Gut microbiota of old mice worsens neurological outcome after brain ischemia via increased valeric acid and IL-17 in the blood.

BACKGROUND: Aging is a significant risk factor for ischemic stroke and worsens its outcome. However, the mechanisms for this worsened neurological outcome with aging are not clearly defined. RESULTS: Old C57BL/6J male mice (18 to 20 months old) had a poorer neurological outcome and more severe inflammation after transient focal brain ischemia than 8-week-old C57BL/6J male mice (young mice). Young mice with transplantation of old mouse gut microbiota had a worse neurological outcome, poorer survival curve, and more severe inflammation than young mice receiving young mouse gut microbiota transplantation. Old mice and young mice transplanted with old mouse gut microbiota had an increased level of blood valeric acid. Valeric acid worsened neurological outcome and heightened inflammatory response including blood interleukin-17 levels after brain ischemia. The increase of interleukin-17 caused by valeric acid was inhibited by a free fatty acid receptor 2 antagonist. Neutralizing interleukin-17 in the blood by its antibody improved neurological outcome and attenuated inflammatory response in mice with brain ischemia and receiving valeric acid. Old mice transplanted with young mouse feces had less body weight loss and better survival curve after brain ischemia than old mice transplanted with old mouse feces or old mice without fecal transplantation. CONCLUSIONS: These results suggest that the gut microbiota-valeric acid-interleukin-17 pathway contributes to the aging-related changes in the outcome after focal brain ischemia and response to stimulus. Valeric acid may activate free fatty acid receptor 2 to increase interleukin-17.

Appropriate exercise level attenuates gut dysbiosis and valeric acid increase to improve neuroplasticity and cognitive function after surgery in mice.

Postoperative cognitive dysfunction (POCD) affects the outcome of millions of patients each year. Aging is a risk factor for POCD. Here, we showed that surgery induced learning and memory dysfunction in adult mice. Transplantation of feces from surgery mice but not from control mice led to learning and memory impairment in non-surgery mice. Low intensity exercise improved learning and memory in surgery mice. Exercise attenuated surgery-induced neuroinflammation and decrease of gut microbiota diversity. These exercise effects were present in non-exercise mice receiving feces from exercise mice. Exercise reduced valeric acid, a gut microbiota product, in the blood. Valeric acid worsened neuroinflammation, learning and memory in exercise mice with surgery. The downstream effects of exercise included attenuating growth factor decrease, maintaining astrocytes in the A2 phenotypical form possibly via decreasing C3 signaling and improving neuroplasticity. Similar to these results from adult mice, exercise attenuated learning and memory impairment in old mice with surgery. Old mice receiving feces from old exercise mice had better learning and memory than those receiving control old mouse feces. Surgery increased blood valeric acid. Valeric acid blocked exercise effects on learning and memory in old surgery mice. Exercise stabilized gut microbiota, reduced neuroinflammation, attenuated growth factor decrease and preserved neuroplasticity in old mice with surgery. These results provide direct evidence that gut microbiota alteration contributes to POCD development. Valeric acid is a mediator for this effect and a potential target for brain health. Low intensity exercise stabilizes gut microbiota in the presence of insult, such as surgery.

The 2-(2-benzofuranyl)-2-imidazoline provides neuroprotection against focal cerebral ischemia-reperfusion injury in diabetic rats: Influence of microglia and possible mechanisms of action.

Increased microglial NADPH oxidase (NOX2) production may make an important contribution to the increased incidence and severity of ischemic stroke associated with diabetes. Imidazoline receptors are closely associated with neuroprotection, but the neuroprotective effects of the selective I2-imidazoline receptor ligand 2-(2-benzofuranyl)-2-imidazoline (2BFI) in diabetes has not been established. The effect of 2BFI on microglial NOX2 production was investigated using a co-culture of neurons and microglia, and the effect on cerebral ischemia-reperfusion (IR) injury was determined in diabetic rats. Garcia neurological scores, brain infarct volumes, brain water content, TUNEL staining, blood-brain barrier, and immunofluorescent labeling for microglia were evaluated. Western blots were used to determine gp91phox and Tyr1472 expression. Anti-inflammatory cytokine (IL-10) and inflammatory cytokine secretion was determined using ELISA kits. The brain infarct volumes, TUNEL-positive neurons, expression of microglia, brain water content, blood-brain barrier structure damage, and gp91phox and Tyr1472 expression were increased, the Garcia neurological scores were significantly decreased in the IR group, and 2BFI relieved these alterations. The IL-10 concentration was increased in the IR group; 2BFI significantly improved this increase. The neuron apoptosis and necrosis rates, and production of reactive oxygen species (ROS) and inflammatory cytokines, including IL-6, IL-8, TNF-α, and 8-iso-PGF2α, were significantly increased by high glucose stimulation combined with oxygen-glucose deprivation treatment, which were inhibited by 2BFI. The 2BFI ameliorated cerebral ischemia-reperfusion injury in diabetes and decreased neuron death in an in vitro model. The mechanism underlying these findings may be related to the decreased production of inflammatory factors and reactive oxygen species from microglia.

