Histamine H2-receptor antagonist ranitidine protects against neural death induced by oxygen-glucose deprivation

A detection method for neuronal death indicates abnormalities in intracellular membranous components in neuronal cells that underwent delayed death

Acute neuronal degeneration is always preceded under the light and electron microscopes by a stage called microvacuolation, which is characterized by a finely vacuolar alteration in the cytoplasm of the neurons destined to death. In this study, we reported a method for detecting neuronal death using two membrane-bound dyes, rhodamine R6 and DiOC₆(3), which may be associated with the so-called microvacuolation. This new method produced a spatiotemporally similar staining pattern to Fluoro-Jade B in kainic acid-damaged brains in mice. Further experiments showed that increased staining of rhodamine R6 and DiOC₆(3) was observed only in degenerated neurons, but not in glia, erythrocytes, or meninges. Different from Fluoro-Jade-related dyes, rhodamine R6 and DiOC₆(3) staining is highly sensitive to solvent extraction and detergent exposure. Staining with Nile red for phospholipids and filipin III for non-esterified cholesterol supports that the increased staining of rhodamine R6 and DiOC₆(3) might be associated with increased levels of phospholipids and free cholesterol in the perinuclear cytoplasm of damaged neurons. In addition to kainic acid-injected neuronal death, rhodamine R6 and DiOC₆(3) were similarly useful for detecting neuronal death in ischemic models either in vivo or in vitro. As far as we know, the staining with rhodamine R6 or DiOC₆(3) is one of a few histochemical methods for detecting neuronal death whose target molecules have been well defined and therefore may be useful for explaining experimental results as well as exploring the mechanisms of neuronal death. (250 words).

Ranitidine Alleviates Anxiety-like Behaviors and Improves the Density of Pyramidal Neurons upon Deactivation of Microglia in the CA3 Region of the Hippocampus in a Cysteamine HCl-Induced Mouse Model of Gastrointestinal Disorder

Elevated levels of histamine cause over-secretion of gastric hydrochloric acid (HCl), leading to gastrointestinal (GI) disorders and anxiety. Ranitidine is an antihistamine drug widely used in the management of GI disorders, as it works by blocking the histamine-2 receptors in parietal cells, thereby reducing the production of HCl in the stomach. While some reports indicate the neuroprotective effects of ranitidine, its role against GI disorder-related anxiety remains unclear. Therefore, we investigated the effect of ranitidine against anxiety-related behaviors in association with changes in neuronal density in the hippocampal cornu ammonis (CA)-3 region of cysteamine hydrochloride-induced mouse model of GI disorder. Results obtained from the open field test (OFT), light and dark box test (LDBT), and elevated plus maze (EPM) test revealed that ranitidine treatment reduces anxiety-like behaviors in experimental animals. Nissl staining and immunohistochemical assessment of ionized calcium-binding adapter molecule (Iba)-1 positive microglia in cryosectioned brains indicated enhanced density of pyramidal neurons and reduced activation of microglia in the hippocampal CA-3 region of brains of ranitidine-treated experimental mice. Therefore, this study suggests that ranitidine mediates anxiolytic effects, which can be translated to establish a pharmacological regime to ameliorate anxiety-related symptoms in humans.

Histamine H3 and H4 receptors modulate Parkinson's disease induced brain pathology. Neuroprotective effects of nanowired BF-2649 and clobenpropit with anti-histamine-antibody therapy

Military personnel deployed in combat operations are highly prone to develop Parkinson's disease (PD) in later lives. PD largely involves dopaminergic pathways with hallmarks of increased alpha synuclein (ASNC), and phosphorylated tau (p-tau) in the cerebrospinal fluid (CSF) precipitating brain pathology. However, increased histaminergic nerve fibers in substantia nigra pars Compacta (SNpc), striatum (STr) and caudate putamen (CP) associated with upregulation of Histamine H3 receptors and downregulation of H4 receptors in human cases of PD is observed in postmortem cases. These findings indicate that modulation of histamine H3 and H4 receptors and/or histaminergic transmission may induce neuroprotection in PD induced brain pathology. In this review effects of a potent histaminergic H3 receptor inverse agonist BF-2549 or clobenpropit (CLBPT) partial histamine H4 agonist with H3 receptor antagonist, in association with monoclonal anti-histamine antibodies (AHmAb) in PD brain pathology is discussed based on our own observations. Our investigation shows that chronic administration of conventional or TiO₂ nanowired BF 2649 (1mg/kg, i.p.) or CLBPT (1mg/kg, i.p.) once daily for 1 week together with nanowired delivery of HAmAb (25μL) significantly thwarted ASNC and p-tau levels in the SNpC and STr and reduced PD induced brain pathology. These observations are the first to show the involvement of histamine receptors in PD and opens new avenues for the development of novel drug strategies in clinical strategies for PD, not reported earlier.

