The Intrinsic PEDF is Regulated by PPARγ in Permanent Focal Cerebral Ischemia of Rat

Inflammatory damage plays a pivotal role in cerebral ischemia and may represent a target for treatment. Pigment epithelium-derived factor (PEDF) is proven to possess neuroprotective property. But there is little known about the intrinsic PEDF after cerebral ischemia. This study evaluated the time course expression of the intrinsic PEDF and its underlying regulation mechanisms after cerebral ischemia. Male Sprague-Dawley rats were subjected to permanent middle cerebral artery occlusion. Telmisartan (PPARγ agonist) and GW9662 (PPARγ antagonist) were systemically administered to explore the effect on PPARγ, PEDF, NF-κB and MMP-9 expression at 24?h after cerebral ischemia by western blot and qRT-PCR. The neurological deficits, brain water content and infarct volume were measured. Compared with normal group, the expressions of PEDF and PPARγ decreased, and the expression of NF-κB and MMP-9 increased at early stage after ischemia (P?相似文献   

Synergetic Effects of Caspase 3 and μ-Calpain in XIAP-Breakdown upon Focal Cerebral Ischemia

Dysregulation of apoptosis is involved in a wide spectrum of disease ranging from proliferative to neurodegenerative disorders. The recently discovered X-linked inhibitor of apoptosis protein (XIAP) is among the most potent inhibitors of apoptosis. This protein binds to and inhibits both initiator caspases and effector caspases such as caspase-3. The aim of this study was to investigate the relationships between XIAP-breakdown, caspase activation in the development of delayed infarct upon ischemia. We demonstrated that endogenous XIAP is cleaved at least into two fragments during reperfusion following the ischemic insult. The two fragments produced seem to be related to caspase-3 and μ-calpain activities, which are massively enhanced in tissues challenged by ischemia. Therefore, degradation of XIAP by μ-calpain in our system may decrease the activation threshold of caspase-3 normally held in check by the IAPs and/or lead to auto-activation of other caspases. Special issue in honor of Naren Banik.     

Effect of Propofol Post-treatment on Blood–Brain Barrier Integrity and Cerebral Edema After Transient Cerebral Ischemia in Rats

Although propofol has been reported to offer neuroprotection against cerebral ischemia injury, its impact on cerebral edema following ischemia is not clear. The objective of this investigation is to evaluate the effects of propofol post-treatment on blood–brain barrier (BBB) integrity and cerebral edema after transient cerebral ischemia and its mechanism of action, focusing on modulation of aquaporins (AQPs), matrix metalloproteinases (MMPs), and hypoxia inducible factor (HIF)-1α. Cerebral ischemia was induced in male Sprague–Dawley rats (n = 78) by occlusion of the right middle cerebral artery for 1 h. For post-treatment with propofol, 1 mg kg^?1 min^?1 of propofol was administered for 1 h from the start of reperfusion. Nineteen rats undergoing sham surgery were also included in the investigation. Edema and BBB integrity were assessed by quantification of cerebral water content and extravasation of Evans blue, respectively, following 24 h of reperfusion. In addition, the expression of AQP-1, AQP-4, MMP-2, and MMP-9 was determined 24 h after reperfusion and the expression of HIF-1α was determined 8 h after reperfusion. Propofol post-treatment significantly reduced cerebral edema (P < 0.05) and BBB disruption (P < 0.05) compared with the saline-treated control. The expression of AQP-1, AQP-4, MMP-2, and MMP-9 at 24 h and of HIF-1α at 8 h following ischemia/reperfusion was significantly suppressed in the propofol post-treatment group (P < 0.05). Propofol post-treatment attenuated cerebral edema after transient cerebral ischemia, in association with reduced expression of AQP-1, AQP-4, MMP-2, and MMP-9. The decreased expression of AQPs and MMPs after propofol post-treatment might result from suppression of HIF-1α expression.     

