Use of a curved needle to facilitate four-in-one nerve block performance after total knee arthroplasty in elderly patients: a randomized clinical trial.

BACKGROUND: Peripheral nerve block is the main analgesic technique for total knee arthroplasty (TKA) in elderly patients. Accurate delivery of the needle tip to the target nerve under ultrasound-guided is a prerequisite for successful nerve block. Failed needle-tip positioning in sciatic nerve (SN) or medial femoral cutaneous nerve (MFCN) block can be due to anatomical structure shadow. The aim of the study was to compare curved and straight needles in regard to the time needed to perform the nerve block for TKA in elderly patients. METHODS: One hundred patients aged 65 to 80 years and ASA II-III, BMI 18-30 kg/m2, who underwent general anesthesia for unilateral TKA received the nerve block under ultrasound guidance after surgery, were included in this study. All patients were randomly divided into two groups (N.=50): straight needle group (Group S) and curved needle group (Group C). The primary outcome measure was the time needed to successfully perform the nerve block. Secondary outcomes included the number of attempts and needle redirections to achieve nerve blockade, as well as the satisfaction of patients and anesthesiologists. RESULTS: Compared with group S, the performance time was shorter in group C (488.0±44.9 vs. 517.8±42.1 P=0.001). The procedural pain score was less in group C (1.8±0.4 vs. 2.4±0.6, P=0.000). The satisfaction score of the anesthesiologist (3.4±0.8 vs. 2.4±0.6, P=0.000) and patients (3.4±0.7 vs. 1.9±0.6, P=0.000) were higher in the curved needle group compared with the straight needle group. CONCLUSIONS: The use of a curved needle can reduce the time required to perform the nerve block, with reduction in the number of attempts and needle redirections. Curved needle also resulted in lesser procedural pain and higher satisfaction compared with the straight needle.

A Multicenter, Randomized, Double-Blind, Positive-Controlled, Non-Inferiority, Phase III Clinical Trial Evaluating the Efficacy and Safety of Emulsified Isoflurane for Anesthesia Induction in Patients.

BACKGROUND: Emulsified isoflurane was designed to circumvent the deficiencies of inhalation anesthetics, which have a longer time to onset, result in a higher drug consumption, and for which a specific anesthesia machine is required for clinical use. The aim of this study was to compare the efficacy and safety of emulsified isoflurane with propofol for anesthesia induction in adults patients. METHODS: This multicenter, randomized, double-blind, positive-controlled, non-inferiority, phase III clinical trial compared the efficacy and safety of emulsified isoflurane with propofol for anesthesia induction. Each patient in the emulsified isoflurane group received a single bolus injection of 12% emulsified isoflurane at a dose of 30 mg/kg, and each patient in the propofol group received a single bolus injection of 0.8% propofol at a dose of 2 mg/kg. The primary outcome of the efficacy evaluation was the proportion of participants with successful anesthesia induction, which was regarded as a Modified Observer's Assessment of Alertness/Sedation (MOAA/S) score of < 1 and lack of use of other sedative drugs. A number of secondary efficacy outcomes were also assessed. Safety was monitored based on (1) adverse events, (2) repeated measurement of vital signs; (3) physical examination, (4) routine laboratory examinations of hematology, biochemistry, urine, coagulation function, and (5) 12-lead electrocardiogram. RESULTS: A total of 416 patients were enrolled (n = 208 in each group) and 398 patients were administered study drug. The proportion of participants with successful anesthesia induction was 100% with a 95% confidence interval of - 1.9% to + 1.9% for the emulsified isoflurane and propofol groups, which met the predesigned non-inferiority criteria of 5%. The study demonstrated the non-inferiority of sedation produced by emulsified isoflurane compared to propofol. Among the secondary efficacy outcomes, emulsified isoflurane showed a better cardiovascular stability than propofol. The number of patients from the emulsified isoflurane group who experienced drug-related adverse events was significantly higher than that of patients from the propofol group. However, there was no significant difference between the two groups in terms of adverse events or drug-related adverse events of grades 3-5. CONCLUSIONS: Emulsified isoflurane exhibited non-inferiority of anesthesia/sedation compared to propofol in patients undergoing anesthesia induction. CLINICAL TRIAL REGISTRATION: ChiCTR2000038185, registered on 12 December, 2020 ( www.chictr.org.cn ).

