), and serum brain-derived neurotrophic factor (BDNF)] before surgery and 12 h and 24 h after surgery, and adverse effects were recorded.

RESULTS

There was no statistically significant difference in SaO₂ among the three groups from T0 to T3 (P > 0.05), and HR and MAP at T1 and T2 were lower in group A than in groups B and C, and in group B than in group C (P < 0.05). VAS scores in group A were lower than those in groups B and C at 6 h, 12 h, and 24 h postoperatively, and the number of analgesic pump compressions and times of remedial analgesia at 24 h postoperatively were less in group A than in groups B and C (P < 0.05), and in group B than in group C (P < 0.05). Serum TNF-α and IL-10 at 12 h and 24 h postoperatively were lower in group A than in groups B and C, and IL-2 was higher than in groups B and C; these indexes in group B were superior to those in group C (P < 0.05). Serum S100B and NSE at 12 h postoperatively were lower in group A than in groups B and C, and BDNF was higher than in groups B and C; these indexes in group B were superior to those in group C (P < 0.05). The differences in the incidence of adverse reactions were not statistically significant among the three groups (P > 0.05).

CONCLUSION

Compared with 0.25 μg/kg dexmedetomidine, 0.5 μg/kg dexmedetomidine combined with ultrasound-guided transverse abdominal fascial block for radical colorectal cancer surgery under general anesthesia can more effectively maintain the stability of patients' vital signs, with less impact on patients' immune function and neurological function, and better postoperative analgesia without increasing the risk of adverse effects.

Dexmedetomidine alleviates cerebral ischemia-reperfusion injury via inhibiting autophagy through PI3K/Akt/mTOR pathway

Dexmedetomidine has been shown to protect against cerebral ischemia-reperfusion injury (CIRI). Nevertheless, the precise mechanism is obscure. In order to explore the effect of dexmedetomidine pre-conditioning on autophagy against CIRI in rats, middle cerebral artery occlusion (MCAO) was conducted to establish cerebral ischemia-reperfusion (I/R) model in male SD rats with 2 h ischemia and 24 h reperfusion. Dexmedetomidine was delivered to rats at 10, 50 and 100 µg/kg doses respectively, and LY294002, a PI3K/Akt/mTOR pathway inhibitor, was administered at 10 mg/kg intraperitoneally 30 min before MCAO. Neurological deficit score was assessed and cerebral infarct size was detected by TTC staining. Morris water maze (MWM) was performed to estimate spatial learning and memory ability. Furthermore, to detect activity of PI3K/Akt/mTOR pathway and autophagy, p-Akt, p-mTOR, Beclin-1 and LC3 were measured by western blot. Our findings revealed that 50 and 100 µg/kg of dexmedetomidine pretreatment could improve the neurological deficit score and reduce cerebral infarct size after CIRI, while these effects were markedly suppressed by LY294002. In MWM test, dexmedetomidine was confirmed to shorten escape latency and increase times across platform after CIRI. Nevertheless, LY294002 pretreatment eliminated the improvement of dexmedetomidine on spatial learning and memory ability. Furthermore, dexmedetomidine pretreatment reduced ratios of Beclin-1 and LC3II/LC3I and elevated p-Akt/Akt and p-mTOR/mTOR after CIRI. However, above effects of dexmedetomidine were partly reversed by LY294002. Overall, dexmedetomidine pretreatment exerted neuroprotection against CIRI in rats by attenuating autophagy via the PI3K/Akt/mTOR pathway.

