Atrial Natriuretic Peptide Alleviates Motion Sickness Potentially through Regulating Endolymph Volume in the Inner Ear Increased by Arginine Vasopressin.

INTRODUCTION: Dimenhydrinate and scopolamine are frequently used drugs, but they cause drowsiness and performance decrement. Therefore, it is crucial to find peripheral targets and develop new drugs without central side effects. This study aimed to investigate the anti-motion sickness action and inner ear-related mechanisms of atrial natriuretic peptide (ANP). METHODS: Endolymph volume in the inner ear was measured with magnetic resonance imaging and expression of AQP2 and p-AQP2 was detected with Western blot analysis and immunofluorescence method. RESULTS: Both rotational stimulus and intraperitoneal arginine vasopressin (AVP) injection induced conditioned taste aversion (CTA) to 0.15% sodium saccharin solution and an increase in the endolymph volume of the inner ear. However, intraperitoneal injection of ANP effectively alleviated the CTA behaviour and reduced the increase in the endolymph volume after rotational stimulus. Intratympanic injection of ANP also inhibited rotational stimulus-induced CTA behaviour, but anantin peptide, an inhibitor of ANP receptor A (NPR-A), blocked this inhibitory effect of ANP. Both rotational stimulus and intraperitoneal AVP injection increased the expression of AQP2 and p-AQP2 in the inner ear of rats, but these increases were blunted by ANP injection. In in vitro experiments, ANP addition decreased AVP-induced increases in the expression and phosphorylation of AQP2 in cultured endolymphatic sac epithelial cells. CONCLUSION: Therefore, the present study suggests that ANP could alleviate motion sickness through regulating endolymph volume of the inner ear increased by AVP, and this action of ANP is potentially mediated by activating NPR-A and antagonising the increasing effect of AVP on AQP2 expression and phosphorylation.

A novel long non-coding RNA LINC00524 facilitates invasion and metastasis through interaction with TDP43 in breast cancer.

Breast cancer (BC) remains a significant health concern worldwide, with metastasis being a primary contributor to patient mortality. While advances in understanding the disease's progression continue, the underlying mechanisms, particularly the roles of long non-coding RNAs (lncRNAs), are not fully deciphered. In this study, we examined the influence of the lncRNA LINC00524 on BC invasion and metastasis. Through meticulous analyses of TCGA and GEO data sets, we observed a conspicuous elevation of LINC00524 expression in BC tissues. This increased expression correlated strongly with a poorer prognosis for BC patients. A detailed Gene Ontology analysis suggested that LINC00524 likely exerts its effects through RNA-binding proteins (RBPs) mechanisms. Experimentally, LINC00524 was demonstrated to amplify BC cell migration, invasion and proliferation in vitro. Additionally, in vivo tests showed its potent role in promoting BC cell growth and metastasis. A pivotal discovery was LINC00524's interaction with TDP43, which leads to the stabilization of TDP43 protein expression, an element associated with unfavourable BC outcomes. In essence, our comprehensive study illuminates how LINC00524 accelerates BC invasion and metastasis by binding to TDP43, presenting potential avenues for therapeutic interventions.

Integrated analysis reveals the protective mechanism and therapeutic potential of hyperbaric oxygen against pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a dreadful, chronic, and irreversibly progressive disease leading to death with few effective treatments. Our previous study suggested that repetitive hyperbaric oxygen (HBO) treatment alleviates bleomycin-induced pulmonary fibrosis in mice. Here, we investigated the protective mechanism of HBO treatment against pulmonary fibrosis using an integrated approach. Analyzing publicly available expression data from the mouse model of bleomycin-induced pulmonary fibrosis as well as IPF patients, several potential mechanisms of relevance to IPF pathology were identified, including increased epithelial-to-mesenchymal transition (EMT) and glycolysis. High EMT or glycolysis scores in bronchoalveolar lavage (BAL) were strong independent predictors of mortality in multivariate analysis. These processes were potentially driven by hypoxia and blocked by HBO treatment. Together, these data support HBO treatment as a viable strategy against pulmonary fibrosis.