Muscone reduced the hypnotic and analgesic effect of ketamine in mice.

BACKGROUND: The aim of this study was to determine the effects of different concentrations of muscone on the ketamine requirement for hypnosis and analgesia and possible mechanism in mice. METHODS: In the hypnotic response experiment, muscone (0.5, 1.0, 2.0, 4.0, and 8.0 mg/kg) was administered 15 minutes before ketamine by intraperitoneal injection. The hypnotic response was evaluated by loss of righting reflex (LORR). In the analgesia experiment, muscone (0.5, 1.0, 2.0, and 4.0 mg/kg) was administered 15 minutes before 50 mg/kg ketamine injection. Pain threshold was assessed by measuring the tail-flick latency induced by heat radiation. Twenty minutes after ketamine injection, the mRNA expression of N-methyl-D-aspartate receptors (NR) subunits, γ-aminobutyric acid (GABA) receptors subunits, opioid receptors subunits, and some Na and Ca channels were detected by qPCR in the hippocampus of mice. RESULTS: The 50% effective dose (ED50) with 95% confidence interval of ketamine-induced LORR was 49.2 (43.4-56.4) mg/kg. About 4.0 or 8.0 mg/kg muscone increased ED50 of ketamine-induced hypnosis, which was 82.7 (70.0-98.4) mg/kg or 72.0 (65.4-85.7) mg/kg, respectively. In the analgesic experiment, ketamine alone caused an obvious analgesic effect, whereas different dose of muscone decreased pain threshold in the presence of ketamine; 4.0 mg/kg muscone up-regulated the mRNA expression of NR1 and inhibited ketamine-induced increase of δ-opioid receptor mRNA level. Muscone also inhibited Cav2.1 mRNA expression in the presence of ketamine. CONCLUSION: Muscone reduced the hypnotic and analgesic effect of ketamine in dose-independent manner in mice, which may be related to the changes of NR1 and δ-opioid receptor.

Sevoflurane Protects against Intestinal Ischemia-Reperfusion Injury by Activating Peroxisome Proliferator-Activated Receptor Gamma/Nuclear Factor-κB Pathway in Rats.

BACKGROUND: Intestinal ischemia/reperfusion (I/R) injury is a clinical challenge with high morbidity and mortality, whereas the effective therapeutic strategy is limited. Inflammatory reaction plays important roles in I/R-induced intestinal damage and multi-organ dysfunction syndrome. Peroxisome proliferator-activated receptor gamma (PPARγ) has been identified as an endogenous anti-inflammatory regulator by inhibiting nuclear factor-κB (NF-κB) activation. Our previous research has shown that the pretreatment with inhaled anesthetic sevoflurane protects intestinal I/R injury. However, whether the protection induced by sevoflurane is mediated by inhibiting intestinal inflammatory reaction via activation of PPARγ/NF-κB pathway is underdetermined. In this study, we investigated the effects of sevoflurane on intestinal inflammatory reaction during intestinal I/R and the role of PPARγ/NF-κB pathway. METHODS: Rat model of intestinal I/R was used in this study. The superior mesenteric artery was clamped for 60 min followed by 120-min reperfusion. Sevoflurane at 0.5 minimum alveolar concentration was inhaled for 30 min before ischemic insult. GW9662, a specific PPARγ antagonist, was injected intraperitoneally before sevoflurane inhalation. RESULTS: Intestinal I/R caused severe intestinal mucosa histopathological injury evaluated by Chiu's scoring, induced epithelial cell apoptosis evaluated by terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling and activation of caspase-3, upregulated serum MOD levels, reduced protein expression of Bcl-2 and PPARγ, increased protein expression of NF-κB P65 and proinflammatory cytokine tumor necrosis factor-α and interleukin-6 in the intestine. Sevoflurane preconditioning significantly ameliorated these changes induced by intestinal I/R. However, GW9662 partly blocked the protective effects induced by sevoflurane. CONCLUSIONS: Our results suggest sevoflurane-induced protection against intestinal I/R injury is partly mediated by inhibiting intestinal inflammatory reaction via activation of PPARγ/NF-κB pathway.

