Electrical stimulation of the vagus nerve protects against cerebral ischemic injury through an anti-infammatory mechanism

Vagus nerve stimulation exerts protective effects against ischemic brain injury; however, the underlying mechanisms remain unclear. In this study, a rat model of focal cerebral ischemia was established using the occlusion method, and the right vagus nerve was given electrical stimulation (constant current of 0.5 mA; pulse width, 0.5 ms; frequency, 20 Hz; duration, 30 seconds; every 5 minutes for a total of 60 minutes) 30 minutes, 12 hours, and 1, 2, 3, 7 and 14 days after surgery. Electrical stimulation of the vagus nerve substantially reduced infarct volume, improved neurological function, and decreased the expression levels of tumor necrosis factor-α and interleukin-6 in rats with focal cerebral ischemia. The experimental findings indicate that the neuroprotective effect of vagus nerve stimulation following cerebral ischemia may be associated with the inhibition of tumor necrosis factor-α and interleukin-6 expression.     

Adaptive and regulatory mechanisms in aged rats with postoperative cognitive dysfunction

Inflammation may play a role in postoperative cognitive dysfunction. 5′ Adenosine monophosphate-activated protein kinase, nuclear factor-kappa B, interleukin-1β, and tumor necrosis factor-α are involved in inflammation. Therefore, these inflammatory mediators may be involved in postoperative cognitive dysfunction. Western immunoblot analysis revealed 5′ adenosine monophosphate-activated protein kinase and nuclear factor-kappa B in the hippocampus of aged rats were increased 1–7 days after splenectomy. Moreover, interleukin-1β and tumor necrosis factor-α were upregulated and gradually decreased. Therefore, these inflammatory mediators may participate in the splenectomy model of postoperative cognitive dysfunction in aged rats.     

Neuropeptide Y protects cerebral cortical neurons by regulating microglial immune function

Neuropeptide Y has been shown to inhibit the immunological activity of reactive microglia in the rat cerebral cortex, to reduce N-methyl-D-aspartate current(INMDA) in cortical neurons, and protect neurons. In this study, after primary cultured microglia from the cerebral cortex of rats were treated with lipopolysaccharide, interleukin-1β and tumor necrosis factor-α levels in the cell culture medium increased, and mRNA expression of these cytokines also increased. After primary cultured cortical neurons were incubated with the lipopolysaccharide-treated microglial conditioned medium, peak INMDA in neurons increased. These effects of lipopolysaccharide were suppressed by neuropeptide Y. After addition of the neuropeptide Y Y1 receptor antagonist BIBP3226, the effects of neuropeptide Y completely disappeared. These results suggest that neuropeptide Y prevents excessive production of interleukin-1β and tumor necrosis factor-α by inhibiting microglial reactivity. This reduces INMDA in rat cortical neurons, preventing excitotoxicity, thereby protecting neurons.     

Puerarin protects brain tissue against cerebral ischemia/reperfusion injury by inhibiting the inflammatory response

Puerarin, a traditional Chinese medicine, exerts a powerful neuroprotective effect in cerebral ischemia/reperfusion injury, but its mechanism is unknown. Here, we established rat models of middle cerebral artery ischemia/reperfusion injury using the suture method. Puerarin(100 mg/kg) was administered intraperitoneally 30 minutes before middle cerebral artery occlusion and 8 hours after reperfusion. Twenty-four hours after reperfusion, we found that puerarin significantly improved neurological deficit, reduced infarct size and brain water content, and notably diminished the expression of Toll-like receptor-4, myeloid differentiation factor 88, nuclear factor kappa B and tumor necrosis factor-α in the ischemic region. These data indicate that puerarin exerts an anti-inflammatory protective effect on brain tissue with ischemia/reperfusion damage by downregulating the expression of multiple inflammatory factors.     

