Use of a rat model to characterize 35 arterial pulse wave parameters in a comparative study of isoflurane and Zoletil/ xylazine anesthesia and the effect of Acanthopanax senticosus extract

Background : Information obtained from arterial pulse waveforms (APW) can be usefulfor characterizing the cardiovascular system. To achieve this, it is necessary to know thedetailed characteristics of APWs in different states of an organism, which would allowAPW parameters (APW- Ps) to be assigned to particular (patho)physiological conditions.Therefore, our work aimed to characterize 35 APW- Ps in rats under the influence ofisoflurane (ISO) and Zoletil/xylazine (ZO/XY) anesthesia and to study the effect of rootextract from Acanthopanax senticosus (ASRE) in these anesthetic conditions.Methods : The right jugular vein of anesthetized rats was cannulated for the administrationof ASRE and the left carotid artery for the detection of APWs from which 35APW- Ps were evaluated.Results : We obtained data on 35 APW- Ps, which significantly depended on the anesthesia,and thus, they characterized the cardiovascular system under these two conditions.ASRE transiently modulated all 35 APW- Ps, including a transient decrease insystolic and diastolic blood pressure (BP) and heart rate or increases in pulse BP, d P /d t max , and systolic and diastolic areas. Whereas the transient effects of ASRE weresimilar, the extract had prolonged disturbing effects on the cardiovascular system inrats under ZO/XY but not under ISO anesthesia. This negative effect can result fromthe disturbance caused by ZO/XY anesthesia on the cardiovascular system.Conclusions : We characterized 35 APW- Ps of rats under ISO and ZO/XY anesthesiaand found that ASRE contains compounds that can modulate the properties of thecardiovascular system, which significantly depended on the status of the cardiovascularsystem. This should be considered when using ASRE as a nutritional supplementby individuals with cardiovascular problems.

ISOFLURANE REDUCES THE SYNTHESIS OF SURFACTANT-RELATED PROTEIN A OF ALVEOLAR TYPE II CELLS INJURED BY H_2O_2

Objective To explore the influence of isoflurane(Iso) on the synthesis of surfactant-related protein(SP-A) of alveolar type II cells(AT II cells) cultured in primary and injured by hydrogen peroxide(H2O2).Methods AT II cells were isolated from adult SD rats and used for experiments after 32h in primary culture and randomized into six groups: control group,0.28 mM Iso group,2.8mM Iso group,75 μM H2O2 group,75 μM H2O2 +0.28 mM Iso group and 75 μM H2O2 +2.8 mM Iso group. Each group was continuously incubated for 3 h after administration of Iso or/and H2O2. The intracellular SP-A and the SP-A of cultured medium were measured with an enzyme-linked immunosorbent assay(ELISA).Results Iso significantly decreased SP-A content of cultured medium and the intracellular,and aggravated the decrease of SP-A content induced by H2O2 in a dose-dependent manner.Conclusion Iso itself may decrease SP-A synthesis of AT II cells in vitro,and aggravate the damage of AT II cells especially under peroxidation condition.

Sevoflurane plays a reduced role in cognitive impairment compared with isoflurane: limited effect on fear memory retention

Isoflurane and sevoflurane are both inhalation anesthetics,but in clinical application,sevoflurane has been considered to be less suitable for long-term anesthesia because of its catabolic compounds and potential nephrotoxicity.Nevertheless,recent studies have shown that these two inhalation anesthetics are similar in hepatorenal toxicity,cost,and long-term anesthetic effect.Moreover,sevoflurane possibly has less cognitive impact on young mice.In this study,C57BL/6 mice aged 8–10 weeks were exposed to 1.2%isoflurane or 2.4%sevoflurane for 6 hours.Cognitive function and memory were examined in young mice using the novel object recognition,contextual fear conditioning,and cued-fear extinction tests.Western blot assay was performed to detect expression levels of D1 dopamine receptor,catechol-O-methyltransferase,phospho-glycogen synthase kinase-3β,and total glycogen synthase kinase-3βin the hippocampus.Our results show that impaired performance was not detected in mice exposed to sevoflurane during the novel object recognition test.Contextual memory impairment in the fear conditioning test was shorter in the sevoflurane group than the isoflurane group.Long-term sevoflurane exposure did not affect memory consolidation,while isoflurane led to memory consolidation and reduced retention.Downregulation of hippocampal D1 dopamine receptors and phosphorylated glycogen synthase kinase-3β/total glycogen synthase kinase-3βand upregulation of catechol-O-methyltransferase may be associated with differing memory performance after exposure to isoflurane or sevoflurane.These results confirm that sevoflurane has less effect on cognitive impairment than isoflurane,which may be related to expression of D1 dopamine receptors and catechol-O-methyltransferase and phosphorylation of glycogen synthase kinase-3βin the hippocampus.This study was approved by the Institutional Animal Care and Use Committee,Nanjing University,China on November 20,2017(approval No.20171102).