Influence of sevoflurane exposure on mitogen-activated protein kinases and Akt/GSK-3ß/CRMP-2 signaling pathways in the developing rat brain.

Prolonged exposure to volatile anesthetics causes neurodegeneration in developing animal brains. However, their underlying mechanisms of action remain unclear. The current study investigated the expression of proteins associated with the mitogen-activated protein kinases (MAPK) and protein kinase B (Akt)/glycogen synthase kinase-3ß (GSK-3ß)/collapsin response mediator protein 2 (CRMP-2) signaling pathways in the cortices of neonatal mice following exposure to sevoflurane. Seven-day-old (P7) neonatal C57BL/6 mice were randomly divided into 2 groups and either exposed to 2.6% sevoflurane or air for 6 h. Terminal deoxyribonucleotide transferase mediated dUTP nick end labeling (TUNEL) staining, as well as the expression of activated caspase-3 and α-fodrin, was used to detect neuronal apoptosis in the cortices of mice. MAPK signaling pathways were investigated by detecting the expression of phosphorylated (p-) extracellular signal-regulated kinase 1/2 (ERK1/2), p-cyclic adenosine monophosphate response element-binding protein (CREB), p-p38, p-nuclear factor (NF-κB) and p-c-Jun N-terminal kinase (p-JNK). Akt/GSK-3ß/CRMP-2 signaling pathways were assessed by detecting the expression of p-Akt, p-GSK-3ß and p-CRMP-2 in the cortices of P7 mice 2 h following exposure to sevoflurane. The results demonstrated that sevoflurane significantly increased the apoptosis of cells in the retrosplenial cortex (RS), frontal cortex (FC) and parietal association cortex (PtA), increased the expression of cleaved caspase-3 expression and promoted the formation of 145 kDa and 120 kDa fragments from α-fodrin. Sevoflurane inhibited the phosphorylation of ERK1/2 and CREB, stimulated the phosphorylation of p38 and NF-κB, but did not significantly affect the phosphorylation of JNK. Furthermore, sevoflurane inhibited the phosphorylation of Akt, decreased the phosphorylation of GSK-3ß at ser9 and increased the phosphorylation of CRMP2 at Thr514. These results suggest that multiple signaling pathways, including ERK1/2, P38 and Akt/GSK-3ß/CRMP-2 may be involved in sevoflurane-induced neuroapoptosis in the developing brain.

Ligustrazine Enhances the Hypnotic and Analgesic Effect of Ketamine in Mice.

The purpose of this study was to determine the effects of different concentrations of ligustrazine, an extract from Chinese herb, on ketamine requirement for hypnosis and analgesia in mice. In the hypnotic response study, mice were randomly allocated to receive saline or ligustrazine at 10, 20, 40, 80 or 160 mg·kg-1 by intraperitoneal injection. Ketamine was administrated 15 min after ligustrazine injection. The hypnotic response was determined by assessing loss of the righting reflex (LORR) after ketamine injection. The dose of ketamine was determined by modified Dixon's up-and-down method in each group. In the analgesia study, different doses of ligustrazine were administrated 15 min before 50 mg·kg-1 ketamine injection. The analgesia effects (pain threshold) were determined by heat radiation-induced tail-flick latency and evaluated before ligustrazine administration or 5, 15, 30 and 60 min after ketamine administration. The ED50 [95% confidence interval (CI)] for hypnosis induced by ketamine was 54.1 (44.8, 65.3) mg·kg-1. Ligustrazine dose-dependently decreased the ED50 for ketamine to induce hypnosis, which was [31.6 (26.2, 38.1)] mg·kg-1 with the addition of 80 mg·kg-1 ligustrazine and [27.7 (22.6, 33.7)] mg·kg-1 with the addition of 160 mg·kg-1 ligustrazine, respectively (p<0.05). Ligustrazine at 160 mg·kg-1 also increased pain threshold in the presence of ketamine. Ligustrazine enhanced the hypnotic effect of ketamine in a dose-dependent manner. Ligustrazine at a large dose also increased the analgesic effect of ketamine.