Isoform-specific functions of c-Jun N-terminal kinase 1 and 2 in lung ischemia-reperfusion injury through the c-Jun/activator protein-1 pathway.

BACKGROUND: c-Jun N-terminal kinase 1 (JNK1) and JNK2 regulate distinct pathological processes in lung diseases. Here we discriminated the respective roles of these kinases in lung transplantation-induced ischemia-reperfusion injury (IRI). METHODS: Rat pulmonary microvascular endothelial cells were transfected with JNK1 small-interfering RNA (siRNA) and JNK2 siRNA and then subjected to in vitro IRI. For the isoform confirmed to aggravate IRI, the delivery of short-hairpin RNA (shRNA) plasmid was performed by intratracheal administration 48 hours before transplantation into donor rats. After a 3-hour reperfusion, the samples were collected. RESULTS: JNK1 siRNA decreased but JNK2 siRNA increased JNK phosphorylation and activity, phosphorylated and total c-Jun, and activator protein-1 activity. Although JNK1 siRNA decreased apoptosis and the levels of malondialdehyde, interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF-α), it increased the levels of superoxide dismutase, S-phase percentage, and cyclin D1; JNK2 siRNA had a converse effect. JNK1 siRNA decreased the level of lactate dehydrogenase and increased the levels of VE-cadherin, nitric oxide, phosphorylated nitric oxide synthase, and cell viability; JNK2 si RNA had a converse effect. Compared with the control group, the JNK1 shRNA group exhibited a higher lung oxygenation index and lower lung apoptosis index, injury score, wet weight:dry weight ratio, and levels of IL-1, IL-6, and TNF-α. CONCLUSIONS: JNK1 aggravated, but JNK2 alleviated, IRI through differential regulation of the JNK1 pathway in in vitro ischemia-reperfusion. JNK1 silence attenuated lung graft dysfunction by inhibiting inflammation and apoptosis. These findings provide a theoretical basis for devising therapeutic strategies against IRI after lung transplantation.

Gp91phox (NOX2) in Activated Microglia Exacerbates Neuronal Damage Induced by Oxygen Glucose Deprivation and Hyperglycemia in an in Vitro Model.

BACKGROUND/AIMS: Peri-operative cerebral ischemia reperfusion injury is one of the most serious peri-operative complications that can be aggravated in patients with diabetes. A previous study showed that microglia NOX2 (a NADPH oxidase enzyme) may play an important role in this process. Here, we investigated whether increased microglial derived gp91phox, also known as NOX2, reduced oxygen glucose deprivation (OGD) after induction of hyperglycemia (HG). METHODS: A rat neuronal-microglial in vitro co-culture model was used to determine the effects of gp91phox knockdown on OGD after HG using six treatment groups: A rat microglia and neuron co-culture model was established and divided into the following six groups: high glucose + scrambled siRNA transfection (HG, n = 5); HG + gp91phoxsiRNA transfection (HG-gp91siRNA, n = 5); oxygen glucose deprivation + scrambled siRNA transfection (OGD, n = 5); OGD + gp91phoxsiRNA transfection (OGD-gp91siRNA, n = 5); HG + OGD + scrambled siRNA transfection (HG-OGD, n = 5); and HG + OGD + gp91phoxsiRNA transfection (HG-OGD-gp91siRNA, n = 5). The neuronal survival rate was measured by the MTT assay, while western blotting was used to determine gp91phox expression. Microglial derived ROS and neuronal apoptosis rates were analyzed by flow cytometry. Finally, the secretion of cytokines, including IL-6, IL-8, TNF-α, and 8-iso-PGF2α was determined using an ELISA kit. RESULTS: Neuronal survival rates were significantly decreased by HG and OGD, while knockdown of gp91phox reversed these rates. ROS production and cytokine secretion were also significantly increased by HG and OGD but were significantly inhibited by knockdown of gp91phoxsiRNA. CONCLUSION: Knockdown of gp91phoxsiRNA significantly reduced oxidative stress and the inflammatory response, and alleviated neuronal damage after HG and OGD treatment in a rat neuronal-microglial co-culture model.

