The role of Bag2 in neurotoxicity induced by the anesthetic sevoflurane

Proteomic analysis of gene expression in the prefrontal cortex in infant rhesus macaques after multiple sevoflurane exposures

PURPOSE

Repeated exposure of infant rhesus macaques to sevoflurane induces neurotoxicity and is associated with neurocognitive impairment in later life. We aimed to investigate the effect of repeated sevoflurane exposure on the expression of proteins in the prefrontal cortex of infant rhesus macaques by proteomics.

METHODS

Rhesus macaques were exposed to sevoflurane three times, on postnatal days 7, 21 and 35. Quantitative proteomics employing LC-MS with isobaric labeling (TMT10plex), western blotting, and transmission electron microscopy (TEM) were utilized in the studies.

RESULTS

The results of a proteomics investigation of the brain revealed that the proteins that were differentially expressed in rhesus macaques after sevoflurane exposures were associated mainly with mitochondrial respiration. Following multiple sevoflurane exposures, the prefrontal cortices of rhesus macaques exhibited increases in NDUFA8 and COX IV protein levels, while no alterations in mitochondrial morphology were observed through TEM.

CONCLUSION

Multiple exposures to sevoflurane increased the mitochondrial protein levels in rhesus macaques.

Sevoflurane postconditioning ameliorates cerebral ischemia-reperfusion injury in rats via TLR4/MyD88/TRAF6 signaling pathway

To determine whether sevoflurane postconditioning protects against cerebral ischemia reperfusion (I/R) injury and its potential mechanism, we employed bioinformatic analysis, neurological assessments, and western blot analysis, as well as triphenyl tetrazolium chloride, hematoxylin and eosin, Nissl, and immunofluorescence staining. We identified 103 differentially expressed genes induced by cerebral I/R, including 75 upregulated genes and 28 downregulated genes enriched for certain biological processes (involving regulation of inflammatory responses, cellular responses to interleukin 1, and chemokine activity) and signaling pathways (such as transcriptional misregulation in cancer, interleukin-17 signaling, rheumatoid arthritis, MAPK signaling, and Toll-like receptor signaling). As a typical path in Toll-like receptor signaling pathway, in the current study, we investigated the protective effect of sevoflurane postconditioning in cerebral I/R rats and further explore the role of TLR4/MyD88/TRAF6 signaling pathway in it. The results showed cerebral I/R-induced neurological deficits were comparatively less severe following sevoflurane postconditioning. In addition, TLR4/MyD88/TRAF6 signaling pathway-related proteins and neuropathic damage were ameliorated in aged rats following sevoflurane postconditioning, while the TLR4 agonist lipopolysaccharide aggravated these changes. Together, these findings suggest that sevoflurane postconditioning ameliorates cerebral I/R injury by a mechanism involving inhibition of the TLR4/MyD88/TRAF6 signaling pathway to suppress neuroinflammatory responses.

Sevoflurane exposure during the second trimester induces neurotoxicity in offspring rats by hyperactivation of PARP-1

RATIONALE

Fetal exposure to general anesthesia may cause noteworthy neurocognitive impairment, but the mechanisms are unclear.

OBJECTIVES

Our study designed to explore the potential mechanism of neurotoxicity in offspring rats after sevoflurane exposure to the pregnant rats during the second trimester.

METHODS

Pregnant rats (G14 day) were administrated with or without 3.5% sevoflurane, 40 mg/kg 3-aminobenzamide (3-AB), inhibitor of poly ADP ribose polymerase 1 (PARP-1), or 10 mg/kg TC-2153, inhibitor of striatal-enriched phosphatase 61 (STEP61). Afterwards, the effects on expression of β-tubulin (TUJ1), neurite outgrowth inhibitor A (Nogo-A), parthanatos-related and STEP61/proline-rich tyrosine kinase 2 (Pyk2) pathway-associated proteins, and reactive oxygen species (ROS) levels were examined by immunofluorescence staining, Western blot, and dihydroethidium (DHE) staining, respectively. Moreover, morphological changes in the hippocampal CA3 region and neuronal cell death were tested by glycine silver staining and TUNEL and immunofluorescence double staining, respectively. Furthermore, spatial learning and memory functions of rats on postnatal 28-33 days (PND 28-33) were evaluated by morris water maze (MWM).