Calpain and JNK pathways participate in isoflurane - induced nucleus translocation of apoptosis-inducing factor in the brain of neonatal rats.

Recent studies have demonstrated that volatile anesthetic causes caspase-dependent neuroapoptosis and persistent cognitive deficits in young animals. Apoptosis-inducing factor (AIF) can trigger apoptosis by caspase-independent pathway. Whether isoflurane induces neuroapoptosis by activation of AIF and its possible mechanism are underdetermined. Rats at postnatal day 7 were exposed to 1.1% isoflurane for 4 h and the expression of AIF, cytochrome c, caspase-3, µ-calpain, m-calpain, Bcl-2 and Bax in the mitochondrial, cytosolic, and nuclear fraction, as well as the number of both AIF and TUNEL positive neurons in the cortices of rats were measured. Moreover, the effects of calpain inhibitor MDL-28170 or JNK inhibitor SP600125 on isoflurane-induced AIF release, caspase activation and cognitive deficits were assessed. We found isoflurane activated CytC-caspase-3 dependent apoptosis pathway mainly in the early phase (0-6 h after exposure). Moreover, isoflurane activated mitochondrial µ-calpain, induced AIF truncation during early phase and activated m-calpain, induced AIF release from the mitochondria to cytosol and translocation into the nucleus in the late phase (6-24 h after exposure). MDL-28170 attenuated the isoflurane-induced mitochondrial AIF truncation, release and nuclear translocation, but did not change the expression of cleaved-caspase-3 and mitochondrial Bax and Bcl-2 proteins. SP600125 attenuated isoflurane-induced neuroapoptosis by inhibiting both AIF and caspase-3 pathways and reduced cognitive impairment in neonatal rats. This is the first study to provide the evidence that isoflurane induced AIF-dependent neuroapoptosis by activation of mitochondrial µ-calpain and m-calpain in neonatal rats. JNK inhibition reversed isoflurane-induced neuroapoptosis and subsequent long-term neurocognitive impairment, acting via inhibiting activation of both AIF and caspase-3 pathways.

Cyclin-dependent kinase 5/Collapsin response mediator protein 2 pathway may mediate sevoflurane-induced dendritic development abnormalities in rat cortical neurons.

Sevoflurane has been reported to induce neurotoxicity and cognitive impairment in the developing brains. However, the underlying molecular mechanisms remain poorly understood. Recent studies have demonstrated aberrant cyclin-dependent kinase 5 (CDK5) activity is implicated in inhaled anesthetic-induced neurotoxicity. CDK5/CRMP2 signaling is involved in the cortical and hippocampal dendritic development. The aim of present study is to investigate whether the CDK5/CRMP2 pathway mediates sevoflurane-induced dendritic development abnormalities. Rat primary cortical neurons were treated with 4% sevoflurane for 6h, the CDK5 inhibitor roscovitine or the vehicle (0.3% DMSO) was administered 12h before sevoflurane or carrying gases exposure. Cortical neurons were harvested for further analysis 0h, 12h and 24h after exposure. Sevoflurane exposure for 6h did not reduce cell viability and slightly increased the expression of cleaved caspase-3. Sevoflurane induced abnormal CDK5 activation by increasing the expression of its activator p25 and promoted the phosphorylation of CRMP2 (Ser522). The increased phospho-CRMP2 (Ser522) was mainly distributed in the cytoplasm of cortical neurons. Sevoflurane significantly reduced the number of primary dendrites and the number of branching points; whereas it did not influence the total dendritic length. Suppression of CDK5 activation with roscovitine attenuated neuronal apoptosis, hyperphosphorylation of CRMP2 (Ser522) and dendritic development abnormalities induced by sevoflurane. Our results indicate that activation of the CDK5/CRMP2 pathway may mediate sevoflurane-induced dendritic development abnormalities in the cortical neurons. The physiological significance of these findings remains to be determined.

