Brain Cyclooxygenase Research Articles

Minocycline reduced Cyclooxygenase-2 (COX-2) expression in Lipopolysaccharide (LPS)-induced neuroinflammation rat model

Lipopolysaccharide (LPS) was used to induce neuroinflammation in rats and the expression of brain cyclooxygenase-2 (COX-2) is the marker for the neuroinflammation process [1]. The effect of minocycline on neuroinflammation-induced LPS is not clearly elucidated.
 
 The objective of this study was to determine the effects of minocycline (MIN) on LPS-induced COX-2 expression and compared it with a clinically approved drug for Alzheimer’s disease named memantine. A total of fifty male Sprague Dawly rats were divided into five groups (n=10): (i) control, (ii) LPS, (iii) LPS-treated with minocycline 25 mg/kg, (iv) LPS-treated with minocycline 50 mg/kg, and (v) LPS-treated with memantine 10 mg/kg. Minocycline and memantine treatments were administered intraperitoneally once daily for 2 weeks and LPS (5 mg/kg) was injected once on day 5. Immunohistochemistry and Western blot for COX-2 protein were performed to measure its expression and level in the hippocampus and cortex. 
 Results showed LPS significantly increased COX-2 expression and its level in the hippocampus and cortex compared to other groups (p<0.05). Minocycline treatment, dependent on dose, reduced COX-2 expression and its level (p<0.05) comparable to the memantine effect (Figure 1).

Ergosta-7,9(11),22-trien-3β-ol Alleviates Intracerebral Hemorrhage-Induced Brain Injury and BV-2 Microglial Activation.

Intracerebral hemorrhage (ICH) is a devastating neurological disorder characterized by an exacerbation of neuroinflammation and neuronal injury, for which few effective therapies are available at present. Inhibition of excessive neuroglial activation has been reported to alleviate ICH-related brain injuries. In the present study, the anti-ICH activity and microglial mechanism of ergosta-7,9(11),22-trien-3β-ol (EK100), a bioactive ingredient from Asian medicinal herb Antrodia camphorate, were evaluated. Post-treatment of EK100 significantly attenuated neurobehavioral deficit and MRI-related brain lesion in the mice model of collagenase-induced ICH. Additionally, EK100 alleviated the inducible expression of cyclooxygenase (COX)-2 and the activity of matrix metalloproteinase (MMP)-9 in the ipsilateral brain regions. Consistently, it was shown that EK100 concentration-dependently inhibited the expression of COX-2 protein in Toll-like receptor (TLR)-4 activator lipopolysaccharide (LPS)-activated microglial BV-2 and primary microglial cells. Furthermore, the production of microglial prostaglandin E2 and reactive oxygen species were attenuated by EK100. EK100 also attenuated the induction of astrocytic MMP-9 activation. Among several signaling pathways, EK100 significantly and concentration-dependently inhibited activation of c-Jun N-terminal kinase (JNK) MAPK in LPS-activated microglial BV-2 cells. Consistently, ipsilateral JNK activation was markedly inhibited by post-ICH-treated EK100 in vivo. In conclusion, EK100 exerted the inhibitory actions on microglial JNK activation, and attenuated brain COX-2 expression, MMP-9 activation, and brain injuries in the mice ICH model. Thus, EK100 may be proposed and employed as a potential therapeutic agent for ICH.

Rifampicin ameliorates lipopolysaccharide-induced cognitive and motor impairments via inhibition of the TLR4/MyD88/NF-κB signaling pathway in mice