RESULTS

Mid-pregnancy exposure to sevoflurane led to excessive PARP-1 activation, poly (ADP-ribose) (PAR) polymer accumulation, apoptosis-inducing factor (AIF) nuclear translocation, and Nogo-A accumulation. Besides, sevoflurane significantly inhibited neurite growth and increased cell death in the fetal rat brain. Additionally, sevoflurane activated STEP61/Pyk2 pathway and increased ROS levels. However, 3-AB or TC-2153 significantly alleviated cell death, promoted neurites growth, and improved sevoflurane-induced spatial learning and memory impairment.

CONCLUSION

This study proposes that sevoflurane exposure during the second trimester incudes neurotoxicity in offspring rats by hyperactivation of PARP-1 via STEP61/Pyk2 pathway.

Docosahexaenoic acid supplementation alleviates behavioral memory impairment caused via repeated administration of sevoflurane in aged rats

Elderly patients often need repeated surgical intervention, so it is important to determine the impact of repeated exposure to anesthetics on learning and memory. Docosahexaenoic acid (DHA) is considered to be an essential nutrient for maintaining brain health. The aim of the present study was to explore the potential effects of DHA on memory impairment induced by repeated sevoflurane anesthesia in aged rats. A total of 54 Sprague Dawley aged rats (18 months) were randomly divided into the following six groups: i) Control group; ii) sevoflurane group (Sev, 2.5% for 5 min); iii) DHA group (3 g/kg); iv) Sev + DHA (0.3 g/kg) group; v) Sev + DHA (1 g/kg) group; and vi) Sev + DHA (3 g/kg) group. Morris water maze experiment was performed to evaluate the learning and memory ability of the rats following treatment. H&E staining was used to observe any histological changes. Superoxide dismutase, malondialdehyde and glutathione peroxidase levels were detected using ELISA. Immunohistochemistry and western blotting were used to determine nuclear factor erythroid-2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) protein expression levels. Following repeated sevoflurane anesthesia, rats exhibited a prolonged escape latency. The number of times rats crossed the platform and the time spent in the target quadrant were also significantly reduced by repeated sevoflurane anesthesia. However, rats treated with Sev + DHA exhibited a reduced escape latency, whilst the number of times they crossed the platform and the time spent in the target quadrant increased compared with Sev treatment alone. Histopathological examination revealed that DHA treatment ameliorated the disordered neuron arrangement, deep staining of the neuronal nucleus pyknosis and cell edema observed in the brain tissue induced by repeated sevoflurane anesthesia. Furthermore, the protein expression levels of Nrf2 and HO-1 were demonstrated to be significantly increased in rats treated with DHA and exposed to repeated sevoflurane anesthesia compared with those in untreated rats that underwent repeated sevoflurane anesthesia. In conclusion, the present study revealed that DHA exerted protective effects against impairments in learning and memory induced by repeated sevoflurane anesthesia in aged rats, which may be associated with the Nrf2/HO-1 signaling pathway.

BAG2 mediates coelomocyte apoptosis in Vibrio splendidus challenged sea cucumber Apostichopus japonicus

MicroRNAs (miRNAs) are closely related to the occurrence, development, and immune response of diseases. BCL2-associated athanogene 2 (BAG2) is a member of the BAG family that functions in diverse cellular processes, including cell death, differentiation, and cell division. In this study, we cloned the cDNA full-length of sea cucumber (Apostichopus japonicus) BAG2 (AjBAG2) and confirmed it is an anti-apoptotic protein in vitro and in vivo during Vibrio splendidus infection. Moreover, we identified a perfect complementarity between miR-375 and the 3'-untranslated region (UTR) sequence of AjBAG2. The miR-375 expression decreased the luciferase activity dose-dependently when co-transfected with the AjBAG2 3'-UTR-luciferase reporter containing the miR-375 target site in epithelioma papulosum cyprini (EPC) cells. This inhibition was partially recovered by a miR-375 specific inhibitor. The mRNA and protein levels of AjBAG2 were opposite to that of coelomocytes in challenged sea cucumber when treated with miR-375 mimics or inhibitors. Additionally, miR-375 expression induced coelomocytes apoptosis and blocked the anti-apoptotic activity of AjBAG2. Our data demonstrated that AjBAG2 is an anti-apoptotic protein during V. splendidus infection and this function can be inhibited by miR-375 in sea cucumbers.