Histamine in the Crosstalk Between Innate Immune Cells and Neurons: Relevance for Brain Homeostasis and Disease

Histamine is a biogenic amine playing a central role in allergy and peripheral inflammatory reactions and acts as a neurotransmitter and neuromodulator in the brain. In the adult, histamine is produced mainly by mast cells and hypothalamic neurons, which project their axons throughout the brain. Thus, histamine exerts a range of functions, including wakefulness control, learning and memory, neurogenesis, and regulation of glial activity. Histamine is also known to modulate innate immune responses induced by brain-resident microglia cells and peripheral circulating monocytes, and monocyte-derived cells (macrophages and dendritic cells). In physiological conditions, histamine per se causes mainly a pro-inflammatory phenotype while counteracting lipopolysaccharide-induced inflammation both in microglia, monocytes, and monocyte-derived cells. In turn, the activation of the innate immune system can profoundly affect neuronal survival and function, which plays a critical role in the onset and development of brain disorders. Therefore, the dual role of histamine/antihistamines in microglia and monocytes/macrophages is relevant for identifying novel putative therapeutic strategies for brain diseases. This review focuses on the effects of histamine in innate immune responses and the impact on neuronal survival, function, and differentiation/maturation, both in physiological and acute (ischemic stroke) and chronic neurodegenerative conditions (Parkinson's disease).

The potential beneficial effects of sildenafil and diosmin in experimentally-induced gastric ulcer in rats

Objectives

research in the treatment of gastric ulcer has involved the investigation of protective drugs. These drugs may be used as adjacent therapy with the traditional pharmacologic treatment of peptic ulcer. The present study is designed to investigate the gastro protective effects of diosmin (DIO), sildenafil (SILD) and their combinations with ranitidine (RANT) against indomethacin (INDO)-induced gastric ulcer in rats. Additionally, the potential mechanisms of their effect are addressed.

Methods

DIO (100 mg/kg) and SILD (10 mg/kg) were administered by oral route for seven days prior to ulcer induction. Moreover, other rats were treated with RANT (50 mg/kg) not only to compare efficiency of the medications but also, to help clarify potential mechanisms of their effect. Following, after 24 h of fasting, INDO (100 mg/kg) was administered for induction of gastric ulcer. Furthermore, rats in each group were sacrificed 4 h later. Biochemical analysis of DIO, SILD, RANT and their combinations pre-treated host tissues demonstrated reduction in tumor necrosis factor (TNF)-α and malondialdehyde (MDA) contents and concomitant increase in gastric pH, nitric oxide (NO) and reduced glutathione (GSH) contents.

Result

It is observed, that SILD and DIO pre-treatment showed non-significant effect on gastric juice PH. However, their combinations with RANT is superior to using RANT alone. In addition, the results revealed, that combinations of (RANT and SILD) and (RANT and DIO) showed the highest increase in gastric tissue NO levels. But, these two combinations achieved the lowest MDA levels relative to the control (INDO) group. Despite, all groups displayed non-significant effect on reduced GSH content, (RANT and SILD) group increased GSH concentration by 39.75% relative to INDO group. In addition, DIO, RANT and (RANT and DIO) pre-treatment have anti-apoptotic activity on gastric mucosa. On the other hand, SILD did not affect caspase-3 immunostaining. These results are confirmed by histopathological findings.

Conclusion

The work outcomes provide a new gastro protective agents in clinical gastropathy. So, this study not only provides an efficient way for peptic ulcer protection, but also it may be considered for future studies in ulcer healing and gastric cancer.

Age-dependent involvement of gut mast cells and histamine in post-stroke inflammation

BACKGROUND

Risk of stroke-related morbidity and mortality increases significantly with age. Aging is associated with chronic, low-grade inflammation, which is thought to contribute to the poorer outcomes after stroke seen in the elderly. Histamine (HA) is a major molecular mediator of inflammation, and mast cells residing in the gut are a primary source of histamine.

METHODS

Stroke was induced in male C57BL/6 J mice at 3 months (young) and 20 months (aged) of age. Role of histamine after stroke was examined using young (Yg) and aged (Ag) mice; mice underwent MCAO surgery and were euthanized at 6 h, 24 h, and 7 days post-ischemia; sham mice received the same surgery but no MCAO. In this work, we evaluated whether worsened outcomes after experimental stroke in aged mice were associated with age-related changes in mast cells, histamine levels, and histamine receptor expression in the gut, brain, and plasma.

