Rett syndrome (RTT) is a rare neurodevelopmental disorder affecting almost exclusively females, caused in the overwhelming majority of the cases by loss-of-function mutations in the gene encoding methyl-CpG binding protein 2 (MECP2). High circulating levels of oxidative stress (OS) markers in patients suggest the involvement of OS in the RTT pathogenesis. To investigate the occurrence of oxidative brain damage in Mecp2 mutant mouse models, several OS markers were evaluated in whole brains of Mecp2-null (pre-symptomatic, symptomatic, and rescued) and Mecp2-308 mutated (pre-symptomatic and symptomatic) mice, and compared to those of wild type littermates. Selected OS markers included non-protein-bound iron, isoprostanes (F2-isoprostanes, F4-neuroprostanes, F2-dihomo-isoprostanes) and 4-hydroxy-2-nonenal protein adducts. Our findings indicate that oxidative brain damage 1) occurs in both Mecp2-null (both −/y and stop/y) and Mecp2-308 (both 308/y males and 308/+ females) mouse models of RTT; 2) precedes the onset of symptoms in both Mecp2-null and Mecp2-308 models; and 3) is rescued by Mecp2 brain specific gene reactivation. Our data provide direct evidence of the link between Mecp2 deficiency, oxidative stress and RTT pathology, as demonstrated by the rescue of the brain oxidative homeostasis following brain-specifically Mecp2-reactivated mice. The present study indicates that oxidative brain damage is a previously unrecognized hallmark feature of murine RTT, and suggests that Mecp2 is involved in the protection of the brain from oxidative stress.

Phytoprostanes are prostaglandin/jasmonate-like products of nonenzymatic lipid peroxidation that not only occur ubiquitously in healthy plants but also increase in response to oxidative stress. In this work, we show that the two naturally occurring B 1 -phytoprostanes (PPB 1 ) regioisomers I and II (each comprising two enantiomers) are short-lived stress metabolites that display a broad spectrum of biological activities. Gene expression analysis of Arabidopsis (Arabidopsis thaliana) cell cultures treated with PPB 1 -I or -II revealed that both regioisomers triggered a massive detoxification and defense response. Interestingly, expression of several glutathione S-transferases, glycosyl transferases, and putative ATP-binding cassette transporters was found to be increased by one or both PPB 1 regioisomers, and hence, may enhance the plant's capacity to inactivate and sequester reactive products of lipid peroxidation. Moreover, pretreatment of tobacco (Nicotiana tabacum) suspension cells with PPB 1 considerably prevented cell death caused by severe CuSO 4 poisoning. Several Arabidopsis genes induced by PPB 1 , such as those coding for adenylylsulfate reductase, tryptophan synthase b-chain, and PAD3 pointed to an activation of the camalexin biosynthesis pathway that indeed led to the accumulation of camalexin in PPB 1 treated leaves of Arabidopsis. Stimulation of secondary metabolism appears to be a common plant reaction in response to PPB 1 . In three different plant species, PPB 1 -II induced a concentration dependent accumulation of phytoalexins that was comparable to that induced by methyl jasmonate. PPB 1 -I was much weaker active or almost inactive. No differences were found between the enantiomers of each regioisomer. Thus, results suggest that PPB 1 represent stress signals that improve plants capacity to cope better with a variety of stresses.Phytoprostanes belong to a novel family of plant effectors that are formed nonenzymatically by a free radical catalyzed biochemical mechanism from a-linolenic acid. Via an identical nonenzymatic mechanism, isoprostanes (isomers of prostaglandins) are formed in animals from arachidonic acid. Nomenclature used to name different phytoprostane classes conforms with the general isoprostane/prostaglandin terminology . Due to the nonenzymatic formation of phytoprostanes, two racemic regioisomers (type I and II) of each class can be generated. One pathway leads to the formation of B 1 -phytoprostanes (PPB 1 ; Fig. 1) that are chemically stable end products of lipid peroxidation. In animals, isoprostanes are not only extremely reliable markers of oxidative stress but also display potent (prostaglandin-) receptor-mediated biological activities in the nanomolar concentration range (Cracowski et al., 2002). Therefore, it is postulated that isoprostanes represent mediators of oxidant injury in animals.In plants, several classes of phytoprostanes are constitutively present, and, notably, their levels increase in a variety of conditions associated with enhanced free radical generatio...

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Administration of the probiotic Escherichia coli strain Nissle 1917 (EcN) decreases visceral pain associated with irritable bowel syndrome. Mutation of clbA, a gene involved in the biosynthesis of secondary metabolites, including colibactin, was previously shown to abrogate EcN probiotic activity. Here, we show that EcN, but not an isogenic clbA mutant, produces an analgesic lipopeptide. We characterize lipoamino acids and lipopeptides produced by EcN but not by the mutant by online liquid chromatography mass spectrometry. One of these lipopeptides, C12AsnGABAOH, is able to cross the epithelial barrier and to inhibit calcium flux induced by nociceptor activation in sensory neurons via the GABAB receptor. C12AsnGABAOH inhibits visceral hypersensitivity induced by nociceptor activation in mice. Thus, EcN produces a visceral analgesic, which could be the basis for the development of new visceral pain therapies.