Argon mitigates post-stroke neuroinflammation by regulating M1/M2 polarization and inhibiting NF-κB/NLRP3 inflammasome signaling.

Neuroinflammation plays a vital role in cerebral ischemic stroke (IS). In the acute phase of IS, microglia are activated toward the pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes. Argon, an inert gas, can reduce neuroinflammation and alleviate ischemia/reperfusion (I/R) injury. However, whether argon regulates M1/M2 polarization to protect against I/R injury as well as the underlying mechanism has not been reported. In this study, we analyzed the activation and polarization of microglia after I/R injury with or without argon administration and explored the effects of argon on NLRP3 inflammasome-mediated inflammation in microglia in vitro and in vivo. The results showed that argon application inhibited the activation of M1 microglia/macrophage in the ischemic penumbra and the expression of proteins related to NLRP3 inflammasome and pyroptosis in microglia. Argon administration also inhibited the expression and processing of IL-1ß, a primary pro-inflammatory cytokine. Thus, argon alleviates I/R injury by inhibiting pro-inflammatory reactions via suppressing microglial polarization toward M1 phenotype and inhibiting the NF-κB/NLRP3 inflammasome signaling pathway. More importantly, we showed that argon worked better than the specific NLRP3 inflammasome inhibitor MCC950 in suppressing neuroinflammation and protecting against cerebral I/R injury, suggesting the therapeutic potential of argon in neuroinflammation-related neurodegeneration diseases as a potent gas inhibitor of the NLRP3 inflammasome signaling pathway.

Association of Lymphatic Fluid Volume in the Inner Ear of Beagle Dogs with the Susceptibility to Motion Sickness.

BACKGROUND: This study aimed to quantify total lymphatic fluid spaces of the inner ears volumetrically in the dog in order to find a correlation between the lymphatic volume of the inner ears and motion sickness susceptibility. METHODS: A total of 16 healthy adult Beagle dogs were used to delineate the lymphatic fluid spaces of inner ears by magnetic resonance imag- ing with a 3-dimensional-constructive interference steady-state sequence. Manual segmentation was applied for 3-dimensional reconstruction and volumetric quantification of total lymphatic space. The susceptibility of Beagle dogs to motion sickness was judged by latency of vomiting during rotatory stimulus. RESULTS: The volume range of total fluid space in the vestibule and cochlea of Beagle dogs is 55.07 ± 6.2 mm3. There is no significant difference in the total lymphatic volume of bilateral inner ears between 2 different motion sickness susceptibility groups (i.e., sensitive group and insensi- tive group), but the difference of lymphatic volume in the cochlea and vestibule between bilateral inner ears in insensitive group is greater than that of sensitive group. Moreover, a significant positive correlation was found between bilateral inner ear difference in lymphatic volume and vomiting latency. CONCLUSION: Magnetic resonance imaging could be used as a method to evaluate the inner ear lymphatic fluid volume of Beagle dogs with different susceptibilities to motion sickness, through which we found that motion sickness susceptibility is related to the difference in lymphatic volume in the vestibule and cochlea between bilateral inner ears, and the larger the volume difference, the lower the susceptibility.

miR-107 is involved in the regulation of NEDD9-mediated invasion and metastasis in breast cancer.