Ginsenoside Rg1 Attenuates Isoflurane-induced Caspase-3 Activation via Inhibiting Mitochondrial Dysfunction

Objective The inhalation anesthetic isoflurane has been shown to induce mitochondrial dysfunction and caspase activation, which may lead to learning and memory impairment. Ginsenoside Rgl is reported to be neuroprotective. We therefore set out to determine whether ginsenoside Rgl can attenuate isoflurane-induced caspase activation via inhibiting mitochondrial dysfunction. Methods We investigated the effects of ginsenoside Rgl at concentrations of 12.5, 25, and 50 μmol/L and pretreatment times of 12 h and 24 h on isoflurane-induced caspase-3 activation in H4 naive and stably transfected H4 human neuroglioma cells that express full-length human amyloid precursor protein （APP） （H4-APP cells）. For mitochondrial dysfunction, we assessed mitochondrial permeability transition pore （mPTP） and adenosine-5＇-triphosphate （ATP） levels. We employed Western blot analysis, chemiluminescence, and flowcytometry. Results Here we show that pretreatment with 50 μmol/L ginsenoside Rgl for 12 h attenuated isoflurane-induced caspase-3 activation and mitochondrial dysfunction in H4-APP cells, while pretreatment with 25 and 50 μmol/L ginsenoside Rgl for 24 h attenuated isoflurane-induced caspase-3 activation and mitochondrial dysfunction in both H4 naive and H4-APP cells. Conclusion These data suggest that ginsenoside Rgl may ameliorate isoflurane-induced caspase-3 activation by inhibiting mitochondrial dysfunction. Pending further studies, these findings might recommend the use of ginsenoside Rgl in preventing and treating isoflurane-induced neurotoxicity.

Effect of emulsified isoflurane on apoptosis of anoxia-reoxygenation neonatal rat cardiomyocytes

Objective:To explore the effect of emulsified isoflurane(EI)on apoptosis of anoxia-reoxygenation neonatal rat cardiomyocytea and relevant protein expression.Methods:Cardiac muscle anoxiareoxygenation damage model was established with culture in vitro neonatal rat cardiomyocytes.The cardiomyocytes were divided into control group,model group,fat emulsion group and EI group.The cardiomyocytes apoptosis rates and lactic dehydrogenase(LDH),superoxide dismutase(SOD)and malondialdehyde(MDA)index standardization were detected after relevant treatment The expression of apoptosis-related proteins Bel-2,Bax and Caspase-3 were detected with Western blot approach.Results:After hypoxia/reoxygenation(H/R)model was treated by EI,the cells apoptosis rate decreased and was dramatically below the fat emulsion group(P<0.05),Cardiomyocytes biochemical index detection presented that,compared with the control group that the LDH activity and MDA content dramatically increased(P<0.05),while the SOD activity notably decreased(P<0.05);compared with the H/R group,the SOD activity of the fat emulsion group and EI group increased(P<0.05);while the LDH activity and MDA content decreased(P<0.05).And the change of the EI group was more remarkable than the fat emulsion group(P<0.05).The Western blot analysis presented that,compared with the control group,the Bcl-2 protein expression of the other groups significantly decreased(P<0.05),the expressions of Bax protein and Caspase-3protein increased significantly(P<0.05);compared with H/R group,cardiomyocytes Bc1-2protein expression of EI group increased significantly(P<0.05),the expressions of Bax protein and Caspase-3 protein decreased significantly(P<0.05),and the change of EI group was more remarkable than the fat emulsion group(P<0.05).Conclusions:EI can inhabit the apoptosis of anoxia-reoxygenation damage model cardiomyocytes,and may he related to the up-regulation of expression of Bcl-2 and down-regulation of expression of Caspase-3 protein.

