Maternal suboptimal selenium intake and low-level lead exposure affect offspring's microglial immune profile and its reactivity to a subsequent inflammatory hit.

Micronutrients such as selenium (Se) are essentials since prenatal life to support brain and cognitive development. Se deficiency, which affects up to 1 billion people worldwide, can interact with common adverse environmental challenges including (Pb), exacerbating their toxic effects. Exploiting our recently validated rat model of maternal Se restriction and developmental low Pb exposure, our aims were to investigate: (i) the early consequences of suboptimal Se intake and low-Pb exposure on neuroinflammation in neonates' whole brains; (ii) the potential priming effect of suboptimal Se and low-Pb exposure on offspring's glial reactivity to a further inflammatory hit. To these aims female rats were fed with suboptimal (0.04 mg/kg; Subopt) and optimal (0.15 mg/kg; Opt) Se dietary levels throughout pregnancy and lactation and exposed or not to environmentally relevant Pb dose in drinking water (12.5 µg/mL) since 4 weeks pre-mating. We found an overall higher basal expression of inflammatory markers in neonatal brains, as well as in purified microglia and organotypic hippocampal slice cultures, from the Subopt Se offspring. Subopt/Pb cultures were highly activated than Subopt cultures and showed a higher susceptibility to the inflammatory challenge lipopolysaccharide than cultures from the Opt groups. We demonstrate that even a mild Se deficiency and low-Pb exposure during brain development can influence the neuroinflammatory tone of microglia, exacerbate the toxic effects of Pb and prime microglial reactivity to subsequent inflammatory stimuli. These neuroinflammatory changes may be responsible, at least in part, for adverse neurodevelopmental outcomes.

Docosahexaenoic acid promotes oligodendrocyte differentiation via PPAR-γ signalling and prevents tumor necrosis factor-α-dependent maturational arrest.

Docosahexaenoic acid (DHA) is an essential omega-3 fatty acid known to be neuroprotective in several models of human diseases, including multiple sclerosis. The protective effects of DHA are largely attributed to its ability to interfere with the activity of transcription factors controlling immune and inflammatory responses, including the agonist-dependent transcription factor peroxisome proliferator-activated receptor-γ (PPAR-γ). In this study, we used primary oligodendrocyte progenitor (OP) cultures from neonatal rat brain to investigate whether DHA could influence OP maturation and directly promote myelination, as previously reported for selective PPAR-γ agonists. We show that, similarly to the selective PPAR-γ agonist pioglitazone (PGZ), DHA promotes OP maturation and counteracts the maturational arrest induced by TNF-α, used to mimic inflammatory conditions. The PPAR-γ antagonist GW9662 prevented both DHA-induced OP maturation and PPAR-γ nuclear translocation, supporting the hypothesis that DHA acts through the activation of PPAR-γ. In addition, both PGZ and DHA induced the phosphorylation of extracellular signal-regulated-kinase 1-2 (ERK1/2), in a PPAR-γ-dependent manner. ERK1/2 activity is known to regulate the transition from OPs to immature oligodendrocytes and the presence of specific inhibitors of ERK1/2 phosphorylation (U0126 or PD98059) prevented the differentiating effects of both DHA and PGZ. These results indicate that DHA might influence the process of OP maturation through its PPAR-γ agonistic activity and provide novel molecular mechanisms for the action of this dietary fatty acid, further supporting the nutritional intervention in demyelinating diseases such as multiple sclerosis.

Stimulation of adenosine A2A receptors reduces intracellular cholesterol accumulation and rescues mitochondrial abnormalities in human neural cell models of Niemann-Pick C1.

