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Brain inflammatory processes underlie the pathogenesis of Alzheimer's disease, and non-steroidal anti-inflammatory drugs have a protective effect in the disease. The aim of this work was to study in vivo whether attenuation of brain inflammatory response to excitotoxic insult by the selective cyclooxygenase-2 inhibitor, rofecoxib, may prevent neurodegeneration, as a contribution to a better understanding of the role inflammation plays in the pathology of Alzheimer's disease. We investigated, by immunohistochemical methods, glia reaction, the activation of p38 mitogen-activated protein kinase (p38MAPK) pathway with an antibody selective for the phosphorylated form of the enzyme and the number of choline acetyltransferase-positive neurons and, by in vivo microdialysis, cortical extracellular levels of acetylcholine following the injection of quisqualic acid into the right nucleus basalis of adult rats. Seven days after injection, a marked reduction in the number of choline acetyltransferase-positive neurons was found, along with an intense glia reaction, selective activation of p38MAPK at the injection site and a significant decrease in the extracellular levels of acetylcholine in the cortex ipsilateral to the injection site. The loss of cholinergic neurons persisted for at least up to 28 days. Rofecoxib (3 mg/kg/day, starting 1 h prior to injection of quisqualic acid) treatment for 7 days significantly attenuated glia activation and prevented the loss of choline acetyltransferase-positive cells and a decrease in cortical acetylcholine release. The prevention of cholinergic cell loss by rofecoxib occurred concomitantly with the inhibition of p38MAPK phosphorylation. Our findings suggest an important role of brain inflammatory reaction in cholinergic degeneration and demonstrate a neuroprotective effect of rofecoxib, presumably mediated through the inhibition of p38MAPK phosphorylation.

Injection into the nucleus basalis of the rat of preaggregated Abeta(1-42) produced a congophylic deposit and microglial and astrocyte activation and infiltration and caused a strong inflammatory reaction characterized by IL-1beta production, increased inducible cyclooxygenase (COX-2), and inducible nitric oxide synthase (iNOS) expression. Many phospho-p38MAPK-positive cells were observed around the deposit at 7 days after Abeta injection. Phospho-p38MAPK colocalized with activated microglial cells, but not astrocytes. The inflammatory reaction was accompanied by cholinergic hypofunction. We investigated the protective effect of the selective COX-2 inhibitor rofecoxib in attenuating the inflammatory response and neurodegeneration evoked by Abeta(1-42). Rofecoxib (3 mg/kg/day, 7 days) reduced microglia and astrocyte activation, iNOS induction, and p38MAPK activation to control levels. Cholinergic hypofunction was also significantly attenuated by treatment with rofecoxib. We show here for the first time in vivo the pivotal role played by the p38MAPK microglial signal transduction pathway in the inflammatory response to the Abeta(1-42) deposit.

To evaluate whether inflammation-like mechanisms present in the brain of Alzheimer’s disease (AD) patients are reflected in the periphery, the expression of CD11b in peripheral blood neutrophils and the expression and activity of inflammatory markers in cultured skin fibroblasts were examined. We found significantly higher levels of CD11b in neutrophils from sporadic AD patients than in controls and this elevation was positively correlated with disease severity and progression rate of mental decline. Cultured skin fibroblasts from familial (FAD) and sporadic AD patients and from controls were immunopositive for both isoforms of cyclooxygenase with no differences between groups. In unstimulated culture, the production of prostaglandin-E2 in the medium was significantly higher in fibroblasts from sporadic AD and FAD patients than in controls, and this elevation was reverted by the addition of 25 μM of ibuprofen. Our findings provide further evidence of the presence of inflammatory and immuno-related markers in the periphery of AD patients and support those studies indicating the beneficial effects of anti-inflammatory therapy in AD.

Brain inflammation underlies the pathogenesis of Alzheimer's disease (AD) and nonsteroidal anti-inflammatory drug therapy may delay the onset of AD. We investigated, in vivo, the effects of NO-flurbiprofen on brain inflammation in rats injected with quisqualic acid into the nucleus basalis and on the release of nitric oxide from the drug in naive rat brains. We showed that the excitotoxin-induced microglia reaction, the expression of inducible nitric oxide synthase-positive cells and the production of interleukin-1beta and prostaglandin-E2 in the injected area were attenuated by the NO-flurbiprofen (15 mg/kg, p.o.) treatment. An oral administration of NO-flurbiprofen (25, 50 and 100 mg/kg) to naive rats was followed by significant increases in cortical nitrite levels. This drug may have important therapeutic implications for the treatment of AD.