RESULTS

We found increased numbers of mast cells in the gut and the brain with aging. Using the middle cerebral artery occlusion (MCAO) model of ischemic stroke, we demonstrate that stroke leads to increased numbers of gut mast cells and gut histamine receptor expression levels. These gut-centric changes are associated with elevated levels of HA and other pro-inflammatory cytokines including IL-6, G-CSF, TNF-α, and IFN-γ in the peripheral circulation. Our data also shows that post-stroke gut inflammation led to a significant reduction of mucin-producing goblet cells and a loss of gut barrier integrity. Lastly, gut inflammation after stroke is associated with changes in the composition of the gut microbiota as early as 24-h post-stroke.

CONCLUSION

An important theme emerging from our results is that acute inflammatory events following ischemic insults in the brain persist longer in the aged mice when compared to younger animals. Taken together, our findings implicate mast cell activation and histamine signaling as a part of peripheral inflammatory response after ischemic stroke, which are profound in aged animals. Interfering with histamine signaling orally might provide translational value to improve stroke outcome.

Translating intracarotid artery transplantation of bone marrow-derived NCS-01 cells for ischemic stroke: Behavioral and histological readouts and mechanistic insights into stem cell therapy

The present study used in vitro and in vivo stroke models to demonstrate the safety, efficacy, and mechanism of action of adult human bone marrow‐derived NCS‐01 cells. Coculture with NCS‐01 cells protected primary rat cortical cells or human neural progenitor cells from oxygen glucose deprivation. Adult rats that were subjected to middle cerebral artery occlusion, transiently or permanently, and subsequently received intracarotid artery or intravenous transplants of NCS‐01 cells displayed dose‐dependent improvements in motor and neurological behaviors, and reductions in infarct area and peri‐infarct cell loss, much better than intravenous administration. The optimal dose was 7.5 × 10⁶ cells/mL when delivered via the intracarotid artery within 3 days poststroke, although therapeutic effects persisted even when administered at 1 week after stroke. Compared with other mesenchymal stem cells, NCS‐01 cells ameliorated both the structural and functional deficits after stroke through a broad therapeutic window. NCS‐01 cells secreted therapeutic molecules, such as basic fibroblast growth factor and interleukin‐6, but equally importantly we observed for the first time the formation of filopodia by NCS‐01 cells under stroke conditions, characterized by cadherin‐positive processes extending from the stem cells toward the ischemic cells. Collectively, the present efficacy readouts and the novel filopodia‐mediated mechanism of action provide solid lab‐to‐clinic evidence supporting the use of NCS‐01 cells for treatment of stroke in the clinical setting.

Oxycodone suppresses the apoptosis of hippocampal neurons induced by oxygen-glucose deprivation/recovery through caspase-dependent and caspase-independent pathways via κ- and δ-opioid receptors in rats

Cerebral ischemia/reperfusion injury (CIRI) can lead to perioperative neurocognitive disorders (PND) during clinical recanalization procedures in cerebral vessels, principally due to neuronal apoptosis in the hippocampus. Oxycodone appears to be a multiple opioid receptor agonist and exerts intrinsic antinociception activity via κ-opioid receptor (KOR). Recent evidence has revealed that activation of both δ-opioid receptor (DOR) and KOR can provide neuroprotection against CIRI in vivo and in vitro. In our study, we established an oxygen-glucose deprivation/recovery (OGD/R) model with fetal hippocampal neurons and found that oxycodone could induce CIRI tolerance in these neurons, primarily through KOR and DOR. Possible mechanisms might involve the regulatory effect of oxycodone on the MAPK-Bcl2/Bax-caspase-9-caspase-3 pathway, as well as its inhibitory effect on cellular reactive oxygen species (ROS) production and mitochondrial membrane potential activation. Taken together, our findings may indicate a potential method for the prevention and treatment of PND associated with CIRI.

Human alpha 1-antitrypsin protects neurons and glial cells against oxygen and glucose deprivation through inhibition of interleukins expression

BACKGROUND

Death due to cerebral stroke afflicts a large number of neuronal populations, including glial cells depending on the brain region affected. Drugs with a wide cellular range of protection are needed to develop effective therapies for stroke. Human alpha 1-antitrypsin (hAAT) is a serine proteinase inhibitor with potent anti-inflammatory, anti-apoptotic and immunoregulatory activities. This study aimed to test whether hAAT can protect different kind of neurons and glial cells after the oxygen and glucose deprivation (OGD).

METHODS

Addition of hAAT to mouse neuronal cortical, hippocampal and striatal cultures, as well as glial cultures, was performed 30 min after OGD induction and cell viability was assessed 24 h later. The expression of different apoptotic markers and several inflammatory parameters were assessed by immunoblotting and RT-PCR.