Niemann Pick C 1 (NPC1) disease is an incurable, devastating lysosomal-lipid storage disorder characterized by hepatosplenomegaly, progressive neurological impairment and early death. Current treatments are very limited and the research of new therapeutic targets is thus mandatory. We recently showed that the stimulation of adenosine A2A receptors (A2ARs) rescues the abnormal phenotype of fibroblasts from NPC1 patients suggesting that A2AR agonists could represent a therapeutic option for this disease. However, since all NPC1 patients develop severe neurological symptoms which can be ascribed to the complex pathology occurring in both neurons and oligodendrocytes, in the present paper we tested the effects of the A2AR agonist CGS21680 in human neuronal and oligodendroglial NPC1 cell lines (i.e. neuroblastoma SH-SY5Y and oligodendroglial MO3.13 transiently transfected with NPC1 small interfering RNA). The down-regulation of the NPC1 protein effectively resulted in intracellular cholesterol accumulation and altered mitochondrial membrane potential. Both effects were significantly attenuated by CGS21680 (500 nM). The protective effects of CGS were prevented by the selective A2AR antagonist ZM241385 (500 nM). The involvement of calcium modulation was demonstrated by the ability of Bapta-AM (5-7 µM) in reverting the effect of CGS. The A2A-dependent activity was prevented by the PKA-inhibitor KT5720, thus showing the involvement of the cAMP/PKA signaling. These findings provide a clear in vitro proof of concept that A2AR agonists are promising potential drugs for NPC disease.

Peroxisome proliferator activated receptor-γ agonists protect oligodendrocyte progenitors against tumor necrosis factor-alpha-induced damage: Effects on mitochondrial functions and differentiation.

The activation of the nuclear receptor peroxisome proliferator-activated receptor-γ (PPAR-γ) is known to exert anti-inflammatory and neuroprotective effects and PPAR-γ agonists are considered potential therapeutic agents in brain diseases including those affecting myelin. In demyelinating diseases such as multiple sclerosis (MS), inflammation is one of the causes of myelin and axonal damage. Oligodendrocyte (OL) differentiation is highly dependent on mitochondria, which are major targets of inflammatory insult. Here we show that PPAR-γ agonists protect OL progenitors against the maturational arrest induced by the inflammatory cytokine TNF-α by affecting mitochondrial functions. We demonstrate that the inhibition of OL differentiation by TNF-α is associated with i) increased mitochondrial superoxide production; ii) decreased mitochondrial membrane potential (mMP); and iii) decreased ADP-induced Ca(2+) oscillations, which we previously showed to be dependent on efficient mitochondria. The TNF-α effects were comparable to those of the mitochondrial toxin rotenone, further suggesting that TNF-α damage is mediated by mitochondrial function impairment. PPAR-γ agonists protected OL progenitors against the inhibitory activities of both TNF-α and rotenone on mMP, mitochondrial ROS production, Ca(2+) oscillations and OL differentiation. Finally, the PPAR-γ agonist pioglitazone increased the expression of PGC-1α (a mitochondrial biogenesis master regulator), UCP2 (a mitochondrial protein known to reduce ROS production), and cytochrome oxidase subunit COX1. These findings confirm the central role of mitochondria in OL differentiation and point to mitochondria as major targets of PPAR-γ agonist protection against TNF-α damage.

Deletion of the lifespan determinant p66(Shc) improves performance in a spatial memory task, decreases levels of oxidative stress markers in the hippocampus and increases levels of the neurotrophin BDNF in adult mice.

Deletion of the p66(Shc) gene in mice results in reduced levels of oxidative stress and longer lifespan. Reactive oxygen species (ROS) can lead to tissue damage, particularly in the brain. In this study we extended previous findings on the behavioral phenotype of the p66(Shc-/-) mice. Cognitive performance of adult and old p66(Shc-/-) and p66(Shc+/+) mice was tested in a Morris water maze (MWM) task while general reactivity and pain sensitivity were assayed at adulthood, respectively, in an open field and by means of a tail flick test. Levels of brain-derived neurotrophic factor (BDNF), a neurotrophin involved in several aspects of synaptic plasticity, emotionality and pain sensitivity, were assessed in selected brain areas. P66(Shc-/-) adult subjects, compared to WT, overall showed a better performance in the MWM, lower emotionality and a higher pain threshold, in addition to increased basal levels of BDNF in the hippocampus, as well as decreased levels of oxidative stress markers in the same brain area. Although all aged subjects failed to learn the cognitive task, aged p66(Shc-/-) mice were characterized by a better physical performance. These results suggest an interaction between the p66(Shc) gene and specific signaling pathways involved in behavioral adaptation to stress and aging.