Dexmedetomidine Protects Cerebellar Neurons against Hyperoxia-Induced Oxidative Stress and Apoptosis in the Juvenile Rat

The risk of oxidative stress is unavoidable in preterm infants and increases the risk of neonatal morbidities. Premature infants often require sedation and analgesia, and the commonly used opioids and benzodiazepines are associated with adverse effects. Impairment of cerebellar functions during cognitive development could be a crucial factor in neurodevelopmental disorders of prematurity. Recent studies have focused on dexmedetomidine (DEX), which has been associated with potential neuroprotective properties and is used as an off-label application in neonatal units. Wistar rats (P6) were exposed to 80% hyperoxia for 24 h and received as pretreatment a single dose of DEX (5µg/kg, i.p.). Analyses in the immature rat cerebellum immediately after hyperoxia (P7) and after recovery to room air (P9, P11, and P14) included examinations for cell death and inflammatory and oxidative responses. Acute exposure to high oxygen concentrations caused a significant oxidative stress response, with a return to normal levels by P14. A marked reduction of hyperoxia-mediated damage was demonstrated after DEX pretreatment. DEX produced a much earlier recovery than in controls, confirming a neuroprotective effect of DEX on alterations elicited by oxygen stress on the developing cerebellum.

Protective Effect of Dexmedetomidine against Hyperoxia-Damaged Cerebellar Neurodevelopment in the Juvenile Rat

Impaired cerebellar development of premature infants and the associated impairment of cerebellar functions in cognitive development could be crucial factors for neurodevelopmental disorders. Anesthetic- and hyperoxia-induced neurotoxicity of the immature brain can lead to learning and behavioral disorders. Dexmedetomidine (DEX), which is associated with neuroprotective properties, is increasingly being studied for off-label use in the NICU. For this purpose, six-day-old Wistar rats (P6) were exposed to hyperoxia (80% O₂) or normoxia (21% O₂) for 24 h after DEX (5 µg/kg, i.p.) or vehicle (0.9% NaCl) application. An initial detection in the immature rat cerebellum was performed after the termination of hyperoxia at P7 and then after recovery in room air at P9, P11, and P14. Hyperoxia reduced the proportion of Calb1+-Purkinje cells and affected the dendrite length at P7 and/or P9/P11. Proliferating Pax6+-granule progenitors remained reduced after hyperoxia and until P14. The expression of neurotrophins and neuronal transcription factors/markers of proliferation, migration, and survival were also reduced by oxidative stress in different manners. DEX demonstrated protective effects on hyperoxia-injured Purkinje cells, and DEX without hyperoxia modulated neuronal transcription in the short term without any effects at the cellular level. DEX protects hyperoxia-damaged Purkinje cells and appears to differentially affect cerebellar granular cell neurogenesis following oxidative stress.

Dexmedetomidine attenuates postoperative spatial memory impairment after surgery by reducing cytochrome C

BACKGROUND

Anesthesia and surgery can induce perioperative neurocognitive disorders (PND). Mitochondrial dysfunction has been proposed to be one of the earliest triggering events in surgery-induced neuronal damage. Dexmedetomidine has been demonstrated to attenuate the impairment of cognition in aged rats induced by surgery in our previous study.

METHODS

Male Sprague-Dawley rats underwent hepatic apex resection under anesthesia with propofol to clinically mimic human abdominal surgery. The rats were divided into three groups: Control group, Model group and Dexmedetomidine (Dex) group. Cognitive function was evaluated with the Morris water maze (MWM), Open Field Test (OFT)and Novel object recognition task (NOR). Ultrastructural change in neuronal mitochondria was measured by transmission electron microscopy. Mitochondrial function was measured by mitochondrial membrane potential and activities of mitochondrial complexes. Neuronal morphology was observed with H&E staining and the activation of glial cells was observed by immunohistochemistry in the hippocampus. Protein levels were measured by Western blot (WB) and immunofluorescence at 3 and 7 days after surgery.

RESULTS

Surgery-induced cognitive decline lasts three days, but not seven days after surgery in the model group. Transmission electron microscope showed the mitochondrial structure damage in the model group, similar changes were not induced in the Dex group. Dexmedetomidine may reverse the decrease in mitochondrial membrane potential and mitochondrial complex activity. Compared with the Control group, the expression of cytochrome c was significantly increased in model group by Western blot and immunofluorescence on days 3, but not day 7. Rats from the Model group expressed significantly greater levels of Iba-1 and GFAP compared with the Control group and the Dex group.