Exercise Protects against Diet-Induced Insulin Resistance through Downregulation of Protein Kinase Cβ in Mice

Physical exercise is an important and effective therapy for diabetes. However, its underlying mechanism is not fully understood. Protein kinase Cβ (PKCβ) has been suggested to be involved in the pathogenesis of obesity and insulin resistance, but the role of PKCβ in exercise-induced improvements in insulin resistance is completely unknown. In this study, we evaluated the involvement of PKCβ in exercise-attenuated insulin resistance in high-fat diet (HFD)-fed mice. PKCβ^-/- and wild-type mice were fed a HFD with or without exercise training. PKC protein expression, body and tissue weight change, glucose and insulin tolerance, metabolic rate, mitochondria size and number, adipose inflammation, and AKT activation were determined to evaluate insulin sensitivity and metabolic changes after intervention. PKCβ expression decreased in both skeletal muscle and liver tissue after exercise. Exercise and PKCβ deficiency can alleviate HFD-induced insulin resistance, as evidenced by improved insulin tolerance. In addition, fat accumulation and mitochondrial dysfunction induced by HFD were also ameliorated by both exercise and PKCβ deficiency. On the other hand, exercise had little effect on PKCβ^-/- mice. Further, our data indicated improved activation of AKT, the downstream signal molecule of insulin, in skeletal muscle and liver of exercised mice, whereas PKCβ deficiency blunted the difference between sedentary and exercised mice. These results suggest that downregulation of PKCβ contributes to exercise-induced improvement of insulin resistance in HFD-fed mice.     

Effects of Exogenous Excitatory Amino Acid Neurotransmitters on Blood–Brain Barrier Disruption in Focal Cerebral Ischemia

This study was performed to determine whether exogenous N-methyl-d-aspartate (NMDA) or alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) would aggravate blood–brain barrier (BBB) disruption in focal cerebral ischemia in rats. Forty-five minutes after middle cerebral artery (MCA) occlusion, one of the following patches was applied to the exposed ischemic cerebral cortex of each rat: normal saline (control), 10⁻⁵ M AMPA, 10⁻⁴ M AMPA, 10⁻⁵ M NMDA, or 10⁻⁴ M NMDA. At 1 h after MCA occlusion, BBB permeability was determined by measuring the transfer coefficient (Ki) of ¹⁴C-α-aminoisobutyric acid (¹⁴C-AIB). In all experimental groups, the Ki of the ischemic cortex (IC) was higher than that of the corresponding contralateral cortex (CC). The Ki of the IC of the animals treated with 10⁻⁴ M AMPA or 10⁻⁴ M NMDA was higher (+41%: P < 0.05 and +33%: P < 0.05, respectively) than that of the control animals. Our data demonstrated that exogenous NMDA or AMPA could further aggravate the BBB disruption in focal cerebral ischemia. Any insult increasing the release of excitatory neurotransmitters could further aggravate BBB disruption and brain edema during the ischemic period.     

Propofol Prevents Oxidative Stress by Decreasing the Ischemic Accumulation of Succinate in Focal Cerebral Ischemia–Reperfusion Injury

Oxidative stress caused by mitochondrial dysfunction during reperfusion is a key pathogenic mechanism in cerebral ischemia–reperfusion (IR) injury. Propofol (2,6-diisopropylphenol) has been proven to attenuate mitochondrial dysfunction and reperfusion injury. The current study reveals that propofol decreases oxidative stress injury by preventing succinate accumulation in focal cerebral IR injury. We evaluated whether propofol could attenuate ischemic accumulation of succinate in transient middle cerebral artery occlusion in vivo. By isolating mitochondria from cortical tissue, we also examined the in vitro effects of propofol on succinate dehydrogenase (SDH) activity and various mitochondrial bioenergetic parameters related to oxidative stress injury, such as the production of reactive oxidative species, membrane potential, Ca²⁺-induced mitochondrial swelling, and morphology via electron microscopy. Propofol significantly decreased the ischemic accumulation of succinate by inhibiting SDH activity and inhibited the oxidation of succinate in mitochondria. Propofol can decrease membrane potential in normal mitochondria but not in ischemic mitochondria. Propofol prevents Ca²⁺-induced mitochondrial swelling and ultrastructural changes to mitochondria. The protective effect of propofol appears to act, at least in part, by limiting oxidative stress injury by preventing the ischemic accumulation of succinate.     

