7-nitroindazole reduces nitrite concentration in rat brain after intrahippocampal kainate-induced seizure

The type 2 diabetes drug liraglutide reduces chronic inflammation induced by irradiation in the mouse brain

Chronic inflammation in the brain is found in a range of neurodegenerative diseases such as Parkinson's or Alzheimer's disease. We have recently shown that analogues of the glucagon-like polypeptide 1 (GLP-1) such as liraglutide have potent neuroprotective properties in a mouse model of Alzheimer's disease. We also found a reduction of activated microglia in the brain. This finding suggests that GLP-1 analogues such as liraglutide have anti-inflammatory properties. To further characterise this property, we tested the effects of liraglutide on the chronic inflammation response induced by exposure of the brain to 6 Gy (X-ray). Animals were injected i.p. with 25 nmol/kg once daily for 30 days. Brains were analysed for cytokine levels, activated microglia and astrocyte levels, and nitrite levels as a measure for nitric oxide production and protein expression of iNOS. Exposure of the brain to 6 Gy induced a pronounced chronic inflammation response in the brain. The activated microglia load in the cortex and dentate gyrus region of hippocampus (P<0.001), and the activated astrocyte load in the cortex (P<0.01) was reduced by liraglutide. Furthermore, the pro-inflammatory cytokine levels of IL-6 (P<0.01), IL-12p70 (P<0.01), IL-1β (P<0.05), and total nitrite concentration were reduced in the brains of animals treated with liraglutide. The results demonstrate that liraglutide is effective in reducing a number of parameters linked to the chronic inflammation response. Liraglutide or similar GLP-1 analogues may be a suitable treatment for reducing the chronic inflammatory response in the brain found in several neurodegenerative conditions.

Role of Lactobacillus acidophilus loaded floating beads in chronic fatigue syndrome: behavioral and biochemical evidences

BACKGROUND

  In recent years the interface between neuropsychiatry and gastroenterology has converged in to a new discipline referred to as enteric neuroscience. Implications of brain-gut communication in the pathogenesis of psychiatric disorders indicate a possible role of suitably packaged/delivered probiotics as newer therapeutic options. In the present study probable role of per-oral administration of free Lactobacillus acidophilus (LAB) and LAB loaded alginate beads in attenuation of the symptoms associated with chronic fatigue syndrome (CFS) were evaluated.

METHODS

  Chronic fatigue syndrome following physical fatigue was induced in rats by forcing them to swim (forced swim test; FST) in water till exhaustion, after weighing them down with 10% their body weight, daily for 28 days. Immobility (I) and postswim fatigue time (PSF) were taken as suitable markers. Free LAB and LAB loaded floating beads (FBs) were administered, from 21 to 28 days.

KEY RESULTS

  Immobility and PSF were found to increase considerably in FST rats (665 ± 22 s and 196 ± 6 s) as compared with the naïve (32 ± 7 s and 22 ± 2 s) at 20 days, establishing severe fatigue like behavior. FST control group exhibited significant (P < 0.05) hypertrophy of spleen, hypotrophy of thymus, and increased oxido-nitrosative stress in brain and tumor necrosis factor-α (TNF-α) levels in serum. Treatment with LAB and LAB FBs significantly decreased I and PSF and attenuated (P < 0.05) oxido-nitrosative stress and TNF-α levels. Spleen and thymus were also restored to their original size in this group.

CONCLUSIONS & INFERENCES

  The findings suggest a valuable therapeutic role of LAB especially when incorporated into alginate beads for the treatment of CFS.

Development and evaluation of a gastro-retentive delivery system for improved antiulcer activity of ginger extract (Zingiber officinale)

Aim was to develop and optimize multiunit gastro-retentive floating beads (FBs) intended for localized and prolonged release of ginger for treating gastric ulcers. Protective effect of ginger extract (GE) against ulcer is well documented, but therapeutic use is compromised due to poor bioavailability and physicochemical properties. GE was only slightly soluble (3.19 ± 0.38 mg/ml) in simulated gastric fluid (SGF; pH 1.2). The solubility decreased in water to 0.69 ± 0.03 mg/ml and further by 26% in the presence of calcium carbonate (0.5% w/v). We prepared FBs of GE using calcium carbonate and sodium alginate in different proportions. Beads were evaluated for diameter, buoyancy, entrapment, and porosity. In vitro dissolution showed a Fickian release with a cumulative release of >80% at 24 h. Preclinical evaluation was done in cold-restraint stress induced gastric ulcers, in albino rats, in terms of (i) ulcer index, hemorrhagic streaks (l), mucus content, (ii) oxido-nitrosative stress, and (iii) histopathology. GE loaded FBs (200 mg/kg) were significantly better than free GE and better/equivalent to cimetidine (10 mg/kg). The system was evaluated for therapeutic effect (curative), i.e. after the induction of ulcers. Most of the natural phytochemical or antioxidants show pretreatment effectiveness. We, however, developed and established GE FBs for sustained curative effect.