CONCLUSION

Dexmedetomidine appears to reverse surgery-induced behavior, mitigate the higher density of Iba-1 and GFAP, reduce the damage of mitochondrial structure and function by alleviating oxidative stress and protect mitochondrial respiratory chain, thus increasing cytochrome c oxidase (COX) expression and downregulate the expression of cytochrome c protein in the hippocampus of rats.

Dexmedetomidine in Psychiatry: Repurposing of its Fast-Acting Anxiolytic, Analgesic and Sleep Modulating Properties

Drug repurposing is a strategy to identify new indications for already approved drugs. A recent successful example in psychiatry is ketamine, an anesthetic drug developed in the 1960s, now approved and clinically used as a fast-acting antidepressant. Here, we describe the potential of dexmedetomidine as a psychopharmacological repurposing candidate. This α₂-adrenoceptor agonist is approved in the US and Europe for procedural sedation in intensive care. It has shown fast-acting inhibitory effects on perioperative stress-related pathologies, including psychomotor agitation, hyperalgesia, and neuroinflammatory overdrive, proving potentially useful in clinical psychiatry. We offer an overview of the pharmacological profile and effects of dexmedetomidine with potential utility for the treatment of neuropsychiatric symptoms. Dexmedetomidine exerts fast-acting and robust sedation, anxiolytic, analgesic, sleep-modulating, and anti-inflammatory effects. Moreover, the drug prevents postoperative agitation and delirium, possibly via neuroprotective mechanisms. While evidence in animals and humans supports these properties, larger controlled trials in clinical samples are generally scarce, and systematic studies with psychiatric patients do not exist. In conclusion, dexmedetomidine is a promising candidate for an experimental treatment targeting stress-related pathologies common in neuropsychiatric disorders such as depression, anxiety disorders, and posttraumatic stress disorder. First small proof-of-concept studies and then larger controlled clinical trials are warranted in psychiatric populations to test the feasibility and efficacy of dexmedetomidine in these conditions.

Effects of dexmedetomidine on evoked potentials in spinal surgery under combined intravenous inhalation anesthesia: a randomized controlled trial

OBJECTIVE

We aimed to investigate the effects of different doses of dexmedetomidine (Dex) on evoked potentials in adult patients undergoing spinal surgery under intravenous anesthesia with low-concentration desflurane.

METHODS

Ninety patients were divided into three groups at random. To maintain anesthesia in the control group (group C), desflurane 0.3 MAC (minimal alveolar concentration), propofol, and remifentanil were administered. Dex (0.5 μg·kg^-1) was injected for 10 min as a loading dose in the low-dose Dex group (group DL), then adjusted to 0.2 μg·kg^-1·h^-1 until the operation was completed. Dex (1 μg·kg^-1) was injected for 10 min as a loading dose in the high-dose Dex group (group DH), then adjusted to 0.7 μg·kg^-1·h^-1 until the operation was completed. The additional medications were similar to those given to group C. The perioperative hemodynamics, body temperature, intraoperative drug dosages, fluid volume, urine volume, blood loss, the latency and amplitude of somatosensory evoked potentials (SEPs) at four different time points, the incidence of positive cases of SEPs and transcranial motor evoked potentials (tcMEPs), and perioperative adverse reactions were all recorded.

RESULTS

Data from 79 patients were analyzed. The MAP measured at points T2-T4 in group DH was higher than at corresponding points in group C (P < 0.05). The MAP at point T4 in group DL was higher than at corresponding points in group C (P < 0.05). The remifentanil dosage in group DH was significantly lower than in group C (P = 0.015). The fluid volume in group DL was significantly lower than in group C (P = 0.009). There were no significant differences among the three groups in the amplitude and latency of SEP at different time points, nor in the incidence of warning SEP signals. The incidence of positive tcMEP signals did not differ significantly between groups C and DL (P > 0.05), but was significantly higher in group DH than in groups DL (P < 0.05) or C (P < 0.05). The incidence of intraoperative hypertension was significantly higher in group DH than in group C (P = 0.017).