BACKGROUND: As a metastasis-related protein, NEDD9 has been reported in breast cancer (BC) metastasis research. However, there are few studies on the upstream regulators of NEDD9, especially involving the potential role of miRNAs. The purpose of this study was to explain whether miR-107 potentially regulates NEDD9, which may lead to invasion and metastasis of BC. METHODS: MCF-7 and MDA-MB-231 cells were transduced with lentiviruses to construct stably transduced cells with miR-107 overexpression, miR-107 silencing or empty vectors. A luciferase reporter assay was performed to verify the binding of miR-107 and NEDD9. The scratch test and Transwell assay were used to measure cell migration and invasion ability, respectively. For the study of metastasis in vivo, we injected MDA-MB-231 cells into the fat pad of nude mice to develop an orthotopic breast cancer model. RESULTS: We found that NEDD9 expression correlates with the prognosis of BC patients. In BC cell lines, NEDD9 was positively correlated with cell migration ability. Further research revealed that miR-107 inhibited NEDD9 expression by targeting the 3'-untranslated region of NEDD9. Overexpression of miR-107 suppressed the expression of NEDD9, thereby inhibiting the invasion, migration and proliferation of BC cells, but interference with miR-107 promoted the expression of NEDD9 as well as invasion, migration and proliferation. In an in vivo model, overexpression of miR-107 decreased the expression of NEDD9 and inhibited tumour growth, invasion and metastasis; however, these effects were reversed by inhibiting miR-107. CONCLUSIONS: These findings indicated the potential role of miR-107 in regulating NEDD9 in the invasion, migration and proliferation of BC.

Timely and Appropriate Administration of Inhaled Argon Provides Better Outcomes for tMCAO Mice: A Controlled, Randomized, and Double-Blind Animal Study.

BACKGROUND: Inhaled argon (iAr) has shown promising therapeutic efficacy for acute ischemic stroke and has exhibited impressive advantages over other inert gases as a neuroprotective agent. However, the optimal dose, duration, and time point of iAr for acute ischemic stroke are unknown. Here, we explored variable iAr schedules and evaluated the neuroprotective effects of acute iAr administration on lesion volume, brain edema, and neurological function in a mouse model of cerebral ischemic/reperfusion injury. METHODS: Adult ICR (Institute of Cancer Research) mice were randomly subjected to sham, moderate (1.5 h), or severe (3 h) transient middle cerebral artery occlusion (tMCAO). One hour after tMCAO, the mice were randomized to variable iAr protocols or air. General and focal deficit scores were assessed during double-blind treatment. Infarct volume, overall recovery, and brain edema were analyzed 24 h after cerebral ischemic/reperfusion injury. RESULTS: Compared with those in the tMCAO-only group, lesion volume (p < 0.0001) and neurologic outcome (general, p < 0.0001; focal, p < 0.0001) were significantly improved in the group administered iAr 1 h after stroke onset (during ischemia). Short-term argon treatment (1 or 3 h) significantly improved the infarct volume (1 vs. 24 h, p < 0.0001; 3 vs. 24 h, p < 0.0001) compared with argon inhalation for 24 h. The concentration of iAr was confirmed to be a key factor in improving focal neurological outcomes relative to that in the tMCAO group, with higher concentrations of iAr showing better effects. Additionally, even though ischemia research has shown an increase in cerebral damage proportional to the ischemia time, argon administration showed significant neuroprotective effects on infarct volume (p < 0.0001), neurological deficits (general, p < 0.0001; focal, p < 0.0001), weight recovery (p < 0.0001), and edema (p < 0.0001) in general, particularly in moderate stroke. CONCLUSIONS: Timely iAr administration during ischemia showed optimal neurological outcomes and minimal infarct volumes. Moreover, an appropriate duration of argon administration was important for better neuroprotective efficacy. These findings may provide vital guidance for using argon as a neuroprotective agent and moving to clinical trials in acute ischemic stroke.

[Intervention effects of miR-125b-5p on cognitive dysfunction induced by traumatic brain injury in rats and its mechanisms].