Dexmedetomidine mitigates isoflurane-induced neurodegeneration in fetal rats during the second trimester of pregnancy

Dexmedetomidine has significant neuroprotective effects. However, whether its protective effects can reduce neurotoxicity caused by isoflurane in fetal brain during the second trimester of pregnancy remains unclear. In this study, timed-pregnancy rats at gestational day 14 spontaneously inhaled 1.5% isoflurane for 4 hours, and were intraperitoneally injected with dexmedetomidine at dosages of 5, 10, 20, and 20 μg/kg 15 minutes before inhalation and after inhalation for 2 hours. Our results demonstrate that 4 hours after inhaling isoflurane, 20 μg/kg dexmedetomidine visibly mitigated isoflurane-induced neuronal apoptosis, reversed downregulation of brain-derived neurotrophic factor expression, and lessened decreased spatial learning and memory ability in adulthood in the fetal rats. Altogether, these findings indicate that dexmedetomidine can reduce neurodegeneration induced by isoflurane in fetal rats during the second trimester of pregnancy. Further, brain-derived neurotrophic factor participates in this process.

Isoflurane preserves energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation

AIM: To investigate the protective effect of isoflurane on energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation, and to compare isoflurane with halothane. METHODS: Hepatocytes freshly isolated from fed rats were suspended in Krebs-Henseleit buffer, and incubated in sealed flasks under O2/CO2 or N2/CO2 (95%/5%, V/V) for 30 or 60 min, followed by 5 or 10 min of reoxygenation, with an added volatile anesthetic or not. ATP, ADP, and adenosine monophosphate in hepatocytes were determined by high performance liquid chromatography, and energy charge was calculated. RESULTS: During 30 min of anoxia, the energy charge and total adenine nudeotide steadily increased with the isoflurane dose from 0 to 2 minimum alveolar anesthetic concentration (MAC), then decreased from 2 to 3 MAC. In short incubations (30-35 min) at 1 MAC isoflurane, energy charge modestly decreased during anoxia, which was partially prevented by isoflurane and completely reversed by reoxygenation, and total adenine nudeotide did not decrease. In long incubations (60-70 min), both energy charge and total adenine nudeotide greatly decreased during anoxia, with partial and no reversal by reoxygenation, respectively. Isoflurane partly prevented decreases in both energy charge and total adenine nudeotide during anoxia and reoxygenation. In addition, 1 MAC isoflurane obviously increased ATP/ADP, which could not be changed by 1 MAC halothane. CONCLUSION: Isoflurane partially protects isolated hepatocytes against decreases in both energy charge and total adenine nudeotide during short (reversible) or long (irreversible) anoxia.

Isoflurane Enhances the Expression of Cytochrome C by Facilitation of NMDA Receptor in Developing Rat Hippocampal Neurons In Vitro

This study examined the effects of clinically relevant concentrations of isoflurane on the amplitude of NMDA receptor current （INMDA） and the expression of cytochrome C in cultured developing rat hippocampal neurons. The hippocampi were dissected from newborn Sprague-Dawley rats. Hippocampal neurons were primarily cultured for 5 days and then treated with different concentrations of isoflurane [（0.25, 0.5, 0.75, 1 minimum alveolar concentration （MAC））]. The peak of INMDA was re- corded by means of the whole cell patch clamp technique. The cytochrome C level was detected by Western blotting and quantitative real-time PCR. Our results showed that isoflurane （0.25, 0.5, 0.75 and 1 MAC） potentiated the amplitude of INMDA by （116±8.8）%, （122±11.7）%, （135±14.3）% and （132~14.6）%, respectively, and isoflurane increased the mRNA expression of cytochrome C in a concentration-dependent manner. The cytochrome C mRNA expression reached a maximum after 0.5 MAC isoflurane stimulation for 6 h （P〈0.05）. It was concluded that isoflurane enhances the expression of cytochrome C in cultured rat hippocampal neurons, which may be mediated by facilitation of NMDA receptor.