Protective Role of Deoxyschizandrin and Schisantherin A against Myocardial Ischemia–Reperfusion Injury in Rats

Background

Our previous studies suggested that deoxyschizandrin (DSD) and schisantherin A (STA) may have cardioprotective effects, but information in this regard is lacking. Therefore, we explored the protective role of DSD and STA in myocardial ischemia–reperfusion (I/R) injury.

Methodology/Principal Findings

Anesthetized male rats were treated once with DSD and STA (each 40 µmol/kg) through the tail vein after 45 min of ischemia, followed by 2-h reperfusion. Cardiac function, infarct size, biochemical markers, histopathology and apoptosis were measured and mRNA expression of gp91^phox in myocardial tissue assessed by RT-PCR. Neonatal rat cardiomyocytes were pretreated with DSD and STA and then damaged by H₂O₂. Cell apoptosis was tested by a flow cytometric assay. Compared with the I/R group: (i) DSD and STA could significantly reduce the abnormalities of LVSP, LVEDP, ±dp/dt_max and arrhythmias, thereby showing their protective roles in cardiac function; (ii) DSD and STA could significantly attenuate the infarct size and MDA release while increasing SOD activity, suggesting a role in reducing myocardial injury; (iii) tissue morphology and myocardial textual analysis revealed that DSD and STA mitigated changes in myocardial histopathology; (iv) DSD and STA decreased apoptosis (33.56±2.58% to 10.28±2.80% and 10.98±1.99%, respectively) and caspase-3 activity in the myocardium (0.62±0.02 OD/mg to 0.38±0.02 OD/mg and 0.32±0.02 OD/mg, respectively), showing their protective effects upon cardiomyocytes; and (v) DSD and STA had similar protective effects on I/R injury as those seen with the positive control metoprolol. In vitro, DSD and STA could significantly decrease the apoptosis of neonatal cardiomyocytes.

Conclusions/Significance

These data suggest that DSD and STA can protect against myocardial I/R injury. The underlining mechanism may be related to their role in inhibiting cardiomyocyte apoptosis.     

Protection of Ischemic Postconditioning against Neuronal Apoptosis Induced by Transient Focal Ischemia Is Associated with Attenuation of NF-κB/p65 Activation

Background and Purpose

Accumulating evidences have demonstrated that nuclear factor κB/p65 plays a protective role in the protection of ischemic preconditioning and detrimental role in lethal ischemia-induced programmed cell death including apoptosis and autophagic death. However, its role in the protection of ischemic postconditioning is still unclear.

Methods

Rat MCAO model was used to produce transient focal ischemia. The procedure of ischemic postconditioning consisted of three cycles of 30 seconds reperfusion/reocclusion of MCA. The volume of cerebral infarction was measured by TTC staining and neuronal apoptosis was detected by TUNEL staining. Western blotting was used to analyze the changes in protein levels of Caspase-3, NF-κB/p65, phosphor- NF-κB/p65, IκBα, phosphor- IκBα, Noxa, Bim and Bax between rats treated with and without ischemic postconditioning. Laser scanning confocal microscopy was used to examine the distribution of NF-κB/p65 and Noxa.

Results

Ischemic postconditioning made transient focal ischemia-induced infarct volume decrease obviously from 38.6%±5.8% to 23.5%±4.3%, and apoptosis rate reduce significantly from 46.5%±6.2 to 29.6%±5.3% at reperfusion 24 h following 2 h focal cerebral ischemia. Western blotting analysis showed that ischemic postconditioning suppressed markedly the reduction of NF-κB/p65 in cytoplasm, but elevated its content in nucleus either at reperfusion 6 h or 24 h. Moreover, the decrease of IκBα and the increase of phosphorylated IκBα and phosphorylated NF-κB/p65 at indicated reperfusion time were reversed by ischemic postconditioning. Correspondingly, proapoptotic proteins Caspase-3, cleaved Caspase-3, Noxa, Bim and Bax were all mitigated significantly by ischemic postconditioning. Confocal microscopy revealed that ischemic postconditioning not only attenuated ischemia-induced translocation of NF-κB/p65 from neuronal cytoplasm to nucleus, but also inhibited the abnormal expression of proapoptotic protein Noxa within neurons.