[Electroacupuncture Intervention Inhibits the Decline of Learning-memory Ability and Overex- pression of Cleaved Caspase-3 and Bax in Hippocampus Induced by Isoflurane in APPswe/PS 1].

OBJECTIVE: To investigate the protection mechanism of electroacupuncture (EA) therapy against Alzheimer's disease (AD)-like neurotoxicity induced by Isoflurane. METHODS: Twenty-four APPswe/PS 1 dE9 double transgenic mice (one of the most extensively used transgenic mouse model of AD) and 24 littermate wild-type mice were randomly assigned into control (Con) group, isoflurane (Iso) group and EA group, respectively (n = 8 in each group). EA (2 Hz/100 Hz, 1 mA) was applied to "Baihui" (GV 20) and "Yongquan" (KI 1) for 15 min, once a day for 3 days. The transgenic mice were exposed to a closed box filled with 1.2% isoflurane + 30% O2 +70% N2 for 4 h. The animals' learning-memory ability was detected by Morris water maze test. The expression of cleaved Caspase-3 in the CA 1 area of hippocampus was detected by immunohistochemistry, and that of hippocampal Bcl-2 and Bax proteins detected by Western blot. RESULTS: Compared with the wilde-type mice, the average escape latency of place navigation test was significantly longer, while the percentage of target-quadrant stay time and the target- platform crossing times of spacial probe test were marked decreased in AD + lso mice (P < 0.05). After acupuncture intervention, the abovementioned changes were reversed (P < 0.05). Correspondingly, compared with the AD-Con group, the number of hippocampal activated Caspase-3-positive cells and the expression of Bax protein were significantly increased in the AD-Iso group (P < 0.05). After EA intervention, the increased Caspase-3-positive cell number and Bax protein expression were remarkably down-regulated in the AD-EA group, and the decreased ratio of Bcl-2/Bax in AD-Iso mice was obviously up-regulated in AD-EA mice (P < 0.05). No significant changes were found in the average escape latency, the percentage of target-quadrant stay time and the target-platofrm corssing times, and inthe number of hippocampal activated Caspase-3-positive cells, the expression levels of hippocampal Bcl-2 and Sax and the ratio of Bcl-2/Bax in the three groups of wilde-type mice (P > 0.05). CONCLUSION: EA intervention can improve the learning-memory ability in AD + Isoflurane mice, suggesting a reduction of AD-like neurotoxicity, which may be associated with its actions in inhibiting the overexpression of activated Caspase-3 and Bax proteins in the hippocampus.

Sevoflurane Preconditioning Reduces Intestinal Ischemia-Reperfusion Injury: Role of Protein Kinase C and Mitochondrial ATP-Sensitive Potassium Channel.

Ischemic preconditioning (IPC) has been considered to be a potential therapy to reduce ischemia-reperfusion injury (IRI) since the 1980s. Our previous study indicated that sevoflurane preconditioning (SPC) also reduced intestinal IRI in rats. However, whether the protective effect of SPC is similar to IPC and the mechanisms of SPC are unclear. Thus, we compared the efficacy of SPC and IPC against intestinal IRI and the role of protein kinase C (PKC) and mitochondrial ATP-sensitive potassium channel (mKATP) in SPC. A rat model of intestinal IRI was used in this study. The superior mesenteric artery (SMA) was clamped for 60 min followed by 120 min of reperfusion. Rats with IPC underwent three cycles of SMA occlusion for 5 min and reperfusion for 5 min before intestinal ischemia. Rats with SPC inhaled sevoflurane at 0.5 minimum alveolar concentration (MAC) for 30 min before the intestinal ischemic insult. Additionally, the PKC inhibitor Chelerythrine (CHE) or mKATP inhibitor 5-Hydroxydecanoic (5-HD) was injected intraperitoneally before sevoflurane inhalation. Both SPC and IPC ameliorated intestinal IRI-induced histopathological changes, decreased Chiu's scores, reduced terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling (TUNEL) positive cells in the epithelium, and inhibited the expression of malondialdehyde (MDA) and tumor necrosis factor-α (TNF-α). These protective effects of SPC were similar to those of IPC. Pretreatment with PKC or mKATP inhibitor abolished SPC-induced protective effects by increasing Chiu's scores, down-regulated the expression of Bcl-2 and activated caspase-3. Our results suggest that pretreatment with 0.5 MAC sevoflurane is as effective as IPC against intestinal IRI. The activation of PKC and mKATP may be involved in the protective mechanisms of SPC.