CONCLUSIONS

Low-dose Dex has no effect on the SEPs and tcMEPs monitoring during spinal surgery. High-dose Dex has no effect on SEPs monitoring, but it may increase the rate of false positive tcMEPs signals and the incidence of intraoperative hypertension.

TRIAL REGISTRATION

This study has completed the registration of the Chinese Clinical Trial Center at 11/09/2020 with the registration number ChiCTR2000038154.

Dexmedetomidine Attenuates Methotrexate-Induced Neurotoxicity and Memory Deficits in Rats through Improving Hippocampal Neurogenesis: The Role of miR-15a/ROCK-1/ERK1/2/CREB/BDNF Pathway Modulation

Methotrexate (MTX) is a widely used neurotoxic drug with broad antineoplastic and immunosuppressant spectra. However, the exact molecular mechanisms by which MTX inhibits hippocampal neurogenesis are yet unclear. Dexmedetomidine (Dex), an α2-adrenergic receptor agonist, has recently shown neuroprotective effects; however, its full mechanism is unexplored. This study investigated the potential of Dex to mitigate MTX-induced neurotoxicity and memory impairment in rats and the possible role of the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway. Notably, no former studies have linked this pathway to MTX-induced neurotoxicity. Male Sprague Dawley rats were placed into four groups. Group 1 received saline i.p. daily and i.v. on days 8 and 15. Group 2 received Dex at 10 μg/kg/day i.p. for 30 days. Group 3 received MTX at 75 mg/kg i.v. on days 8 and 15, followed by four i.p. doses of leucovorin at 6 mg/kg after 18 h and 3 mg/kg after 26, 42, and 50 h. Group 4 received MTX and leucovorin as in group 3 and Dex daily dosages as in group 2. Bioinformatic analysis identified the association of miR-15a with ROCK-1/ERK1/2/CREB/BDNF and neurogenesis. MTX lowered hippocampal doublecortin and Ki-67, two markers of neurogenesis. This was associated with the downregulation of miR-15a, upregulation of its target ROCK-1, and reduction in the downstream ERK1/2/CREB/BDNF pathway, along with disturbed hippocampal redox state. Novel object recognition and Morris water maze tests demonstrated the MTX-induced memory deficiencies. Dex co-treatment reversed the MTX-induced behavioral, biochemical, and histological alterations in the rats. These neuroprotective actions could be partly mediated through modulating the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway, which enhances hippocampal neurogenesis.

Old and Promising Markers Related to Autophagy in Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the first causes of death and disability in the world. Because of the lack of macroscopical or histologic evidence of the damage, the forensic diagnosis of TBI could be particularly difficult. Considering that the activation of autophagy in the brain after a TBI is well documented in literature, the aim of this review is to find all autophagy immunohistological protein markers that are modified after TBI to propose a method to diagnose this eventuality in the brain of trauma victims. A systematic literature review on PubMed following PRISMA 2020 guidelines has enabled the identification of 241 articles. In all, 21 of these were enrolled to identify 24 markers that could be divided into two groups. The first consisted of well-known markers that could be considered for a first diagnosis of TBI. The second consisted of new markers recently proposed in the literature that could be used in combination with the markers of the first group to define the elapsed time between trauma and death. However, the use of these markers has to be validated in the future in human tissue by further studies, and the influence of other diseases affecting the victims before death should be explored.

Could dexmedetomidine be repurposed as a glymphatic enhancer?