Brain inflammatory processes underlie the pathogenesis of Alzheimer's disease, and nonsteroidal anti-inflammatory drugs have a protective effect in the disease. The aim of this study was to characterize in vivo in the rat brain the inflammatory reaction in response to excitotoxic insult and to investigate the efficacy of nimesulide treatment. Quisqualic acid was injected into the right nucleus basalis of rats. The excitotoxin induced cholinergic degeneration, an intense glial reaction and the production of inflammatory mediators. Three hours after injection, a five-fold elevation in the concentration of interleukin-1beta in the injected area was observed. This elevation was reduced by 50% by nimesulide (10 mg/kg, i.m.) pretreatment. Electron microscope examination and immunocytochemical staining revealed an intense activation of microglia and astrocytes at both 24 h and 7 days after injection. Cyclooxygenase-2-immunoreactivity was induced in the blood vessels of the injected hemisphere in perivascular microglial and endothelial cells 24 h after injection. Seven days postinjection, a cyclooxygenase-2-positive signal was induced in the parenchymal microglia and large amounts of prostaglandin-E2 were measured in the injected area. Twenty-four hours and 7 days after injection, many inducible nitric oxide synthase-positive cells and a high level of nitrite were detected at the injection site. Seven days of nimesulide (10 mg/kg/day, i.m.) treatment strongly attenuated the microglial reaction, reduced the number of inducible nitric oxide synthase-positive cells and completely abolished the increase in prostaglandin-E2 formation. These data provide valuable support in vivo for the potential efficacy of cyclooxygenase-2 inhibitors in Alzheimer's disease therapy.

The effects of metrifonate were investigated in 4-6- and 22-24-month-old rats. Extracellular acetylcholine levels were measured by transversal microdialysis in vivo. Baseline extracellular acetylcholine levels in the cerebral cortex and hippocampus were 42% and 60% lower, respectively, in old than in young rats. Old rats did not discriminate between familiar and novel objects. In old rats, metrifonate (80 mg/kg p.o.) brought about 85% inhibition of cholinesterase activity in the cortex and hippocampus, a 4-fold increase in extracellular acetylcholine levels in the cortex only, and restored object recognition. In young rats, metrifonate caused 75% cholinesterase inhibition in the cerebral cortex and hippocampus, a 2-fold increase in cortical and hippocampal extracellular acetylcholine levels, and no effect on object recognition. The slight cholinesterase inhibition following metrifonate (30 mg/kg) in aged rats had no effect on cortical acetylcholine levels and object recognition. In conclusion, metrifonate may improve the age-associated cholinergic hypofunction and cognitive impairment.

The nucleus basalis of adult rats was injected with β(1–40) amyloid peptide. A marked increase in basal and K+-evoked GABA release in the ipsilateral cortex and a significant decrease in GAD activity in the injected NB were found 30 days after injection. An intense activation of microglial cells that surrounded and infiltrated the deposit was observed. These data demonstrate that a local injection of β(1–40) peptide into the NB induces glia activation and affects GABAergic neurons.

Interleukin-1beta (10 U) was injected into the nucleus basalis of adult male Wistar rats. The inflammation-induced changes in glial cell morphology and expression of inducible nitric oxide synthase in the injected area, the release of acetylcholine, GABA and glutamate from the ipsilateral cortex, the production of nitrite levels in the injected area and ipsilateral cortex, and changes in motor activity were investigated. Saline-injected rats were used as control. Interleukin-1beta induced an activation of both microglia and astrocytes which was already evident 24 h after injection. Seven days after injection, many reactive microglial cells and astrocytes were seen in the injected area and in other brain regions of the same hemisphere. Microglia reaction, but not astrocyte activation, disappeared 30 days post-injection. Seven days after interleukin-1beta injection, many cells immunopositive for inducible nitric oxide synthase were found surrounding the injection site. Inducible nitric oxide synthase-positive cells were identified, by double staining immunohistochemistry, in the reactive microglial cells and, by electron microscope examination, in the perineuronal subpopulation of resident activated microglia. Microdialysis investigations revealed a transient increase in reactive nitrogen intermediates (at seven days post-injection), a delayed (at 30 days post-injection) increase in GABA and glutamate release, and no changes in acetylcholine release in the ipsilateral cortex in interleukin-1beta, but not saline, injected rats. Inhibition of inducible nitric oxide synthase expression by N(G)-nitro-L-arginine methyl ester administration prevented the increase in nitrogen intermediates and GABA release, but not in glutamate release. Our findings suggest that an inflammatory reaction of the basal forebrain facilitates GABA release through the production of nitric oxide.