OBJECTIVE: To investigate the effects and molecular mechanisms of miR-125b-5p on cognitive dysfunction caused by traumatic brain injury (TBI). METHODS: The rats were randomly divided into control group, TBI group (model group), NC Agomir group (false negative group) and miR-125b-5p agomir group (high expression group), with 5 rats in each group. The false negative group and the high expression group were injected with NC agomir and miR-125b-5p agomir, respectively. The brain injury model was established by modified Feeney method except control group. Animal behavioral experiments were utilized for evaluation of the motor coordination, learning and memory and the degree of nerve damage in rats; and enzyme-linked immunosorbent assays (ELISA) and Western blot (WB) were used for determination of the expression levels of inflammatory factors and nerve-related factors in the hippocampus of rats in each group respectively. Finally, combined with bioinformatics, downstream target genes of miR-125b-5p were predicted and verified by reverse transcription polymerase chain reaction (RT-PCR) and WB. RESULTS: Compared with control group, mir-125b-5p expression level, motor coordination ability, learning and memory ability, brain-derived neurotrophic factor(BDNF) and nerve growth factor(NGF) expression levels of rats in model group and false negative group were decreased significantly, the MNSS score, the expressions of interleukins (IL-1ß, IL 6), tumor necrosis factor-α(TNF-α) and glial fibrillary acid protein(GFAF) were increased significantly (P＜0.01);However, compared with model group and false negative group, the above situation of rats in high expression group was opposite (P＜0.01). Bioassay showed that MMP-15 was the downstream target gene of miR-125b-5p. Compared with the control group, the expression of MMP-15 in model group and false negative group was increased significantly (P＜0.01);Compared with model group and false negative group, the expression of MMP-15 in high expression group was decreased significantly (P＜0.01) . CONCLUSION: miR-125b-5p can improve cognitive dysfunction induced by TBI in rats, which may be related to regulating the expression level of MMP-15, thereby inhibiting the neuroinflammatory response after TBI and promoting neuronal regeneration.

L-Serine, an Endogenous Amino Acid, Is a Potential Neuroprotective Agent for Neurological Disease and Injury.

Central nervous system (CNS) lesions are major causes of human death and disability worldwide, and they cause different extents of motor and sensory dysfunction in patients. Thus, it is crucial to develop new effective neuroprotective drugs and approaches targeted to the heterogeneous nature of CNS injury and disease. L-serine is an indispensable neurotrophic factor and a precursor for neurotransmitters. Although L-serine is a native amino acid supplement, its metabolic products have been shown to be essential not only for cell proliferation but also for neuronal development and specific functions in the brain. Growing evidence has suggested that L-serine regulates the release of several cytokines in the brain under some neuropathological conditions to recover cognitive function, improve cerebral blood flow, inhibit inflammation, promote remyelination and exert other neuroprotective effects on neurological injury. L-serine has also been used to treat epilepsy, schizophrenia, psychosis, and Alzheimer's Disease as well as other neurological diseases. Furthermore, the dosing of animals with L-serine and human clinical trials investigating the therapeutic effects of L-serine generally support the safety of L-serine. The high significance of this review lies in its emphasis on the therapeutic potential of using L-serine as a general treatment for numerous CNS diseases and injuries. Because L-serine performs a broad spectrum of functions, it may be clinically used as an effective neuroprotective agent.

Hyperbaric Oxygen Ameliorates Bleomycin-Induced Pulmonary Fibrosis in Mice.

The prevalence of pulmonary fibrosis is increasing with an aging population and its burden is likely to increase following COVID-19, with large financial and medical implications. As approved therapies in pulmonary fibrosis only slow disease progression, there is a significant unmet medical need. Hyperbaric oxygen (HBO) is the inhaling of pure oxygen, under the pressure of greater than one atmosphere absolute, and it has been reported to improve pulmonary function in patients with pulmonary fibrosis. Our recent study suggested that repetitive HBO exposure may affect biological processes in mice lungs such as response to wounding and extracellular matrix. To extend these findings, a bleomycin-induced pulmonary fibrosis mouse model was used to evaluate the effect of repetitive HBO exposure on pulmonary fibrosis. Building on our previous findings, we provide evidence that HBO exposure attenuates bleomycin-induced pulmonary fibrosis in mice. In vitro, HBO exposure could reverse, at least partially, transforming growth factor (TGF)-ß-induced fibroblast activation, and this effect may be mediated by downregulating TGF-ß-induced expression of hypoxia inducible factor (HIF)-1α. These findings support HBO as a potentially life-changing therapy for patients with pulmonary fibrosis, although further research is needed to fully evaluate this.

Apoptosis-antagonizing transcription factor is involved in rat post-traumatic epilepsy pathogenesis.