Conclusions

We demonstrated in this study that the protection of ischemic postconditioning on neuronal apoptosis caused by transient focal ischemia is associated with attenuation of the activation of NF-κB/p65 in neurons.     

Morphine Protects against Methylmercury Intoxication: A Role for Opioid Receptors in Oxidative Stress?

Mercury is an extremely dangerous environmental contaminant responsible for episodes of human intoxication throughout the world. Methylmercury, the most toxic compound of this metal, mainly targets the central nervous system, accumulating preferentially in cells of glial origin and causing oxidative stress. Despite studies demonstrating the current exposure of human populations, the consequences of mercury intoxication and concomitant use of drugs targeting the central nervous system (especially drugs used in long-term treatments, such as analgesics) are completely unknown. Morphine is a major option for pain management; its global consumption more than quadrupled in the last decade. Controversially, morphine has been proposed to function in oxidative stress independent of the activation of the opioid receptors. In this work, a therapeutic concentration of morphine partially protected the cellular viability of cells from a C6 glioma cell line exposed to methylmercury. Morphine treatment also reduced lipid peroxidation and totally prevented increases in nitrite levels in those cells. A mechanistic study revealed no alteration in sulfhydryl groups or direct scavenging at this opioid concentration. Interestingly, the opioid antagonist naloxone completely eliminated the protective effect of morphine against methylmercury intoxication, pointing to opioid receptors as the major contributor to this action. Taken together, the experiments in the current study provide the first demonstration that a therapeutic concentration of morphine is able to reduce methylmercury-induced oxidative damage and cell death by activating the opioid receptors. Thus, these receptors may be a promising pharmacological target for modulating the deleterious effects of mercury intoxication. Although additional studies are necessary, our results support the clinical safety of using this opioid in methylmercury-intoxicated patients, suggesting that normal analgesic doses could confer an additional degree of protection against the cytotoxicity of this xenobiotic.     

Can Gender Differences Be Evaluated in a Rhesus Macaque (Macaca mulatta) Model of Focal Cerebral Ischemia?