Investigation of single-dose thoracic paravertebral analgesia for postoperative pain control after thoracoscopic lobectomy - A randomized controlled trial.

BACKGROUND: Thoracoscopic lobectomy is less painful than normal thoracotomy, but pain management is still an issue in the postoperative period. Thoracic epidural analgesia (TEA) is considered as the gold standard for post-thoracotomy pain control, but is associated with numerous risks. METHODS: A total of 114 patients undergoing thoracoscopic lobectomy were randomly divided into three groups. Patients in the PVB-R group received a single-dose 0.5% ropivacaine paravertebral block (PVB), combined with patient-controlled intravenous analgesia (PCIA) after extubation during the 48-h postoperative period; those in the PVB-RD group received a single-dose 0.5% ropivacaine and dexmedetomidine (1 µg/kg) PVB, combined with the same PCIA scheme; and those in the TEA group received intraoperative thoracic epidural anesthesia with 0.5% ropivacaine, and a single dose of epidural morphine (0.03 mg/kg) after extubation combined with the same PCIA scheme. The dose and first time of postoperative analgesia, verbal rating score (VRS), change in catecholamine, cortisol and cytokine levels, change in hemodynamic parameters, and side effects during the postoperative period were recorded. RESULTS: Compared to the PVB-R group, the dose of postoperative analgesia and VRS were lower and the first time of postoperative analgesia were longer in the PVB-RD and TEA group. Patients in the PVB-RD group had a lower incidence of side effects compared to those in the TEA group. CONCLUSIONS: Single-dose 0.5% ropivacaine combined with dexmedetomidine (1 µg/kg) PVB provides satisfactory postoperative pain control after thoracoscopic lobectomy, and can reduce the incidence of postoperative side effects.

CONSORT-epidural dexmedetomidine improves gastrointestinal motility after laparoscopic colonic resection compared with morphine.

BACKGROUND: We have previously shown that epidural dexmedetomidine, when used as an adjunct to levobupivacaine for control of postoperative pain after open colonic resection, improves recovery of gastrointestinal motility compared with morphine. METHODS: Sixty patients undergoing laparoscopic colonic resection were enrolled and allocated randomly to treatment with dexmedetomidine (group D) or morphine (group M). Group D received an epidural loading dose of dexmedetomidine (5 mL, 0.5 µg/kg), followed by continuous epidural administration of dexmedetomidine (80 µg) in 0.125% levobupivacaine (240 mL) at a rate of 5 mL/h for 2 days. Group M received an epidural loading dose of morphine (5 mL, 0.03 mg/kg) followed by continuous epidural administration of morphine (4.5 mg) in 0.125% levobupivacaine (240 mL) at a rate of 5 mL/h for 2 days. Verbal rating score (VRS) of pain, postoperative analgesic requirements, side effects related to analgesia, and time to postoperative first flatus (FFL) and first feces (FFE) were recorded. RESULTS: VRS and postoperative analgesic requirements were not significantly different between the treatment groups. In contrast, FFL and FFE were significant delayed in group M compared with group D (P < .05). Patients in group M also had a significantly higher incidence of nausea, vomiting, and pruritus (P < .05). No neurological deficits were observed in either group. CONCLUSIONS: Compared with morphine, epidural dexmedetomidine is a better adjunct to levobupivacaine for control of postoperative pain after laparoscopic colonic resection.

Epidural Dexmedetomidine Reduces the Requirement of Propofol during Total Intravenous Anaesthesia and Improves Analgesia after Surgery in Patients undergoing Open Thoracic Surgery.

The aim of this study was to assess the systemic and analgesic effects of epidural dexmedetomidine in thoracic epidural anaesthesia (TEA) combined with total intravenous anaesthesia during thoracic surgery. Seventy-one patients undergoing open thoracotomy were included in this study and randomly divided into three groups: Control group (Group C): patients received TEA with levobupivacaine alone and were intravenously infused with saline; Epidural group (Group E): patients received TEA with levobupivacaine and dexmedetomidine, and were intravenously infused with saline; Intravenous group (group V): patients received TEA with levobupivacaine alone and were intravenously infused with dexmedetomidine. The doses of propofol used in the induction and maintenance of general anaesthesia, cardiovascular response, dose and first time of postoperative analgesia and verbal rating scale were recorded. The induction and maintenance were significantly lower in the Groups E and V. Verbal rating scale and postoperative analgesic requirements were significantly lower in Group E than in Groups C and V. Patients in Group C had more severe cardiovascular responses, as compared with Groups E and V. Epidural administration of dexmedetomidine reduced the induction and maintenance of propofol, and inhibited the cardiovascular response after intubation and extubation. Moreover, epidural dexmedetomidine provided better analgesia after open thoracotomy.