The present study aimed to explore the pathogenesis behind post-traumatic epilepsy (PTE). In the present study, a chloride ferric injection-induced rat PTE model was established. The expression levels of apoptosis-antagonizing transcription factor (AATF), cleaved caspase-3, p53, Bcl-2 and Bax were measured by western blotting or immunofluorescence staining (IF). The expression of AATF in vivo was downregulated by microinjection of lentiviral-mediated short-hairpin RNA. Compared with control and sham groups, at day 5 after PTE, neuron apoptosis was significantly increased and the expression levels of AATF, p53, cleaved caspase-3 and Bax were significantly upregulated. In addition, IF revealed co-localization of AATF and cleaved caspase-3 in the cortex. Additionally, AATF was expressed mainly in neurons and astrocytes. Following AATF inhibition, the expression levels of p53 and cleaved caspase-3 were significantly reduced as compared with the control group. Taken together, these findings suggested that following PTE, AATF is involved in neuronal apoptosis and may serve as a potential target for its alleviation.

PPAR-γ Is Critical for HDAC3-Mediated Control of Oligodendrocyte Progenitor Cell Proliferation and Differentiation after Focal Demyelination.

Disruption of remyelination contributes to neurodegeneration and cognitive impairment in chronically disabled patients. Valproic acid (VPA) inhibits histone deacetylase (HDAC) function and probably promotes oligodendrocyte progenitor cell (OPC) proliferation and differentiation; however, the relevant molecular mechanisms remain unknown. Here, focal demyelinating lesions (FDLs) were generated in mice by two-point stereotactic injection of lysophosphatidylcholine (LPC) into the corpus callosum. Cognitive functions, sensorimotor abilities and histopathological changes were assessed for up to 28 days post-injury with or without VPA treatment. Primary OPCs were harvested and used to study the effect of VPA on OPC differentiation under inflammatory conditions. VPA dose-dependently attenuated learning and memory deficits and robustly protected white matter after FDL induction, as demonstrated by reductions in SMI-32 and increases in myelin basic protein staining. VPA also promoted OPC proliferation and differentiation and increased subsequent remyelination efficiency by day 28 post-FDL induction. VPA treatment did not affect HDAC1, HDAC2 or HDAC8 expression but reduced HDAC3 protein levels. In vitro, VPA improved the survival of mouse OPCs and promoted their differentiation into oligodendrocytes following lipopolysaccharide (LPS) stimulation. LPS caused OPCs to overexpress HDAC3, which translocated from the cytoplasm into the nucleus, where it directly interacted with the nuclear transcription factor PPAR-γ and negatively regulated PPAR-γ expression. VPA decreased the expression of HDAC3 and promoted remyelination and functional neurological recovery after FDL. These findings may support the use of strategies modulating HDAC3-mediated regulation of protein acetylation for the treatment of demyelination-related cognitive dysfunction.

Inner Ear Arginine Vasopressin-Vasopressin Receptor 2-Aquaporin 2 Signaling Pathway Is Involved in the Induction of Motion Sickness.

It has been identified that arginine vasopressin (AVP), vasopressin receptor 2(V2R), and the aquaporin 2 (AQP2) signaling pathway in the inner ear play important roles in hearing and balance functions through regulating the endolymph equilibrium; however, the contributions of this signaling pathway to the development of motion sickness are unclear. The present study was designed to investigate whether the activation of the AVP-V2R-AQP2 signaling pathway in the inner ear is involved in the induction of motion sickness and whether mozavaptan, a V2R antagonist, could reduce motion sickness. We found that both rotatory stimulus and intraperitoneal AVP injection induced conditioned taste aversion (a confirmed behavioral index for motion sickness) in rats and activated the AVP-V2R-AQP2 signaling pathway with a responsive V2R downregulation in the inner ears, and AVP perfusion in cultured epithelial cells from rat endolymphatic sacs induced similar changes in this pathway signaling. Vestibular training, V2R antagonist mozavaptan, or PKA inhibitor H89 blunted these changes in the V2R-AQP2 pathway signaling while reducing rotatory stimulus- or DDAVP (a V2R agonist)-induced motion sickness in rats and dogs. Therefore, our results suggest that activation of the inner ear AVP-V2R-AQP2 signaling pathway is potentially involved in the development of motion sickness; thus, mozavaptan targeting AVP V2Rs in the inner ear may provide us with a new application option to reduce motion sickness. SIGNIFICANCE STATEMENT: Motion sickness affects many people traveling or working. In the present study our results showed that activation of the inner ear arginine vasopressin-vaspopressin receptor 2 (V2R)-aquaporin 2 signaling pathway was potentially involved in the development of motion sickness and that blocking V2R with mozavaptan, a V2R antagonist, was much more effective in reducing motion sickness in both rat and dog; therefore, we demonstrated a new mechanism to underlie motion sickness and a new candidate drug to reduce motion sickness.