GLYX-13 pretreatment ameliorates long-term isoflurane exposure-induced cognitive impairment in mice

Accumulating evidence indicates that inhalation anesthetics induce or increase the risk of cognitive impairment. GLYX-13（rapastinel） acts on the glycine site of N-methyl-D-aspartate receptors（NMDARs） and has been shown to enhance hippocampus-dependent learning and memory function. However, the mechanisms by which GLYX-13 affects learning and memory function are still unclear. In this study, we investigated these mechanisms in a mouse model of long-term anesthesia exposure. Mice were intravenously administered 1 mg/kg GLYX-13 at 2 hours before isoflurane exposure（1.5% for 6 hours）. Cognitive function was assessed using the contextual fear conditioning test and the novel object recognition test. The mRNA expression and phosphorylated protein levels of NMDAR pathway components, N-methyl-D-aspartate receptor subunit 2B（NR2B）-Ca2+/calmodulin dependent protein kinase II（CaMKII）-cyclic adenosine monophosphate response element binding protein（CREB）, in the hippocampus were evaluated by quantitative RT-PCR and western blot assay. Pretreatment with GLYX-13 ameliorated isoflurane exposure-induced cognitive impairment and restored NR2B, CaMKII and CREB mRNA and phosphorylated protein levels. Intracerebroventricular injection of KN93, a selective CaMKII inhibitor, significantly diminished the effect of GLYX-13 on cognitive function and NR2B, CaMKII and CREB levels in the hippocampus. Taken together, our findings suggest that GLYX-13 pretreatment alleviates isoflurane-induced cognitive dysfunction by protecting against perturbation of the NR2B/CaMKII/CREB signaling pathway in the hippocampus. Therefore, GLYX-13 may have therapeutic potential for the treatment of anesthesia-induced cognitive dysfunction. This study was approved by the Experimental Animal Ethics Committee of Drum Tower Hospital affiliated to the Medical College of Nanjing University, China（approval No. 20171102） on November 20, 2017.

Inhibition of α5 GABAA receptors has preventive but not therapeutic effects on isoflurane-induced memory impairment in aged rats

The α5 subunit-containing gamma-amino butyric acid type A receptors(α5 GABAARs) are a distinct subpopulation that are specifically distributed in the mammalian hippocampus and also mediate tonic inhibitory currents in hippocampal neurons. These tonic currents can be enhanced by low-dose isoflurane, which is associated with learning and memory impairment. Inverse agonists of α5 GABAARs, such as L-655,708, are able to reverse the short-term memory deficit caused by low-dose isoflurane in young animals. However, whether these negative allosteric modulators have the same effects on aged rats remains unclear. In the present study, we mainly investigated the effects of L-655,708 on low-dose(1.3%) isoflurane-induced learning and memory impairment in elderly rats. Young(3-month-old) and aged(24-month-old) Wistar rats were randomly assigned to receive L-655,708 0.5 hour before or 23.5 hours after 1.3% isoflurane anesthesia.The Morris Water Maze tests demonstrated that L-655,708 injected before or after anesthesia could reverse the memory deficit in young rats. But in aged rats, application of L-655,708 only before anesthesia showed similar effects. Reverse transcription-polymerase chain reaction showed that low-dose isoflurane decreased the mRNA expression of α5 GABAARs in aging hippocampal neurons but increased that in young animals. These findings indicate that L-655,708 prevented but could not reverse 1.3% isoflurane-induced spatial learning and memory impairment in aged Wistar rats. All experimental procedures and protocols were approved by the Experimental Animal Ethics Committee of Academy of Military Medical Science of China(approval No. NBCDSER-IACUC-2015128) in December 2015.

An appropriate level of autophagy reduces emulsified isoflurane-induced apoptosis in fetal neural stem cells

Autophagy plays essential roles in cell survival.However,the functions and regulation of the autophagy-related proteins Atg5,LC3B,and Beclin 1 during anesthetic-induced developmental neurotoxicity remain unclear.This study aimed to understand the autophagy pathways and mechanisms that affect neurotoxicity,induced by the anesthetic emulsified isoflurane,in rat fetal neural stem cells.Fetal neural stem cells were cultured,in vitro,and neurotoxicity was induced by emulsified isoflurane treatment.The effects of pretreatment with the autophagy inhibitors 3-methyladenine and bafilomycin and the effects of transfection with small interfering RNA against ATG5(siRNA-Atg5)were observed.Cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay,and apoptosis was assessed using flow cytometry.Ultrastructural changes were analyzed through transmission electron microscopy.The levels of the autophagy-related proteins LC3B,Beclin 1,Atg5,and P62 and the pro-apoptosis-related protein caspase-3 were analyzed using western blot assay.The inhibition of cell proliferation and that of apoptosis rate increased after treatment with emulsified isoflurane.Autophagolysosomes,monolayer membrane formation due to lysosomal degradation,were observed.The autophagy-related proteins LC3B,Beclin 1,Atg5,and P62 and caspase-3 were upregulated.These results confirm that emulsified isoflurane can induce toxicity and autophagy in fetal neural stem cells.Pre-treatment with 3-methyladenine and bafilomycin increased the apoptosis rate in emulsified isoflurane-treated fetal neural stem cells,which indicated that the complete inhibition of autophagy does not alleviate emulsified isoflurane-induced fetal neural stem cell toxicity.Atg5 expression was decreased significantly by siRNA-Atg5 transfection,and cell proliferation was inhibited.These results verify that the Atg5 autophagy pathway can be regulated to maintain appropriate levels of autophagy,which can inhibit the neurotoxicity induced by emulsified isoflurane anesthetic in fetal neural stem cells.