RESULTS

hAAT had a concentration-dependent survival effect in all neuronal cultures exposed to OGD, with a maximal effect at 1-2 mg/mL. The addition of hAAT at 1 mg/mL reduced the OGD-mediated necrotic and apoptotic death in all neuronal cultures. This neuroprotective activity of hAAT was associated with a decrease of cleaved caspase-3 and an increase of MAP2 levels. It was also associated with a reduction of pro-inflammatory cytokines protein levels and expression, increase of IL-10 protein levels and decrease of nuclear localization of nuclear factor-kappaB. Similar to neurons, addition of hAAT protected astrocytes and oligodendrocytes against OGD-induced cell death.

CONCLUSIONS

Human AAT protects neuronal and glial cells against OGD through interaction with cytokines.

GENERAL SIGNIFICANCE

Human AAT could be a good therapeutic neuroprotective candidate to treat ischemic stroke.

Immunoregulatory effect of mast cells influenced by microbes in neurodegenerative diseases

When related to central nervous system (CNS) health and disease, brain mast cells (MCs) can be a source of either beneficial or deleterious signals acting on neural cells. We review the current state of knowledge about molecular interactions between MCs and glia in neurodegenerative diseases such as Multiple Sclerosis, Alzheimer's disease, Amyotrophic Lateral Sclerosis, Parkinson's disease, Epilepsy. We also discuss the influence on MC actions evoked by the host microbiota, which has a profound effect on the host immune system, inducing important consequences in neurodegenerative disorders. Gut dysbiosis, reduced intestinal motility and increased intestinal permeability, that allow bacterial products to circulate and pass through the blood-brain barrier, are associated with neurodegenerative disease. There are differences between the microbiota of neurologic patients and healthy controls. Distinguishing between cause and effect is a challenging task, and the molecular mechanisms whereby remote gut microbiota can alter the brain have not been fully elucidated. Nevertheless, modulation of the microbiota and MC activation have been shown to promote neuroprotection. We review this new information contributing to a greater understanding of MC-microbiota-neural cells interactions modulating the brain, behavior and neurodegenerative processes.

Histamine H2 receptor activation exacerbates myocardial ischemia/reperfusion injury by disturbing mitochondrial and endothelial function

There is evidence that H2R blockade improves ischemia/reperfusion (I/R) injury, but the underlying cellular mechanisms remain unclear. Histamine is known to increase vascular permeability and induce apoptosis, and these effects are closely associated with endothelial and mitochondrial dysfunction, respectively. Here, we investigated whether activation of the histamine H2 receptor (H2R) exacerbates myocardial I/R injury by increasing mitochondrial and endothelial permeability. Serum histamine levels were measured in patients with coronary heart disease, while the influence of H2R activation was assessed on mitochondrial and endothelial function in cultured cardiomyocytes or vascular endothelial cells, and myocardial I/R injury in mice. The serum histamine level was more than twofold higher in patients with acute myocardial infarction than in patients with angina or healthy controls. In neonatal rat cardiomyocytes, histamine dose-dependently reduced viability and induced apoptosis. Mitochondrial permeability and the levels of p-ERK1/2, Bax, p-DAPK2, and caspase 3 were increased by H2R agonists. In cultured human umbilical vein endothelial cells (HUVECs), H2R activation increased p-ERK1/2 and p-moesin levels and also enhanced permeability of HUVEC monolayer. All of these effects were abolished by the H2R blocker famotidine or the ERK inhibitor U0126. After I/R injury or permanent ischemia, the infarct size was reduced by famotidine and increased by an H2R agonist in wild-type mice. In H2R KO mice, the infarct size was smaller; myocardial p-ERK1/2, p-DAPK2, and mitochondrial Bax were downregulated. These findings indicate that H2R activation exaggerates myocardial I/R injury by promoting myocardial mitochondrial dysfunction and by increasing cardiac vascular endothelial permeability.

Purification and neuroprotective effects of polysaccharides from Opuntia Milpa Alta in cultured cortical neurons

Opuntia is a traditional plant from China with medicinal applications. In this experiment, polysaccharides from Opuntia Milpa Alta (MAPs) were analyzed using gas chromatograph-mass spectrometer (GC-MS) method and result showed that MAPs contained mannose (6.37%), rhamnose (14.94%), xylose (1.99%), arabinose (24.07%), galactose (38.25%), ribose (2.63%) and glucose (11.48%). The neuroprotective effects of MAPs were evaluated at the mechanistic level in vitro models of cerebral ischemic injury. In vitro oxygen/glucose deprivation (OGD) model, MAPs (0.5 μg/ml, 5 μg/ml, 50 μg/ml) effectively increased cell viability by methyl thiazolyl tetrazolium (MTT) assay, inhibited cell cytotoxicity by lactate dehydrogenase (LDH) assay, reduced neuronal cell death, suppressed the production of intracellular reactive oxygen species (ROS), decreased of intracellular free Ca(2+) concentrations ([Ca(2+)](i)), and reduced extracellular glutamate level. Therefore, MAPs might prevent intracellular calcium overload and decreased glutamate excitotoxicity, both of which can cause neuronal injury and death in vitro models of cerebral ischemic injury.