NGF promotes microglial migration through the activation of its high affinity receptor: modulation by TGF-beta.

Activation and mobilization of microglia are early events in the majority of brain pathologies. Among the signalling molecules that can affect microglial behaviour, we investigated whether nerve growth factor (NGF) was able to influence microglial motility. We found that NGF induced chemotaxis of microglial cells through the activation of TrkA receptor. In addition, NGF chemotactic activity was increased in the presence of low concentrations (< or =0.2 ng/ml) of transforming growth factor-beta (TGF-beta), which at this concentration showed chemotactic activity per se. On the contrary, NGF-induced microglial migration was reduced in the presence of chemokinetic concentration of TGF-beta (> or =2 ng/ml). Finally, both basal and NGF-induced migratory activity of microglial cells was increased after a long-term exposure of primary mixed glial cultures to 2 ng/ml of TGF-beta. Our observations suggest that both NGF and TGF-beta contribute to microglial recruitment. The chemotactic activities of these two pleiotropic factors could be particularly relevant during chronic diseases in which recruited microglia remove apoptotic neurons in the absence of a typical inflammatory reaction.

Adenosine A(2A) receptors modulate BDNF both in normal conditions and in experimental models of Huntington's disease.

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, enhances synaptic transmission and regulates neuronal proliferation and survival. Functional interactions between adenosine A(2A) receptors (A(2A)Rs) and BDNF have been recently reported. In this article, we report some recent findings from our group showing that A(2A)Rs regulate both BDNF functions and levels in the brain. Whereas BDNF (10 ng/ml) increased the slope of excitatory postsynaptic field potentials (fEPSPs) in hippocampal slices from wild-type (WT) mice, it was completely ineffective in slices taken from A(2A)R knock-out (KO) mice. Furthermore, enzyme immunoassay studies showed a significant reduction in hippocampal BDNF levels in A(2A)R KO vs. WT mice. Having found an even marked reduction in the striatum of A(2A)R KO mice, and as both BDNF and A(2A)Rs have been implicated in the pathogenesis of Huntington's disease (HD), an inherited striatal neurodegenerative disease, we then evaluated whether the pharmacological blockade of A(2A)Rs could influence striatal levels of BDNF in an experimental model of HD-like striatal degeneration (quinolinic acid-lesioned rats) and in a transgenic mice model of HD (R6/2 mice). In both QA-lesioned rats and early symptomatic R6/2 mice (8 weeks), the systemic administration of the A(2A)R antagonist SCH58261 significantly reduced striatal BDNF levels. These results indicate that the presence and the tonic activation of A(2A)Rs are necessary to allow BDNF-induced potentiation of synaptic transmission and to sustain a normal BDNF tone. The possible functional consequences of reducing striatal BDNF levels in HD models need further investigation.

Microglia-neuron interaction in inflammatory and degenerative diseases: role of cholinergic and noradrenergic systems.

