Possible interaction of central noradrenergic, serotoninergic and oxytocin systems with nesfatin-1 induced hypophagia and feeding behavior in newborn broiler.

There are some differences between mammals and birds in terms of central food intake regulation. In avian species, the hypophagic role of nesfatin-1 has not been investigated with other neurotransmitters. Therefore, this study aimed to determine the alteration of feeding behavior following intracerebroventricular (ICV) injection of nesfatin-1 and its possible interaction with central noradrenergic, serotoninergic, and oxytocin systems in newborn broiler chicks. In experiment 1, birds received ICV injection of phosphate-buffered saline (PBS), prazosin (α1 receptors antagonist, 10 nmol), nesfatin-1 (40 ng), and co-administration of prazosin and nesfatin-1. Experiments 2-10 were similar to experiment 1, except that yohimbine (α2 receptors antagonist, 13 nmol), metoprolol (ß1 receptors antagonist, 24 nmol), IC1118,551 (ß2 receptors antagonist for, 5nmol), SR59230R (ß3 receptors antagonist, 20 nmol), fluoxetine (serotonin reuptake inhibitor, 10 µg), PCPA (serotonin synthesis inhibitor, 1.5 µg), 8-OH-DPAT (5-HT1A receptors agonist, 15.25 nmol), SB242084 (5-HT2C receptors antagonist,1.5 µg) and tocinoic acid (oxytocin receptors antagonist, 2 µg) were injected instead of prazosin. Immediately after the injection, food consumption and behavioral traits were recorded. Nesfatin-1 decreased food consumption (P < 0.05). Nesfatin-1 along with ICI118551 decreased food consumption (P < 0.05). The nesfatin-1- induced hypophagia were reduced by the simultaneous injection of PCPA and nesfatin-1 (P < 0.05). Nesfatin-1induced hypophagia were decreased by the simultaneous injection of SB242084 (P < 0.05). The nesfatin-1 -induced hypophagia were abolished by the simultaneous injection of the tocinoic acid and nesfatin-1 (P < 0.05). ICV injection of the nesfatin-1 decreased the number of steps, jumps, exploratory food, and pecks (P < 0.05) with no effect on drink pecks (P > 0.05). Nesfatin-1 significantly decreased standing time and increased both sitting time and rest time (P < 0.05). Nesfatin-1 could play an important role in feeding behavior, and its hypophagic effects were mediated by ß2 adrenergic, 5-HT2C serotoninergic, and oxytocin receptors in neonatal chickens.

Neuroprotective effect of alpha-pinene is mediated by suppression of the TNF-α/NF-κB pathway in Alzheimer's disease rat model.

Monoterpene alpha-pinene possesses antioxidant, cardioprotective, and neuroprotective properties. We evaluated the effect of alpha-pinene on oxidative/nitrosative stress, neuroinflammation, and molecular and behavioral changes induced by beta-amyloid (Aß)1-42 in rats and investigated the possible mechanisms of these outcomes. Male Wistar rats received alpha-pinene (50 mg/kg intraperitoneally) for 14 consecutive days after intrahippocampal injection of Aß1-42 . Alpha-pinene decreased malondialdehyde and nitric oxide levels, increased glutathione content, and enhanced catalase activity in Aß-injected rats. Also, messenger RNA expression of tumor necrosis factor-α, interleukin-1ß, interleukin-6, nuclear factor κB, and N-methyl- d-aspartate receptor subunits 2A and 2B reduced in the hippocampus of these animals. Besides this, alpha-pinene repressed the Aß1-42 -induced reduction of nicotinic acetylcholine receptor α7 subunit and brain-derived neurotrophic factor expression. Treatment with alpha-pinene caused Aß-receiving rats to spend more time in the target quadrant in the Morris water maze test and led to an increase in percentages of open arm entrance and time spent in the open arm in the elevated plus-maze test. We concluded that alpha-pinene strengthens the antioxidant system and prevents neuroinflammation in the hippocampus of rats receiving Aß. It improves spatial learning and memory and reduces anxiety-like behavior in these animals. Consequently, alpha-pinene alleviates Aß-induced oxidative/nitrosative stress, neuroinflammation, and behavioral deficits. It is probably a suitable candidate for the treatment of neurodegenerative diseases.