Induction of ER stress in response to oxygen-glucose deprivation of cortical cultures involves the activation of the PERK and IRE-1 pathways and of caspase-12

Disturbance of calcium homeostasis and accumulation of misfolded proteins in the endoplasmic reticulum (ER) are considered contributory components of cell death after ischemia. However, the signal-transducing events that are activated by ER stress after cerebral ischemia are incompletely understood. In this study, we show that caspase-12 and the PERK and IRE pathways are activated following oxygen-glucose deprivation (OGD) of mixed cortical cultures or neonatal hypoxia–ischemia (HI). Activation of PERK led to a transient phosphorylation of eIF2α, an increase in ATF4 levels and the induction of gadd34 (a subunit of an eIF2α-directed phosphatase). Interestingly, the upregulation of ATF4 did not lead to an increase in the levels of CHOP. Additionally, IRE1 activation was mediated by the increase in the processed form of xbp1, which would be responsible for the observed expression of edem2 and the increased levels of the chaperones GRP78 and GRP94. We were also able to detect caspase-12 proteolysis after HI or OGD. Processing of procaspase-12 was mediated by NMDA receptor and calpain activation. Moreover, our data suggest that caspase-12 activation is independent of the unfolded protein response activated by ER stress.

Temporal differences in microRNA expression patterns in astrocytes and neurons after ischemic injury

MicroRNAs (miRNAs) are small, non-protein-coding RNA molecules that modulate gene translation. Their expression is altered in many central nervous system (CNS) injuries suggesting a role in the cellular response to stress. Current studies in brain tissue have not yet described the cell-specific temporal miRNA expression patterns following ischemic injury. In this study, we analyzed the expression alterations of a set of miRNAs in neurons and astrocytes subjected to 60 minutes of ischemia and collected at different time-points following this injury. To mimic ischemic conditions and reperfusion in vitro, cortical primary neuronal and astrocytic cultures prepared from fetal rats were first placed in oxygen and glucose deprived (OGD) medium for 60 minutes, followed by their transfer into normoxic pre-conditioned medium. Total RNA was extracted at different time-points after the termination of the ischemic insult and the expression levels of miRNAs were measured. In neurons exposed to OGD, expression of miR-29b was upregulated 2-fold within 6 h and up to 4-fold at 24 h post-OGD, whereas induction of miR-21 was upregulated 2-fold after 24 h when compared to expression in neurons under normoxic conditions. In contrast, in astrocytes, miR-29b and miR-21 were upregulated only after 12 h. MiR-30b, 107, and 137 showed expression alteration in astrocytes, but not in neurons. Furthermore, we show that expression of miR-29b was significantly decreased in neurons exposed to Insulin-Like Growth Factor I (IGF-I), a well documented neuroprotectant in ischemic models. Our study indicates that miRNAs expression is altered in neurons and astrocytes after ischemic injury. Furthermore, we found that following OGD, specific miRNAs have unique cell-specific temporal expression patterns in CNS. Therefore the specific role of each miRNA in different intracellular processes in ischemic brain and the relevance of their temporal and spatial expression patterns warrant further investigation that may lead to novel strategies for therapeutic interventions.

Apocynum venetum leaf extract protects rat cortical neurons from injury induced by oxygen and glucose deprivation in vitro

This study aimed to investigate the protective effect of Apocynum venetum leaf extract (AVLE) on an in vitro model of ischemia–reperfusion induced by oxygen and glucose deprivation (OGD) and further explored the possible mechanisms underlying protection. Cell injury was assessed by morphological examination using phase-contrast microscopy and quantified by measuring the amount of lactate dehydrogenase (LDH) leakage; cell viability was measured by XTT reduction. Neuronal apoptosis was determined by flow cytometry, and electron microscopy was used to study morphological changes of neurons. Caspase-3, -8, and -9 activation and Bcl-2/Bax protein expression were determined by Western blot analysis. We report that treatment with AVLE (5 and 50 µg/mL) effectively reduced neuronal cell death and relieved cell injury induced by OGD. Moreover, AVLE decreased the percentage of apoptotic neurons, relieved neuronal morphological damage, suppressed overexpression of active caspase-3 and -8 and Bax, and inhibited the reduction of Bcl-2 expression. These findings indicate that AVLE protects against OGD-induced injury by inhibiting apoptosis in rat cortical neurons by down-regulating caspase-3 activation and modulating the Bcl-2/Bax ratio.