Gender differences, sex steroid effects, and sex-specific candidate therapeutics in ischemic stroke have been studied in rodents but not in nonhuman primates. In this feasibility study (n = 3 per group), we developed a model of transient focal cerebral ischemia in adult male and female rhesus macaques that consistently includes white matter injury. The animals also were used to determine whether gender-linked differences in histopathologic outcomes could be evaluated in this model in future, larger preclinical trials. Histologic brain pathology was evaluated at 4 d after 90 min of reversible occlusion of the middle cerebral artery (MCA). MCA occlusion was accomplished by using a transorbital approach and temporary placement of an aneurysm clip. Male and female rhesus macaques 7 to 11 y of age were studied. Baseline and intraischemic blood glucose, systolic blood pressure, heart rate, oxygen saturation, end-tidal CO₂, and rectal temperatures were not different among groups. The variability in injury volume was comparable to that observed in human focal cerebrovascular ischemia and in other nonhuman primate models using proximal MCA occlusion. In this small sample, the volume of injury was not different between male and female subjects, but observed variability was higher in female caudate nucleus, putamen, and hemisphere. This report is the first to compare cerebral ischemic outcomes in female and male rhesus macaques. The female rhesus macaque ischemic stroke model could be used after rodent studies to provide preclinical data for clinical trials in women.Abbreviations: BP, blood pressure; EtCO₂, end-tidal CO₂; MCA, middle cerebral artery; SpO₂, oxygen saturation of peripheral bloodStroke is defined as the symptomatic loss or alteration of bodily function that results from an insufficient supply of blood to part of the brain. The most common type of stroke is ischemic stroke, which accounts for 87% of stroke cases.¹ Ischemic stroke occurs with greater frequency in men than in women across diverse ethnic backgrounds and nationalities.^1,25,38 This sexually dimorphic epidemiology is present in childhood¹⁰ until late in life, well beyond the menopausal years.^13,31 These observations suggest that the presence of female sex steroids may not completely explain stroke''s sexual dimorphism.One of the new concepts that must be considered in stroke research is that therapies and treatments for this disease operate in different genetic landscapes in women and men. Consequently, any prospective neuroprotective or injurious compound may act differently in female and male ischemic brains. For example, the Women''s Health Study recently evaluated aspirin use over 10 y for primary prevention of cardiovascular events, including stroke, and in reduction of mortality from cardiovascular causes.³⁰ Aspirin lowered ischemic stroke risk by 24% in healthy women, in contrast to results from the men-only Physicians Health study,²⁷ in which aspirin had no effect on stroke in men. These differences in how women compared with men respond to candidate agents potentially could influence clinical trial outcomes.Ischemic stroke models have been developed and characterized in many animal species,¹⁴ including several nonhuman primate species like baboons, macaques, marmosets, and squirrel monkeys.^9,26 There are several advantages to using nonhuman primate ischemic stroke models. First, the neuroanatomy and cerebrovascular anatomy of nonhuman primates is highly similar to that in humans. For example, rodents have lissencephalic brains, whereas humans and many nonhuman primate species have gyrencephalic brains.⁹ Moreover, the striatal gray matter of rats and mice is interleaved with white matter, whereas the white matter tracts of nonhuman primates are organized predominantly in the internal capsule.⁹ This arrangement in nonhuman primates ensures homogeneity of tissue and microvascular architecture with that of humans. Second, there are well known and often paradoxical differences between hemostatic and vascular mechanisms in rodents and rabbits and in their responses to antithrombotic and fibrinolytic agents compared with those of humans.⁹ However, several nonhuman primate species show close analogy to human hemostatic and coagulation systems. Finally, nonhuman primate models demonstrate a close similarity to human cerebral embolism without the effect of thrombus on the ischemic territory; lower animal species frequently lack this trait.⁹Most focal ischemic stroke models in nonhuman primates involve occlusion of a single artery, such as the middle cerebral artery (MCA).^9,14 Vascular clipping, use of an extrinsic balloon device or snare ligature, electrocoagulation or photocoagulation, and embolization by means of an interventional approach are common methods to induce MCA occlusion in nonhuman primates.⁹ In an MCA occlusion model, the degree and distribution of blood flow depends on the duration of occlusion (transient occlusion for minutes to hours with or without reperfusion compared with permanent occlusion for hours to days with no reperfusion), site of occlusion along the MCA (proximal versus distal part of the artery), and the amount of collateral blood flow into the MCA territory.^9,14The study of gender differences, effects of sex steroids, and sex-specific candidate therapeutics in experimental stroke has been limited primarily to rodent models.²⁵ These issues have not been addressed directly in nonhuman primate models, because many stroke studies involving nonhuman primate subjects reported use of male animals only,^{6,7,16,18,20,22,33,40} did not indicate the gender of animals used,^{5,15,17,21,42,44,45} or did not stratify outcomes with respect to sex.^12,23 The lack of data from female animals of higher-order species severely limits the translation of experimental data to women requiring treatment for stroke or neuroprotection during stroke. Similarly, the lack of suitably controlled preclinical data in both sexes of higher-order species potentially can lead to poorly designed clinical trials or failure of clinical trials when an agent or therapy of interest may have real benefit (or lack thereof) in a single gender. Nonhuman primate models could be invaluable in stroke studies of gender differences, the response to therapeutics in each gender, and the perimenopausal state. These models might serve as a useful bridge between experimental gender-based studies in rodents and the design of clinical trials in humans, because female nonhuman primate species such as the rhesus macaque have menstrual cycles and hormonal responses analogous to those of female humans.²We present here the results of a feasibility study in which we developed a model of transient focal cerebral ischemia in male and female rhesus macaques (Macaca mulatta) that would consistently include white matter injury. We also examined whether gender differences in histopathologic outcomes might be evaluated in this model in future, larger experimental trials examining the response to potential new stroke therapeutics initially screened and identified in rodent studies.     

