anisomycin and Brain-Ischemia

The main objective of our research was to explore the neuroprotective effect and underlying mechanism of β-caryophyllene (BCP) pretreatment against cerebral ischemia/reperfusion injury (CIRI). Neurological deficit score, infarct size, and sensorimotor function were assessed 24 h following reperfusion. Additionally, histopathological damage of neurons was evaluated using hematoxylin-eosin staining. The mRNA level of nod-like receptor family pyrin domain-containing 3 (NLRP3) was determined using quantitative real-time PCR. The expressions of p-p38, p38, NLRP3, procaspase-1, and ASC (apoptosis-associated speck-like protein containing a CARD) were measured using western blot analysis. The levels of interleukin-1β (IL-1β) and interleukin-18 (IL-18) were quantified utilizing the ELISA. Our findings indicated that BCP pretreatment significantly reduced the infarct volume, neurologic deficit score, sensorimotor deficits, histopathological damage, and expression of inflammatory factors. Besides, BCP pretreatment effectively suppressed the expression of p-p38, as well as the activation of NLRP3 inflammasome. The administration of anisomycin, an activator of p38 MAPK, was found to notably impede the favorable outcomes conferred by BCP pretreatment, which included reducing the infarct volume, improving the neurologic deficit score, mitigating the sensorimotor deficits, and attenuating the histopathological damage. Furthermore, anisomycin effectively reversed the suppressive impact of BCP on NLRP3 inflammasome activation. This research uncovered that pretreatment with BCP has the potential to alleviate CIRI by effectively suppressing the activation of NLRP3 inflammasome through the p38 MAPK signaling pathway.

Topics: Animals; Anisomycin; Brain Ischemia; Inflammasomes; MAP Kinase Signaling System; Neuroprotection; NLR Family, Pyrin Domain-Containing 3 Protein; p38 Mitogen-Activated Protein Kinases; Rats; Rats, Sprague-Dawley; Reperfusion Injury

Fluoxetine, a selective serotonin reuptake inhibitor, exerts neuroprotective effects in a variety of neurological diseases including stroke, but the underlying mechanism remains obscure. In the present study, we addressed the molecular events in fluoxetine against ischemia/reperfusion-induced acute neuronal injury and inflammation-induced neuronal apoptosis. We showed that treatment of fluoxetine (40 mg/kg, i.p.) with twice injections at 1 h and 12 h after transient middle cerebral artery occlusion (tMCAO) respectively alleviated neurological deficits and neuronal apoptosis in a mouse ischemic stroke model, accompanied by inhibiting interleukin-1β (IL-1β), Bax and p53 expression and upregulating anti-apoptotic protein Bcl-2 level. We next mimicked neuroinflammation in ischemic stroke with IL-1β in primary cultured cortical neurons and found that pretreatment with fluoxetine (1 μM) prevented IL-1β-induced neuronal apoptosis and upregulation of p53 expression. Furthermore, we demonstrated that p53 overexpression in N2a cell line abolished the anti-apoptotic effect of fluoxetine, indicating that p53 downregulation is required for the protective role of fluoxetine in IL-1β-induced neuronal apoptosis. Fluoxetine downregulating p53 expression could be mimicked by SB203580, a specific inhibitor of p38, but blocked by anisomycin, a p38 activator. Collectively, our findings have revealed that fluoxetine protects against IL-1β-induced neuronal apoptosis via p38-p53 dependent pathway, which give us an insight into the potential of fluoxetine in terms of opening up novel therapeutic avenues for neurological diseases including stroke.

Topics: Animals; Anisomycin; Apoptosis; bcl-2-Associated X Protein; Brain Ischemia; Cell Line, Tumor; Disease Models, Animal; Enzyme Inhibitors; Fluoxetine; Gene Expression; Imidazoles; Interleukin-1beta; MAP Kinase Signaling System; Mice, Inbred C57BL; Neuroimmunomodulation; Neurons; Neuroprotective Agents; p38 Mitogen-Activated Protein Kinases; Proto-Oncogene Proteins c-bcl-2; Pyridines; Stroke; Tumor Suppressor Protein p53