Effects of isoflurane on ICAM-1 expression and neutrophils infiltration in rats with liver ischemia and reperfusion injury

Objective： To establish a rat model of warm partial hepatic ischemia-reperfusion （IR）, and investigate the protective and anti-inflammatory effects of isoflurane on warm hepatic ischemia-reperfusion injury （IRI） in rats. Methods： Thirty-two female Sprague-Dawley rats were divided equally into 4 groups （n-8）： PB-Sham group in which the rats were anesthetized by intraperitoneal injection of pentobarbital sodium （1.0%, 40 mg/kg, PB） and received a sham operation without occlusion of liver blood flow; PB-IR group whose rats underwent partial hepatic IR after anesthesia; Iso-Sham group in which inhalation of 1.0 MAC isoflurane and sham operation was performed; Iso-IR group in which 1.0 MAC isoflurane was inhaled for 4 h and IR was performed. Rat model of warm partial hepatic IR was established by clamping the hepatic arteries and hilar vessels distributing to the left and median lobes to induce partial hepatic ischemia （70%） for 60 rain followed by reperfusion for 3 h. The rats were killed 3 h after declamping, and specimens of liver tissue and blood were obtained. The serum ALT and AST were detected as liver damage markers. Viability of myeloperoxidase （MPO） in liver was measured. The protein level of ICAM-1 in the liver was detected by immunohistochemistry and Western blotting. Results： Rats treated with 1.0 MAC isoflurane during warm partial （70%） hepatic ischemia 60 rain and 3 h reperfusion had significantly lower serum ALT and AST compared with rats anesthetized with pentobarbital sodium subjected to hepatic IRI. The expression of ICAM-1 in hepatic tissue was significantly increased by hepatic IRI after pentobarbital sodium anesthesia. Isoflurane significantly inhibited protein expression of ICAM-1 in hepatic IR injury compared with pentobarbital sodium anesthesia. Viability of liver MPO was significantly increased by hepatic IRI after pentobarbital sodium anesthesia; Isoflurane can significantly inhibit MPO alteration in rat liver ischemia-reperfusion injury compared with rats anesthetized with pentobarbital sodium. Conclusion： Isoflurane anesthesia can attenuate liver IR injury in rats that maybe by inhibiting ICAM-I expression and reducing the infiltration of neutrophils.

Protective Effect of Isoflurane and Sevoflurane on Ischemic Neurons and Expression of Bcl-2 and ICE Genes in Rat Brain

Objective To study the protective effect of volatile anesthetics, isoflurane and sevoflurane, on ischemic neurons after cerebral ischemia-reperfusion in rats and its possible molecular mechanism. Methods Rat cerebral ischemia-reperfusion model was developed by occlusion of the middle cerebral artery （MCA） and bilateral common carotid arteries （CCAs） 1 h after reperfusion. Using flow cytometry （FCM） and Northern blot hybridization, we calculated the number of apoptotic bodies and detected the expression of bcl-2 mRNA and interleukin-113 converting enzyme （ICE） mRNA. Results The apoptotic bodies in hippocampus analyzed by FCM peaked at appeared 24 h after reperfusion, and decreased about 54% and 40%, respectively, after treatment with isoflurane and sevoflurane, as compared with ischemic group. There was no significant difference in the expression of bcl-2 mRNA and ICE mRNA between the inhaled anesthetic groups and ischemic group in hippocampus 24 h after MCA/CCAs occlusion. Conclusion Isoflurane and sevoflurane partially inhibit apoptosis but have no significant effect on the expression of bcl-2 and ICE genes.