Cerebrospinal fluid (CSF) flows through the central nervous system (CNS) via the glymphatic pathway to clear the interstitium of metabolic waste. In preclinical studies, glymphatic fluid flow rate increases with low central noradrenergic tone and slow-wave activity during natural sleep and general anesthesia. By contrast, sleep deprivation reduces glymphatic clearance and leads to intracerebral accumulation of metabolic waste, suggesting an underlying mechanism linking sleep disturbances with neurodegenerative diseases. The selective α₂-adrenergic agonist dexmedetomidine is a sedative drug that induces slow waves in the electroencephalogram, suppresses central noradrenergic tone, and preserves glymphatic outflow. As recently developed dexmedetomidine formulations enable self-administration, we suggest that dexmedetomidine could serve as a sedative-hypnotic drug to enhance clearance of harmful waste from the brain of those vulnerable to neurodegeneration.

Mechanistic considerations and biomarkers level in nickel-induced neurodegenerative diseases: An updated systematic review

The environment has been implicated to be a strong determinant of brain health with higher risk of neurodegeneration. The drastic rise in the prevalence of neurodegenerative diseases (NDDs) including Alzheimer's disease (AD), Parkinson's disease (PD), autism spectrum disorder (ASD), multiple sclerosis (MS) etc., supports the idea that environmental factors may play a major role in NDDs aetiology. Nickel is one of the listed environmental metals reported to pose a serious threat to human health. This paper reported available studies on nickel level in NDDs covering both animal and human studies. Different databases were searched for articles reporting the main neurotoxicity mechanisms and the concentration of nickel in fluids and tissues of NDDs patients compared to controls. Data were extracted and synthesized by ensuring the articles were related to nickel and NDDs. Various mechanisms were reported as oxidative stress, disturbances in mitochondrial membrane potential, trace elements homeostasis destabilization, etc. Nickel was found elevated in biological fluids as blood, serum/plasma and CSF and in the brain of NDDs, as a consequence of unintentional exposure thorough nickel-contaminated air, food, water, and skin contact. In addition, after exposure to nickel, the concentration of markers of lipid peroxidation were increased, while some antioxidant defence systems decreased. Thus, the reduction in the exposure to nickel contaminant may hold a promise in reducing the incidence of NDDs.

Dexmedetomidine pretreatment alleviates ropivacaine-induced neurotoxicity via the miR-10b-5p/BDNF axis

BACKGROUND

Ropivacaine is commonly applied for local anesthesia and may cause neurotoxicity. Dexmedetomidine (DEX) exhibits neuroprotective effects on multiple neurological disorders. This study investigated the mechanism of DEX pretreatment in ropivacaine-induced neurotoxicity.

METHODS

Mouse hippocampal neuronal cells (HT22) and human neuroblastoma cells (SH-SY5Y) were treated with 0.5 mM, 1 mM, 2.5 mM, and 5 mM ropivacaine. Then the cells were pretreated with different concentrations of DEX (0.01 μM, 0.1 μM, 1 μM, 10 μM, and 100 μM) before ropivacaine treatment. Proliferative activity of cells, lactate dehydrogenase (LDH) release, and apoptosis rate were measured using CCK-8 assay, LDH detection kit, and flow cytometry, respectively. miR-10b-5p and BDNF expressions were determined using RT-qPCR or Western blot. The binding of miR-10b-5p and BDNF was validated using dual-luciferase assay. Functional rescue experiments were conducted to verify the role of miR-10b-5p and BDNF in the protective mechanism of DEX on ropivacaine-induced neurotoxicity.

RESULTS

Treatment of HT22 or SH-SY5Y cells with ropivacaine led to the increased miR-10b-5p expression (about 1.7 times), decreased BDNF expression (about 2.2 times), reduced cell viability (about 2.5 times), elevated intracellular LDH level (about 2.0-2.5 times), and enhanced apoptosis rate (about 3.0-4.0 times). DEX pretreatment relieved ropivacaine-induced neurotoxicity, as evidenced by enhanced cell viability (about 1.7-2.0 times), reduced LDH release (about 1.7-1.8 times), and suppressed apoptosis rate (about 1.8-1.9 times). DEX pretreatment repressed miR-10b-5p expression (about 2.5 times). miR-10b-5p targeted BDNF. miR-10b-5p overexpression or BDNF silencing reversed the protective effect of DEX pretreatment on ropivacaine-induced neurotoxicity, manifested as reduced cell viability (about 1.3-1.6 times), increased intracellular LDH level (about 1.4-1.7 times), and elevated apoptosis rate (about 1.4-1.6 times).