Inhibition of inflammatory mediator release from microglia can treat ischemic/hypoxic brain injury

Interleukin-1α and interleukin-1β aggravate neuronal injury by mediating the inflammatory reaction following ischemic/hypoxic brain injury. It remains unclear whether interleukin-1α and interleukin-1β are released by microglia or astrocytes. This study prepared hippocampal slices that were subsequently subjected to oxygen and glucose deprivation. Hematoxylin-eosin staining verified that neurons exhibited hypoxic changes. Results of enzyme-linked immunosorbent assay found that interleukin-1α and interleukin-1β participated in this hypoxic process. Moreover, when hypoxic injury occurred in the hippocampus, the release of interleukin-1α and interleukin-1β was mediated by the P2X4 receptor and P2X7 receptor. Immunofluorescence staining revealed that during ischemia/hypoxia, the P2X4 receptor, P2X7 receptor, interleukin-1α and interleukin-1β expression was detectable in rat hippocampal microglia, but only P2X4 receptor and P2X7 receptor expression was detected in astrocytes. Results suggested that the P2X4 receptor and P2X7 receptor, respectively, mediated interleukin-1α and interleukin-1β released by microglia, resulting in hippocampal ischemic/hypoxic injury. Astrocytes were activated, but did not synthesize or release interleukin-1α and interleukin-1β.     

Neuroprotective effects of SMAds in a rat model of cerebral ischemia/reperfusion

Previous studies have shown that up-regulation of transforming growth factor β1 results in neuroprotective effects. However, the role of the transforming growth factor β1 downstream molecule, SMAD2/3, following ischemia/reperfusion remains unclear. Here, we investigated the neuroprotective effects of SMAD2/3 by analyzing the relationships between SMAD2/3 expression and cell apoptosis and inflammation in the brain of a rat model of cerebral ischemia/reperfusion. Levels of SMAD2/3 m RNA were up-regulated in the ischemic penumbra 6 hours after cerebral ischemia/reperfusion, reached a peak after 72 hours and were then decreased at 7 days. Phosphorylated SMAD2/3 protein levels at the aforementioned time points were consistent with the m RNA levels. Over-expression of SMAD3 in the brains of the ischemia/reperfusion model rats via delivery of an adeno-associated virus containing the SMAD3 gene could reduce tumor necrosis factor-α and interleukin-1β m RNA levels, down-regulate expression of the pro-apoptotic gene, capase-3, and up-regulate expression of the anti-apoptotic protein, Bcl-2. The SMAD3 protein level was negatively correlated with cell apoptosis. These findings indicate that SMAD3 exhibits neuroprotective effects on the brain after ischemia/reperfusion through anti-inflammatory and anti-apoptotic pathways.     

Neuroprotective effect of pretreatment with ganoderma lucidum in cerebral ischemia/reperfusion injury in rat hippocampus

Ganoderma lucidum is a traditional Chinese medicine,which has been shown to have both anti-oxidative and anti-inflammatory effects,and noticeably decreases both the infarct area and neuronal apoptosis of the ischemic cortex.This study aimed to investigate the protective effects and mechanisms of pretreatment with ganoderma lucidum(by intragastric administration)in cerebral ischemia/reperfusion injury in rats.Our results showed that pretreatment with ganoder-ma lucidum for 3 and 7 days reduced neuronal loss in the hippocampus,diminished the content of malondialdehyde in the hippocampus and serum,decreased the levels of tumor necrosis fac-tor-αand interleukin-8 in the hippocampus,and increased the activity of superoxide dismutase in the hippocampus and serum.These results suggest that pretreatment with ganoderma lucidum was protective against cerebral ischemia/reperfusion injury through its anti-oxidative and an-ti-inflammatory actions.     

T cells promote the regeneration of neural precursor cells in the hippocampus of Alzheimer＇s disease mice

Alzheimer's disease is closely associated with disorders of neurogenesis in the brain, and growing evidence supports the involvement of immunological mechanisms in the development of the disease. However, at present, the role of T cells in neuronal regeneration in the brain is unknown. We injected amyloid-beta 1–42 peptide into the hippocampus of six BALB/c wild-type mice and six BALB/c-nude mice with T-cell immunodeficiency to establish an animal model of Alzheimer's disease. A further six mice of each genotype were injected with same volume of normal saline. Immunohistochemistry revealed that the number of regenerated neural progenitor cells in the hippocampus of BALB/c wild-type mice was significantly higher than that in BALB/c-nude mice. Quantitative fluorescence PCR assay showed that the expression levels of peripheral T cell-associated cytokines(interleukin-2, interferon-γ) and hippocampal microglia-related cytokines(interleukin-1β, tumor necrosis factor-α) correlated with the number of regenerated neural progenitor cells in the hippocampus. These results indicate that T cells promote hippocampal neurogenesis in Alzheimer's disease and T-cell immunodeficiency restricts neuronal regeneration in the hippocampus. The mechanism underlying the promotion of neuronal regeneration by T cells is mediated by an increased expression of peripheral T cells and central microglial cytokines in Alzheimer's disease mice. Our findings provide an experimental basis for understanding the role of T cells in Alzheimer's disease.     