Neuroprotective effects of water-soluble Ganoderma lucidum polysaccharides on cerebral ischemic injury in rats

AIM OF THE STUDY

To investigate the neuroprotective effects of water-soluble Ganoderma lucidum polysaccharides (GLPS) on cerebral ischemic injury in rats, and to explore the involved mechanisms.

MATERIALS AND METHODS

Two models [middle cerebral artery occlusion (MCAO) in Sprague-Dawley (SD) rats and oxygen and glucose deprivation (OGD) in primary cultured rat cortical neurons] were employed to mimic ischemia-reperfusion (I/R) damage, in vivo and in vitro, respectively. Cerebral infarct area was measured by tetrazolium staining, and neurological functional deficits were assessed at 24h after I/R. Neuronal apoptosis was studied by Nissl staining and DNA fragmentation assay. Neuronal injury was assessed by morphological examination using phase-contrast microscopy and quantified by measuring the amount of lactate dehydrogenase (LDH) leakage, cell viability was measured by sodium 3'-1- (phenylaminocarbonyl)-3, 4-tetrazolium-bis (4-methoxy-6-nitro) benzene sulfonic acid (XTT) reduction. Neuronal apoptosis was determined by flow cytometry, and electron microscopy was used to study morphological changes of neurons. Caspase-3, -8 and -9 activation and Bcl-2, Bax protein expression were determined by western blot analysis.

RESULTS

Oral administration of GLPS (100, 200 and 400mg/kg) significantly reduced cerebral infarct area, attenuated neurological functional deficits, and reduced neuronal apoptosis in ischemic cortex. In OGD model, GLSP (0.1, 1 and 10 microg/ml) effectively reduced neuronal cell death and relieved cell injury. Moreover, GLPS decreased the percentage of apoptotic neurons, relieved neuronal morphological damage, suppressed overexpression of active caspases-3, -8 and -9 and Bax, and inhibited the reduction of Bcl-2 expression.

CONCLUSIONS

Our findings indicate that GLPS protects against cerebral ischemic injury by inhibiting apoptosis by downregulating caspase-3 activation and modulating the Bcl-2/Bax ratio.

Menstrual blood cells display stem cell-like phenotypic markers and exert neuroprotection following transplantation in experimental stroke

Cell therapy remains an experimental treatment for neurological disorders. A major obstacle in pursuing the clinical application of this therapy is finding the optimal cell type that will allow benefit to a large patient population with minimal complications. A cell type that is a complete match of the transplant recipient appears as an optimal scenario. Here, we report that menstrual blood may be an important source of autologous stem cells. Immunocytochemical assays of cultured menstrual blood reveal that they express embryonic-like stem cell phenotypic markers (Oct4, SSEA, Nanog), and when grown in appropriate conditioned media, express neuronal phenotypic markers (Nestin, MAP2). In order to test the therapeutic potential of these cells, we used the in vitro stroke model of oxygen glucose deprivation (OGD) and found that OGD-exposed primary rat neurons that were co-cultured with menstrual blood-derived stem cells or exposed to the media collected from cultured menstrual blood exhibited significantly reduced cell death. Trophic factors, such as VEGF, BDNF, and NT-3, were up-regulated in the media of OGD-exposed cultured menstrual blood-derived stem cells. Transplantation of menstrual blood-derived stem cells, either intracerebrally or intravenously and without immunosuppression, after experimentally induced ischemic stroke in adult rats also significantly reduced behavioral and histological impairments compared to vehicle-infused rats. Menstrual blood-derived cells exemplify a source of "individually tailored" donor cells that completely match the transplant recipient, at least in women. The present neurostructural and behavioral benefits afforded by transplanted menstrual blood-derived cells support their use as a stem cell source for cell therapy in stroke.

Therapeutic targets and limits of minocycline neuroprotection in experimental ischemic stroke

BACKGROUND

Minocycline, a second-generation tetracycline with anti-inflammatory and anti-apoptotic properties, has been shown to promote therapeutic benefits in experimental stroke. However, equally compelling evidence demonstrates that the drug exerts variable and even detrimental effects in many neurological disease models. Assessment of the mechanism underlying minocycline neuroprotection should clarify the drug's clinical value in acute stroke setting.