Deconvolution of RNA-Seq Analysis of Hyperbaric Oxygen-Treated Mice Lungs Reveals Mesenchymal Cell Subtype Changes.

Hyperbaric oxygen (HBO) is widely applied to treat several hypoxia-related diseases. Previous studies have focused on the immediate effect of HBO-exposure induced oxidative stress on the lungs, but knowledge regarding the chronic effects from repetitive HBO exposure is limited, especially at the gene expression level. We found that repetitive HBO exposure did not alter the morphology of murine lungs. However, by deconvolution of RNA-seq from those mice lungs using CIBERSORTx and the expression profile matrices of 8 mesenchymal cell subtypes obtained from bleomycin-treated mouse lungs, we identify several mesenchymal cell subtype changes. These include increases in Col13a1 matrix fibroblasts, mesenchymal progenitors and mesothelial cell populations and decreases in lipofibroblasts, endothelial and Pdgfrb high cell populations. Our data suggest that repetitive HBO exposure may affect biological processes in the lungs such as response to wounding, extracellular matrix, vasculature development and immune response.

Inhibition of NR2B-containing NMDA receptors during nitrogen narcosis.

INTRODUCTION: When humans breathe compressed air or N2-O2 mixtures at three to four atmospheres pressure, they will experience nitrogen narcosis that may possibly lead to a diving accident, but the underlying mechanisms remain unclear. METHODS: Mice were exposed to 1.6 MPa breathing a N2-O2 mixture adjusted to deliver an inspired PO2 of 32-42 kPa. The electroencephalogram (EEG) and forced swimming test were used to evaluate the narcotic effect of nitrogen. Neuronal activity was observed via c-Fos expression in cortex and hippocampus tissue after decompressing to the surface. To further investigate underlying molecular mechanisms, we incubated cultured hippocampal neurons with various NMDA concentrations, and measured expression of NMDA receptors and its down-stream signal with or without 1.6 MPa N2-O2 exposure. RESULTS: Both the frequency of the EEG and the drowning time using the forced swimming test were significantly decreased during exposure to 1.6 MPa N2-O2 (P < 0.001). Additionally, in cultured hippocampal neurons, the increased levels of phosphorylated NR2B and cAMP-response element binding protein (CREB) induced by NMDA stimulation were significantly inhibited by exposure to 1.6 MPa N2-O2. CONCLUSIONS: Our findings indicated that NR2B-containing NMDA receptors were inhibited during nitrogen narcosis.

Changes in the gut microbiota during and after commercial helium-oxygen saturation diving in China.