Dab2 attenuates brain injury in APP/PS1 mice via targeting transforming growth factor-beta/SMAD signaling简

Transforming growth factor-beta(TGF-β)type II receptor(TβRII)levels are extremely low in the brain tissue of patients with Alzheimer’s disease.This receptor inhibits TGF-β1/SMAD signaling and thereby aggravates amyolid-beta deposition and neuronal injury.Dab2,a specific adapter protein,protects TβRII from degradation and ensures the effective conduction of TGF-β1/SMAD signaling.In this study,we used an adenoviral vector to overexpress the Dab2 gene in the mouse hippocampus and investigated the regulatory effect of Dab2 protein on TGF-β1/SMAD signaling in a mouse model of Alzheimer’s disease,and the potential neuroprotective effect.The results showed that the TβRII level was lower in APP/PS1 mouse hippocampus than in normal mouse hippocampus.After Dab2 expression,hippocampal TβRII and p-SMAD2/3 levels were significantly increased,while amyloid-beta deposition,microglia activation,tumor necrosis factor-βand interleulin-6 levels and neuronal loss were significantly attenuated in APP/PS1 mouse brain tissue.These results suggest that Dab2 can exhibit neuroprotective effects in Alzheimer’s disease by regulating TGF-β1/SMAD signaling.     

Protective effects of Lingguizhugan decoction on amyloid-beta peptide (25-35)-induced cell injury Anti-inflammatory effects

In the present study, a human neuroblastoma cell line (SH-SY5Y) and BV-2 microglia were treated with amyloid-β peptide (25-35) , as a model of Alzheimer’s disease, to evaluate the protective effects of 10-3-10-8 g/mL Lingguizhugan decoction and to examine the underlying anti-inflammatory mechanism. Lingguizhugan decoction significantly enhanced the viability of SH-SY5Y cells with amyloid-β peptide-induced injury, and lowered levels of interleukin-1β, interleukin-6, tumor necrosis factor-α and nitric oxide in the culture supernatant of activated BV-2 microglia. The effects of 10-3 g/mL Lingguizhugan decoction were more significant. These results suggest that Lingguizhugan decoction can protect SH-SY5Y cells against amyloid-β peptide (25-35)-induced injury in a dose-dependent manner by inhibiting overexpression of inflammatory factors by activated microglia.     

Buyang Huanwu Decoction fraction protects against cerebral ischemia/reperfusion injury by attenuating the inflammatory response and cellular apoptosis

Buyang Huanwu Decoction fraction extracted from Buyang Huanwu Decoction contains saponins of Astragalus, total paeony glycoside and safflower flavones. The aim of this study was to demonstrate the neuroprotective effect and mechanism of Buyang Huanwu Decoction fraction on ischemic injury both in vivo and in vitro. In vivo experiments showed that 50-200 mg/kg Buyang Huanwu Decoction fraction reduced infarct volume and pathological injury in ischemia/reperfusion rats, markedly inhibited expression of nuclear factor-κB and tumor necrosis factor-α and promoted nestin protein expression in brain tissue. Buyang Huanwu Decoction fraction (200 mg/kg) exhibited significant effects, which were similar to those of 100 mg/kg Ginkgo biloba extract. In vitro experimental results demonstrated that 10-100 mg/L Buyang Huanwu Decoction fraction significantly improved cell viability, decreased the release of lactate dehydrogenase and malondialdehyde levels, and inhibited the rate of apoptosis in HT22 cells following oxygen-glucose deprivation. Buyang Huanwu Decoction fraction (100 mg/L) exhibited significant effects, which were similar to those of 100 mg/L Ginkgo biloba extract. These findings suggest that Buyang Huanwu Decoction fraction may represent a novel, protective strategy against cerebral ischemia/reperfusion injury in rats and oxygen-glucose deprivation-induced damage in HT22 cells in vitro by attenuating the inflammatory response and cellular apoptosis.     