The c-Jun N-terminal kinase (JNK) undergoes complete inactivation following the intense activation induced by cerebral ischemia and reperfusion in rat hippocampi. This study examines the molecular mechanism underlying JNK dephosphorylation and inactivation evoked by dual-specificity phosphates following cerebral ischemia. The results revealed upregulation of dual-specificity phosphatase M3/6 (DUSP8) activity at 4 h of reperfusion in rat hippocampi. This was accompanied by the dephosphorylation of JNK. The M3/6 inhibitor, anisomycin, was found to enhance JNK activity following postischemic reperfusion, suggesting that M3/6 is closely associated with JNK inactivation following cerebral ischemia. Cerebral ischemia also induced an increase in heat shock protein (HSP70) levels, which is involved in the upregulation of soluble cytoplasmic M3/6 levels. The inhibition of HSP70 using quercetin resulted in an elevation of JNK activity by decreasing the cytoplasmic solubility of M3/6. The findings of the current study suggest that M3/6 is implicated in the inactivation of JNK in response to cerebral ischemia, which requires the molecular chaperone HSP70 to facilitate the correction of folding defects.

Topics: Animals; Anisomycin; Brain Ischemia; Dual-Specificity Phosphatases; Hippocampus; JNK Mitogen-Activated Protein Kinases; Male; Rats; Rats, Sprague-Dawley; Up-Regulation

Transient global brain ischemia results in an immediate inhibition of protein translation upon reperfusion. During early brain reperfusion protein synthesis is inhibited by alpha subunit of eukaryotic initiation factor 2 (eIF2alpha) phosphorylation by the PKR-like endoplasmic reticulum kinase (PERK). Normally, PERK is held in an inactive, monomeric state by the binding of the endoplasmic reticulum (ER) chaperone GRP78 to the lumenal end of PERK. The prevailing view is that ER stress leads to the accumulation of unfolded proteins in the ER lumen. GRP78 dissociates from PERK to bind these accumulated unfolded proteins, leading to PERK activation, phosphorylation of eIF2alpha, and inhibition of translation. To determine if an increase in unfolded nascent proteins following transient brain ischemia contributes to PERK activation, protein synthesis was blocked by intracerebral injection of anisomycin prior to induction of ischemia. Anisomycin inhibited protein synthesis by over 99% and reduced newly synthesized proteins in the ER to approximately 20% of controls. With an ER nearly devoid of newly synthesized proteins, PERK was still activated and was able to phosphorylate eIF2alpha in CA1 neurons during reperfusion. These data strongly argue that PERK activation is independent of the large increase in unfolded nascent proteins within the ER following transient global brain ischemia.

Topics: Animals; Anisomycin; Brain Ischemia; CA1 Region, Hippocampal; eIF-2 Kinase; Endoplasmic Reticulum; Enzyme Activation; Eukaryotic Initiation Factor-2; Male; Molecular Chaperones; Neurons; Phosphorylation; Protein Synthesis Inhibitors; Rats; Rats, Long-Evans; Unfolded Protein Response

We previously reported in rats that preconditioning with hyperbaric oxygen (HBO; 100% O(2) 3.5-atomsphere absolute (ATA), 1 h/day for 5 days) provided neuroprotection against transient (8 min) forebrain ischemia possibly through protein synthesis relevant to neurotrophin receptor and inflammatory-immune system. A recent report suggested that HBO-induced neuroprotection is relevant to brain derived neurotrophic factor and its downstream event involving suppression of p38 mitogen activated protein kinase (p38) activation. In the present study, we first performed a dose comparison (1, 2, and 3.5 ATA) of HBO-induced neuroprotection and then investigated pharmacological modification by 10 mg/kg anisomycin (a protein synthesis inhibitor and potent activator for p38) and 200 microg/kg SB203580 (a p38 inhibitor), which were given intraperitoneally 60 and 30 min before every 3.5 ATA-HBO treatment, respectively. Most prominent protective effect on hippocampal CA1 neurons was observed with 3.5 ATA-HBO (survived neurons: 69% [62-73%] vs. untreated: 3.9% [2-8%], 1 ATA: 8.8% [0-26%], 2 ATA-HBO: 46% [22-62%] (median [range]) (7 days after ischemia). Anisomycin abolished a neuroprotective effect (survived neuron: 1.2% [0-7%]). SB203580, when given between administration of anisomycin and HBO treatment, resumed a neuroprotective effect (survived neuron: 52% [37-62%]). The level of phosphorylated p38 at 10-min reperfusion was significantly decreased in 3.5 ATA-HBO group (32% [12-53%] of sham). Single pretreatment with 100 and 200 microg/kg of SB203580 exerted a similar neuroprotective effect (39% [25-51%] and 59% [50-72%]) to 2 and 3.5 ATA-HBO preconditioning, respectively. It is concluded that suppression of p38 phosphorylation plays a key role in HBO-induced neuroprotection and that pretreatment with a p38 inhibitor (SB203580) can provide similar neuroprotection.