RESULTS

Here, we demonstrate that minocycline attenuates both in vitro (oxygen glucose deprivation) and in vivo (middle cerebral artery occlusion) experimentally induced ischemic deficits by direct inhibition of apoptotic-like neuronal cell death involving the anti-apoptotic Bcl-2/cytochrome c pathway. Such anti-apoptotic effect of minocycline is seen in neurons, but not apparent in astrocytes. Our data further indicate that the neuroprotection is dose-dependent, in that only low dose minocycline inhibits neuronal cell death cascades at the acute stroke phase, whereas the high dose exacerbates the ischemic injury.

CONCLUSION

The present study advises our community to proceed with caution to use the minimally invasive intravenous delivery of low dose minocycline in order to afford neuroprotection that is safe for stroke.

Protective effect of histamine H2 receptor antagonist ranitidine against rotenone-induced apoptosis

Histamine H(2) receptor antagonists have been reported to improve the motor symptoms of Parkinson's disease (PD) patients and to exert neuroprotective effects. In this study, we investigated the protective effects of the H(2) receptor antagonist ranitidine on rotenone-induced apoptosis in human dopaminergic SH-SY5Y cells, focusing on mitogen-activated protein kinases (MAPKs) and caspases (CASPs)-mediated apoptotic events. Ranitidine blocked the rotenone-induced phosphorylation of c-Jun NH(2)-terminal protein kinase (JNK) and P38 MAPK (P38), and promoted the phosphorylation of extracellular signal-regulated protein kinase (ERK). Ranitidine also prevented the down-regulation of B-cell CLL/lymphoma 2 (BCL2) and the up-regulation of BCL2-associated X protein (BAX) by rotenone. Furthermore, ranitidine not only attenuated rotenone-induced cleavages of CASP9, poly(ADP-ribose) polymerase-1 (PARP) and CASP3, but also suppressed CASP3 enzyme activity. These results indicate that ranitidine protects against rotenone-induced apoptosis, inhibiting phosphorylation of JNK and P38, and activation of CASPs in human dopaminergic SH-SY5Y cells.

Activation of caspase-8 by tumour necrosis factor receptor 1 is necessary for caspase-3 activation and apoptosis in oxygen-glucose deprived cultured cortical cells

TNF-alpha has been reported to be relevant in stroke-induced neuronal death. However the precise function of TNF-alpha in brain ischemia remains controversial since there are data supporting either a detrimental or a protective effect. Here we show that TNF-alpha is released after oxygen-glucose deprivation (OGD) of cortical cultures and is a major contributor to the apoptotic death observed without affecting the OGD-mediated necrotic cell death. In this paradigm, apoptosis depends on TNF-alpha-induced activation of caspase-8 and -3 without affecting the activation of caspase-9. By using knock-out mice for TNF-alpha receptor 1, we show that the activation of both caspase-3 and -8 by TNF-alpha is mediated by TNF-alpha receptor 1. The pro-apoptotic role of TNF-alpha in OGD is restricted to neurons and microglia, since astrocytes do not express either TNF-alpha or TNF-alpha receptor 1. Altogether, these results show that apoptosis of cortical neurons after OGD is mediated by TNF-alpha/TNF-alpha receptor 1.

Constitutive histamine H2 receptor activity regulates serotonin release in the substantia nigra

The substantia nigra pars reticulata (SNr) forms a principal output from the basal ganglia. It also receives significant histamine (HA) input from the tuberomammillary nucleus whose functions in SNr remain poorly understood. One identified role is the regulation of serotonin (5-HT) neurotransmission via the HA-H(3) receptor. Here we have explored regulation by another HA receptor expressed in SNr, the H(2)-receptor (H(2)R), by monitoring electrically evoked 5-HT release with fast-scan cyclic voltammetry at carbon-fiber microelectrodes in SNr in rat brain slices. Selective H(2)R antagonists (inverse agonists) ranitidine and tiotidine enhanced 5-HT release while the agonist amthamine suppressed release. The 'neutral' competitive antagonist burimamide alone was without effect but prevented ranitidine actions indicating that inverse agonist effects result from constitutive H(2)R activity independent of HA tone. H(2)R control of 5-HT release was most apparent (from inverse agonist effects) at lower frequencies of depolarization (< or = 20 Hz), and prevailed in the presence of antagonists of GABA, glutamate or H(3)-HA receptors. These data reveal that H(2)Rs in SNr are constitutively active and inhibit 5-HT release through H(2)Rs on 5-HT axons. These data may have therapeutic implications for Parkinson's disease, when SNr HA levels increase, and for neuropsychiatric disorders in which 5-HT is pivotal.