Isoflurane-induced neuronal apoptosis in developing hippocampal neurons

We hypothesized that the P2X7 receptor may be the target of isoflurane, so we investigated the roles of the P2X7 receptor and inositol triphosphate receptor in calcium overload and neuronal apoptosis induced by isoflurane in cultured embryonic rat hippocampal neurons. Results showed that isoflurane induced widespread neuronal apoptosis and significantly increased cytoplasmic Ca^2＋ Blockade of P2X7 receptors or removal of extracellular Ca^2＋ combined with blockade of inositol triphosphate receptors completely inhibited apoptosis or increase in cytoplasmic Ca^2＋. Removal of extracellular Ca^2＋ or blockade of inositol triphosphate receptor alone could partly inhibit these effects of isoflurane. Isoflurane could directly activate P2X7-gated channels and induce inward currents, but did not affect the expression of P2X7 receptor protein in neurons. These findings indicate that the mechanism by which isoflurane induced neuronal apoptosis in rat developing brain was mediated by intracellular calcium overload, which was caused by P2X7 receptor mediated calcium influx and inositol triphosphate receptor mediated calcium release.

Role of GSK-3β in Isoflurane-induced Neuroinflammation and Cognitive Dysfunction in Aged Rats

Summary： This study investigated the role of glycogen synthase kinase-3D （GSK-3β） in isoflu- rane-induced neuroinflammation and cognitive dysfunction in aged rats. The hippocampi were dissected from aged rats which had been intraperitoneally administered lithium chloride （LiC1, 100 mg/kg） and then exposed to 1.4% isoflurane for 6 h. The expression of GSK-313 was detected by Western blotting. The mRNA and protein expression levels of tumor necrosis factor （TNF）-a, interleukin （IL）-lβ and IL-6 were measured by real-time PCR and enzyme-linked immunosorbent assay （ELISA）, respectively. Mor- ris water maze was employed to detect spatial memory ability of rats. The results revealed that the level of GSK-3β was upregulated after isofurane exposure. Real-time PCR analysis demonstrated that isoflu- rane anesthesia increased mRNA levels of TNF-a IL-Iβ and IL-6, which was consistent with the ELISA results. However, these changes were reversed by prophylactic LiC1, a non-selective inhibitor of GSK-3β. Additionally, we discovered that LiC1 alleviated isoflurane-induced cognitive impairment in aged rats. Furthermore, the role of GSK-313 in isoflurae-induced neuroinflammation and cognitive dysfunction was associated with acetylation of NF-r,B p65 （Lys310）. In conclusion, these results suggested that GSK-3β is associated with isoflurane-induced upregulation of proinflammatory cytokines and cognitive disorder in aged rats.

Ginsenoside Rb1 Attenuates Isoflurane/surgery-induced Cognitive Dysfunction via Inhibiting Neuroinflammation and Oxidative Stress

Objective Anesthetic isoflurane plus surgery has been reported to induce cognitive impairment. The underlying mechanism and targeted intervention remain largely to be determined. Ginsenoside Rb1 was reported to be neuroprotective. We therefore set out to determine whether ginsenoside Rb1 can attenuate isoflurane/surgery-induced cognitive dysfunction via inhibiting neuroinflammation and oxidative stress. Methods Five-months-old C57BL/6J female mice were treated with 1.4% isoflurane plus abdominal surgery for two hours. Sixty mg/kg ginsenoside Rb1 were given intraperitoneally from 7 days before surgery. Cognition of the mice were assessed by Barnes Maze. Levels of postsynaptic density-95 and synaptophysin in mice hippocampus were measured by Western blot. Levels of reactive oxygen species, tumor necrosis factor-α and interleukin-6 in mice hippocampus were measured by ELISA. Results Here we show for the first time that the ginsenoside Rb1 treatment attenuated the isoflurane/surgery-induced cognitive impairment. Moreover, ginsenoside Rb1 attenuated the isoflurane/surgery-induced synapse dysfunction. Finally, ginsenoside Rb1 mitigated the isoflurane/surgery-induced elevation levels of reactive oxygen species, tumor necrosis factor-α and interleukin-6 in the mice hippocampus. Conclusion These results suggest that ginsenoside Rb1 may attenuate the isoflurane/surgery-induced cognitive impairment by inhibiting neuroinflammation and oxidative stress pending future studies.