Involvement of hippocampal serotonin and neuropeptide Y in depression induced by chronic unpredicted mild stress

Accumulated evidence indicates a role of the hippocampal 5-hydroxy-tryptamine (5-HT) and neuropeptide Y (NPY) in the response to stress and modulation of depression, but it is unclear whether and how the hippocampal 5-HT and NPY systems make contributions to chronic unpredicted mild stress (CUMS)-induced depression. Here we observed that rats receiving a variety of chronic unpredictable mild stressors for 3 weeks showed a variety of depression-like behavioral changes, including a significant reduction in body weight, sucrose preference, and locomotion, rearing and grooming in open field test, and a significant increase in immobility time in forced swimming test. These CUMS-induced behavioral changes were suppressed or blocked by intra-hippocampal injection of 5-HT (31.25 microg/microl) or NPY (10 microg/microl). These data suggest a critical role of reduced hippocampal 5-HT and NPY neurotransmission in CUMS-induced depression.

Effect of 7-nitroindazoleon superoxide production and MnSOD activity in threat brain following kainate-induced neurotoxicity

We investigated the effect of 7-nitroindazole (7-NI), a selective neuronal nitric oxide synthase inhibitor in vivo, on superoxide concentration as well its influence on mitochondrial MnSOD activity since this activity is associated with the production of reactive oxygen species after kainate-induced neurotoxicity. The time course of in vivo oxidative damage in different brain regions was investigated. Measurements were performed at different times (5 min, 15 min, 2 h, 48 h, and 7 days) in the ipsi- and contralateral hippocampus, forebrain cortex, striatum, and cerebellum homogenates. Our results indicated that 7-NI had no statistically significant influence on superoxide concentrations in the tested brain structures compared to the control values. However, superoxide concentrations after kainate-induced neurotoxicity returned to the control values after pretreatment with 7-NI in all tested brain structures. Regarding the activity of MnSOD, our results demonstrated statistically significant increase 7 days after intrahippocampal KA treatment in all tested brain structures after pretreatment with 7-NI. The obtained results suggest that neuronal NO synthase inhibitors may be useful in the treatment of neurological diseases in which excitotoxic mechanisms play a role. <br><br><font color="red"><b> This article has been retracted. Link to the retraction <u><a href="http://dx.doi.org/10.2298/ABS150330033E">10.2298/ABS150330033E</a><u></b></font>

Effect of glutamate antagonists on nitric oxide production in rat brain following intrahippocampal injection

Stimulation of glutamate receptors induces neuronal nitric oxide (NO) release, which in turn modulates glutamate transmission. The involvement of ionotropic glutamate NMDA and AMPA/kainate receptors in induction of NO production in the rat brain was examined after injection of kainate, a non-NMDA receptor agonist; kainate plus 6-cyano- 7-nitroquinoxaline-2,3-dione (CNQX), a selective AMPA/kainate receptor antagonist; or kainate plus 2-amino-5-phosphonopentanoic acid (APV), a selective NMDA receptor antagonist. Competitive glutamate receptor antagonists were injected with kainate unilaterally into the CA3 region of the rat hippocampus. The accumulation of nitrite, the stable metabolite of NO, was measured by the Griess reaction at different times (5 min, 15 min, 2 h, 48 h, and 7 days) in hippocampus, forebrain cortex, striatum, and cerebellum homogenates. The used glutamate antagonists APV and CNQX both provided sufficient neuroprotection in the sense of reducing nitrite concentrations, but with different mechanisms and time dynamics. Our findings suggest that NMDA and AMPA/kainate receptors are differentially involved in nitric oxide production. <br><br><font color="red"><b> This article has been retracted. Link to the retraction <u><a href="http://dx.doi.org/10.2298/ABS150319031E">10.2298/ABS150319031E</a><u></b></font>