Role of histamine in brain protection in surgical brain injury in mice

Surgical resection of brain tissue is associated with tissue damage at the resection margin. Studies of ischemic brain injury in rodents have shown that administration of L-histidine and thioperamide reduces ischemic tissue loss, in part by inhibition of apoptotic cell death. In this study we tested administration of L-histidine and thioperamide in surgical brain injury in mice. Mice were randomized to one of three groups: Sham surgery (n=18), surgical brain injury without treatment (SBI) (n=33), and surgical brain injury with combined l-histidine and thioperamide treatment (SBI+H) (n=29). Surgical brain injury was induced via right frontal craniotomy with resection of the right frontal lobe. L-histidine (1000 mg/kg) and thioperamide (5 mg/kg) were administered to the SBI+H group immediately following surgical resection. Postoperative assessment included neurobehavioral scores, Evans blue measurement of blood-brain barrier breakdown, brain water content, Nissl histology, and immunohistochemistry for IgG and cleaved caspase 3. Postoperative findings included equivalent neurobehavioral outcomes at 24 and 72 h in the SBI and SBI+H groups, similar histological outcomes between SBI and SBI+H, and similar qualitative staining for cleaved caspase 3. SBI+H had increased BBB breakdown on Evans blue analysis and a trend towards increased brain edema which was significant at 72 h. We conclude that combined treatment with l-histidine and thioperamide leads to increased BBB breakdown and brain edema in surgical brain injury.

Effect of oxygen-glucose deprivation on degranulation and histamine release of mast cells

The purpose of this study was to investigate the effect of oxygen-glucose deprivation (OGD) on degranulation and histamine release of mast cells. Cultured mast cells were exposed to OGD for 1, 2, 4, 8, or 16 h. At 2 h of OGD exposure, the degranulation percentage of mast cells had increased and subsequently showed a progressive further increase, associated with a similar change in lactate dehydrogenase release. Histamine release increased significantly from 1 h of OGD exposure. These results indicate that OGD induces mast cells to degranulate, possibly via a cytotoxic response. This in vitro ischemic model of mast cells might clarify their roles in the pathological processes induced by cerebral ischemia.

D-beta-hydroxybutyrate is neuroprotective against hypoxia in serum-free hippocampal primary cultures

Hypoxia decreased survival of cultured rat primary hippocampal neurons in a time dependent manner. Addition of 4 mM Na D-beta-hydroxybutyrate (bHB), a ketone body, protected the cells for 2 hr and maintained the increase in survival compared to that of controls for up to 6 hr. Trypan blue exclusion indicated that acute cell death was reduced markedly after 2-hr exposure to hypoxia in the bHB-treated group. The presence of bHB also decreased the number of neurons exhibiting condensed nuclei visualized by propidium iodide, indicative of apoptosis. The mitochondrial transmembrane potential (Em/c) was maintained for up to 2 hr exposure to hypoxia in the bHB-treated group, whereas the potential in the control group was decreased. Furthermore, cytochrome C release, caspase-3 activation, and poly (ADP-ribose) polymerase (PARP) cleavage were decreased in the bHB-treated group for the first 2 hr of exposure. These findings indicate that ketone bodies may be a candidate for widening the therapeutic window before thrombolytic therapy and at the same time decreasing apoptotic damage in the ischemic penumbra.

Insulin receptor-protein kinase C-gamma signaling mediates inhibition of hypoxia-induced necrosis of cortical neurons

Ischemic stress causes neuronal death and functional impairment. Evidence has suggested that cells in the ischemic core first lose viability due to the decline in blood flow and cellular energy metabolism and then die by necrosis. Although inhibition of necrosis could be a potent therapeutic target for brain ischemia, known neurotrophic factors are ineffective for neuronal necrosis. We previously reported that insulin, but not brain-derived neurotrophic factor or insulin like-growth factor-1, inhibited neuronal necrosis under serum-free starvation stress. Although insulin receptors are abundant in the central nervous system as well as in peripheral tissues, neurons are not dependent upon insulin for their glucose supply, indicating that insulin receptors have other roles in the central nervous system. In the present study, by using hypoxia-reperfusion stress, we showed that cortical neurons rapidly died by necrosis as evaluated by propidium iodide staining and transmission electron microscopic analysis. As expected, insulin treatment significantly inhibited neuronal necrosis, although this effect was blocked by pretreatment with an antisense oligonucleotide for the insulin receptor. Furthermore, an inhibitor of protein kinase C (PKC) eliminated the insulin-induced antinecrotic effect. The addition of insulin induced significant translocation of only the PKC-gamma isoform, whereas antisense oligonucleotide treatment for this isoform abolished the insulin-induced inhibition of necrosis. Together, these results suggest that insulin mediates inhibition of neuronal necrosis through a novel mechanism involving PKC-gamma activation.