CONCLUSIONS

DEX pretreatment elevated BDNF expression by reducing miR-10b-5p expression, thereby alleviating ropivacaine-induced neurotoxicity.

Sustainable Release of Propranolol Hydrochloride Laden with Biconjugated-Ufasomes Chitosan Hydrogel Attenuates Cisplatin-Induced Sciatic Nerve Damage in In Vitro/In Vivo Evaluation

Peripheral nerve injuries significantly impact patients' quality of life and poor functional recovery. Chitosan-ufasomes (CTS-UFAs) exhibit biomimetic features, making them a viable choice for developing novel transdermal delivery for neural repair. This study aimed to investigate the role of CTS-UFAs loaded with the propranolol HCl (PRO) as a model drug in enhancing sciatica in cisplatin-induced sciatic nerve damage in rats. Hence, PRO-UFAs were primed, embedding either span 20 or 60 together with oleic acid and cholesterol using a thin-film hydration process based on full factorial design (24). The influence of formulation factors on UFAs' physicochemical characteristics and the optimum formulation selection were investigated using Design-Expert® software. Based on the optimal UFA formulation, PRO-CTS-UFAs were constructed and characterized using transmission electron microscopy, stability studies, and ex vivo permeation. In vivo trials on rats with a sciatic nerve injury tested the efficacy of PRO-CTS-UFA and PRO-UFA transdermal hydrogels, PRO solution, compared to normal rats. Additionally, oxidative stress and specific apoptotic biomarkers were assessed, supported by a sciatic nerve histopathological study. PRO-UFAs and PRO-CTS-UFAs disclosed entrapment efficiency of 82.72 ± 2.33% and 85.32 ± 2.65%, a particle size of 317.22 ± 6.43 and 336.12 ± 4.9 nm, ζ potential of -62.06 ± 0.07 and 65.24 ± 0.10 mV, and accumulatively released 70.95 ± 8.14% and 64.03 ± 1.9% PRO within 6 h, respectively. Moreover, PRO-CTS-UFAs significantly restored sciatic nerve structure, inhibited the cisplatin-dependent increase in peripheral myelin 22 gene expression and MDA levels, and further re-established sciatic nerve GSH and CAT content. Furthermore, they elicited MBP re-expression, BCL-2 mild expression, and inhibited TNF-α expression. Briefly, our findings proposed that CTS-UFAs are promising to enhance PRO transdermal delivery to manage sciatic nerve damage.

Dexmedetomidine pretreatment alleviates cerebral ischemia/reperfusion injury by inhibiting neuroinflammation through the JAK2/STAT3 pathway

Dexmedetomidine (DEX) is known to provide neuroprotection against cerebral ischemia and reperfusion injury (CIRI), but the exact mechanisms remain unclear. This study was conducted to investigate whether DEX pretreatment conferred neuroprotection against CIRI by inhibiting neuroinflammation through the JAK2/STAT3 signaling pathway. Middle cerebral artery occlusion (MCAO) was performed to establish a cerebral ischemia/reperfusion (I/R) model. Specific-pathogen-free male Sprague-Dawley rats were randomly divided into Sham, I/R, DEX, DEX+IL-6, and AG490 (a selective inhibitor of JAK2) groups. The Longa score, TTC staining, and HE staining were used to evaluate brain damage. ELISA was used to exam levels of TNF-α. Western blotting was used to assess the levels of JAK2, phosphorylated-JAK2 (p-JAK2), STAT3, and phosphorylated-STAT3 (p-STAT3). Our results suggested that both pretreatment with DEX and AG490 decreased the Longa score and cerebral infarct areas following cerebral I/R. After treatment with IL-6, the effects of DEX on abrogating these pathological changes were reduced. HE staining revealed that I/R-induced neuronal pathological changes were attenuated by DEX application, consistent with the AG490 group. However, these effects of DEX were abolished by IL-6. Furthermore, TNF-α levels were significantly increased in the I/R group, accompanied by an increase in the levels of the p-JAK2 and p-STAT3. DEX and AG490 pretreatment down-regulated the expressions of TNF-α, p-JAK2, and p-STAT3. In contrast, the down-regulation of TNF-α, p-JAK2, and p-STAT3 induced by DEX was reversed by IL-6. Collectively, our results indicated that DEX pretreatment conferred neuroprotection against CIRI by inhibiting neuroinflammation via negatively regulating the JAK2/STAT3 signaling pathway.