L-Carnitine Protects against Carboplatin-Mediated Renal Injury: AMPK- and PPARα-Dependent Inactivation of NFAT3

We have previously shown that carboplatin induces inflammation and apoptosis in renal tubular cells (RTCs) through the activation of the nuclear factor of activated T cells-3 (NFAT3) protein by reactive oxygen species (ROS), and that the ROS-mediated activation of NFAT3 is prevented by N-acetyl cysteine and heme oxygenase-1 treatment. In the current study, we investigated the underlying molecular mechanisms of the protective effect of L-carnitine on carboplatin-mediated renal injury. Balb/c mice and RTCs were used as model systems. Carboplatin-induced apoptosis in RTCs was examined using terminal-deoxynucleotidyl-transferase-mediated dUTP nick end labeling. We evaluated the effects of the overexpression of the peroxisome-proliferator-activated receptor alpha (PPARα) protein, the knockdown of PPARα gene, and the blockade of AMPK activation and PPARα to investigate the underlying mechanisms of the protective effect of L-carnitine on carboplatin-mediated renal injury. Carboplatin reduced the nuclear translocation, phosphorylation, and peroxisome proliferator responsive element transactivational activity of PPARα. These carboplatin-mediated effects were prevented by L-carnitine through a mechanism dependent on AMPK phosphorylation and subsequent PPARα activation. The activation of PPARα induced cyclooxygenase 2 (COX-2) and prostacyclin (PGI2) synthase expression that formed a positive feedback loop to further activate PPARα. The coimmunoprecipitation of the nuclear factor (NF) κB proteins increased following the induction of PPARα by L-carnitine, which reduced NFκB transactivational activity and cytokine expression. The in vivo study showed that the inactivation of AMPK suppressed the protective effect of L-carnitine in carboplatin-treated mice, indicating that AMPK phosphorylation is required for PPARα activation in the L-carnitine-mediated protection of RTC apoptosis caused by carboplatin. The results of our study provide molecular evidence that L-carnitine prevents carboplatin-mediated apoptosis through AMPK-mediated PPARα activation.     

Suppressive Role of PPARγ-Regulated Endothelial Nitric Oxide Synthase in Adipocyte Lipolysis

Introduction

Metabolic syndrome causes insulin resistance and is associated with risk factor clustering, thereby increasing the risk of atherosclerosis. Recently, endothelial nitric oxide synthase deficient (eNOS-/-) mice have been reported to show metabolic disorders. Interestingly, eNOS has also been reported to be expressed in non-endothelial cells including adipocytes, but the functions of eNOS in adipocytes remain unclear.

Methods and Results

The eNOS expression was induced with adipocyte differentiation and inhibition of eNOS/NO enhanced lipolysis in vitro and in vivo. Furthermore, the administration of a high fat diet (HFD) was able to induce non-alcoholic steatohepatitis (NASH) in eNOS-/- mice but not in wild type mice. A PPARγ antagonist increased eNOS expression in adipocytes and suppressed HFD-induced fatty liver changes.

Conclusions

eNOS-/- mice induce NASH development, and these findings provide new insights into the therapeutic approach for fatty liver disease and related disorders.     

Phosphorylation State,Solubility, and Activity of Calcium/Calmodulin-Dependent Protein Kinase IIα in Transient Focal Ischemia in Mouse Brain

During and after middle cerebral artery occlusion in mice, CaMKII protein was irreversibly translocated from the soluble to the Triton X-100–nonsoluble fraction. This decrease in solubility had a strong effect on activity: CaMKII was almost completely inactivated after being translocated. Results from solubilization experiments suggest that different mechanisms underlie the conversion of CaMKII protein from a soluble to a detergent nonsoluble form in ischemic as opposite to nonischemic tissue. Analysis of the phosphorylation state of CaMKII revealed that in the total homogenate and the Triton X-100–nonsoluble fraction, CaMKII phosphorylated at only one site was the dominant phosphorylated form, whereas in the soluble fraction CaMKII phosphorylated at two sites was the predominant phosphorylated species. Investigation of the mechanisms underlying ischemia-induced changes in the solubility of CaMKII could help to elucidate processes triggered by transient focal cerebral ischemia that lead to neuronal cell injury.     