Reciprocal interactions between glia and neurons are essential for many critical functions in brain health and disease. Microglial cells, the brain resident macrophages, and astrocytes, the most prevalent type of cell in brain, are actively involved in the control of neuronal activities both in developing and adult organisms. At the same time, neurons influence glial functions, through direct cell-to-cell interactions as well as the release of soluble mediators. Among signals from neurons that may have an active role in controlling glial activation are two major neurotransmitters: acetylcholine and noradrenaline. Several studies indicate that microglia and astrocytes express adrenergic receptors, whose activation influences the release of pro-inflammatory mediators, controlling the extent of glial reactivity. Acetylcholine receptors are also expressed by glial cells. In particular, microglial cells express the nicotinic receptor alpha7 and its activation attenuates the pro-inflammatory response of microglial cultures, suggesting that acetylcholine may control brain inflammation, in analogy to what demonstrated in peripheral tissues. Deficiencies of noradrenergic and cholinergic systems are linked to important neurodegenerative diseases such as Parkinson's disease (PD) and Alzheimer's disease (AD) and it has been suggested that in addition to impairing neuron-to-neuron transmission, noradrenergic and cholinergic hypofunction may contribute to dysregulation of the normal neuron-glia interaction, abnormal glial reaction and, eventually, neurodegeneration. A deeper knowledge of role of cholinergic and noradrenergic systems in controlling neuron-glia interactions may offer new venues for disease treatments.

Levels of CSF prostaglandin E2, cognitive decline, and survival in Alzheimer's disease.

BACKGROUND: Although epidemiological, clinical, and experimental evidence indicates that the inducible isoform of cyclo-oxygenase (COX-2) may be involved in the pathogenesis of several neurodegenerative disorders, the mechanisms whereby COX-2 contributes to Alzheimer's disease are largely unknown. OBJECTIVE: To undertake a longitudinal study of CSF levels of a major product of COX activity, prostaglandin E2 (PGE2), in relation to cognitive decline and survival in patients with Alzheimer's disease. METHODS: CSF PGE2 was measured on at least three annual visits in 35 controls and 33 Alzheimer patients (26 necropsy confirmed) who completed the Cambridge cognitive assessment (CAMCOG). RESULTS: Compared with controls, CSF PGE2 was higher in patients with mild memory impairment, but lower in those with more advanced Alzheimer's disease. The median survival time of patients with higher initial PGE2 levels was five years longer than those with lower levels. CONCLUSIONS: COX activity in Alzheimer's disease varies with stage of the disease. PGE2 levels correlate positively with patient survival. These findings suggest that inhibition of COX activity does not represent a major target for the pharmacological treatment of Alzheimer's disease.

Prolonged exposure of microglia to lipopolysaccharide modifies the intracellular signaling pathways and selectively promotes prostaglandin E2 synthesis.

During inflammatory or degenerative processes microglial cells are likely to be exposed to activating agents that persist in brain parenchyma for prolonged periods. As our knowledge on microglial activation is largely based on in vitro studies in which microglial cultures are activated by a single administration of pro-inflammatory stimuli, we investigated the effects of repeated endotoxin (LPS) challenges on microglial functional state. Primary rat microglial cultures were subjected to one, two or three consecutive LPS-stimulation and the production of tumor necrosis factor-alpha (TNF-alpha), nitric oxide (NO), prostaglandin E2 (PGE2) and 15-deoxy-Delta12,14-PGJ2 (15d-PGJ2) measured. The ability of microglial cells to produce NO, TNF-alpha and 15d-PGJ2 upon the first LPS challenge rapidly declined after the second and the third stimulations, whereas PGE2 synthesis remained constantly elevated. Accordingly, the expression of inducible NO synthase decreased whereas cyclooxygenase-2 and microsomal PGE synthase remained up-regulated. The signaling pathways evoked by single or multiple LPS-stimulation were also profoundly different, when considering the activation of the transcription factors nuclear factor-kappa B and CREB, and of the p38 MAPK. Our observations suggest that prolonged exposure to LPS, and likely other activating agents, induces in microglia a functional state clearly distinct from that triggered by acute stimulation. The progressive down-regulation of pro-inflammatory molecules and the sustained release of PGE2 could have important implications for the resolution of brain inflammation.

Effects of phosphatidylserine on p38 mitogen activated protein kinase, cyclic AMP responding element binding protein and nuclear factor-kappaB activation in resting and activated microglial cells.