Changes in proteins related to early nerve repair in a rat model of sciatic nerve injury

Peripheral nerves have a limited capacity for self-repair and those that are severely damaged or have significant defects are challenging to repair. Investigating the pathophysiology of peripheral nerve repair is important for the clinical treatment of peripheral nerve repair and regeneration. In this study, rat models of right sciatic nerve injury were established by a clamping method. Protein chip assay was performed to quantify the levels of neurotrophic, inflammation-related, chemotaxis-related and cell generation-related factors in the sciatic nerve within 7 days after injury. The results revealed that the expression levels of neurotrophic factors (ciliary neurotrophic factor) and inflammation-related factors (intercellular cell adhesion molecule-1, interferon γ, interleukin-1α, interleukin-2, interleukin-4, interleukin-6, monocyte chemoattractant protein-1, prolactin R, receptor of advanced glycation end products and tumor necrosis factor-α), chemotaxis-related factors (cytokine-induced neutrophil chemoattractant-1, L-selectin and platelet-derived growth factor-AA) and cell generation-related factors (granulocyte-macrophage colony-stimulating factor) followed different trajectories. These findings will help clarify the pathophysiology of sciatic nerve injury repair and develop clinical treatments of peripheral nerve injury. This study was approved by the Ethics Committee of Peking University People’s Hospital of China (approval No. 2015-50) on December 9, 2015.

Chinese Library Classification No. R446; R745; R363     

Long-lasting protection in brain trauma by endotoxin preconditioning

We investigated the occurrence of endotoxin (lipopolysaccharide, LPS) preconditioning in traumatic brain injury (TBI), evaluating the time window of LPS-induced protection, its persistence, and the associated molecular mechanisms. Mice received 0.1 mg/kg LPS or saline intraperitoneally and subsequently TBI (by controlled cortical impact brain injury) at various time intervals. Mice receiving LPS 3, 5, or 7 days before TBI showed attenuated motor deficits at 1 week after injury compared with mice receiving saline. Those receiving LPS 5 days before injury had also a reduced contusion volume (7.9±1.3 versus 12±2.3 mm³) and decreased cell death. One month after injury, the protective effect of LPS on contusion volume (14.5±1.2 versus 18.2±1.2 mm³) and neurologic function was still present. Traumatic brain injury increased glial fibrillary acidic protein, CD11b, CD68, tumor necrosis factor-α, interleukin (IL)-10, and IL-6 mRNA expression 24 hours after injury. Lipopolysaccharide administered 5 (but not 9) days before injury increased the expression of CD11b (233%) and of interferon β (500%) in uninjured mice, while it reduced the expression of CD68 (by 46%) and increased that of IL-6 (by 52%) in injured mice. Lipopolysaccharide preconditioning conferred a long-lasting neuroprotection after TBI, which was associated with a modulation of microglia/macrophages activity and cytokine production.     

Prolonged electrical stimulation causes no damage to sacral nerve roots in rabbits

Previous studies have shown that, anode block electrical stimulation of the sacral nerve root can produce physiological urination and reconstruct urinary bladder function in rabbits. However, whether long-term anode block electrical stimulation causes damage to the sacral nerve root remains unclear, and needs further investigation. In this study, a complete spinal cord injury model was established in New Zealand white rabbits through T9–10 segment transection. Rabbits were given continuous electrical stimulation for a short period and then chronic stimulation for a longer period. Results showed that compared with normal rabbits, the structure of nerve cells in the anterior sacral nerve roots was unchanged in spinal cord injury rabbits after electrical stimulation. There was no significant difference in the expression of apoptosis-related proteins such as Bax, Caspase-3, and Bcl-2. Experimental findings indicate that neurons in the rabbit sacral nerve roots tolerate electrical stimulation, even after long-term anode block electrical stimulation.     

Paeonol attenuates inflammation-mediated neurotoxicity and microglial activation

Chronic activation of microglial cells endangers neuronal survival through the release of various proinflammatory and neurotoxic factors. The root of Paeonia lactiflora Pall has been considered useful for the treatment of various disorders in traditional oriental medicine. Paeonol, found in the root of Paeonia lactiflora Pall, has a wide range of pharmacological functions, including anti-oxidative, anti-inflammatory and neuroprotective activities. The objective of this study was to examine the efficacy of paeonol in the repression of inflammation-induced neurotoxicity and microglial cell activation. Organotypic hippocampal slice cultures and primary microglial cells from rat brain were stimulated with bacterial lipopolysaccharide. Paeonol pretreatment was performed for 30 minutes prior to lipopolysaccharide addition. Cell viability and nitrite (the production of nitric oxide), tumor necrosis factor-alpha and interleukin-1beta products were measured after lipopolysaccharide treatment. In organotypic hippocampal slice cultures, paeonol blocked lipopolysaccharide-related hippocampal cell death and inhibited the release of nitrite and interleukin-1beta. Paeonol was effective in inhibiting nitric oxide release from primary microglial cells. It also reduced the lipopolysaccharide-stimulated release of tumor necrosis factor-alpha and interleukin-1β from microglial cells. Paeonol possesses neuroprotective activity in a model of inflammation-induced neurotoxicity and reduces the release of neurotoxic and proinflammatory factors in activated microglial cells.     