Mediatory role of the central NPY, melanocortine and corticotrophin systems on phoenixin-14 induced hyperphagia in neonatal chicken.

Animal research indicates the neuropeptide Y (NPY), corticotrophin and melanocortin systems have a mediatory role in reward, however, how these substances interact with phenytoin-14 (PNX-14) induced food intake in birds remains to be identified. Accordingly, in this research eight tests were carried out to investigate the potential interactions of the NPY, melanocortin, as well as corticotrophin systems with PNX-14 on food consumption in neonatal chickens. In the first experiment, chickens were intracerebroventricular (ICV) injected with phosphate-buffered saline (PBS) and PNX-14 (0.8, 0.16, and 3.2 nmol). In second experiment, PBS, the antagonist of CRF1/CRF2 receptors (astressin-B, 30 µg) and PNX-14 + astressin-B were injected. In the rest of the experiments chicken received astressin2-B (CRF2 receptor antagonist; 30 µg), SHU9119 (MCR3/MCR4 receptor antagonist, 0.5nomol), MCL0020 (MCR4 receptor agonist, 0.5 nmol), B5063 (NPY1 receptor antagonist, 1.25 µg), SF22 (NPY2 receptor antagonist, 1.25 µg) and SML0891 (NPY5 receptor antagonist, 1.25 µg) rather than astressin-B. Then, cumulative intake of food was recorded for 2 h. Based on the findings, PNX-14 (0.16 and 3.2 nmol) led to increment in food consumption compared with the control (P < 0.05). Co-administration of the PNX-14 and astressin-B promoted PNX-14-induced hyperphagia (P < 0.05). Co-injection of the PNX-14 + astressin2-B potentiated hyperphagia PNX-14 (P < 0.05). Co-injection of PNX-14 + B5063 inhibited the effects of the PNX-14 (P < 0.05). The co-administration of the PNX-14 and SML0891 potentiated hypophagic effects of the PNX-14 (P < 0.05). The results showed that PNX-14-induced hyperphagia mediates via NPY1, NPY5, and CRF1/CRF2 receptors in neonatal chickens.

Viola tricolor Hydroalcoholic Extract Improves Behavioral Deficiencies in Rats Exposed to Chronic Immobilization Stress

Abstract This study aims to investigate the effect of Viola tricolor extract on hippocampal neuronal death, interleukin (IL) -6 and IL-10 expression, spatial memory, anxiety, and depression in rats exposed to chronic immobilization stress. Rats were divided into groups Control, Viola300, Viola600, Stress, Stress-Viola300, and Stress-Viola600. Animals were placed in a restrainer (6 h / 21 days) to stress exposure. V. tricolor hydro-alcoholic extract was also administrated at doses of 300 and 600 mg/kg by gavage. The extract caused immobilized animals to spend more time in the target quadrant in the Morris water maze test. It also increased the percentage of entries into the open arm and the percentage of time spent in the open arm of the elevated plus-maze in immobilized rats. Treatment with the V. tricolor extract significantly reduced the immobility time of stressed rats in the forced swimming test. Furthermore, it significantly reduced neuronal death and expression of IL-6 in the hippocampus of immobilized animals but could not prevent the decrease of IL-10 expression. We concluded that V. tricolor protects rats from stress-induced behavioral damages, at least in part, by suppressing neuronal death and decreasing IL-6 expression.

Morin attenuates memory deficits in a rat model of Alzheimer's disease by ameliorating oxidative stress and neuroinflammation.