OBJECTIVES: The influence of commercial helium-oxygen saturation diving on divers' gut microbiotas was assessed to provide dietary suggestion. METHODS: Faecal samples of 47 divers working offshore were collected before (T1), during (T2) and after (T3) saturation diving. Their living and excursion depths were 55-134 metres underwater with a saturation duration of 12-31 days and PaO2 of 38-65 kPa. The faecal samples were examined through 16S ribosomal DNA amplicon sequencing based on the Illumina sequencing platform to analyse changes in the bacteria composition in the divers' guts. RESULTS: Although the α and ß diversity of the gut microbiota did not change significantly, we found that living in a hyperbaric environment of helium-oxygen saturation decreased the abundance of the genus Bifidobacterium, an obligate anaerobe, from 2.43%±3.83% at T1 to 0.79%±1.23% at T2 and 0.59%±0.79% at T3. Additionally, the abundance of some short-chain fatty acid (SCFA)-producing bacteria, such as Fusicatenibacter, Faecalibacterium, rectale group and Anaerostipes, showed a decreased trend in the order of before, during and after diving. On the contrary, the abundance of species, such as Lactococcus garvieae, Actinomyces odontolyticus, Peptoclostridium difficile, Butyricimonas virosa, Streptococcus mutans, Porphyromonas asaccharolytica and A. graevenitzii, showed an increasing trend, but most of them were pathogens. CONCLUSIONS: Occupational exposure to high pressure in a helium-oxygen saturation environment decreased the abundance of Bifidobacterium and some SCFA-producing bacteria, and increased the risk of pathogenic bacterial infection. Supplementation of the diver diet with probiotics or prebiotics during saturation diving might prevent these undesirable changes.

Regulation of AKT phosphorylation by GSK3ß and PTEN to control chemoresistance in breast cancer.

BACKGROUND: Phosphorylated AKT is highly expressed or overexpressed in chemoresistant tumor samples. However, the precise molecular mechanism involved in AKT phosphorylation-related chemoresistance in breast cancer is still elusive. The present research was designed to estimate the effect of AKT phosphorylation on cell viability and chemoresistance in breast cancer. METHODS: We utilized MCF-7 and MDA-MB468 human breast cancer cell lines and developed multidrug-resistant MCF-7/MDR and cisplatin-resistant MDA-MB-468 cells. Immunofluorescence analysis and Western blotting were employed to test the level of glycogen synthase kinase 3 beta (GSK3ß), phosphorylated phosphatase and tension homologue (p-PTEN) and phosphorylated AKT (p-AKT) in MCF-7/MDR and MDA-MB468 cells. Xenograft assays in nude mice were performed with MCF-7/MDR cells to verify chemoresistance and the signaling pathway upstream of phosphatidylinositide 3-kinase (PI3K)/AKT. RESULTS: An increase in GSK3ß, p-PTEN and p-AKT expression was strongly induced in MCF-7/MDR and cisplatin-resistant MDA-MB-468 cells, and augmented GSK3ß phosphorylation and PTEN inactivation enhanced AKT signaling. The elevation in GSK3ß, p-PTEN and p-AKT was associated with cell viability based on a CCK-8 assay. The results of in vivo and in vitro assays indicated that GSK3ß knockdown with lentiviral shRNA (shRNA-GSK3ß) promoted apoptosis and suppressed the migration of cisplatin-resistant MCF-7/MDR cells, while these effects were reversed by activating p-AKT with the PTEN inhibitor bpV(pic). CONCLUSIONS: AKT phosphorylation mediated by GSK3ß and PTEN were correlated with cell viability, migration and apoptosis, which may promote chemoresistance in breast cancer. Furthermore, GSK3ß can regulate cell viability through the PTEN/PI3K/AKT signaling pathway and induce chemoresistance, serving as a valuable molecular strategy for breast cancer therapy.

Neuroprotective effect of l-serine against white matter demyelination by harnessing and modulating inflammation in mice.