Isoflurane anesthesia suppresses distortion product otoacoustic emissions in rats

A commonly used anesthetic, isoflurane, can impair auditory function in a dose-dependent manner. However, in rats, isoflurane-induced auditory impairments have only been assessed with auditory brainstem responses; a measure which is unable to distinguish if changes originate from the central or peripheral auditory system. Studies performed in other species, such as mice and guinea-pigs, suggests auditory impairment stems from disrupted OHC amplification. Despite the wide use of the rat in auditory research, these observations have yet to be replicated in the rat animal model. This study used distortion product otoacoustic emissions to assess outer hair cell function in rats that were anesthetized with either isoflurane or a ketamine/xylazine cocktail for approximately 45 min. Results indicate that isoflurane can significantly reduce DPOAE amplitudes compared to ketamine/xylazine, and that responses were more variable with isoflurane than ketamine/xylazine over the 45-min test period. Based on these observations, isoflurane should be used with caution when assessing peripheral auditory function to avoid potentially confounding effects.

The Effect of Nitrous Oxide and Isoflurane on the Total RNA Yield from the Cochlea of the Rats

The possible mechanism of inhalation anesthetics on the internal auditory impairment of the rat was investigated by determining the effect of nitrous oxide （N2O） and isoflurane on the total RNA yield from the cochlea of the rats. Thirty healthy Wistar rats were randomly divided into 3 groups： group C （control group, n=10） with a 3-h unremitting inhalation of 50% 02, group N （experiment group, n= 10） with a continuous inhalation of 50% N20＋50% O2for 3 h, and group I （experiment group, n=10） with a 3-h sustained inhalation of 2.5% isoflurane. The TRIzol in combination with RNeasy was used to respectively extract the total RNA from cochlea of rats in the 3 groups. Spectrophotometry was used to detect total RNA yield and electrophoresis to detect the quality. The total RNA extracted from the cochlea of the rats in the groups C and N was 7.69 and 6.51 μg, respectively. There was a 15% decrease in the N group as compared with group C. The total RNA from the rats in the group I was 7.32μg, and there was hardly any change in the group as compared with the group C. The value of A260/A280 in groups C, N and I was 2.07, 2.04 and 2.04, respectively, showing a very high RNA purity. The result of gel electrophoresis suggested that there was no degradation in the total RNA. It was suggested that the interference of N20 on the cochlear RNA yield might be one of the reasons which cause an injury of the ear. The isoflurane shows no harm on the hearing.

Effects of Isoflurane on the Actions of Neuromuscular Blockers on the Muscle Nicotine Acetylcholine Receptors

Summary: In this study, we tested the hypothesis that volatile anesthetic enhancement of muscle relaxation is the result of combined drug effects on the nicotinic acetylcholine receptors. The poly A m RNA from muscle by isolation were microinjected into Xenopus oocytes for receptor expression. Concentration-effect curves for the inhibition of Ach-induced currents were established for vecuronium, rocuranium, and isoflurane. Subsequently, inhibitory effects of NDMRs were studied in the presence of the isoflurane at a concentration equivalent to half the concentration producing a 50 % inhibition alone. All tested drugs produced rapid and readily reversible concentration-dependent inhibition. The 50 % inhibitory concentration values were 889 μmol/L (95 % CI: 711-1214 μmol), 33.4 μmol (95 % CI: 27.1-41.7 nmol) and 9.2 nmol (95 % CI: 7.9-12.3 nmol) for isoflurane, rocuranium and vecuronium, respectively. Coapplication of isoflurane significantly enhanced the inhibitory effects of rocuranium and vecuronium, and it was especially so at low concentration of NMDRs. Isoflurane increases the potency of NDMRs, possibly by enhancing antagonist affinity at the receptor site.

In vivo field recordings effectively monitor the mouse cortex and hippocampus under isoflurane anesthesia

Isoflurane is a widely used inhaled anesthetic in the clinical setting. However, the mechanism underlying its effect on consciousness is under discussion. Therefore, we investigated the effect of isoflurane on the hippocampus and cortex using an in vivo field recording approach. Our results showed that 1.3%, 0.8%, and 0.4% isoflurane exerted an inhibitory influence on the mouse hippocampus and cortex. Further, high frequency bands in the cortex and hippocampus showed greater suppression with increasing isoflurane concentration. Our findings suggest that in vivo field recordings can monitor the effect of isoflurane anesthesia on the mouse cortex and hippocampus.