This study aimed to investigate the effect of flavonoid morin on oxidative/nitrosative stress, neuroinflammation, and histological, molecular, and behavioral changes caused by amyloid-beta (Aß)1-42 in male Wistar rats (Alzheimer's disease model). Rats received morin (20 mg/kg, oral gavage) for 14 consecutive days after intrahippocampal injection of Aß1-42. Morin decreased the levels of malondialdehyde and nitric oxide, increased glutathione content, and enhanced catalase activity in the hippocampus of animals receiving Aß1-42. It also reduced the expression of tumor necrosis factor-α, interleukin-1ß, interleukin-6, nuclear factor-kappa B, and N-methyl-D-aspartate receptor subunits 2A and 2B and increased the expression of brain-derived neurotrophic factor and α7 nicotinic acetylcholine receptor in the hippocampus of Aß1-42-injected rats. Besides, morin modified neuronal loss and histological changes in the CA1 region of the hippocampus. Morin allowed Aß1-42-infused rats to swim more time in the target quadrant in the Morris water maze test. It is concluded that morin may be suitable for the prevention and treatment of Alzheimer's disease by strengthening the antioxidant system, inhibiting neuroinflammation, preventing neuronal death, and enhancing memory function.

Neuroprotective Effects of Normobaric Hyperoxia and Transplantation of Encapsulated Choroid Plexus Epithelial Cells on The Focal Brain Ischemia.

OBJECTIVE: Choroid plexus epithelial cells (CPECs) have the epithelial characteristic, produce cerebrospinal fluid, contribute to the detoxification process in the central nervous system (CNS), and are responsible for the synthesis and release of many nerve growth factors. On the other hand, studies suggest that normobaric hyperoxia (HO) by induction of ischemic tolerance (IT) can protect against brain damage and neurological diseases. We examined the effect of combination therapy of encapsulated CPECs and HO to protect against ischemic brain injury. MATERIALS AND METHODS: In this experimental study, six groups of adult male Wistar rats were randomly organized: sham, room air (RA)+middle cerebral artery occlusion (MCAO), HO+MCAO, RA+MCAO+encapsulated CPECs, HO+MCAO+encapsulated CPECs, RA+MCAO+empty capsules. RA/HO were pretreatment. The CPECs were isolated from the brain of neonatal Wistar rats, cultured, and encapsulated. Then microencapsulated CPECs were transplanted in the neck of the animal immediately after the onset of reperfusion in adult rats that had been exposed to 60 minutes MCAO. After 23 hours of reperfusion, the neurologic deficit score (NDS) was assessed. Next, rats were killed, and brains were isolated for measuring brain infarction volume, blood-brain barrier (BBB) permeability, edema, the activity of superoxide dismutase (SOD), and catalase (CAT) and also, the level of malondialdehyde (MDA). RESULTS: Our results showed that NDS decreased equally in HO+MCAO, RA+MCAO+encapsulated CPECs, and HO+MCAO+encapsulated CPECs groups. Brain infarction volume decreased up 79%, BBB stability increased, edema decreased, SOD and CAT activities increased, and MDA decreased in the combination group of HO and transplantation of encapsulated CPECs in the ischemic brain as compared with when HO or transplantation of encapsulated CPECs was applied alone. CONCLUSION: The combination of HO and transplantation of encapsulated CPECs for stroke in rats was more effective than the other treatments, and it can be taken into account as a promising treatment for ischemic stroke.

