Medical Gas Research

: 2022  |  Volume : 12  |  Issue : 3  |  Page : 73--76

Current research progress of isoflurane in cerebral ischemia/reperfusion injury: a narrative review

Shu-Jun Chen1, Xia-Qing Yuan1, Qun Xue1, Hai-Feng Lu1, Gang Chen2,  
1 Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
2 Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China

Correspondence Address:
Hai-Feng Lu
Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province
Qun Xue
Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province


Cerebral ischemia/reperfusion injury is an important factor leading to poor prognosis in ischemic stroke patients. Therefore, it is particularly important to find effective remedial measures to promote the health of patients to return to society. Isoflurane is a safe and reliable anesthetic gas with a long history of clinical application. In recent years, its protection function to human body has been widely recognized, and nowadays isoflurane for cerebral protection has been widely studied, and the stable effect of isoflurane has satisfied many researchers. Basic studies have shown that isoflurane’s protection of brain tissue after ischemia/reperfusion involves a variety of signaling pathways and effector molecules. Even though many signaling pathways have been described, more and more studies focus on exploring their mechanisms of action, in order to provide strong evidence for clinical application. This could prompt the introduction of isoflurane therapy to clinical patients as soon as possible. In this paper, several confirmed signaling pathways will be reviewed to find possible strategies for clinical treatment.

How to cite this article:
Chen SJ, Yuan XQ, Xue Q, Lu HF, Chen G. Current research progress of isoflurane in cerebral ischemia/reperfusion injury: a narrative review.Med Gas Res 2022;12:73-76

How to cite this URL:
Chen SJ, Yuan XQ, Xue Q, Lu HF, Chen G. Current research progress of isoflurane in cerebral ischemia/reperfusion injury: a narrative review. Med Gas Res [serial online] 2022 [cited 2022 Jan 21 ];12:73-76
Available from:

Full Text


With the aging of the population, stroke has a tendency to become the first disease threatening human health, the disability rate and mortality rate of stroke is extremely high, but there is no good treatment.[1] Stroke currently accounts for 55% of the incidence in neuroscience and is the leading cause of physical disability and impairment of consciousness.[2],[3] It poses serious health threats and economic pressures for people around the world.[4] At present, most elderly people suffer from insufficient blood supply to the brain due to vascular problems, resulting in ischemic necrosis of the brain tissue, and the incidence of ischemic stroke accounts for the vast majority.[5] Cerebral ischemia can lead to defects such as inflammation, reperfusion injury, and dysfunction. At present, thrombolysis and endovascular intervention are the most effective strategies at the acute phase of ischemic stroke.[6] At present, most views believe that after thrombolytic therapy or thrombectomy, the blood flow of the brain tissue will be restored and the brain tissue will be damaged again.[7] Therefore, a series of problems caused by blood flow recovery in blood vessels need to be solved urgently.[8] Cerebrovascular accident is a terrible event with severe sequelae, which has a tendency to become a major threat to the health of people around the world. Four fifths strokes occur in all patients with ischemic stroke.[9] Because neurons are non-regenerative cells, the necrosis of nerve tissue caused by ischemia and hypoxia is an irreversible event, making stroke the world’s leading cause of death and disability.[10] The main treatment of the acute phase of ischemic stroke is recanalization, not only removing toxic metabolites but also replenishing nutrients and oxygen.[11] Cerebral ischemia/reperfusion (I/R) injury refers to the reflow of blood leads to damage and inflammation to brain. These cascading injuries leave the central nervous system vulnerable, eventually leads to the occurrence of serious adverse events.[12] After cerebral ischemia, cerebral ischemia hypoxia resulting in a large number of brain cell death and neural function defect,[13] primary injury caused by ischemia has been unable to recover, and the secondary brain injury caused by restored blood flow, resulting in the release of various neurotoxic molecules, the expansion of inflammation, cell electrolyte accumulation, brain disorder environment. All of these factors interact to result in a cascade of brain tissue damage, a breakdown of the blood- brain barrier, a weakened nerve function, and ultimately a poor overall prognosis for patients.[14] All injuries cause edema of brain tissue and injury of the extracellular matrix, which may lead to ischemia and rebleeding. Therefore, it is considered that the recovery of microcirculation is the key to save the partial biological function of patients.[15] Existing study has shown that the degree of microcirculation recovery after cerebral ischemia is positively correlated with the overall survival rate of patients.[16] After cerebral ischemia, the body starts the vascular regeneration system. The newly generated capillaries can reduce the blood flow in the low perfusion area, providing a good microenvironment for the repair of nerve cells, attempting to restore and replace the nerve function which has been damaged. However, the body’s self-angiogenesis is often insufficient, so we need to look for relevant treatments from this perspective.[17]