Effect of Adding Dexmedetomidine to Ropivacaine on Ultrasound-Guided Dual Transversus Abdominis Plane Block after Gastrectomy.

OBJECTIVES: Transversus abdominis plane (TAP) block is an analgesic technique. Adding dexmedetomidine can enhance regional anesthesia. This study's aim was to evaluate whether dexmedetomidine prolonged analgesic time of TAP block after gastrectomy. METHODS: Patients scheduled for gastrectomy were randomly assigned to receive a TAP block with saline (group S), ropivacaine (group R), or ropivacaine and dexmedetomidine (group RD). Visual analogue scale (VAS) scores, postoperative nausea and vomiting (PONV) scores, sedation scores, tramadol consumption, ropivacaine concentration, and Quality of Recovery Questionnaire 40 (QoR-40) were recorded. RESULTS: Patients in group R and group RD had lower VAS scores 2, 4, 12, and 24 h after surgery compared with group S (P < 0.05). PONV scores were lower in group R and group RD compared with group S after 2, 12, 24, and 36 h (P < 0.05). Patients in group R and group RD required less tramadol and had better QoR-40 scores than those in group S (P < 0.05). The aforementioned variables and ropivacaine concentrations did not differ between group R and group RD (P > 0.05). Sedation scores were similar between three groups (P > 0.05). CONCLUSIONS: TAP block can provide analgesia and improve the quality of recovery. Adding dexmedetomidine does not significantly improve the quality or duration of TAP block.

Protective effects of propofol against whole cerebral ischemia/reperfusion injury in rats through the inhibition of the apoptosis-inducing factor pathway.

Cerebral ischemia/reperfusion (I/R) injury could cause neural apoptosis that involved the signaling cascades. Cytochrome c release from the mitochondria and the followed activation of caspase 9 and caspase 3 are the important steps. Now, a new mitochondrial protein, apoptosis-inducing factor (AIF), has been shown to have relationship with the caspase-independent apoptotic pathway. In this study, we investigated the protective effects of propofol through inhibiting AIF-mediated apoptosis induced by whole cerebral I/R injury in rats. 120 Wistar rats that obtained the permission of the animal care committee of Harbin Medical University were randomly divided into three groups: sham group (S group), cerebral ischemia/reperfusion injury group (I/R group), and propofol treatment group (P group). Propofol (1.0mg/kg/min) was administered intravenously for 1h before the induction of ischemia in P group. The apoptotic rate in three groups was detected by flow cytometry after 24h of reperfusion. The mitochondrial membrane potential (MMP) changes were detected via microplate reader. The expressions of B-cell leukemia-2 (Bcl-2), Bcl-2 associated X protein (Bax) and AIF were evaluated using Western blot after 6h, 24h and 48h of reperfusion. The results of our study showed that apoptotic level was lower in P group compared with I/R group and propofol could protect MMP. The ratio of Bcl-2/Bax was significantly higher in P group compared with I/R group. The translocation of AIF from mitochondrial to nucleus was lower in P group than that in I/R group. Our findings suggested that the protective effects of propofol on cerebral I/R injury might be associated with inhibiting translocation of AIF from mitochondrial to the nucleus in hippocampal neurons.

Dexmedetomidine Protects against Transient Global Cerebral Ischemia/Reperfusion Induced Oxidative Stress and Inflammation in Diabetic Rats.

BACKGROUND: Transient global cerebral ischemia/reperfusion (I/R) is a major perioperative complication, and diabetes increases the response of oxidative stress and inflammation induced by I/R. The objective of this study was to determine the protective effect of dexmedetomidine against transient global cerebral ischemia/reperfusion induced oxidative stress and inflammation in diabetic rats. METHODS: Sixty-four rats were assigned into four experimental groups: normoglycemia, normoglycemia + dexmedetomidine, hyperglycemia, and hyperglycemia + dexmedetomidine and all subsequent neurological examinations were evaluated by a blinded observer. Damage to the brain was histologically assessed using the TUNEL staining method while western blotting was used to investigate changes in the expression levels of apoptosis-related proteins as well as the microglia marker, ionized calcium-binding adapter molecule 1 (Iba1). Water content in the brain was also analyzed. In addition, hippocampal concentrations of malondialdehyde (MDA) and Nox2 (a member of the Nox family of NADPH oxidases), and the activity of superoxide dismutase and catalase were analyzed. Finally, changes in serum concentrations of tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 were detected. RESULTS: Results showed that diabetes increased brain water content, the number of apoptotic neurons, early neurological deficit scores, oxidative stress (MDA and Nox2) and inflammation (pro-inflammatory cytokines including TNF-α and IL-6) levels following transient global I/R injury, but that these symptoms were attenuated following administration of dexmedetomidine. CONCLUSIONS: These findings suggest that dexmedetomidine can significantly alleviate damage resulting from I/R, and this mechanism may be related to a reduction in both oxidative stress and inflammation which is normally associated with I/R.