Sevoflurane protects against intestinal ischemia-reperfusion injury partly by phosphatidylinositol 3 kinases/Akt pathway in rats.

BACKGROUND: Intestinal ischemia-reperfusion injury (IRI) is a clinical challenge with high morbidity and mortality, leading to intestine damage, systemic inflammation, and multiorgan failure. Previous research has shown that the inhaled anesthetic sevoflurane protects various organs from IRI. However, whether sevoflurane protects against intestinal IRI and which application condition is the most effective are not completely clear. Thus, we investigated the effects of sevoflurane on intestinal IRI with sevoflurane given before, during or after intestinal ischemia, and the role of phosphatidylinositol 3 kinases (PI3K)/Akt pathway in these effects. METHODS: Rat model of intestinal ischemia-reperfusion (IR) was used in this study. The superior mesenteric artery was clamped for 60 minutes followed by 120 minutes of reperfusion. Sevoflurane at 0.25, 0.5, and 1.0 minimum alveolar concentration (MAC) was inhaled for 30 minutes before, during, or after ischemic insult. LY294002, a PI3K inhibitor, was injected intraperitoneally before sevoflurane inhalation. RESULTS: Intestinal IR caused a significant decrease of mean arterial blood pressure, severe intestinal mucosa injury and epithelial cell apoptosis, downregulation of the levels of phospho-Akt and phospho-Bad proteins. Exposure to 0.5 or 1.0 MAC sevoflurane before or after intestinal ischemia or 0.5 MAC during intestinal ischemia significantly ameliorated IR-induced histopathologic changes and decreased Chiu's scores. Pretreatment with 0.5 MAC sevoflurane also inhibited intestinal IR-induced increase of terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling-positive cells and activation of caspase-3 and restored expression of phospho-Akt and phospho-Bad. LY294002 partly blocked the protective effects induced by 0.5 MAC sevoflurane pretreatment. CONCLUSION: Our results suggest that sevoflurane inhalation at clinical related concentration before, during, or after ischemia protects against IR-induced intestinal injury. The pretreatment-induced protection was partly mediated by inhibiting intestinal mucosal epithelial apoptosis via activation of the PI3K/Akt pathway.

Both JNK and P38 MAPK pathways participate in the protection by dexmedetomidine against isoflurane-induced neuroapoptosis in the hippocampus of neonatal rats.

Dexmedetomidine, a highly selective α2-adrenergic agonist, has been reported to attenuate isoflurane-induced cognitive impairment and neuroapoptosis. However, the underlying molecular mechanisms remain poorly understood. The aim of this study was to investigate whether mitogen-activated protein kinase (MAPK) pathway was involved in dexmedetomidine-induced neuroprotection against isoflurane effects. Seven-day-old (P7) neonatal Sprague-Dawley rats were pretreated with various concentrations of dexmedetomidine, and then exposed to 0.75% isoflurane or air for 6h. Terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling (TUNEL) was used to detect neuronal apoptosis in their hippocampus. Activated caspase-3, extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun NH2-terminal kinases (JNK), p38, phospho-ERK1/2, phospho-JNK and phospho-p38 proteins were detected by Western blotting in the hippocampus at the end of exposure. Also, P7 rats were pretreated with 75 µg/kg dexmedetomidine alone, or given the ERK inhibitor U0126 before dexmedetomidine pretreatment, or pretreated with the p38 MAPK inhibitor SB203580 or JNK inhibitor SP600125 alone, and then exposed to 0.75% isoflurane for 6h. Isoflurane induced significant neuroapoptosis, increased the protein expression of phospho-JNK, phospho-c-Jun, phospho-p38 and phospho-nuclear factor-κB (NF-κB), decreased the level of phospho-ERK1/2 protein and reduced the ratio of Bcl-2/Bax in the hippocampus. Dexmedetomidine pretreatment inhibited isoflurane-induced neuroapoptosis and restored proteins expression of MAPK pathways and the Bcl-2/Bax ratio after isoflurane exposure. Moreover, SB203580 and SP600125 also partly attenuated the isoflurane-induced protein changes. However, U0126 did not reverse dexmedetomidine-induced neuroprotection. Our results indicate that the JNK and p38 pathways, not the ERK pathway are involved in dexmedetomidine-induced neuroprotection against isoflurane effects.