Isoflurane (ISO) is a kind of commonly gaseous anesthetic that is often used for sedation and anesthesia in neurosurgery.[18] As the widely used inhalation anesthetic, ISO has been widely recognized for its safety and neuroprotective effects. In short, short-term and low-concentration ISO therapy has a protective effect on ischemic brain tissue.[19] After cerebral ischemia, the disorder of the central nervous system becomes more and more unpredictable, so it is urgent to find a quick and effective treatment method. As a treatment method, ISO has obvious advantages and is now attracting more and more attention from the majority of scholars. However, the mechanism of brain protection in ISO is unclear.[20] It is worth noting that researches on signal transduction pathways in the central nervous system after ectopic location are limited and worthy of further study. We searched the recent studies on ISO in I/R injury from PubMed to provide potential targets for current treatment.

 Existing Signaling Pathways and Brief Mechanism

Sonic hedgehog/Gli signaling pathway

After I/R injury, angiogenesis is the key factor leading to good recovery. Angiogenesis requires the synergistic action of many cytokines. Angiogenesis is a synergistic function of multiple cytokines and signal transduction pathways, among which transforming growth factor β (TGF-β), vascular endothelial growth factor (VEGF) and CD34 are the most critical ones.[21] Modern medical research shows that sonic hedgehog (Shh)/ Gli signaling pathway plays an important role in almost every process of mammalian growth and development.[22] ISO can regulate the production of VEGF and CD34 through Shh/ Gli signaling pathway.[21] In other words, ISO treatment can promote the formation of new blood vessels after I/R, and further improve the microvascular network of the central nervous system. After ISO treatment, infarction area of rats was reduced and neurological function score was improved. However, there was no difference in injury changes of rats compared with the control group after Shh inhibitor was given, indicating that ISO can achieve cerebral protection through Shh/Gli pathway[21] [Figure 1].{Figure 1}

TGF-β2/mothers against decapentaplegic homolog 3 signaling pathway

ISO was shown to up-regulate TGF-β2 expression in the hippocampus and cortex after I/R, while phosphorylated mothers against decapentaplegic homolog 3 (Smad-3) expression was also increased. These results suggest that ISO treatment is likely to activate the TGF-β2/Smad3 signaling pathway.[23] TGF-β2 has been recognized as a necessary protective molecule of the central nervous system, and experiment has confirmed the protective effect of TGF-β2.[24] The TGF-β2/Smad3 signaling pathway participates in and regulates the expression of VEGF and CD34, promoting the repair of cerebral microvascular network after I/R. In summary, ISO can promote the formation of new blood vessels through T cell receptor signaling pathway and reduce brain injury. In addition, other studies have shown that the expression of TGF-β2 protein in neurons of animals with chronic ischemia can be continuously increased, which is helpful for the body to fight against transient ischemic attack[25] [Figure 1].

Wnt/β-catenin signaling pathway

The importance of Wnt/β-catenin signaling pathway in central nervous system genesis, development, differentiation has been widely recognized.[26] After I/R injury, the expression of Wnt3a, β-catenin and cyclin D1 proteins were inhibited, related proteins in the pathway were activated and increased after ISO treatment. Meanwhile, after activation of this pathway, unphosphorylated β-catenin entered the nucleus to regulate the expression of related molecules such as VEGF and apoptosis related proteins.[27]

c-Jun N-terminal kinase signaling pathway

Mitogen activated protein kinase kinase kinase is activated after cerebral I/R injury, then mitogen-activated protein kinase kinase is activated as well, finally the c-Jun N-terminal kinase (JNK) is included in the JNK signaling pathway is activated. The activated JNK has two main functions. First, JNK can up-regulate the expression of pro-apoptotic proteins and activate the apoptosis pathway of the death receptor.[28] Secondly, JNK regulates the activity of members of the Bcl-2 family through mitochondria-mediated apoptosis. These two pathways eventually activate caspase-3. Caspase-3 activated by these two pathways activates caspase-activated DNase, which cuts nuclear DNA repair enzyme poly(DP-ribose) polymerase, leading to irreversible nuclear DNA damage and ultimately apoptosis.[29] The experimental results showed that the phosphorylation level of JNK protein increased gradually after I/R injury, while 1.5% ISO post-treatment obviously reduced the effect. It was surprising that, at the level of 4.5% of the ISO post-adaptation group, it increased. After injection of JNK blocker SP600125, the brain I/R injury was significantly reduced. This result indicates that JNK signal is involved in the protective effect of ISO adaptation on brain I/R injury [Table 1].[30],[31] JNK is an important signaling pathway in the downstream of TGF-β1. TGF-β1 inhibitor LY2157299 treatment distinctly enhanced JNK phosphorylation. No significant brain protective effect was observed after 1.5% ISO treatment. The expression levels of TGF-β1 and phosphorylated Smad2/3 significantly increased after JNK-specific inhibitor (SP600125) was applied. Cell death was reduced in 1.5% ISO treatment group, suggesting that TGF-β1 and JNK signaling pathways have adverse effects on the post-I/R brain tissue [Figure 1].{Table 1}