Effects of Dexmedetomidine on Hemodynamics and Anesthesia Effect of Different Doses of General Anesthesia in Patients Undergoing Hepatobiliary Surgery

In order to provide corresponding anesthesia methods of hepatobiliary diseases and obtain better clinical effect, the hemodynamics and clinical efficacy are evaluated by using different doses of dexamethasone (DEX) during the operation. 97 patients undergoing general anesthesia for hepatobiliary surgery in our hospital from April 2020 to August 2021 are analyzed retrospectively. All patients are divided into G1 (n = 24), G2 (n = 24), G3 (n = 24), and control group (n = 25) according to the random number table method. The G1, G2, and G3 groups are injected with DEX 1.0 ug/kg, DEX 0.8 ug/kg, and DEX 0.5 ug/kg by intravenous infusion pump before induction of general anesthesia, and the control group is injected with 0.9%Nacl solution 10 mL. Intraoperative anesthesia time, postoperative eye opening time, and extubation time of all groups are observed, and the incidences of postoperative adverse reactions are compared. The experimental results show that during general anesthesia in the liver and gallbladder surgery, the patients with high dose of DEX can better maintain the intraoperative hemodynamic parameters, and effectively restrain the postoperative stress reaction.

Protective effects of brain-targeted dexmedetomidine nanomicelles on mitochondrial dysfunction in astrocytes of cerebral ischemia/reperfusion injury rats

Cerebral ischemia/reperfusion injury (CIRI) is closely related to mitochondrial dysfunction in astrocytes. Therefore, based on glucose transporter 1 (GLUT1), which is highly expressed in the brain tissue of rats with CIRI, we design a kind of brain-targeted dexmedetomidine (Man@Dex) nanomicelles. The results showed that Man@Dex not only had the advantages of small particle size, stability and non-toxicity, but also realized brain-targeted drug delivery. Primary astrocytes were cultured in vitro to construct CIRI cell model. It was found that Man@Dex could improve the activity of injured astrocytes. Man@Dex could exert antioxidant activity by inhibiting the reactive oxygen species (ROS) production of astrocytes, thus inhibiting the cytotoxicity induced by hypoxia and reoxygenation. Man@Dex could improve the ATP level and mitochondrial membrane potential (MMP) to protect mitochondrial function of damaged astrocytes. The CIRI rat model was constructed and confirmed by hematoxylin and eosin (HE), Triphenyl-2H-tetrazolium chloride (TTC) staining and nerve defect score. It indicated that Man@Dex could alleviate CIRI and improve MMP, which was beneficial to the recovery of brain injury in rats. This research provides a new theoretical basis and target for the development of brain-targeted nano-drugs of CIRI.