Protective effect of alpha-linoleic acid on Aß-induced oxidative stress, neuroinflammation, and memory impairment by alteration of α7 nAChR and NMDAR gene expression in the hippocampus of rats.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects many older people around the world. Numerous studies are underway to evaluate the protective effects of natural products in AD. Alpha-linoleic acid (ALA) is an essential unsaturated fatty acid that exhibits neuroprotective outcomes in rat models of ischemic stroke and Parkinson's disease. This research aimed to investigate the effect of ALA on oxidative stress, neuroinflammation, neuronal death, and memory deficit induced by amyloid-beta (Aß) peptide. After intrahippocampal injection of Aß1-42, rats received ALA (150 µg/kg, subcutaneously) for 14 consecutive days. ALA decreased the levels of malondialdehyde and nitric oxide, enhanced glutathione content, and increased the activity of catalase in the hippocampus of the rat model of AD. It also reduced the expression of tumor necrosis factor-α, interleukin-1ß, interleukin-6, nuclear factor-kappa B, and N-methyl-d-aspartate receptor subunits NR2A and NR2B mRNAs in the hippocampus, prevented the neuronal loss in the CA1 region, and enhanced the expression of α7 nicotinic acetylcholine receptor. In addition, ALA allowed Aß1-42-injected rats to spend less time and distance to reach the hidden platform in the Morris water maze test and to swim longer in the target quadrant. We concluded that ALA reduces the biochemical, molecular, histological, and behavioral changes caused by Aß1-42 and it may be an effective option for treating AD.

The Positive Effect of MiR1 Antagomir on Ischemic Neurological Disorders Via Changing the Expression of Bcl-w and Bad Genes.

INTRODUCTION: MicroRNAs (miRNAs or miRs) are non-coding RNAs. Studies have shown that miRNAs are expressed aberrantly in stroke. The miR1 enhances ischemic damage, and a previous study has demonstrated that reduction of miR1 level has a neuroprotective effect on the Middle Cerebral Artery Occlusion (MCAO). Since apoptosis is one of the important processes in neural protection, the possible effect of miR1 on this pathway has been tested in this study. Post-ischemic administration of miR1 antagomir reduces infarct volume via bcl-w and bad expression. METHODS: Rats were divided into four experimental groups: sham, control, positive control, and antagomir treatment group. One hour after MCAO surgery, the rats were received intravenously (Tail vein) 0.1 mL Normal Saline (NS), 0.1 mL rapamycin, and 300 pmol/g miR1 antagomir (soluble in 0.1 mL normal saline) in control, positive control, and treatment group, respectively. Twenty-four hours after reperfusion infarct volume was measured. The expression of miR1, bcl-w, and bad were analyzed using real-time PCR in sham, control, and treated groups. RESULTS: Our results indicate that administration of miR1 antagomir reduces infarct volume significantly, it also decreases miR1 and bad expression while increases bcl-w expression. CONCLUSION: Understanding the precise neuroprotective mechanism of miR1 antagomir can make it a proper treatment and an innovative approach for stroke therapy.

Effect of intravenous injection of antagomiR-1 on brain ischemia.

Stroke is one of the leading causes of death in the world, but the underlying molecular mechanism of this disease remains elusive, thus it will be great challenges to finding appropriate protection. MicroRNAs are short, single-stranded, non-coding RNAs and recent studies have shown that they are aberrantly expressed in ischemic condition. Due to the fact that miR-1 has harmful effects on neural damages during brain ischemia, limited miR-1 has been proven to be protective in middle cerebral artery occlusion (MCAO). Here, the possible positive effect of intravenous injection of antagomiR-1 as a post-ischemic treatment on neurological deficits, infarct volume, brain edema and blood-brain barrier (BBB) permeability was evaluated. The rats were divided randomly into three experimental groups, each with 21 animals. MCAO surgery was performed on all groups and one hour later, 0.1 ml normal saline, 0.1 ml rapamycin and 300 pmol/g miR-1 antagomir (soluble in 0.1 ml normal saline), were injected intravenously into control, positive control and treatment group, respectively. After 24 h, neurologic deficits score, infarct volume, brain edema and BBB permeability were measured. The results indicated that post-treatment with miR-1 antagomir significantly improved neurological deficits and reduced infarction volume, brain edema, and BBB permeability. These data proved that there is a positive effects of antagomiR-1 on ischemic neuronal injury and neurological impairment. Due to the fact that microRNAs are able to protect the brain, it would be a promising therapeutic approach to stroke treatment.