A feasible strategy for focal cerebral ischemia-reperfusion injury： remote ischemic postconditioning

It is difficult to control the degree of ischemic postconditioning in the brain and other ischemia-sensitive organs.Remote ischemic postconditioning could protect some ischemia-sensitive organs through measures on terminal organs.In this study,a focal cerebral ischemia-reperfusion injury model was established using three cycles of remote ischemic postconditioning,each cycle consisted of 10-minute occlusion of the femoral artery and 10-minute opening.The results showed that,remote ischemic postconditioning significantly decreased the percentage of the infarct area and attenuated brain edema.In addition,inflammatory nuclear factor-κB expression was significantly lower,while anti-apoptotic Bcl-2 expression was significantly elevated in the cerebral cortex on the ischemic side.Our findings indicate that remote ischemic postconditioning attenuates focal cerebral ischemia/reperfusion injury,and that the neuroprotective mechanism is mediated by an anti-apoptotic effect and reduction of the inflammatory response.     

Does progesterone show neuroprotective effects on traumatic brain injury through increasing phosphorylation of Akt in the hippocampus？

There are currently no federally approved neuroprotective agents to treat traumatic brain injury. Progesterone, a hydrophobic steroid hormone, has been shown in recent studies to exhibit neu-roprotective effects in controlled cortical impact rat models. Akt is a protein kinase known to play a role in cell signaling pathways that reduce edema, inlfammation, apoptosis, and promote cell growth in the brain. This study aims to determine if progesterone modulates the phosphor-ylation of Aktvia its threonine 308 phosphorylation site. Phosphorylation at the threonine 308 site is one of several sites responsible for activating Akt and enabling the protein kinase to carry out its neuroprotective effects. To assess the effects of progesterone on Akt phosphorylation, C57BL/6 mice were treated with progesterone （8 mg/kg） at 1 （intraperitonally）, 6, 24, and 48 hours （subcutaneously） post closed-skull traumatic brain injury. The hippocampus was harvest-ed at 72 hours post injury and prepared for western blot analysis. Traumatic brain injury caused a signiifcant decrease in Akt phosphorylation compared to sham operation. However, mice treat-ed with progesterone following traumatic brain injury had an increase in phosphorylation of Akt compared to traumatic brain injury vehicle. Our ifndings suggest that progesterone is a viable treatment option for activating neuroprotective pathways after traumatic brain injury.     

Reducing LncRNA-5657 expression inhibits the brain inflammatory reaction in septic rats

Our preliminary study found that the long noncoding RNA(LncRNA)-5657 can reduce the expression of inflammatory factors during inflammatory reactions in rat glial cells.However, the role played by LncRNA-5657 during septic brain injury remains unclear.In the present study, rat models of septic encephalopathy were established by cecal ligation and puncture, and then the rats were treated with a hippocampal injection small hairpin RNA(sh RNA) against LncRNA-5657(sh-LnCRNA-5657).The sh-LncRNA-5657 treatment reduced the level of neuronal degeneration and necrosis in the rat hippocampus, reduced the immunoreactivities of aquaporin 4, heparanase, and metallopeptidase-9, and lowered the level of tumor necrosis factor-alpha.Glial cells were pre-treated with sh-LncRNA-5657 and then treated with 1 μg/mL lipopolysaccharide.Sh-LncRNA-5657 transfection decreased the expression of LncRNA-5657 in lipopolysaccharide-treated glial cells and decreased the mRNA and protein levels of tumor necrosis factor-alpha, interleukin-1β, and interleukin-6.These findings suggested that LncRNA-5657 expression can significantly reduce the inflammatory reaction during septic encephalopathy and induce protective effects against this disease.This study was approved by the Institutional Ethics Committee at the First Affiliated Hospital of Nanchang University of China(approval No.2017-004) in 2017.