ABSTRACT Objectives Aberrant microglial responses promote neuroinflammation in neurodegenerative diseases. However, rifampicin’s effect on cognitive and motor sequelae of inflammation remains unknown. Therefore, we investigated whether rifampicin exerts neuroprotection against lipopolysaccharide (LPS)-induced cognitive and motor impairments. Methods A mouse model of LPS-induced cognitive and motor impairment was established. Adult C57BL/6 mice were injected intraperitoneally with 25 mg/kg rifampicin 30 min before intraperitoneal microinjection of LPS (750 μg/kg) daily until study end. Treatments and behavioral experiments were performed once daily for 7 days. Behavioral tests and pathological/biochemical assays were performed to evaluate LPS-induced damage to the hippocampus and substantia nigra (SN). Results Rifampicin attenuated LPS-induced cognitive and motor impairments, based on performance in the behavioral tests. Rifampicin suppressed the release of pro-inflammatory mediators, including tumor necrosis factor-α, interleukin-1β, and prostaglandin E2 in the serum and nitric oxide (NO) in brain tissue, and cyclooxygenase-2 and inducible nitric oxide synthase levels. Immunofluorescence revealed that rifampicin inhibited LPS-induced microglial activation in the hippocampus and SN, thus protecting the neurons. Rifampicin inhibited the activation of the toll-like receptor 4 (TLR4)/myeloid differentiation primary response 88 (MyD88)/nuclear factor kappa B (NF-κB) signaling pathway. Rifampicin downregulated TLR4 and MyD88 protein levels and inhibited NF-κB inhibitor alpha and NF-κB inhibitor kinase beta phosphorylation, thus reducing p65 nuclear transfer by inhibiting NF-κB signaling activation in LPS-treated mice. Conclusion Rifampicin protects against LPS-induced neuroinflammation and attenuates cognitive and motor impairments by inhibiting the TLR4/MyD88/NF-κB signaling pathway. Our findings might aid the development of novel therapies to treat progressive neurodegenerative diseases.

Paracetamol analogues conjugated by FAAH induce TRPV1-mediated antinociception without causing acute liver toxicity.

Paracetamol, one of the most widely used pain-relieving drugs, is deacetylated to 4-aminophenol (4-AP) that undergoes fatty acid amide hydrolase (FAAH)-dependent biotransformation into N-arachidonoylphenolamine (AM404), which mediates TRPV1-dependent antinociception in the brain of rodents. However, paracetamol is also converted to the liver-toxic metabolite N-acetyl-p-benzoquinone imine already at therapeutic doses, urging for safer paracetamol analogues. Primary amine analogues with chemical structures similar to paracetamol were evaluated for their propensity to undergo FAAH-dependent N-arachidonoyl conjugation into TRPV1 activators both invitro and invivo in rodents. The antinociceptive and antipyretic activity of paracetamol and primary amine analogues was examined with regard to FAAH and TRPV1 as well as if these analogues produced acute liver toxicity. 5-Amino-2-methoxyphenol (2) and 5-aminoindazole (3) displayed efficient target protein interactions with a dose-dependent antinociceptive effect in the mice formalin test, which in the second phase was dependent on FAAH and TRPV1. No hepatotoxicity of the FAAH substrates transformed into TRPV1 activators was observed. While paracetamol attenuates pyrexia via inhibition of brain cyclooxygenase, its antinociceptive FAAH substrate 4-AP was not antipyretic, suggesting separate mechanisms for the antipyretic and antinociceptive effect of paracetamol. Furthermore, compound 3 reduced fever without a brain cyclooxygenase inhibitory action. The data support our view that analgesics and antipyretics without liver toxicity can be derived from paracetamol. Thus, research into the molecular actions of paracetamol could pave the way for the discovery of analgesics and antipyretics with a better benefit-to-risk ratio.

Effect of doxycycline and meloxicam on cytokines, brain-derived neurotrophic factor, matrix metalloproteinase-3, tissue inhibitor of metalloproteinase-3 and cyclooxygenase-2 in brain.

Objective(s):Prevention of inflammation in early stages will be useful in maintaining vitality of the organism. The objective of this study was to evaluate the effects of doxycycline (DOX) or meloxicam (MLX) monotherapy and combination therapy on the levels of inflammatory mediators in the brain tissues of rats with Escherichia coli lipopolysaccharide (LPS)-induced brain inflammation.Materials and Methods:Seventy-eight rats were divided into the following groups: control (n=6), LPS (0.5 μg/10 μl intracranial) (n=18), LPS (0.5 μg/10 μl intracranial)+DOX (40 mg/kg intraperitoneal) (n=18), LPS (0.5 μg/10 μl intracranial)+MLX (2 mg/kg intraperitoneal) (n=18) and LPS (0.5 μg/10 μl intracranial)+DOX (40 mg/kg intraperitoneal)+MLX (2 mg/kg intraperitoneal) (n=18) groups. Brain tissues were harvested from all rats in the control group and from six rats each in the four experimental groups at 1, 3 and 6 hr under anaesthesia. The levels of tumor necrosis factor α (TNFα), interleukin 4 (IL-4), IL-6, IL-10, IL-17, brain-derived neurotrophic factor (BDNF), matrix metalloproteinase 3 (MMP-3), tissue inhibitor of metalloproteinase 3 (TIMP-3) and cyclooxygenase 2 (COX-2) in the brain tissues were measured using ELISA kits with ELISA device.Results: LPS administration increased proinflammatory cytokines (TNF, IL-6, IL-17), and MMP-3 levels and decreased anti-inflammatory cytokines (IL-10, IL-4), and BDNF levels. The lowest TNFα levels were detected in the LPS+MLX group (P<0.05). All the drug treatment groups showed decreased IL-17 and COX-2 levels compared to the LPS groups.Conclusion:DOX or MLX monotherapy exerts neuroprotective effects against brain inflammation by decreasing proinflammatory cytokine levels and by increasing anti-inflammatory cytokines levels.