Effect Evaluation of Dexmedetomidine Intravenous Anesthesia on Postoperative Agitation in Patients with Craniocerebral Injury by Magnetic Resonance Imaging Based on Sparse Reconstruction Algorithm

The effect of dexmedetomidine on postoperative agitation of patients with craniocerebral injury was investigated based on magnetic resonance imaging (MRI) with the sparse reconstruction algorithm. Sixty patients with craniocerebral injury who underwent tracheal intubation and craniotomy hematoma removal under general anesthesia in hospital were selected as the research objects. Patients were randomly and averagely divided into the normal saline group (group A) and the dexmedetomidine (DEX) group (group B). DEX was added to patients in group A during anesthesia. Other operations in group B were the same as those in group A, where DEX needed to be used was replaced by an equal amount of the normal saline. All patients received the MRI examination, and the images were processed by using the sparse reconstruction algorithm. After the surgery, some indexes, such as hemodynamics (mean arterial pressure (MAP) and hear rate (HR)), the Riker sedation agitation score, the Ramsay sedation score, and the visual analogue scale (VAS) score were recorded and compared. The results showed that the MRI image quality processed by sparse reconstruction algorithm was observably improved. After reconstruction, the sharpness of the image was significantly improved, and the distinction between lesions and tissues was also increased. The Riker sedation agitation score and the incidence of agitation in group A were greatly lower than those in group B (16% VS 76%, P < 0.05). The Ramsay sedation score of group A was manifestly higher than that of group B. The cases of postoperative nausea, vomiting, chills, delirium, and bradycardia in group A were 2, 1, 1, 0, and 1, respectively. The cases of postoperative nausea, vomiting, chills, delirium, and bradycardia in group B were 3, 9, 6, 5, and 0, respectively. The cases of chills and delirium in group A were observably less than those in group B (P < 0.05). In conclusion, based on the sparse reconstruction algorithm, the MRI technology and DEX had high adoption value in preventing postoperative agitation of patients with craniocerebral injury. Compared with group B, the hemodynamics of patients in group A was more stable.

Protective effects of dexmedetomidine in vital organ injury: crucial roles of autophagy

Vital organ injury is one of the leading causes of global deaths. Accumulating studies have demonstrated that dexmedetomidine (DEX) has an outstanding protective effect on multiple organs for its antiinflammatory and antiapoptotic properties, while the underlying molecular mechanism is not clearly understood. Autophagy, an adaptive catabolic process, has been found to play a crucial role in the organ-protective effects of DEX. Herein, we present a first attempt to summarize all the evidence on the proposed roles of autophagy in the action of DEX protecting against vital organ injuries via a comprehensive review. We found that most of the relevant studies (17/24, 71%) demonstrated that the modulation of autophagy was inhibited under the treatment of DEX on vital organ injuries (e.g. brain, heart, kidney, and lung), but several studies suggested that the level of autophagy was dramatically increased after administration of DEX. Albeit not fully elucidated, the underlying mechanisms governing the roles of autophagy involve the antiapoptotic properties, inhibiting inflammatory response, removing damaged mitochondria, and reducing oxidative stress, which might be facilitated by the interaction with multiple associated genes (i.e., hypoxia inducible factor-1α, p62, caspase-3, heat shock 70 kDa protein, and microRNAs) and signaling cascades (i.e., mammalian target of rapamycin, nuclear factor-kappa B, and c-Jun N-terminal kinases pathway). The authors conclude that DEX hints at a promising strategy in the management of vital organ injuries, while autophagy is crucially involved in the protective effect of DEX.

Analgesia in the Neurosurgical Intensive Care Unit

Acute pain in neurosurgical patients is an important issue. Opioids are the most used for pain treatment in the neurosurgical ICU. Potential side effects of opioid use such as oversedation, respiratory depression, hypercapnia, worsening intracranial pressure, nausea, and vomiting may be problems and could interfere with neurologic assessment. Consequently, reducing opioids and use of non-opioid analgesics and adjuvants (N-methyl-D-aspartate antagonists, α2 -adrenergic agonists, anticonvulsants, corticosteroids), as well as non-pharmacological therapies were introduced as a part of a multimodal regimen. Local and regional anesthesia is effective in opioid reduction during the early postoperative period. Among non-opioid agents, acetaminophen and non-steroidal anti-inflammatory drugs are used frequently. Adverse events associated with opioid use in neurosurgical patients are discussed. Larger controlled studies are needed to find optimal pain management tailored to neurologically impaired neurosurgical patients.