ABSTRACT
Oxygen and glucose deprivation (OGD) are the most important factors related to tissue damage resulting from stroke. Microglial cells have been found to be very vulnerable to ischemia and OGD. It has been reported that isoflurane exposure can protect the mammalian brain from insults such as ischemic stroke; however, the effects of isoflurane on OGD-induced injury in microglia are as yet unknown. In this study, we investigated the effects of isoflurane on OGD-induced injury in microglia. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) revealed that OGD did indeed induce cell death in microglia. However, isoflurane preconditioning attenuated OGD-induced cell death. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay demonstrated that isoflurane treatment alleviated OGD-induced apoptosis. Toll-like receptor 4 (TLR4) plays a considerable role in the induction of innate immune and inflammatory responses. Our results indicate that isoflurane preconditioning inhibits the upregulation of TLR4 as well as the activation of its downstream molecules, such as c-Jun N-terminal kinase (JNK) and nuclear factor kappa B (NF-κB), in BV-2 microglia exposed to OGD. Importantly, we also found that isoflurane pretreatment significantly reduces the production of proinflammatory factors such as tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), IL-ß, and nitric oxide (NO). The results indicate that TLR4 and its downstream NF-κB-dependent signaling pathway contribute to the neuroprotection of microglia exposed to OGD/reoxygenation by administration of isoflurane.
Subject(s)
Glucose/deficiency , Isoflurane/pharmacology , Microglia/drug effects , Oxygen/metabolism , Toll-Like Receptor 4/metabolism , Animals , Apoptosis , Cell Hypoxia , Cell Line , Interleukin-1beta/genetics , Interleukin-1beta/metabolism , Interleukin-6/genetics , Interleukin-6/metabolism , JNK Mitogen-Activated Protein Kinases/metabolism , Mice , Microglia/metabolism , NF-kappa B/metabolism , Nitric Oxide/metabolism , Signal Transduction , Toll-Like Receptor 4/genetics , Tumor Necrosis Factor-alpha/genetics , Tumor Necrosis Factor-alpha/metabolismABSTRACT
OBJECTIVE: To observe the effect of transcutaneous acupoint electrical stimulation (TAES) on serum superoxide dismutase (SOD) activity, malondialdehyde (MDA) and S100beta contents in craniotomy patients for studying its cerebral protection mechanism. METHODS: Fifty patients scheduled for neurosurgery were randomly divided into TAES group (n = 25) and control group (n=25) with randomized block method. For patients of TAES group, TAES was applied to bilateral Hegu (LI 4) and Quchi (LI 11), Zusanli (ST 36) and Sanyinjiao (SP 6) from 30 minutes on before anesthesia to the end of operation. Patients of control group were anesthetized with sevoflurane inhalation and intermittent (i.v.) of sulfenany and vecurnium bromide. Blood samples were taken for assaying serum SOD activity, MDA and S100beta contents with purinase oxydasis, biochemiluminescence and enzyme linked immunosorbent assay separately. Scores of cognitive ability were given by using Mini Mental State Examination (MMSE). RESULTS: In comparison with pre-anesthesia, serum SOD activity decreased significantly 1 h after craniotomy in control group, at the end of operation in both control and TAES groups (P<0.05, P<0.01), and increased markedly 48 h after operation in control group (P<0.05). Serum MDA in control group increased significantly 48 h after operation, while that in TAES group reduced apparently 24 h after operation (P<0.01). Serum S100beta content in TAES group decreased remarkably 48 h after operation (P<0.01). Serum SOD activity of TAES group was significantly higher than that of control group 24 h after operation (P<0.05). Compared with control group, serum MDA contents of 24 h and 48 h after operation and serum S100beta levels at 1 h after craniotomy and 48 h after operation were markedly lower in TAES group (P<0.01, P<0.05). No significant differences were found between two groups in the cognitive function scores (P>0.05). CONCLUSION: TAES can increase serum SOD activity and reduce MDA and S100beta levels in patients undergoing craniotomy, which may contribute to its effect in reducing lipid peroxidation induced cerebral injury. But its impact on the patient's cognitive function needs study further.