The Role of Brain Cyclooxygenase-2 (Cox-2) Beyond Neuroinflammation: Neuronal Homeostasis in Memory and Anxiety.

Cyclooxygenases are a group of heme-containing isozymes (namely Cox-1 and Cox-2) that catalyze the conversion of arachidonic acid to largely bioactive prostaglandins (PGs). Cox-1 is the ubiquitous housekeeping enzyme, and the mitogen-inducible Cox-2 is activated to cause inflammation. Interestingly, Cox-2 is constitutively expressed in the brain at the postsynaptic dendrites and excitatory terminals of the cortical and spinal cord neurons. Neuronal Cox-2 is activated in response to synaptic excitation to yield PGE2, the predominant Cox-2 metabolite in the brain, which in turn stimulates the release of glutamate and neuronal firing in a retrograde fashion. Cox-2 is also engaged in the metabolism of new endocannabinoids from 2-arachidonoyl-glycerol to modulate their actions at presynaptic terminals. In addition to these interactions, the induction of neuronal Cox-2 is coupled to the trans-synaptic activation of the dopaminergic mesolimbic system and some serotoninergic receptors, which might contribute to the development of emotional behavior. Although much of the focus regarding the induction of Cox-2 in the brain has been centered on neuroinflammation-related neurodegenerative and psychiatric disorders, some evidence also suggests that Cox-2 release during neuronal signaling may be pivotal for the fine tuning of cortical networks to regulate behavior. This review compiles the evidence supporting the homeostatic role of neuronal Cox-2 in synaptic transmission and plasticity, since neuroinflammation is originally triggered by the induction of glial Cox-2 expression. The goal is to provide perspective on the roles of Cox-2 beyond neuroinflammation, such as those played in memory and anxiety, and whose evidence is still scant.

Propofol Reduces Inflammatory Brain Injury after Subarachnoid Hemorrhage: Involvement of PI3K/Akt Pathway

Background: Our previous study showed that propofol, one of the widely used anesthetic agents, can attenuate subarachnoid hemorrhage (SAH)-induced early brain injury (EBI) via inhibiting inflammatory and oxidative reaction. However, it is perplexing whether propofol attenuates inflammatory and oxidative reaction through modulating PI3K/Akt pathway. The present study investigated whether PI3K/Akt pathway is involved in propofol's anti-inflammation, antioxidation, and neuroprotection against SAH-induced EBI. Materials and methods: Adult Sprague-Dawley rats underwent SAH and received treatment with propofol or vehicle after 2 and 12 hours of SAH. LY294002 was injected intracerebroventricularly to selectively inhibit PI3K/Akt signaling. Mortality, SAH grading, neurological scores, brain water content, evans blue extravasation, myeloperoxidase, malondialdehyde, superoxide dismutase, and glutathione peroxidase were measured 24 hours after SAH. Immunoreactivity of p-Akt, t-Akt, nuclear factor- kappa B (NF-κB) p65, nuclear factor erythroid-related factor 2 (Nrf2), NAD(P)H:quinone oxidoreductase (NQO1), and cyclooxygenase-2 (COX-2) in rat brain was determined by western blot. Tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in rat brain were examined by ELISA. Results: Propofol significantly reduces neurological dysfunction, BBB permeability, brain edema, inflammation, and oxidative stress, all of which were reversed by LY294002. Propofol significantly upregulates the immunoreactivity of p-Akt, Nrf2, and NQO1, all of which were abolished by LY294002. Propofol significantly downregulates the overexpression of NF-κB p65, COX-2, TNF-α, and IL-1β, all of which were inhibited by LY294002. Conclusion: These results suggest that propofol attenuates SAH-induced EBI by inhibiting inflammatory reaction and oxidative stress, which might be associated with the activation of PI3K/Akt signaling pathway.

Evaluation of urinary 8-hydroxy-2-deoxyguanosine level in experimental Alzheimer's disease: Impact of carvacrol nanoparticles.