Notch signaling pathway

Notch signaling pathway is highly conserved and widely expressed in the animal kingdom. In terms of function, Notch plays an important role in cell self-renewal, individual growth and development as well as a series of physiological and pathological processes.[32] Notch is associated with differentiation, maturation, regeneration and functional maturation of intracranial cells in the central nervous system, and is closely related to neurodegenerative diseases.[33] Notch signaling pathway is actively involved in the dynamic changes of cell structure and nervous system function throughout its life cycle. By observing the changes of notch intracellular domain, notch-1 and split-1 expression enhancement factors, it was found that inhaling ISO can activate notch signaling pathway in advance and advance the peak value of Notch signal to 24 hours after reperfusion. The activation of Notch pathway is of great significance in reducing brain injury and cell death after I/R.[31]

 Conclusions and Prospects

As an inhalational anesthetic gas, ISO can play an important role in the treatment of cerebral I/R injury. Existing studies have shown that these effects are safe and reliable with basic experimental support. Due to the high disability rate and mortality rate of cerebrovascular disease, it is urgent to find effective approaches. It can be predicted that the high therapeutic value of ISO will certainly enter the clinic for clinical treatment as soon as possible, which will greatly alleviate the current shortage of treatment approaches.

Author contributions

SJC were responsible for writing the manuscript. XQY and QX were responsible for its revision. HFL and GC were responsible for its drafting and revision. All the authors read and approved the final version of the manuscript for publication.

Conflicts of interest


Open access statement

This is an open access journal, and articles are distributed under the terms of the Creative Commons AttributionNonCommercial- ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. ©Article authors (unless otherwise stated in the text of the article) 2022. All rights reserved. No commercial use is permitted unless otherwise expressly granted.