MicroRNA-204-5p mediates sevoflurane-induced cytotoxicity in HT22 cells by targeting brain-derived neurotrophic factor

BACKGROUND

Sevoflurane is widely used as an inhalational anesthetic in clinical practice. However, sevoflurane can cause cytotoxicity and induce learning capacity decline in patients. A previous publication indicated that miR-204-5p might have a close relationship with sevoflurane-induced neurotoxicity. When exposed to sevoflurane, the expression of miR-204-5p in neonatal hippocampus of rats was significantly increased. Hence, we aimed to investigate the role of miR-204-5p in sevoflurane-induced neurotoxicity using a mouse hippocampal neuronal cell line (HT22).

METHODS

The levels of miR-204-5p in HT22 cells were detected by RT-qPCR. In addition, the effects of miR-204-5p on cell viability, apoptosis and proliferation were evaluated by CCK-8, flow cytometric, and immunofluorescence assay, respectively. Western blotting was used to detect expressions of Bax, Bcl-2, active caspase 3, BDNF, TrkB, p-TrkB, Akt and p-Akt in HT22 cells. ELISA assay was used to examine the levels of total superoxide dismutase (SOD), reduced glutathione (GSH), malondialdehyde (MDA) and reactive oxygen species (ROS) in cells. Meanwhile, the dual luciferase reporter system assay was employed to explore the interaction of miR-204-5p and BDNF in cells.

RESULTS

The level of miR-204-5p was increased in sevoflurane-treated HT22 cells. Moreover, downregulation of miR-204-5p inhibited sevoflurane-induced apoptosis and promoted cell proliferation by upregulating the proteins of Bcl-2 and downregulating the expressions of Bax and active caspase-3 in HT22 cells. In addition, inhibition of miR-204-5p alleviated sevoflurane-induced oxidative injuries in HT22 cells via decline of ROS and MDA and upregulation of SOD and GSH. Furthermore, bioinformatics and dual luciferase assay demonstrated that miR-204-5p can inhibit the TrkB/Akt pathway by targeting BDNF.

CONCLUSION

Our findings indicated that downregulation of miR-204-5p can decrease oxidative status in HT22 cells and alleviate sevoflurane-induced cytotoxicity through stimulating the BDNF/TrkB/Akt pathway. Therefore, miR-204-5p might be a potential biomarker and therapeutic target for the treatment of sevoflurane-induced neurotoxicity.

BAG2 Promotes Proliferation and Metastasis of Gastric Cancer via ERK1/2 Signaling and Partially Regulated by miR186

Bcl2-associated athanogene (BAG)2 as a co-chaperone has been demonstrated to be involved in tumor growth and metastasis, but its biological function in gastric cancer remains unknown. Here, we reported that BAG2 was highly expressed in gastric cancer cell lines and tissues, indicating poor prognosis. High expression of BAG2 was significantly associated with T stage and differentiation level of gastric cancer (P < 0.001). Functional experiments revealed that BAG2 knockdown in gastric cancer cells inhibited the proliferation, invasion and migration of cells through AKT/mTOR and extracellular regulated kinase (ERK) pathways. Proteomic analysis identified that BAG2 may be involved in the regulation of mitogen-activated protein kinase (MAPK) pathway. In addition, immunoprecipitation showed that BAG2 could bind to ERK1/2. Luciferase reporter assay and Western blot verified that BAG2 was down-regulated by miR186. Taken together, our findings may reveal the basic function of BAG2 and uncover a potential therapeutic target for gastric cancer.

Anesthetics: from modes of action to unconsciousness and neurotoxicity

Modern anesthetic compounds and advanced monitoring tools have revolutionized the field of medicine, allowing for complex surgical procedures to occur safely and effectively. Faster induction times and quicker recovery periods of current anesthetic agents have also helped reduce health care costs significantly. Moreover, extensive research has allowed for a better understanding of anesthetic modes of action, thus facilitating the development of more effective and safer compounds. Notwithstanding the realization that anesthetics are a prerequisite to all surgical procedures, evidence is emerging to support the notion that exposure of the developing brain to certain anesthetics may impact future brain development and function. Whereas the data in support of this postulate from human studies is equivocal, the vast majority of animal research strongly suggests that anesthetics are indeed cytotoxic at multiple brain structure and function levels. In this review, we first highlight various modes of anesthetic action and then debate the evidence of harm from both basic science and clinical studies perspectives. We present evidence from animal and human studies vis-à-vis the possible detrimental effects of anesthetic agents on both the young developing and the elderly aging brain while discussing potential ways to mitigate these effects. We hope that this review will, on the one hand, invoke debate vis-à-vis the evidence of anesthetic harm in young children and the elderly, and on the other hand, incentivize the search for better and less toxic anesthetic compounds.