The present study aimed to compare the effect of carvacrol essential oil and carvacrol nanoemulsion against experimental Alzheimer's (AD). Forty male albino rats were used and divided into four groups as follow: control, AlCl3 induced AD, carvacrol oil treated and carvacrol nanoemulsion treated groups. Brain nor-epinephrine, serotonin and dopamine were analyzed by high performance liquid chromatography (HPLC). Levels of brain Thiobarbituric acid-reactive substances (TBARS), Superoxide dismutase (SOD), reduced glutathione (GSH), cholinesterase, and advanced oxidation protein product (AOPP) were evaluated. Urinary 8-hydroxyguanosine (8-OHdG) level was evaluated by HPLC. Brain Cyclooxygenase 1 and 2 (COX 1and 2) were analyzed by immunohistochemistry. AD induced by AlCl3 in rats was depicted by the significant increase in the neurotransmitters levels which is accompanied with high degree of oxidative stress that was revealed in the elevated level of urinary 8-OHdG along with significant elevation in AOPP, TBARS, and cholinesterase levels and a significant decrease in SOD and GSH; these results are confirmed by immunohistochemistry analysis of COX 1 and 2. On the other hand, the treatment with carvacrol oil and carvacrol nanoemulsion were capable of mitigate effects mediated by AlCl3 administration in treated rats. While the treatment with both approached succeeded to retract the negative impact of AlCl3; but the effect of carvacrol nanoemulsion was more notable than the essential oil. Carvacrol oil and carvacrol nanoemulsion were eminent to overturn AlCl3 induced brain AD which could be imputed to antioxidant and anti-inflammatory capabilities of carvacrol to alter oxidative stress effect. In extension; carvacrol nanoemulsion were evident to give more effective and efficient way in carvacrol delivery to pass through blood brain barriers and ameliorate brain changes.

Methamphetamine-Induced Brain Injury and Alcohol Drinking.

A majority of methamphetamine (Meth) abusers also abuse alcohol but the neurochemical consequences of this co-abuse are unknown. Individually, alcohol and Meth cause inflammation and long-term alterations in dopamine and serotonin signaling within the brain. Experiments were conducted to identify if serial exposure to alcohol and Meth has neurochemical consequences that are greater than after either drug alone. Male Sprague Dawley rats voluntarily drank 10% ethanol (EtOH) every other day for 4weeks and were then exposed to a binge injection regimen of Meth (10mg/kg injected every 2h, for a total of 4 injections). EtOH drinking and preference increased over the 4weeks and caused inflammation evidenced by increases in serum and brain lipopolysaccharide (LPS) and brain cyclooxygenase-2 (COX-2) 24h after the last day of drinking. Meth alone depleted dopamine and serotonin in the striatum, as well as serotonin in the prefrontal cortex when measured 1week later. In contrast, EtOH drinking alone did not affect dopamine and serotonin content in the striatum and prefrontal cortex, but prior EtOH drinking followed by injections of Meth enhanced Meth-induced depletions of dopamine, serotonin, as well as dopamine and serotonin transporter immunoreactivities in a manner that was correlated with the degree of EtOH consumption. Cyclooxygenase inhibition by ketoprofen during EtOH drinking blocked the increases in LPS and COX-2 and the enhanced decreases in dopamine and serotonin produced by Meth. Therefore, prior EtOH drinking causes an increase in inflammatory mediators that mediate a synergistic interaction with Meth to cause an enhanced neurotoxicity.

Chicoric acid supplementation prevents systemic inflammation-induced memory impairment and amyloidogenesis via inhibition of NF-κB.