Interest in the basal forebrain cholinergic system has greatly increased sinceneuropathological studies in humans provided evidence that this system is severely affected inAlzheimer fn2 s disease and other dementing disorders. In laboratory animals, disruption of the nucleusbasalis cholinergic neurones has been produced by several neurotoxic insults in order to obtain amodel reproducing the behavioural impairment related to the cholinergic deficits. The experiments reported in this review demonstrate that excitotoxic amino acids, β -amyloid and lipopolysaccharide, injected directly in the nucleus basalis are toxic to thecholinergic neurones in the rat. The excitotoxin lesions of the nucleus basalis, although notselective, are a useful tool for producing experimental animals with cholinergic hypofunction andfor investigating drugs able to ameliorate the cholinergic functions. Local injections of amyloidpeptides in the rat nucleus basalis produced cholinergic hypofunction and some behaviouralimpairment. Finally, an intense glia reaction with a limited cholinergic hypofunction and nobehavioural impairment was induced by a 4-week infusion of lipopolysaccharide in the nucleusbasalis. In conclusion, all three models, in spite of their limitations, offer useful tools for the studyof the pathogenetic mechanisms of Alzheimers disease and for investigating potentially usefuldrugs.

The effect of oral tacrine administration on cortical and hippocampal extracellular acetylcholine (ACh) levels has been investigated by a microdialysis technique, coupled to a HPLC method, in 6- and 22-24-month-old rats. In order to assess whether the increase in extracellular ACh levels was associated with an improvement in the age-related cognitive impairment, the object recognition and step-trough passive avoidance tests were carried out in the treated rats. The extracellular ACh levels measured in the cortex and hippocampus of aged rats without cholinesterase inhibitor in the perfusion Ringer solution were 39 and 54% lower, respectively, than in the young rats. At the dose of 3 mg kg-1, tacrine brought about a three- to four-fold increase in extracellular ACh levels, both in young and aged rats, which peaked 60-80 min after administration and disappeared within the next 60 min. At the same dose, tacrine caused a twofold increase in extracellular ACh levels in the hippocampus of young rats and a sixfold increase in aged rats. The absolute ACh levels at the peak in aged rats were not significantly different from those of young rats. In the object recognition test, aging rats were unable to discriminate between the familiar and novel object. Discrimination was restored by the administration of tacrine at the dose of 1 and 3 mg kg-1, but not 0. 3 mg kg-1 given 30 min before the first trial. Tacrine (3 mg kg-1 p. o.) administered to aging rats before the training trial significantly improved the acquisition of the passive avoidance conditioned response. Our findings demonstrate that tacrine increased both cortical and hippocampal extracellular ACh levels and improved behavioural functions in aged rats.

Brain inflammation is an underlying factor in the pathogenesis of Alzheimer's disease (AD) and epidemiological studies indicate that a sustained use of non-steroidal anti-inflammatory drugs (NSAIDs) has a protective effect on the disease. We investigated, in vivo, whether differences exist in the antiinflammatory and neuroprotective actions of flurbiprofen and its two nitric oxide-donor derivatives, HCT-1026 and NCX-2216, and the ability of these two derivatives to release nitric oxide in the brain. In adult rats injected into the nucleus basalis with preaggregated Aβ(1-42) we investigated by immunohistochemical methods glia reaction, the induction of inducible nitric oxide synthase (iNOS), the activation of p38 mitogen-activated protein kinase (p38MAPK) pathway and the number of choline acetyltransferase (ChAT)-positive neurons and, in naïve rats we investigated, by microdialysis, cortical extracellular levels of nitrite. Injection of Aβ(1-42) induced iNOS at the injection site, activated p38MAPK 7 days after injection and brought about an intense microglia and astrocyte reaction along with a marked reduction in the number of ChAT-positive neurones, persisting up to at least up to 21 days. Flurbiprofen, HCT-1026 and NCX-2216 (15 mg/kg) significantly attenuated the Aβ(1-42)-induced glia reaction, iNOS induction and p38MAPK activation 7 days after treatment and astrocytes reaction 21 days after treatment. On an equimolar basis, HCT-1026 resulted the most active agent in reducing the Aβ(1-42)-induced microglia reaction. The cholinergic cell loss was also significantly reduced by 21 days of HCT-1026 treatment. No differences in the body weight were found between the animals treated for 21 days with 15 mg/kg of either HCT-1026 or NCX-2216 and the controls. An oral administration of HCT-1026 (15 mg/kg) or NCX-2216 (100 mg/kg) to naiïve rats was followed by significant and long long -lasting increases in cortical nitrite levels. These findings indicate that the addition of a nitric oxide donor potentiates the anti-inflammatory activity of flurbiprofen in a model of brain inflammation.