Topics: Analysis of Variance; Animals; Anisomycin; Blotting, Western; Brain Ischemia; CA1 Region, Hippocampal; Cell Count; Cell Survival; Cytoprotection; Dose-Response Relationship, Drug; Enzyme Inhibitors; Exploratory Behavior; Hyperbaric Oxygenation; Imidazoles; Ischemic Preconditioning; Male; Memory, Short-Term; Neurons; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Prosencephalon; Protein Synthesis Inhibitors; Pyridines; Rats; Rats, Wistar

Many neurological insults are accompanied by a marked acute inflammatory reaction, involving the activation of microglia. Using a model of exogenous application of fluorescence-labeled BV2 microglia in pathophysiologically relevant concentrations onto organotypic hippocampal slice cultures, we investigated the specific effects of microglia on neuronal damage after ischemic injury. Neuronal cell death after oxygen-glucose deprivation (OGD) was determined by propidium iodide incorporation and Nissl staining. Migration and interaction with neurons were analyzed by time resolved 3-D two-photon microscopy. We show that microglia protect against OGD-induced neuronal damage and engage in close physical cell-cell contact with neurons in the damaged brain area. Neuroprotection and migration of microglia were not seen with integrin regulator CD11a-deficient microglia or HL-60 granulocytes. The induction of migration and neuron-microglia interaction deep inside the slice was markedly increased under OGD conditions. Lipopolysaccharide-prestimulated microglia failed to provide neuroprotection after OGD. Pharmacological interference with microglia function resulted in a reduced neuroprotection. Microglia proved to be neuroprotective even when applied up to 4 h after OGD, thus defining a "protective time window." In acute injury such as trauma or stroke, appropriately activated microglia may primarily have a neuroprotective role. Anti-inflammatory treatment within the protective time window of microglia would therefore be counterintuitive.

Topics: Animals; Anisomycin; Anti-Bacterial Agents; Brain Ischemia; CD11a Antigen; Cell Death; Cell Line; Glucose; Granulocytes; Hippocampus; HL-60 Cells; Humans; Hypoxia; Mice; Mice, Transgenic; Microglia; Minocycline; Neurons; Rats; Rats, Wistar

Delayed resistance to ischemic injury can be induced by a variety of conditioning stimuli. This phenomenon, known as delayed ischemic tolerance, is initiated over several hours or a day, and can persist for up to a week or more. The present paper describes recent experiments in which transient hypothermia was used as a conditioning stimulus to induce ischemic tolerance. A brief period of hypothermia administered 6 to 48 hours prior to focal ischemia reduces subsequent cerebral infarction. Hypothermia-induced ischemic tolerance is reversed by 7 days postconditioning, and is blocked by the protein synthesis inhibitor anisomycin. Electrophysiological studies utilizing in vitro brain slices demonstrate that hypoxic damage to synaptic responses is reduced in slices prepared from hypothermia-preconditioned animals. Taken together, these findings indicate that transient hypothermia induces tolerance in the brain parenchyma, and that increased expression of one or more gene products contributes to this phenomenon. Inasmuch as hypothermia is already an approved clinical procedure for intraischemic and postischemic therapy, it is possible that hypothermia could provide a clinically useful conditioning stimulus for limiting injury elicited by anticipated periods of ischemia.

Topics: Animals; Anisomycin; Brain Ischemia; Carotid Artery Injuries; Cerebral Infarction; Hypothermia, Induced; Ischemic Preconditioning; Middle Cerebral Artery; Protein Synthesis Inhibitors; Rats; Rats, Sprague-Dawley

We examined whether MK-801, an N-methyl-D-aspartate (NMDA)-receptor antagonist, or anisomycin, a reversible protein synthesis inhibitor, inhibits the induction of ischemic tolerance following preconditioning with sublethal ischemia in gerbil hippocampus. Preconditioning with 2 min of ischemia, which induced heat shock protein-72 immunoreactivity, prevented hippocampal CA1 neuronal damage following 3 min of ischemia produced 3 days later. MK-801, but not anisomycin, inhibited the induction of tolerance although the heat shock protein synthesis was reduced in both groups. The present result suggests that NMDA receptor activation, causing stress response, induces the ischemic tolerance.

Topics: Animals; Anisomycin; Body Temperature; Brain Ischemia; Dizocilpine Maleate; Electroencephalography; Gerbillinae; Hippocampus; Immunohistochemistry; Male; Receptors, N-Methyl-D-Aspartate