Chicoric acid (CA), a natural phenolic acid extracted from chicory and the echinacea (purple coneflower) plant (Echinacea purpurea), has been regarded as a nutraceutical that has powerful antioxidant and antiobesity activities. We investigated the inhibitory effects of CA on systemic inflammation-induced neuroinflammation, amyloidogenesis, and cognitive impairment. C57BL/6J mice were treated with 0.05% CA in the drinking water for 45 d. The mice were then treated by intraperitoneal injection of lipopolysaccharide (LPS). It was found that CA prevented LPS-induced memory impairment and neuronal loss through behavioral tests and histological examination. Furthermore, amyloidogenesis in the CNS was detected. The results showed that CA prevented LPS-induced increases in amyloid β (1-42 specific) (Aβ1-42) accumulation, levels of amyloid precursor protein, and neuronal β-secretase 1 (BACE1), as well as the equilibrium cholinergic system in mouse brain. Moreover, CA down-regulated LPS-induced glial overactivation by inhibiting the MAPK and NF-κB pathway. Consequently, CA reduced the levels of NF-κB transcriptionally regulated inflammatory mediators and cytokines such as iNOS, cyclooxygenase-2 (COX-2), IL-1β, and TNF-α in both mouse brain and BV2 microglial cells. These results demonstrated that CA alleviated memory impairment and amyloidogenesis triggered by LPS through suppressing NF-κB transcriptional pathway, suggesting that CA might be a plausible therapeutic intervention for neuroinflammation-related diseases such as Alzheimer disease.-Liu, Q., Chen, Y., Shen, C., Xiao, Y., Wang, Y., Liu, Z., Liu, X. Chicoric acid supplementation prevents systemic inflammation-induced memory impairment and amyloidogenesis via inhibition of NF-κB.

EPA or DHA enhanced oxidative stress and aging protein expression in brain of d-galactose treated mice

Background:Effects of eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) upon fatty acid composition, oxidative and inflammatory factors and aging proteins in brain of d-galactose (DG) treated aging mice were examined.Methods:Each fatty acid at 7 mg/kg BW/week was supplied for 8 weeks. Brain aging was induced by DG treatment (100 mg/kg body weight) via daily subcutaneous injection for 8 weeks.Results:DG, EPA and DHA treatments changed brain fatty acid composition. DG down-regulated brain Bcl-2 expression and up-regulated Bax expression. Compared with DG groups, EPA and DHA further enhanced Bax expression. DG decreased glutathione content, increased reactive oxygen species (ROS) and oxidized glutathione (GSSG) production, the intake of EPA or DHA caused greater ROS and GSSG formation. DG treatments up-regulated the protein expression of p47phox and gp91phox, and the intake of EPA or DHA led to greater p47phox and gp91phox expression. DG increased brain prostaglandin E2 (PGE2) levels, and cyclooxygenase (COX)-2 expression and activity, the intake of EPA or DHA reduced brain COX-2 activity and PGE2 formation. DG enhanced brain p53, p16 and p21 expression. EPA and DHA intake led to greater p21 expression, and EPA only caused greater p53 and p16 expression. Conclusion: These findings suggest that these two PUFAs have toxic effects toward aging brain.

Microglial activation induces neuronal death in Chandipura virus infection.

Neurotropic viruses induce neurodegeneration either directly by activating host death domains or indirectly through host immune response pathways. Chandipura Virus (CHPV) belonging to family Rhabdoviridae is ranked among the emerging pathogens of the Indian subcontinent. Previously we have reported that CHPV induces neurodegeneration albeit the root cause of this degeneration is still an open question. In this study we explored the role of microglia following CHPV infection. Phenotypic analysis of microglia through lectin and Iba-1 staining indicated cells were in an activated state post CHPV infection in cortical region of the infected mouse brain. Cytokine Bead Array (CBA) analysis revealed comparatively higher cytokine and chemokine levels in the same region. Increased level of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), Nitric Oxide (NO) and Reactive Oxygen species (ROS) in CHPV infected mouse brain indicated a strong inflammatory response to CHPV infection. Hence it was hypothesized through our analyses that this inflammatory response may stimulate the neuronal death following CHPV infection. In order to validate our hypothesis supernatant from CHPV infected microglial culture was used to infect neuronal cell line and primary neurons. This study confirmed the bystander killing of neurons due to activation of microglia post CHPV infection.

Isomeric methoxy analogs of nimesulide for development of brain cyclooxygense-2 (COX-2)-targeted imaging agents: Synthesis, in vitro COX-2-inhibitory potency, and cellular transport properties

Nimesulide analogs bearing a methoxy substituent either at the ortho-, meta- or para-position on the phenyl ring, were designed, synthesized, and evaluated for potential as radioligands for brain cyclooxygenase-2 (COX-2) imaging. The synthesis of nimesulide and regioisomeric methoxy analogs was based on the copper-mediated arylation of phenolic derivatives for the construction of diaryl ethers. These isomeric methoxy analogs displayed lipophilicity similar to that of nimesulide itself, as evidenced by their HPLC logP7.4 values. In vitro inhibition studies using a colorimetric COX (ovine) inhibitor-screening assay demonstrated that the para-methoxy substituted analog retains the inhibition ability and selectivity observed for parent nimesulide toward COX-2 enzyme, whereas the meta- and ortho-methoxy substituents detrimentally affected COX-2-inhibition activity, which was further supported by molecular docking studies. Bidirectional transport cellular studies using Caco-2 cell culture model in the presence of the P-glycoprotein (P-gp) inhibitor, verapamil, showed that P-gp did not have a significant effect on the efflux of the para-methoxy substituted analog. Further investigations using the radiolabeled form of the para-methoxy substituted analog is warranted for in vivo characterization.