Demyelination in white matter is the end product of numerous pathological processes. This study was designed to evaluate the neuroprotective effect of l-serine and the underlying mechanisms against the demyelinating injury of white matter. A model of focal demyelinating lesions (FDL) was established using the two-point stereotactic injection of 0.25% lysophosphatidylcholine (LPC, 10 µg per point) into the corpus callosum of mice. Mice were then intraperitoneally injected with one of three doses of l-serine (114, 342, or 1026 mg/kg) 2 h after FDL, and then twice daily for the next five days. Behavior tests and histological analysis were assessed for up to twenty-eight days post-FDL induction. Electron microscopy was used for ultrastructural investigation. In vitro, we applied primary co-cultures of microglia and oligodendrocytes for oxygen glucose deprivation (OGD). After establishing FDL, l-serine treatment: 1) improved spatial learning, memory and cognitive ability in mice, and relieved anxiety for 4 weeks post-FDL induction; 2) reduced abnormally dephosphorylated neurofilament proteins, increased myelin basic protein, and preserved anatomic myelinated axons; 3) inhibited microglia activation and reduced the release of inflammatory factors; 4) promoted recruitment and proliferation of oligodendrocyte progenitor cells, and the efficiency of subsequent remyelination on day twenty-eight post-FDL induction. In vitro experiments, showed that l-serine not only directly protected against oligodendrocytes from OGD damage, but also provided an indirect protective effect by regulating microglia. In our study, l-serine offered long-lasting behavioral and oligodendrocyte protection and promoted remyelination. Therefore, l-serine may be an effective clinical treatment aganist white matter injury.

A stable and easily reproducible model of focal white matter demyelination.

BACKGROUND: Demyelination is the end product of numerous pathological processes, and also is one of the main causes of neurological disability in Multiple sclerosis (MS). Research into the pathogenesis of MS is hampered by the conventional rodent models' inability to produce stable demyelination. NEW METHOD: Focal demyelinating lesions were stereotactically targeted to the corpus callosum with a two-point injection of lysophosphatidylcholine (LPC-2) in mice. Three groups were analyzed (n = 8, each) and water maze, sensorimotor test, and compound action potential were included in functional tests. Electron microscopy was used for morphological analyses while western blot and immunohistochemistry were included for molecular detection. RESULTS: Ten days after the LPC-2 injection, the expression of myelin basic protein (MBP) was reduced, while non-phosphorylated neurofilament (SMI-32) was increased. The amplitude of the N1 segment decreased and less well-defined myelin sheaths was found. Behavioral tests showed increased latency to escape and reduced time spent in target quadrant. Four weeks later, MBP expression still reduced, SMI-32 expression was increased, both spatial learning (D24-D27) and spatial memory (D28) were still significantly impaired in LPC-2 injection mice. COMPARISON WITH EXISTING METHOD(S): Compared with the classic single-point LPC-injection model, our studies showed that the two-point LPC-injection not only could induce demyelination in a short-term manner, but also could cause demyelination in a long-term manner with little remyelination in the mouse corpus callosum. CONCLUSIONS: We established a simple, reliable, and inexpensive model of demyelination in the corpus callosum in mice, with functional and morphological reproducibility, and good validity.

Nitrogen narcosis induced by repetitive hyperbaric nitrogen oxygen mixture exposure impairs long-term cognitive function in newborn mice.

Human beings are exposed to compressed air or a nitrogen-oxygen mixture, they will produce signs and symptoms of nitrogen narcosis such as amnesia or even loss of memory, which may be disappeared once back to the normobaric environment. This study was designed to investigate the effect of nitrogen narcosis induced by repetitive hyperbaric nitrogen-oxygen mixture exposure on long-term cognitive function in newborn mice and the underlying mechanisms. The electroencephalogram frequency was decreased while the amplitude was increased in a pressure-dependent manner during 0.6, 1.2, 1.8 MPa (million pascal) nitrogen-oxygen mixture exposures in adult mice. Nitrogen narcosis in postnatal days 7-9 mice but not in adult mice induced by repetitive hyperbaric exposure prolonged the latency to find the platform and decreased the number of platform-site crossovers during Morris water maze tests, and reduced the time in the center during the open field tests. An increase in the expression of cleaved caspase-3 in the hippocampus and cortex were observed immediately on the first day after hyperbaric exposure, and this lasted for seven days. Additionally, nitrogen narcosis induced loss of the dendritic spines but not of the neurons, which may mainly account for the cognitive dysfunction. Nitrogen narcosis induced long-term cognitive and emotional dysfunction in the postnatal mice but not in the adult mice, which may result from neuronal apoptosis and especially reduction of dendritic spines of neurons.