1Wang SN, Wang Z, Xu TY, Cheng MH, Li WL, Miao CY. Cerebral organoids repair ischemic stroke brain injury. Transl Stroke Res. 2020;11:983-1000.
2Bernstein DL, Zuluaga-Ramirez V, Gajghate S, et al. miR-98 reduces endothelial dysfunction by protecting blood-brain barrier (BBB) and improves neurological outcomes in mouse ischemia/re- perfusion stroke model. J Cereb Blood Flow Metab. 2020;40:1953- 1965.
3Liu Y, Min JW, Feng S, et al. Therapeutic role of a cysteine precursor, OTC, in ischemic stroke is mediated by improved proteostasis in mice. Transl Stroke Res. 2020;11:147-160.
4Zhao H, Li G, Zhang S, et al. Inhibition of histone deacetylase 3 by MiR-494 alleviates neuronal loss and improves neurological recovery in experimental stroke. J Cereb Blood Flow Metab. 2019;39:2392-2405.
5Yang S, Liu K, Ding H, et al. Longitudinal in vivo intrinsic optical imaging of cortical blood perfusion and tissue damage in focal photothrombosis stroke model. J Cereb Blood Flow Metab. 2019;39:1381-1393.
6Qin C, Zhou P, Wang L, et al. Dl-3-N-butylphthalide attenuates ischemic reperfusion injury by improving the function of cerebral artery and circulation. J Cereb Blood Flow Metab. 2019;39:2011- 2021.
7Wang Z, Higashikawa K, Yasui H, et al. FTY720 protects against ischemia-reperfusion injury by preventing the redistribution of tight junction proteins and decreases inflammation in the subacute phase in an experimental stroke model. Transl Stroke Res. 2020;11:1103-1116.
8Liang TY, Peng SY, Ma M, Li HY, Wang Z, Chen G. Protective effects of sevoflurane in cerebral ischemia reperfusion injury: a narrative review. Med Gas Res. 2021;11:152-154.
9Cinar T, Hayiroglu M, Çiçek V, et al. Predictors of left atrial thrombus in acute ischemic stroke patients without atrial fibrillation: A single-center cross-sectional study. Rev Assoc Med Bras (1992) 2020;66:1437-1443.
10Su XT, Wang L, Ma SM, et al. Mechanisms of acupuncture in the regulation of oxidative stress in treating ischemic stroke. Oxid Med Cell Longev. 2020;2020:7875396.
11He J, Liu J, Huang Y, et al. Olfactory mucosa mesenchymal stem cells alleviate cerebral ischemia/reperfusion injury via Golgi apparatus secretory pathway Ca(2+) -ATPase isoform. Front Cell Dev Biol. 2020;8:586541.
12Qiao D, Zhang Y, Rehman AU, Khosravi MR. Big data-enabled analysis of DRGs-based payment on stroke patients in Jiaozuo, China. J Healthc Eng. 2020;2020:6690019.
13Xu M, Wu R, Liang Y, et al. Protective effect and mechanism of Qishiwei Zhenzhu pills on cerebral ischemia-reperfusion injury via blood-brain barrier and metabonomics. Biomed Pharmacother. 2020;131:110723.
14Zhang ML, Peng W, Ni JQ, Chen G. Recent advances in the protective role of hydrogen sulfide in myocardial ischemia/reperfusion injury: a narrative review. Med Gas Res. 2021;11:83-87.
15Kanazawa M, Takahashi T, Ishikawa M, Onodera O, Shimohata T, Del Zoppo GJ. Angiogenesis in the ischemic core: a potential treatment target? J Cereb Blood Flow Metab. 2019;39:753-769.
16Adamczak J, Hoehn M. Poststroke angiogenesis, con: dark side of angiogenesis. Stroke. 2015;46:e103-104.
17Marti HJ, Bernaudin M, Bellail A, et al. Hypoxia-induced vascular endothelial growth factor expression precedes neovascularization after cerebral ischemia. Am J Pathol. 2000;156:965-976.
18Moody AE, Beutler BD, Moody CE. Predicting cost of inhalational anesthesia at low fresh gas flows: impact of a new generation carbon dioxide absorbent. Med Gas Res. 2020;10:64-66.
19Kim EJ, Kim SY, Lee JH, et al. Effect of isoflurane post-treatment on tPA-exaggerated brain injury in a rat ischemic stroke model. Korean J Anesthesiol. 2015;68:281-286.
20Zhang HP, Yuan LB, Zhao RN, et al. Isoflurane preconditioning induces neuroprotection by attenuating ubiquitin-conjugated protein aggregation in a mouse model of transient global cerebral ischemia. Anesth Analg. 2010;111:506-514.
21Peng L, Yin J, Ge M, et al. Isoflurane post-conditioning ameliorates cerebral ischemia/reperfusion injury by enhancing angiogenesis through activating the Shh/Gli signaling pathway in rats. Front Neurosci. 2019;13:321.
22Varjosalo M, Taipale J. Hedgehog: functions and mechanisms. Genes Dev. 2008;22:2454-2472.
23Peng L, Yin J, Wang S, et al. TGF-β2/Smad3 signaling pathway activation through enhancing VEGF and CD34 ameliorates cerebral ischemia/reperfusion injury after isoflurane post-conditioning in rats. Neurochem Res. 2019;44:2606-2618.
24Polazzi E, Altamira LE, Eleuteri S, et al. Neuroprotection of microglial conditioned medium on 6-hydroxydopamine-induced neuronal death: role of transforming growth factor beta-2. J Neurochem. 2009;110:545-556.
25Hu Z, Fan J, Zeng L, et al. Transient cerebral ischemia leads to TGF-beta2 expression in Golgi apparatus organelles. Curr Neurovasc Res. 2008;5:178-184.
26Wisniewska MB. Physiological role of β-catenin/TCF signaling in neurons of the adult brain. Neurochem Res. 2013;38:1144-1155.
27Shi ZY, Deng JX, Fu S, et al. Protective effect of autophagy in neural ischemia and hypoxia: Negative regulation of the Wnt/β- catenin pathway. Int J Mol Med. 2017;40:1699-1708.
28Akhter R, Sanphui P, Das H, Saha P, Biswas SC. The regulation of p53 up-regulated modulator of apoptosis by JNK/c-Jun pathway in β-amyloid-induced neuron death. J Neurochem. 2015;134:1091- 1103.
29Huang XP, Tan H, Chen BY, Deng CQ. Combination of total Astragalus extract and total Panax notoginseng saponins strengthened the protective effects on brain damage through improving energy metabolism and inhibiting apoptosis after cerebral ischemia-reperfusion in mice. Chin J Integr Med. 2017;23:445-452.
30Wang S, Yin J, Ge M, et al. Transforming growth-beta 1 contributes to isoflurane postconditioning against cerebral ischemia-reperfusion injury by regulating the c-Jun N-terminal kinase signaling pathway. Biomed Pharmacother. 2016;78:280-290.
31Zhang HP, Sun YY, Chen XM, et al. The neuroprotective effects of isoflurane preconditioning in a murine transient global cerebral ischemia-reperfusion model: the role of the Notch signaling pathway. Neuromolecular Med. 2014;16:191-204.
32Artavanis-Tsakonas S, Rand MD, Lake RJ. Notch signaling: cell fate control and signal integration in development. Science. 1999;284:770-776.
33Yoon K, Gaiano N. Notch signaling in the mammalian central nervous system: insights from mouse mutants. Nat Neurosci. 2005;8:709-715.