The inhibitory effect of propofol on Kv2.1 potassium channel in rat parietal cortical neurons.

Excessive K(+) efflux via activated voltage-gated K(+) channels can deplete intracellular K(+) and lead to long-lasting membrane depolarization which will promote neuronal apoptosis during ischemia/hypoxia injury. The Kv2.1 potassium channel was the major component of delayed rectifier potassium current (Ik) in pyramidal neurons in cortex and hippocampus. The neuronal protective effect of propofol has been proved. Delayed rectifier potassium current (Ik) has been shown to have close relationship with neuronal damage. The study was designed to test the inhibitory effect of propofol on Kv2.1 potassium channel in rat parietal cortical neurons. Whole-cell patch clamp recordings and Western blot analysis were used to investigate the electrophysiological function and protein expression of Kv2.1 in rat parietal cortical neurons after propofol treatment. We found that propofol concentration-dependently inhibited Ik in pyramidal neurons. Propofol also caused a downward shift of the I-V curve of Ik at 30µM concentration. Propofol significantly inhibited the expression of Kv2.1 protein level at 30µM, 50µM, 100µM concentration. In conclusion, our data showed that propofol could inhibit Ik, probably via depressing the expression of Kv2.1 protein in rat cerebral parietal cortical neurons.

Epidural Co-Administration of Dexmedetomidine and Levobupivacaine Improves the Gastrointestinal Motility Function after Colonic Resection in Comparison to Co-Administration of Morphine and Levobupivacaine.

UNLABELLED: Gastrointestinal motility may be impaired after intestinal surgery. Epidural morphine is effective in controlling postoperative pain, but can further reduce gastrointestinal motility. Here, we aimed to investigate the effects of epidural dexmedetomidine on gastrointestinal motility in patients undergoing colonic resection. Seventy-four patients undergoing colonic resection were enrolled in this clinical trial and allocated randomly to treatment with dexmedetomidine (D group) or morphine (M group). The D group received a loading dose epidural administration of 3 ml dexmedetomidine (0.5 µg kg(-1)) and then a continuous epidural administration of 80 µg dexmedetomidine in 150 ml levobupivacaine (0.125%) at 3 ml h(-1) for two days. The M group received a loading dose epidural administration of 3 ml morphine (0.03 mg kg(-1)) and then a continuous epidural administration of 4.5 mg morphine in 150 ml levobupivacaine at 3 ml h(-1) for two days. Verbal rating score (VRS), postoperative analgesic requirements, side effects related to analgesia, the time to postoperative first flatus (FFL) and first feces (FFE) were recorded. VRS and postoperative analgesic requirements were not significantly different between treatment groups. In contrast, the time to FFL and time to FFE were significant longer in M group in comparison to D group (P < 0.05). Moreover, patients in M group had a significantly higher incidence of nausea, vomiting, and pruritus (P < 0.05). No patients showed neurologic deficits in either group. In comparison to morphine, epidural dexmedetomidine is safe and beneficial for the recovery of gastrointestinal motility after colonic resection when used as an adjunct with levobupivacaine for postoperative pain control. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR-TRC-14004644.

Stellate ganglion block may prevent the development of neurogenic pulmonary edema and improve the outcome.

Neurogenic pulmonary edema (NPE) is an acute and serious complication after a central nervous system insult with high mortality. The pronounced activation of sympathetic nervous system and the release of vasoactive substances are necessary prerequisites for the development of NPE. We introduce a hypothesis that stellate ganglion block (SGB) may prevent NPE development on the basis of the inhibition of sympathetic overactivation, reduction of the concentration of norepinephrine and attenuation of baroreflex sensitivity, and improve the outcome by improving cerebral blood flow and pulmonary circulation and maintaining cardiovascular stability. In clinical practice, the guidance technique and close monitoring might guarantee the safety of SGB. If our hypothesis is supported by further experiments, this may open a new doorway for the treatment of NPE.