In the last few years, the interaction between phosphatidylserine (PS), a phospholipid that becomes permanently exposed on the external cell surface in the early phases of apoptosis, and its specific receptor (PtdSerR) has emerged as a crucial event for the engulfing of apoptotic cells and for preventing the acquisition of pro-inflammatory functions by peripheral macrophages. Recently, we demonstrated that PtdSerR is expressed in microglial cultures purified from neonatal rat brain, and that PS-liposomes, used to mimic apoptotic cells, strongly reduce the lipopolysaccharide (LPS)-induced release of inflammatory mediators. Here, we show that in resting microglia, PS-liposomes induce cyclic AMP responding element binding protein (CREB) phosphorylation but do not activate nuclear factor-kappaB (NF-kappaB) and p38 mitogen-activated protein kinase (p38), in line with the non-inflammatory consequences of the recognition and removal of apoptotic cells by macrophages. In LPS-activated microglia, PS-liposomes did not affect NF-kappaB activation but inhibited the phosphorylation of p38 and delayed that of CREB. To our knowledge, this is the first biochemical evidence of the molecular signaling evoked by PS/PtdSerR interaction possibly related to repression of pro-inflammatory activities in microglial cells.

The presence of astrocytes enhances beta amyloid-induced neurotoxicity in hippocampal cell cultures.

A characteristic feature of neuritic plaques in Alzheimer's disease is represented by the presence of activated astrocytes, surrounding dystrophic neurons and beta-amyloid deposition. To explore the role of astrocytes in in vitro beta-amyloid neurotoxicity, we studied the effect of beta-amyloid treatment in hippocampal neurons in two different cell models: pure cultures, where neurons were grown in absence of astrocytes and mixed cultures, where neurons were seeded on a confluent layer of astrocytes. We evaluated two characteristic aspects of in vitro beta-amyloid neurotoxicity: reduction of cell viability and degeneration of the neuritic tree. We demonstrated that neurons growing on astrocytes were more prone to the detrimental effect of the amyloid peptide, with respect to neurons grown in absence of the glial component. Our results support the hypothesis that beta-amyloid-astrocyte interaction can adversely condition neurons and contribute to neuronal damage in Alzheimer's disease.

In vivo activation of N-methyl-D-aspartate receptors in the rat hippocampus increases prostaglandin E(2) extracellular levels and triggers lipid peroxidation through cyclooxygenase-mediated mechanisms.

Cyclooxygenases (COX) are a family of enzymes involved in the biosynthesis of prostaglandin (PG) and thromboxanes. The inducible enzyme cyclooxygenase-2 (COX-2) is the major isoform found in normal brain, where it is constitutively expressed in neurons and is further up-regulated during several pathological events, including seizures and ischaemia. Emerging evidence suggests that COX-2 is implicated in excitotoxic neurodegenerative phenomena. It remains unclear whether PGs or other products associated to COX activity take part in these processes. Indeed, it has been suggested that reactive oxygen species, produced by COX, could mediate neuronal damage. In order to obtain direct evidence of free radical production during COX activity, we undertook an in vivo microdialysis study to monitor the levels of PGE(2) and 8-epi-PGF(2alpha) following infusion of N-methyl-D-aspartate (NMDA). A 20-min application of 1 mm NMDA caused an immediate, MK-801-sensitive increase of both PGE(2) and 8-epi-PGF(2alpha) basal levels. These effects were largely prevented by the specific cytosolic phospholipase A(2) (cPLA(2) ) inhibitor arachidonyl trifluoromethyl ketone (ATK), by non- selective COX inhibitors indomethacin and flurbiprofen or by the COX-2 selective inhibitor NS-398, suggesting that the NMDA-evoked prostaglandin synthesis and free radical-mediated lipid peroxidation are largely dependent on COX-2 activity. As several lines of evidence suggest that prostaglandins may be potentially neuroprotective, our findings support the hypothesis that free radicals, rather than prostaglandins, mediate the toxicity associated to COX-2 activity.

Increased CSF levels of prostaglandin E(2) in variant Creutzfeldt-Jakob disease.