Dexmedetomidine reduces isoflurane-induced neuroapoptosis partly by preserving PI3K/Akt pathway in the hippocampus of neonatal rats.

Prolonged exposure to volatile anesthetics, such as isoflurane and sevoflurane, causes neurodegeneration in the developing animal brains. Recent studies showed that dexmedetomidine, a selective α2-adrenergic agonist, reduced isoflurane-induced cognitive impairment and neuroapoptosis. However, the mechanisms for the effect are not completely clear. Thus, we investigated whether exposure to isoflurane or sevoflurane at an equivalent dose for anesthesia during brain development causes different degrees of neuroapoptosis and whether this neuroapoptosis is reduced by dexmedetomidine via effects on PI3K/Akt pathway that can regulate cell survival. Seven-day-old (P7) neonatal Sprague-Dawley rats were randomly exposed to 0.75% isoflurane, 1.2% sevoflurane or air for 6 h. Activated caspase-3 was detected by immunohistochemistry and Western blotting. Phospho-Akt, phospho-Bad, Akt, Bad and Bcl-xL proteins were detected by Western blotting in the hippocampus at the end of exposure. Also, P7 rats were pretreated with various concentrations of dexmedetomidine alone or together with PI3K inhibitor LY294002, and then exposed to 0.75% isoflurane. Terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling (TUNEL) and activated caspase-3 were used to detect neuronal apoptosis in their hippocampus. Isoflurane, not sevoflurane at the equivalent dose, induced significant neuroapoptosis, decreased the levels of phospho-Akt and phospho-Bad proteins, increased the expression of Bad protein and reduced the ratio of Bcl-xL/Bad in the hippocampus. Dexmedetomidine pretreatment dose-dependently inhibited isoflurane-induced neuroapoptosis and restored protein expression of phospho-Akt and Bad as well as the Bcl-xL/Bad ratio induced by isoflurane. Pretreatment with single dose of 75 µg/kg dexmedetomidine provided a protective effect similar to that with three doses of 25 µg/kg dexmedetomidine. Moreover, LY294002, partly inhibited neuroprotection of dexmedetomidine. Our results suggest that dexmedetomidine pretreatment provides neuroprotection against isoflurane-induced neuroapoptosis in the hippocampus of neonatal rats by preserving PI3K/Akt pathway activity.

JNK pathway may be involved in isoflurane-induced apoptosis in the hippocampi of neonatal rats.