Supplementation with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been reported to reduce lipid peroxidation products formed from arachidonic acid (F(2)-isoprostanes) in healthy humans, as well as in those under oxidative stress. alpha-Linolenic acid (ALA) is a precursor to EPA and DHA; however, its conversion in humans is thought to be inefficient. ALA can also undergo free radical oxidation, forming compounds known as F(1)-phytoprostanes, which are found in all plants and are in high concentrations in plant pollens. In this study, we examined the effect of ALA supplementation on plasma and urine F(1)-phytoprostane and F(2)-isoprostane concentrations in men. Thirty-six nonsmoking men, aged 20-65 y, were recruited from the general population and randomly allocated to consume 9 g/d of either flaxseed oil (62% ALA, 5.4 g/d) or olive oil (placebo) for 4 wk in a parallel design. At baseline and after 4 wk of supplementation, blood samples and a 24-h urine sample were collected for measurement of plasma and urinary F(1)-phytoprostanes and F(2)-isoprostanes and plasma fatty acids. Compared with the olive oil group, plasma phospholipid ALA was greater (P < 0.0001), as were F(1)-phytoprostanes in plasma (P = 0.049) and urine (P = 0.06) in the flaxseed oil group after 4 wk supplementation. Flaxseed oil did not affect plasma or urinary F(2)-isoprostanes. The greater plasma F(1)-phytoprostane concentration in the flaxseed oil group most likely resulted from the increased plasma concentration of the ALA substrate and/or the F(1)-phytoprostane content of the flaxseed oil. Future studies are needed to determine the physiological importance of increased plasma and urine F(1)-phytoprostanes and their relevance to heart disease prevention.

Phytoprostanes (PhytoP's) are formed in higher plants from α-linolenic acid via a nonenzymatic free radical-catalyzed pathway and act as endogenous mediators capable of protecting cells from damage under various conditions related to oxidative stress. Humans are exposed to PhytoP's, as they are present in relevant quantities in vegetable food and pollen. The uptake of PhytoP's through the olfactory epithelium of the nasal mucosa, upon pollen grain inhalation, is of interest as the intranasal pathway is regarded as a direct route of communication between the environment and the brain. On this basis, we sought to investigate the potential activities of PhytoP's on immature cells of the central nervous system, which are particularly susceptible to oxidative stress. In neuroblastoma SH-SY5Y cells, used as a model for undifferentiated neurons, B1-PhytoP's, but not F1-PhytoP's, increased cell metabolic activity and protected them from oxidant damage caused by H2O2. Moreover, B1-PhytoP's induced a moderate depolarization of the mitochondrial inner membrane potential. These effects were prevented by the PPAR-γ antagonist GW9662. When SH-SY5Y cells were induced to differentiate toward a more mature phenotype, they became resistant to B1-PhytoP activities. B1-PhytoP's also influenced immature cells of an oligodendroglial line, as they increased the metabolic activity of oligodendrocyte progenitors and strongly accelerated their differentiation to immature oligodendrocytes, through mechanisms at least partially dependent on PPAR-γ activity. However, B1-PhytoP's did not protect oligodendrocyte progenitors against oxidant injury. Taken together, these data suggest that B1-PhytoP's, through novel mechanisms involving PPAR-γ, can specifically affect immature brain cells, such as neuroblasts and oligodendrocyte progenitors, thereby conferring neuroprotection against oxidant injury and promoting myelination.

F 2 -isoprostanes are prostaglandin-like compounds derived from nonenzymatic free radical-catalyzed peroxidation of arachidonic acid. 8-epi-Prostaglandin (PG) F 2␣ , a major component of the F 2 -isoprostane family, can be conveniently measured in urine to assess noninvasively lipid peroxidation in vivo. Measurement of major metabolites of endogenous 8-epi-PGF 2␣ , in addition to the parent compound, may be useful to better define its formation in vivo. 2,3-Dinor-5,6-dihydro-8-epi-PGF 2␣ is the only identified metabolite of 8-epi-PGF 2␣ in man, but its endogenous levels are unknown. In addition to this metabolite, we have identified another major endogenous metabolite, 2,3-dinor-8-epi-PGF 2␣ , in human and rat urine. The identity of these compounds, present at the pg/ml level in urine, was proven by a number of complementary approaches, based on: (a) immunoaffinity chromatography for selective extraction; (b) gas chromatography-mass spectrometry for structural analysis; (c) in vitro metabolism in isolated rat hepatocytes; and (d) chemical synthesis of the enantiomer of 2,3-dinor-5,6-dihydro-8-epi-PGF 2␣ as a reference standard. In humans, the urinary excretion rate of both dinor metabolites is comparable with that of 8-epi-PGF 2␣ . Both metabolites increase in parallel with the parent compound in cigarette smokers, and they are not reduced during cyclooxygenase inhibition. Another ␤-oxidation product, 2,3,4,5-tetranor-8-epi-PGF 2␣ , was identified as a major product of rat hepatocyte metabolism. In conclusion, at least two major ␤-oxidation products of 8-epi-PGF 2␣ are present in urine, which may be considered as additional analytical targets to evaluate 8-epi-PGF 2␣ formation and degradation in vivo.