Increased neuronal nuclear calcium influx in neonatal seizures

We hypothesized that neonatal seizures lead to increased Ca(2+) influx (nCa(2+)I) in neuronal nuclei of newborn rats and that such increase is nitric-oxide mediated. Neuronal nuclear (45)Ca(2+) influx (nCa(2+)I) was measured in neuronal nuclei of 25 10-day-old male rat-pups newborn brains. They were divided into five groups (n = 5/group). (I) control; (II) hypoxia without seizures; (III) hypoxia with seizures; (IV) kainate, 2 mg/kg intraperitoneal (i.p.)-induced seizures and (V) 7-nitroindazole (7-NINA), 1 mg/kg i.p. pretreated, kainate-induced seizures. nCa(2+)I was significantly (P < 0.05) increased following hypoxia or seizures (hypoxic- or kainate-induced). Post-hypoxic seizures further enhanced nCa(2+)I increase induced by hypoxia (P < 0.05). 7-NINA abated the nCa(2+)I increase induced by kainate. We conclude that (1) kainate or hypoxia-induced seizures in newborn rats modify the neuronal nuclear membrane function, resulting in increased nCa(2+)I, (2) seizures exacerbate the hypoxia-induced increased nCa(2+)I incurred after hypoxia and (3) intranuclear calcium surges during kainate-induced neonatal seizures are nitric oxide-mediated.

Differential effects of NMDA and AMPA/kainate receptor antagonists on nitric oxide production in rat brain following intrahippocampal injection

Stimulation of glutamate receptors induces neuronal nitric oxide (NO) release, which in turn modulates glutamate transmission. The involvement of ionotropic glutamate NMDA and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/kainite (KA) receptors in the induction of NO production in the rat brain was examined after injection of kainate, non-NMDA receptor agonist, KA+6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), selective AMPA/KA receptor antagonist, or KA+2-amino-5-phosphonopentanoic acid (APV), selective NMDA receptor antagonist. Competitive glutamate receptor antagonists were injected with KA unilaterally into the CA3 region of the rat hippocampus. The accumulation of nitrite, the stable metabolite of NO, was measured by the Griess reaction at different times (5 min, 15 min, 2 h, 48 h and 7 days) in the ipsi- and contralateral hippocampus, forebrain cortex, striatum and cerebellum homogenates. The detected increase of NO production in distinct brain regions, which are functionally connected via afferents and efferents, suggests that these regions are affected by the injury. The effect of KA on nitrite production was blocked by the glutamate antagonists. Intrahippocampal KA+CNQX injection resulted in decrease of nitrite production, around control levels, in all tested brain structures. Significant decrease in nitrite levels was found only in comparison to KA-treated animals, i.e. the overall effect of selective AMPA/KA receptor antagonist was a decrease of KA-induced excitotoxicity. The accent effect of intrahippocampal KA+APV injection resulted, also, in decrease of nitrite production. However, this effect was detected after 5 min from the injection indicating the existence of an NMDA receptor-mediated component of basal nitrite production in physiological conditions and difference in mechanisms and time dynamics between CNQX and APV. The used antagonists showed same pattern in all tested brain structures. APV and CNQX both expressed sufficient neuroprotection in sense of reducing nitrite concentrations, but with differential effect in mechanisms and time dynamics. Our findings suggest that NMDA and AMPA/KA receptors are differentially involved in NO production.

Kainate-induced oxidative stress and neurotoxicity in the rat brain

We investigated superoxide production and MnSOD activity after kainate injection into the CA3 region of the rat hippocampus. The measurements took place at different times in hippocampus, forebrain cortex, striatum, and cerebellum homogenates. Free radicals including superoxide are responsible for post-lesional cytotoxicity. Neuronal cells responded to oxidative stress in kainate-induced neurotoxicity and caused the protective mechanism to increase MnSOD levels. The increase of MnSOD in distinct brain regions functionally connected via afferents and efferent suggests that these regions are affected by the injury. It implies that MnSOD protects the cells in these regions from superoxide-induced damage and therefore may limit the retrograde and anterograde spread of neurotoxicity. <br><br><font color="red"><b> This article has been retracted. Link to the retraction <u><a href="http://dx.doi.org/10.2298/ABS150318027E">10.2298/ABS150318027E</a><u></b></font>

Mitochondrial superoxide production and MnSOD activity following exposure to an agonist and antagonists of ionotropic receptors in rat brain

The involvement of NMDA and AMPA/kainate receptors in the induction of superoxide production in the rat brain was examined after intrahippocampal injection of kainate, a non-NMDA receptor agonist; kainate plus CNQX, a selective AMPA/kainate receptor antagonist; or kainate plus APV, a selective NMDA receptor antagonist. The measurements took place at different times in the ipsi- and contralateral hippocampus, forebrain cortex, striatum, and cerebellum homogenates. The used glutamate antagonists both ensured sufficient neuroprotection in the sense of lowering superoxide production and raising MnSOD levels, but in the mechanisms and time dynamics of their effects were different. Our findings suggest that NMDA and AMPA/kainate receptors are differentially involved in superoxide production. <br><br><font color="red"><b> This article has been retracted. Link to the retraction <u><a href="http://dx.doi.org/10.2298/ABS150318026E">10.2298/ABS150318026E</a><u></b></font>