Effect of Baicalin on Matrix Metalloproteinase-9 Expression and Blood–Brain Barrier Permeability Following Focal Cerebral Ischemia in Rats

Focal cerebral ischemia results in an increased expression of matrix metalloproteinase-9 (MMP-9), which induces vasogenic brain edema via disrupting the blood–brain barrier (BBB) integrity. Recent studies from our laboratory showed that baicalin reduces ischemic brain damage by inhibiting inflammatory reaction and neuronal apoptosis in a rat model of focal cerebral ischemia. In the present study, we first explored the effect of baicalin on the neuronal damage, brain edema and BBB permeability, then further investigated its potential mechanisms. Sprague–Dawley rats underwent permanent middle cerebral artery occlusion (MCAO). Baicalin was administrated by intraperitoneally injected twice at 2 and 12 h after the onset of MCAO. Neuronal damage, brain edema and BBB permeability were measured 24 h following MCAO. Expression of MMP-9 protein and mRNA were determined by western blot and RT–PCR, respectively. Expression of tight junction protein (TJP) occludin was detected by western blot. Neuronal damage, brain edema and BBB permeability were significantly reduced by baicalin administration following focal cerebral ischemia. Elevated expression of MMP-9 protein and mRNA were significantly down-regulated by baicalin administration. In addition, MCAO caused the decreased expression of occludin, which was significantly up-regulated by baicalin administration. Our study suggested that baicalin reduces MCAO-induced neuronal damage, brain edema and BBB permeability, which might be associated with the inhibition of MMP-9 expression and MMP-9-mediated occludin degradation.     

Stimulation of the α7 Nicotinic Acetylcholine Receptor Protects against Neuroinflammation after Tibia Fracture and Endotoxemia in Mice

Surgery and critical illness often associate with cognitive decline. Surgical trauma or infection can lead independently to learning and memory impairments via similar, but not identical, cellular signaling of the innate immune system that promotes neuroinflammation. In this study we explored the putative synergism between aseptic orthopedic surgery and infection, the latter reproduced by postoperative lipopolysaccharide (LPS) administration. We observed that surgery and LPS augmented systemic inflammation up to postoperative d 3 and this was associated with further neuroinflammation (CD11b and CD68 immunoreactivity) in the hippocampus in mice compared with those receiving surgery or LPS alone. Administration of a selective α7 subtype nicotinic acetylcholine receptor (α7 nAChR) agonist 2 h after LPS significantly improved neuroinflammation and hippocampal-dependent memory dysfunction. Modulation of nuclear factor-kappa B (NF-κB) activation in monocytes and regulation of the oxidative stress response through nicotinamide adenine dinucleotide phosphate (NADPH) signaling appear to be key targets in modulating this response. Overall, these results suggest that it may be conceivable to limit and possibly prevent postoperative complications, including cognitive decline and/or infections, through stimulation of the cholinergic antiinflammatory pathway.     

DC260126: A Small-Molecule Antagonist of GPR40 that Protects against Pancreatic β-Cells Dysfunction in db/db Mice

G protein-coupled receptor 40 (GPR40) mediates both acute and chronic effects of free fatty acids (FFAs) on insulin secretion. However, it remains controversial whether inhibition of GPR40 would be beneficial in prevention of type 2 diabetes. This study is designed to evaluate the potential effects of DC260126, a small molecule antagonist of GPR40, on β-cell function following administration of 10 mg/kg dose of DC260126 to obese diabetic db/db mice. Oral glucose tolerance test, glucose stimulated insulin secretion and insulin tolerance test were used to investigate the pharmacological effects of DC260126 on db/db mice after 21-days treatment. Immunohistochemistry and serum biochemical analysis were also performed in this study. Although no significant change of blood glucose levels was found in DC260126-treated mice, DC260126 significantly inhibited glucose stimulated insulin secretion, reduced blood insulin level and improved insulin sensitivity after 3 weeks administration in db/db mice. Moreover, DC260126 reduced the proinsulin/insulin ratio and the apoptotic rate of pancreatic β-cells remarkably in DC260126-treated db/db mice compared to vehicle-treated mice (p<0.05, n = 8). The results suggest that although DC260126 could not provide benefit for improving hyperglycemia, it could protect against pancreatic β-cells dysfunction through reducing overload of β-cells, and it increases insulin sensitivity possibly via alleviation of hyperinsulinemia in db/db mice.