Protection of BALB/c mice against pathogenic Brucella abortus and Brucella melitensis by vaccination with recombinant Omp16.

OBJECTIVES: Prevention of the globally spread zoonotic infection, brucellosis which affects an extensive range of hosts is still challenging researchers. There are no approved vaccines for the prevention of human disease and those used for animal brucellosis have adverse properties, which limit their application. We investigated the immunological and protective effects of recombinant 16 kDa outer membrane protein of Brucella abortus (Omp16) which introduced a new candidate for brucellosis subunit vaccine. MATERIALS AND METHODS: Brucella Omp16 gene was cloned in pET-23a and expressed in Escherichia coli BL21 (DE3). Recombinant Omp16 (rOmp16) was purified using nickel resin and confirmed by Western blot analysis. BALB/c mice were immunized with rOmp16, afterward, specific serum antibodies and cytokine responses were evaluated. Protection of immunized mice against pathogenic B. abortus 544 and B. melitensis 16M was evaluated by the intraperitoneal bacterial challenge. RESULTS: Sequencing results of the recombinant plasmid vector along with Western blotting confirmed the cloning procedure. Recognition of rOmp16 by specific IgG from serum samples of infected cases suggests the stimulation of immune response to this protein. Significant total serum IgG along with remarkable IgG1 and IgG2a response to the protein was recorded. A significant increase in IFN-γ, and IL-4 levels were observed from splenocyte cultures of immunized mice which were stimulated with rOmp16 suggesting the development of T-lymphocyte mediated immunity against the recombinant antigen. CONCLUSION: The intraperitoneal challenge with B. abortus 544 and B. melitensis 16M confirmed that rOmp16 is able to elicit efficient protective immune responses in the animal host.

The Neuroprotective Effect of Rosemary (Rosmarinus officinalis L.) Hydro-alcoholic Extract on Cerebral Ischemic Tolerance in Experimental Stroke.

The prevention of BBB breakdown and the subsequent vasogenic edema are important parts of the medical management of ischemic stroke. The purpose of this study was to investigate the ischemic tolerance effect of Rosmarinus officinalis leaf hydro-alcoholic extract (RHE). Five groups of animals were designed: sham (underwent surgery without MCAO) and MCAO groups, the MCAO groups were pretreated orally by gavages with RHE (50, 75, and 100 mg/Kg/day), daily for 30 days. Two hours after the last dose, serum lipid levels were determined and then the rats were subjected to 60 min of middle cerebral artery occlusion followed by 24 h of reperfusion. Subsequently, brain infarct size, brain edema and Evans Blue dye extravasations were measured and neurological deficits were scored. Dietary RHE could significantly reduce cortical and sub-cortical infarct volumes (211.55 ± 24.88 mm3vs. 40.59 ± 10.04 mm3vs. 29.96 ± 12.19 mm3vs. 6.58 ± 3.2 mm3), neurologic deficit scores, cerebral edema (82.34 ± 0.42% vs. 79.92 ± 0.49% vs. 79.45 ± 0.26% vs. 79.30 ± 0.19%), blood-brain barrier (BBB) permeability (7.73 ± 0.4 µg/g tissue vs. 4.1 ± 0.23 µg/g tissue vs. 3.58 ± 0.3 µg/g tissue vs. 3.38 ± 0.25 µg/g tissue) in doses of 50, 75 and 100 mg/Kg/day as compared with the control group in the transient model of focal cerebral ischemia. Although pretreatment with RHE plays an important role in the generation of tolerance against cerebral I/R injury, further studies are needed to clarify the mechanism of the ischemic tolerance.

Synthesis, characterization and immunological properties of Escherichia coli 0157:H7 lipopolysaccharide- diphtheria toxoid conjugate vaccine.