The concentration of the cyclooxygenase product prostaglandin E(2) was sixfold higher in CSF samples from 18 cases of variant Creutzfeldt-Jakob disease (CJD) than in a group of eight subjects with other noninflammatory neurologic diseases, and comparable to those found in a group of six patients affected by diseases with a known inflammatory component. This finding suggests that cyclooxygenase activity may have a role in variant CJD pathogenesis, as previously reported in sporadic CJD.

Differential effects of the nonsteroidal antiinflammatory drug flurbiprofen and its nitric oxide-releasing derivative, nitroflurbiprofen, on prostaglandin E(2), interleukin-1beta, and nitric oxide synthesis by activated microglia.

Increasing experimental, clinical, and epidemiological studies point to the pivotal role of inflammation in the pathogenesis of acute and chronic neurodegenerative diseases and to the protective effects of nonsteroidal antiinflammatory drug (NSAID) therapies. Nonetheless, NSAID long-term therapies are limited by their significant adverse effects on gastrointestinal tract and kidneys. Nitroflurbiprofen (NO-flurbiprofen) belongs to a novel class of antiinflammatory agents obtained by derivatization of conventional NSAIDs with a nitric oxide (NO)-releasing moiety, which strongly reduces their untoward side effects without altering the antiinflammatory effectiveness. The recent evidence of neuroprotective effects of NO-NSAIDs in animal models of chronic brain inflammation prompted us to investigate the activities of NO-flurbiprofen and its parent molecule flurbiprofen on activated rat microglia, the brain resident macrophages. We found that NO-flurbiprofen was as potent as flurbiprofen in preventing prostaglandin E(2) synthesis in lipopolysaccharide-activated microglial cultures. At variance with previous observations on peripheral macrophages is that NO-flurbiprofen did not show any additional capacity to inhibit interleukin-1beta synthesis compared with flurbiprofen. Moreover, NO enhanced the expression of the inducible NO synthase; this effect was most likely attributable to the NO released from the drug, as suggested by experiments performed in the presence of the NO donor Deta-NONOate, which similarly to NO-flurbiprofen is characterised by a slow and long-lasting release. Our findings indicate that NO-NSAIDs may differently affect peripheral and brain macrophages. Given their potential therapeutic role in brain inflammation, further in vivo and in vitro studies are required to understand fully their mechanism of action in the CNS.

Human immunodeficiency virus type-1 Tat protein induces nuclear factor (NF)-kappaB activation and oxidative stress in microglial cultures by independent mechanisms.

We have extended our previous findings and shown that human immunodeficiency virus Tat protein, in addition to nitric oxide (NO), stimulated rat microglial cultures to release pro-inflammatory cytokine interleukin-1beta and tumour necrosis factor-alpha in a nuclear factor (NF)-kappaB-dependent manner. At the same time, Tat stimulated the accumulation of free radicals, as indicated by the increased levels of isoprostane 8-epi-prostaglandin F(2alpha) (8-epi-PGF(2alpha)), a reliable marker of lipid peroxidation and oxidative stress, by a mechanism unrelated to NF-kappaB activation. The presence of free radical scavengers abrogated Tat-induced 8-epi-PGF(2alpha) accumulation without affecting NO and cytokine production. Consistently, Tat-induced IkappaBalpha degradation - an index of NF-kappaB activation - was not affected by free radical scavengers, but was prevented by an NF-kappaB-specific inhibitor. Our observations indicate that NF-kappaB plays a key role in Tat-dependent microglial activation, and that oxidative stress and NF-kappaB activation induced by Tat occur by independent mechanisms.

Astrocytes contribute to neuronal impairment in beta A toxicity increasing apoptosis in rat hippocampal neurons.