Phenolic alkaloids from Menispermum dauricum reduce inflammatory reaction and ischemic brain damage in cerebral ischemia rats

Stroke is a debilitating disease for which limited therapeutic approaches are available currently. Thus, there is an urgent need for developing novel therapies for stroke. Inflammatory damage plays a pivotal, mainly detrimental role in cerebral ischemic pathogenesis and may represent a promising target for treatment. Phenolic alkaloids from Menispermum dauricum (PAMD) have gained growing appreciation for its beneficial biological effects through its anti-inflammatory property. Whether this protective effect applies to cerebral ischemic injury, we therefore investigated the potential neuroprotective role of PAMD and the underlying mechanisms. Cerebral ischemia in male Sprague–Dawley rats was induced by middle cerebral artery occlusion (MCAO) and PAMD was pre-administered intragastrically once daily for five consecutive days before surgery. The effect of the PAMD on the ethology and pathomorphology of the rats with MCAO were observed before and after treatment. Neurological deficit scores and morphological characteristic were measured after cerebral ischemia. The expression of intercellular adhesion molecule-1 (ICAM-1) and cyclooxygenase-2 (COX-2) in ischemic rat brain was determined by immunohistochemistry at 24, 48, and 72 h after cerebral ischemia. Compared with MCAO groups, PAMD noticeably improved neurological deficit at 24, 48, and 72 h after ischemic insult. Consistent with these results, our data also indicated that PAMD significantly downregulated the expression of ICAM-1 and COX-2 (P < 0.05). The results provided a neuroprotective effect of PAMD in cerebral ischemia and this effect was exerted by downregulating the expression of ICAM-1and COX-2. Our results demonstrated that PAMD reduced inflammatory reaction and brain damage in cerebral ischemia in rats. PAMD exerts neuroprotection against ischemic brain damage, which might be associated with the attenuation of inflammatory reaction and the inhibition of inflammatory genes.

Repetitive ischemic preconditioning attenuates inflammatory reaction and brain damage after focal cerebral ischemia in rats: involvement of PI3K/Akt and ERK1/2 signaling pathway.

Ischemic preconditioning (IPC) has been demonstrated to provide a neuroprotection against brain damage produced by focal cerebral ischemia. However, it is elusive whether ischemic preconditioning attenuates ischemic brain damage through modulating phosphatidylinositol 3-kinase/Akt (PI3K/Akt) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway. In the present study, we first explored the best scheme of repetitive ischemic preconditioning (RIPC) to protect rat brain against ischemic damage and then further investigated the underlying mechanisms in RIPC's neuroprotection. Adult male Sprague-Dawley rats underwent ischemic preconditioning or (and) middle cerebral artery occlusion (MCAO). LY294002 or (and) PD98059 were injected intracerebroventricularly to selectively inhibit the activation of PI3K/Akt or ERK1/2. Neurological deficit scores, cerebral infarct volume, and morphological characteristic were detected at corresponding time after cerebral ischemia. The enzymatic activity of myeloperoxidase (MPO) was measured 24h after cerebral ischemia. Expressions of p-Akt, t-Akt, p-ERK1/2, t-ERK1/2, nuclear factor-kappa B (NF-κB) p65, and cyclooxygenase-2 (COX-2) in ischemic brain were determined by Western blot. The release of tumor necrosis factor-α (TNF-α) in blood was examined by ELISA. In the various schemes of RIPC, IPC2 × 5min causes less neuronal damage in the cortex and subcortex of ischemic brain and provides an obvious alleviation of cerebral infarction and neurological deficit after lethal ischemia. IPC2 × 5min significantly reduces cerebral infarct volume, neurological deficit scores, and MPO activity; all of which were diminished by LY294002 or (and) PD98059. IPC2 × 5min significantly upregulates the expressions of p-Akt and p-ERK1/2, which were inhibited by LY294002 or (and) PD98059. IPC2 × 5min significantly downregulates the expressions of NF-κB p65 and COX-2 and attenuates the release of TNF-α; all of which were abolished by LY294002 or (and) PD98059. IPC2 × 5min is the best scheme of RIPC to protect rat brain against cerebral ischemia. IPC2 × 5min attenuates brain damage in rats subjected to lethal ischemia, and this neuroprotection is associated with inhibition of neuroinflammation through modulating PI3K/Akt and ERK1/2 signaling pathway.