BACKGROUND AND OBJECTIVE: Escherichia coli O157:H7, an emerging pathogen, causes severe enteritis and the extraintestinal complication of hemolytic-uremic syndrome. The goal of this study was to evaluate the conjugate of E. coli O157: H7 lipopolysaccharide (LPS) with diphtheria toxoid (DT) as a candidate vaccine in mice model. MATERIAL AND METHODS: LPS from E. coli O157:H7 was extracted by hot phenol method and then detoxified. Purified LPS was coupled to DT with adipic acid dihydrazide (ADH) as a spacer and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as a linker. The coupling molar ratio of LPS to DT was 3:1. Clinical evaluation of E. coli O157:H7 LPS-DT conjugate was also performed. RESULTS: The conjugate was devoid of endotoxin activity and indicated 0.125 U/ml of D-LPS. Mice immunization with D-LPS DT conjugate elicited fourfold higher IgG antibody in comparison to D-LPS. Also, in vivo protection of mice with conjugate provided high protection against the LD50 of E. coli O157:H7, which indicated a good correlation with the IgG titer. CONCLUSION: Our results showed that the suggested vaccine composed of E. coli O157:H7 LPS and DT had a significant potential to protect against E. coli infections.

Pseudomonas aeruginosa PAO-1 Lipopolysaccharide-Diphtheria Toxoid Conjugate Vaccine: Preparation, Characterization and Immunogenicity.

BACKGROUND: Treatment of Pseudomonas aeruginosa PAO-1 infections through immunological means has been proved to be efficient and protective. OBJECTIVES: The purpose of this study was to produce a conjugate vaccine composed of detoxified lipopolysaccharide (D-LPS) P. aeruginosa and diphtheria toxoid (DT). MATERIALS AND METHODS: Firstly, LPS was purified and characterized from P. aeruginosa PAO1 and then detoxified. D-LPS was covalently coupled to DT as a carrier protein via amidation method with adipic acid dihydrazide (ADH) as a spacer molecule and 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (EDAC) as a linker. The molar ratio of LPS to DT in the prepared conjugate was 3:1. The immunogenicity of D-LPS-DT conjugate vaccine in mice model was evaluated as well. RESULTS: The conjugate was devoid of endotoxin activity and 0.125 U/mL of D-LPS was acceptable for immunization. D-LPS-DT conjugate was nonpyrogenic for rabbits and nontoxic for mice. Mice immunization with D-LPS-DT conjugate vaccine elicited the fourfold higher IgG antibody compared to D-LPS. Anti-LPS IgG antibody was predominantly IgG1 subclass and then IgG3, IgG2a and IgG2b, respectively. CONCLUSIONS: Vaccine based on the conjugation of P. aeruginosa PAO-1 LPS with DT increased anti-LPS antibodies and had a significant potential to protect against Pseudomonas infections.

Immunogenicity comparison of conjugate vaccines composed of alginate and lipopolysaccharide of Pseudomonas aeruginosa bound to diphtheria toxoid.

BACKGROUND AND OBJECTIVES: Treatment of Pseudomonas aeruginosa infections is greatly hampered by innate and acquired antibiotic resistance. The goal of this study was to compure the immunogenicity of conjugates of P. aeruginosa depolymerized alginate-diphtheria toxoid (D-ALGDT) and P. aeruginosa detoxified lipopolysaccharidediphtheria toxoid (D-LPSDT) in mouse model. MATERIALS AND METHODS: Alginate and LPS were purified from P. aeruginosa strain PAO1. The resulting depolymerized alginate (D-ALG) and detoxified LPS (D-LPS) were covalently coupled to diphtheria toxoid (DT) as a carrier protein with adipic acid dihydrazide (ADH) as a spacer molecule and carbodiimide as a linker. Sterility, safety and pyrogenicity tests were performed. 30 mice in two groups were immunized intraperitoneally on days 0, 14 and 28 with 10 µg of D-ALGDT and D-LPSDT. Conjugates specific antibody levels were also determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: The conjugates were non-toxic and non-pyrogenic. Conjugates of D-ALGDT and D-LPSDT were shown to be safe and to elicit total IgG, IgM, IgA, IgG1, IgG2a, IgG2b and IgG3 antibodies in mice. ELISA results indicated that antibodies titer of D-ALGDT was more than D-LPSDT. CONCLUSION: Immunization with D-ALGDT showed significant increase in all types of antibodies titers in versus D-LPSDT, suggesting D-ALGDT as a vaccine candidate against P. aeruginosa infections.