Astrocytosis is a common feature of amyloid plaques, the hallmark of Alzheimer's disease (AD), along with activated microglia, neurofibrillary tangles, and beta-amyloid (beta A) deposition. However, the relationship between astrocytosis and neurodegeneration remains unclear. To assess whether beta A-stimulated astrocytes can damage neurons and contribute to beta A neurotoxicity, we studied the effects of beta A treatment in astrocytic/neuronal co-cultures, obtained from rat embryonic brain tissue. We found that in neuronal cultures conditioned by beta A-treated astrocytes, but not directly in contact with beta A, the number of apoptotic cells increased, doubling the values of controls. In astrocytes, beta A did not cause astrocytic cell death, nor did produce changes in nitric oxide or prostaglandin E(2) levels. In contrast, S-100 beta expression was remarkably increased. Our data show for the first time that beta A--astrocytic interaction produces a detrimental effect on neurons, which may contribute to neurodegeneration in AD.

[Isoprostanes and oxidative stress in brain damage in newborns]. / Isoprostani e stress ossidativo nel danno cerebrale del neonato.

Isoprostanes are a family of biologically active molecules recently characterized, which is emerging as a new class of specific and reliable markers of in vivo and ex vivo lipid peroxidation and oxidative damage. These molecules are stable, relatively abundant and easily detectable by sensitive and specific analytical methods. In the last years, the measurement of their levels in tissue homogenates or biological fluids has significantly improved our knowledge on the involvement of oxidative stress in several neurological diseases. Here we present evidence indicating that isoprostanes can be successfully used also to study the mechanisms involved in free radical brain damage following hypoxic-ischaemic or inflammatory conditions in newborns and preterm infants.

Isoprostanes, novel markers of oxidative injury, help understanding the pathogenesis of neurodegenerative diseases.

Isoprostanes are prostaglandin-like compounds which are formed by free radical catalysed peroxidation of arachidonic acid esterified in membrane phospholipids. They are emerging as a new class of sensitive, specific and reliable markers of in vivo lipid peroxidation and oxidative damage. Since their initial description of in 1990, the rapid development of analytical methods for isoprostane measurement has allowed to overcome some of the pitfalls of the previous and most widely used methods of assessing free radical injury. Here, we summarise the current knowledge on these novel class lipid peroxidation products and the advantages of monitoring their formation to better define the involvement of oxidative stress in neurological diseases. Although the literature data are still not abundant, they indicate that in vivo or post mortem cerebrospinal fluid and brain tissue levels of isoprostane are increased in some diseases such as multiple sclerosis, Alzheimer's disease, Huntington's disease, and Creutzfeldt-Jakob disease.

Increased brain synthesis of prostaglandin E2 and F2-isoprostane in human and experimental transmissible spongiform encephalopathies.

The levels of 2 arachidonic acid metabolites formed either by enzymatic activity of cyclooxygenase, i.e. prostaglandin E2 (PGE2), or by free radical-catalyzed peroxidation, i.e. F2-isoprostane 8-epi-prostaglandin F2alpha (8-epi-PGF2alpha), were measured in the CSF of subjects with sporadic and familial Creutzfeldt-Jakob disease (CJD) and in brain homogenates of scrapie-infected mice. The CSF levels of both metabolites were increased in sporadic CJD (n = 52) and familial CJD (n = 10) patients when compared with a group of patients with noninflammatory disorders. Similarly, PGE2 and 8-epi-PGF2alpha levels were higher in brain homogenates obtained from C57BL/6J mice infected with the ME7 scrapie strain than in brain homogenates from control animals. As PGE2 is 1 of the most abundant prostaglandins released during inflammation and 8-epi-PGF2alpha is a quantitative marker of lipid peroxidation, our results provide in vivo biochemical evidence for the occurrence of inflammation and oxidative stress in human and experimental transmissible spongiform encephalopathies (TSEs), a concept so far based mainly on histopathological and in vitro evidence. Interestingly, in sporadic CJD patients, high CSF levels of PGE2, but not 8-epi-PGF2alpha, correlated with short survival time, suggesting that the inflammatory response correlates with the clinical duration of disease.