Lithium and the other mood stabilizers effective in bipolar disorder target the rat brain arachidonic acid cascade.

This Review evaluates the arachidonic acid (AA, 20:4n-6) cascade hypothesis for the actions of lithium and other FDA-approved mood stabilizers in bipolar disorder (BD). The hypothesis is based on evidence in unanesthetized rats that chronically administered lithium, carbamazepine, valproate, or lamotrigine each downregulated brain AA metabolism, and it is consistent with reported upregulated AA cascade markers in post-mortem BD brain. In the rats, each mood stabilizer reduced AA turnover in brain phospholipids, cyclooxygenase-2 expression, and prostaglandin E2 concentration. Lithium and carbamazepine also reduced expression of cytosolic phospholipase A2 (cPLA2) IVA, which releases AA from membrane phospholipids, whereas valproate uncompetitively inhibited in vitro acyl-CoA synthetase-4, which recycles AA into phospholipid. Topiramate and gabapentin, proven ineffective in BD, changed rat brain AA metabolism minimally. On the other hand, the atypical antipsychotics olanzapine and clozapine, which show efficacy in BD, decreased rat brain AA metabolism by reducing plasma AA availability. Each of the four approved mood stabilizers also dampened brain AA signaling during glutamatergic NMDA and dopaminergic D2 receptor activation, while lithium enhanced the signal during cholinergic muscarinic receptor activation. In BD patients, such signaling effects might normalize the neurotransmission imbalance proposed to cause disease symptoms. Additionally, the antidepressants fluoxetine and imipramine, which tend to switch BD depression to mania, each increased AA turnover and cPLA2 IVA expression in rat brain, suggesting that brain AA metabolism is higher in BD mania than depression. The AA hypothesis for mood stabilizer action is consistent with reports that low-dose aspirin reduced morbidity in patients taking lithium, and that high n-3 and/or low n-6 polyunsaturated fatty acid diets, which in rats reduce brain AA metabolism, were effective in BD and migraine patients.

Arsenic reduces the antipyretic activity of paracetamol in rats: Modulation of brain COX-2 activity and CB1 receptor expression

We examined whether subacute arsenic exposure can reduce paracetamol-mediated antipyretic activity by affecting COX pathway and cannabinoid CB1 receptor regulation. Rats were preexposed to elemental arsenic (4ppm) as sodium arsenite through drinking water for 28 days. Next day pyrexia was induced with lipopolysaccharide and paracetamol's (200mg/kg, oral) antipyretic activity was assessed. The activities of COX-1 and COX-2, the levels of PGE2, TNF-α and IL-1β and expression of CB1 receptors were assessed in brain. Arsenic inhibited paracetamol-mediated antipyretic activity. COX-1 activity was not affected by any treatments. Paracetamol decreased COX-2 activity, levels of PGE2, TNF-α and IL-1β and caused up-regulation of CB1 receptors. Arsenic caused opposite effects on these parameters. In the arsenic-preexposed rats, paracetamol-mediated effects were attenuated, while CB1 receptor up-regulation was reversed to down-regulation. Results suggest that elevated COX-2 activity and reduced CB1 expression could be involved in the arsenic-mediated attenuation of the antipyretic activity of paracetamol.

POSSIBLE THERAPEUTIC ROLE OF &lt;I&gt;JASONIA CANDICANS&lt;/I&gt; AND &lt;I&gt;JASONIA MONTANA&lt;/I&gt; EXTRACTS IN THE REGRESSION OF ALZHEIMER’S DISEASE IN EXPERIMENTAL MODEL