Previous studies have demonstrated that isoflurane, a commonly used volatile anesthetic, can induce widespread apoptosis in the neonatal animal brains and result in persistent cognitive impairment. Isoflurane-induced cytosolic Ca(2+) overload and activation of mitochondrial pathway of apoptosis may be involved in this neurodegeneration. The c-Jun N-terminal kinase (JNK) signaling can regulate the expression of the Bcl-2 family members that modulates mitochondrial membrane integrity. Therefore, we hypothesize that JNK signaling pathway activation contributes to isoflurane-induced apoptosis in the brain. In this study, Sprague-Dawley neonatal rats at postnatal day 7 were exposed to 1.1% isoflurane or air for 4h. The JNK inhibitor SP600125 at 5 µg, 10 µg, 20 µg, 30 µg or the vehicle was intraventricularly administered before the exposure. Neuronal apoptosis in the hippocampi of neonatal rats was detected by TUNEL 6h after isoflurane or air exposure. The protein expression of phospho-JNK, phospho-c-Jun, and caspase-3 as well as the antiapoptotic protein Bcl-xL and Akt/glycogen synthase kinase (GSK)-3ß pathway was detected by Western blotting. Isoflurane significantly increased apoptotic cells in the hippocampal CA1, CA3, and DG regions. The JNK inhibitor SP600125 dose-dependently inhibited isoflurane-induced neuronal apoptosis and increase of caspase-3 and phospho-JNK. SP600125 also attenuated isoflurane-induced down-regulation of Bcl-xL and maintained the activated Akt level to increase the phosphorylation of GSK-3ß at Ser9. Our results indicate that JNK activation contributes to isoflurane-induced neuroapoptosis in the developing brain. Maintaining Bcl-xL and Akt activation may be involved in the neuroprotective effects of SP600125.

Brain and behavior changes in 12-month-old Tg2576 and nontransgenic mice exposed to anesthetics.

Inhaled anesthetics have been shown to increase the aggregation of amyloid beta in vitro through the stabilization of intermediate toxic oligomers, which are thought to contribute to neurocognitive dysfunction in Alzheimer's disease. Inhaled anesthetics may escalate cognitive dysfunction through enhancement of these intermediate oligomer concentrations. We intermittently exposed 12-month-old Tg2576 transgenic mice and nontransgenic littermates to isoflurane and halothane for 5 days. Cognitive function was measured before and after anesthetic exposures using the Morris Water Maze; amyloid beta plaque burden and caspase-3 mediated apoptosis were quantified by immunohistochemistry. At 12 months of age, anesthetic exposure did not further enhance cognitive decline in the transgenic mice. Immunohistochemistry, however, revealed that the halothane-exposed Tg2576 mice had more amyloidopathy than the isoflurane treated mice or the nonexposed transgenic mice. Isoflurane exposure impaired cognitive function in the nontransgenic mice, implying an alternative pathway for neurodegeneration. These findings indicate that inhaled anesthetics influence cognition and amyloidogenesis, but that the mechanistic relationship remains unclear.

Ginkgo biloba extract (EGb 761) attenuates lung injury induced by intestinal ischemia/reperfusion in rats: roles of oxidative stress and nitric oxide.

AIM: To investigate the effect of ginkgo biloba extract (EGb 761) on lung injury induced by intestinal ischemia/reperfusion (II/R). METHODS: The rat model of II/R injury was produced by clamping the superior mesenteric artery for 60 min followed by reperfusion for 180 min. The rats were randomly allocated into sham, II/R, and EGb + II/R groups. In EGb + II/R group, EGb 761 (100 mg/kg per day) was given via a gastric tube for 7 consecutive days prior to surgery. Rats in II/R and sham groups were treated with equal volumes of the vehicle of EGb 761. Lung injury was assessed by light microscopy, wet-to-dry lung weight ratio (W/D) and pulmonary permeability index (PPI). The levels of malondialdehyde (MDA) and nitrite/nitrate (NO2(-)/NO3(-)), as well as the activities of superoxide dismutase (SOD) and myeloperoxidase (MPO) were examined. Western blot was used to determine the expression of inducible nitric oxide synthase (iNOS). RESULTS: EGb 761 markedly improved mean arterial pressure and attenuated lung injury, manifested by the improvement of histological changes and significant decreases of pulmonary W/D and PPI (P < 0.05 or 0.01). Moreover, EGb 761 markedly increased SOD activity, reduced MDA levels and MPO activity, and suppressed NO generation accompanied by down-regulation of iNOS expression (P < 0.05 or 0.01). CONCLUSION: The results indicate that EGb 761 has a protective effect on lung injury induced by II/R, which may be related to its antioxidant property and suppressions of neutrophil accumulation and iNOS-induced NO generation. EGb 761 seems to be an effective therapeutic agent for critically ill patients with respiratory failure related to II/R.