Activation of sphingosine 1-phosphate receptor-1 by SEW2871 improves cognitive function in Alzheimer's disease model rats.

Sphingosine-1 phosphate (S1P) is involved in a variety of cellular processes via activation of S1P receptors (S1PRs; S1PR1 to S1PR5) that are highly expressed in the brain. It has been shown that the level of S1P is reduced in the brain of Alzheimer's disease (AD) patients. However, there is no study designed to evaluate the expression of S1PRs in AD brains. The objectives of the present work are (1) to examine the expression of S1PR1-3 in the hippocampus of beta amyloid (Aß) 1-42 injected rats and (2) to clarify the effects of chronic S1PR1 activation on S1PR1-3 levels, spatial memory deficit and hippocampal damage in AD rats. SEW2871, the S1PR1 selective agonist, repeatedly was injected intraperitoneally during a period of two weeks. Upon Western Blot data bilateral intrahippocampal injection of Aß1-42 decreased the expression of S1PR1 while increased S1PR2 level and did not affect that of S1PR3. We found that chronic administration of SEW2871 inhibited the reduction of S1PR1 expression and ameliorated spatial memory impairment in the Morris water maze task in rats. In addition, SEW2871 attenuated the Aß1-42-induced hippocampal neuronal loss according to Nissl staining findings. Data in the current study highlights the importance of S1PR1 signaling pathway deregulation in AD development and suggests that activation of S1PR1 may represent a potential approach for developing new therapeutics to manage memory deficit and apoptosis associated with neurodegenerative disorders such as AD.

Preconditioning with sublethal ischemia or intermittent normobaric hyperoxia up-regulates glutamate transporters and tumor necrosis factor-alpha converting enzyme in the rat brain.

INTRODUCTION: Recent studies suggest that sublethal ischemia and intermittent normobaric hyperoxia (InHO) protect the brain from subsequent ischemic injury. In this, changes in the expression of excitatory amino-acid transporters (EAATs) and tumor necrosis factor-alpha converting enzyme (TACE) may play a role. We sought to identify and clarify the nature of any such changes. METHOD: Rats were divided into 3 experimental groups, each of 15 animals. The first group was exposed to normobaric hyperoxia (fractional inspired oxygen concentration 95%) for 4 hours/day for 6 consecutive days (InHO). The second group acted as controls, and was exposed to 21% oxygen in the same chamber (room air). The third group acted as a model of ischemic preconditioning, and was exposed to 21% oxygen in the same chamber and subjected to 10 minutes of temporary middle cerebral artery (MCA) occlusion (tMCAO). After 24 hours, 9 animals from each group were subjected to 60 minutes of right MCA occlusion (MCAO). After 24 hours of reperfusion, neurologic deficit score and infarct volume were assessed in MCAO-operated subgroups. The remaining 6 animals in each group remained intact and, 48 hours after pretreatment, were killed for assessment of EAATs and TACE expression in the ipsilateral hemisphere. RESULTS: Preconditioning with InHO and tMCAO decreased neurologic deficit score and infarct volume, and increased expression of EAAT1, EAAT2, EAAT3, and TACE. CONCLUSION: InHO and tMCAO are associated with expression of EAAT1, EAAT2, EAAT3, and TACE, consistent with an active role in the genesis of ischemic protection.