The present article aimed to investigate the potent ial role of the ethanolic extracts of the aerial pa rts of Jasonia candicans and Jasonia montana in management of Alzheimer’s Disease (AD) in experimental model. Supplementation of drinking water AlCl 3 (0.3%) for 16 weeks induced AD in male rats with siginifcant increase in brain Acetylcholinesterase (AchE) activity, Tumour Necrosis Factor (TNF-α), Transforming Growth Factor β (TGF-β) and 8 hydroxydeoxyguanosine (8-OHdG) levels. AlCl3 supplementation produced significant decrease in Br ain insulin Like Growth Factor (IGF-1) and Derived Neurotrophic Factor (BDNF) levels as compared to the control values. Also, AlCl 3 supplementation caused significant decline in the expression levels of nuc leoporin P 62 (P 62 ) and a disintegrin and metalloproteinase 17 (ADAM 17) genes accompanied with significant elevation in the expression levels of brain cyclooxygenase (Cox-2) gene. Brain histopa thological examination of AD-induced rats showed formation of amyloid plaques in hippocampus and cerebrum. Oral administration of each of selected extract (150 mg/kg b.wt) in AD-induced rats daily f or 6 weeks resulted in significant decrease in brai n AchE activity, TNF-α, TGF-β and 8-OHdG levels. The treatment produced signific ant increase in brain IGF-1 and BDNF levels as compared to AD-induced rats. The treatment with these extracts could significantly increase the gene expression levels o f brain P 62 and ADAM17 accompanied with significant decrease in the expression levels of Cox-2 gene in the brain. Histopathological examination of brain tissue of the treated rats showed marked improvement in the morphological structure of the brain especially in the hippocampus and cerebrum areas. H igh content of terpenes, sesquiterpenes and flavonoids in the ethanolic extract of the selected plants may responsible for the anticholinesterase activity, anti-inflammatory action, antioxidant cap acity and neurotrophic effect as well as antiamyloidogenic potential of these extracts. These re sults suggest that these extracts may effectively ameliorate the inflammation and neurodegeneration characterizing AD. Thus, these extracts may have a therapeutic application in the treatment of Alzheim er’s disease.

The effect of picroside II on the expressions of AQP4, MMP9 and COX2 in cerebral ischemic injury in rats

The aim is to study the neuroprotective effect and optimize the therapeutic dose and time window of picrosede II by orthogonal test in cerebral ischemic injury in rats. The forebrain ischemia models of rats were established by bilateral common carotid artery occlusion (BCCAO) methods. The successful models were randomly grouped according to orthogonal experimental design and treated by injecting picroside II intraperitonenally with different therapeutic dose at different ischemic time. The contents of aquaporins 4 (AQP4), matrix metalloproteinases 9 (MMP 9) and cyclooxygenase 2 (COX2) in brain tissue were determined by enzyme linked immunosorbent assay to evaluate the therapeutic effect of picroside II on cerebral ischemic injury. The results indicated that the best therapeutic time window and dose of picroside II in cerebral ischemic injury should be 1) ischemia 1.5 h with 20 mg/kg body weight according to the content of AQP4; 2) ischemia 2.0 h with 20 mg/kg according to the content of MMP9; and 3) ischemia 1.5 h with 20 mg/kg according to the content of COX2 inbrain tissue. It is concluded that the optimized therapeutic dose and time window is injecting picroside II peritonenally with 10 - 20 mg/kg body weight at ischemia 1.5 - 2.0 h in cerebral ischemic injury according to the principle of lowest therapeutic dose with longest time window.

Chronic clozapine reduces rat brain arachidonic acid metabolism by reducing plasma arachidonic acid availability

Chronic administration of mood stabilizers to rats down-regulates the brain arachidonic acid (AA) cascade. This down-regulation may explain their efficacy against bipolar disorder (BD), in which brain AA cascade markers are elevated. The atypical antipsychotics, olanzapine (OLZ) and clozapine (CLZ), also act against BD. When given to rats, both reduce brain cyclooxygenase activity and prostaglandin E(2) concentration; OLZ also reduces rat plasma unesterified and esterified AA concentrations, and AA incorporation and turnover in brain phospholipid. To test whether CLZ produces similar changes, we used our in vivo fatty acid method in rats given 10 mg/kg/day i.p. CLZ, or vehicle, for 30 days; or 1 day after CLZ washout. [1-(14) C]AA was infused intravenously for 5 min, arterial plasma was collected and high-energy microwaved brain was analyzed. CLZ increased incorporation coefficients ki * and decreased [corrected] rates J(in,i) of plasma unesterified AA into brain phospholipids. [corrected]. These effects disappeared after washout. Thus, CLZ and OLZ similarly down-regulated kinetics and cyclooxygenase expression of the brain AA cascade, likely by reducing plasma unesterified AA availability. Atypical antipsychotics and mood stabilizers may be therapeutic in BD by down-regulating, indirectly or directly respectively, the elevated brain AA cascade of that disease.