Hydrogen Peroxide-Induced Oxidative Stress Activates Proteasomal Trypsin-Like Activity in Human U373 Glioma Cells.

Degradation of oxidized or oxidatively modified proteins is an essential part of the cellular antioxidant defense system. 4-Hydroxy-2-nonenal, a major reactive aldehyde formed by lipid peroxidation, causes many types of cellular damage. The major proteolytic system for modified protein degradation is the ubiquitin-proteasome pathway.

Axonal transport of neprilysin in rat sciatic nerves.

Axonal transport of neprilysin, a putative neuropeptide degrading-enzyme, was examined in the proximal, middle, and distal segments of rat sciatic nerves using a double ligation technique. Neprilysin activity was significantly increased not only in the proximal segment but also in the distal segment 12-120 h after ligation, and the maximal neprilysin activity was found in the proximal and distal segments at 96 and 72 h, respectively. Western blot analysis of neprilysin showed that its immunoreactivities in the proximal and distal segments were 2.

Key role of chemical hardness to compare 2,2-diphenyl-1-picrylhydrazyl radical scavenging power of flavone and flavonol O-glycoside and C-glycoside derivatives.

The antioxidant activities of flavonoids and their glycosides were measured with the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH radical, DPPH(·)) scavenging method. The results show that free hydroxyl flavonoids are not necessarily more active than O-glycoside. Quercetin and kaempferol showed higher activity than apigenin.

4-hydroxy-2-nonenal-modified glyceraldehyde-3-phosphate dehydrogenase is degraded by cathepsin G in rat neutrophils.

Degradation of oxidized or oxidatively modified proteins is an essential part of the antioxidant defenses of cells. 4-Hydroxy-2-nonenal, a major reactive aldehyde formed by lipid peroxidation, causes many types of cellular damage. It has been reported that 4-hydroxy-2-nonenal-modified proteins are degraded by the ubiquitin-proteasome pathway or, in some cases, by the lysosomal pathway.

Products of thymine oxygenation by a non-heme oxygenation model, Fe(II)(MeCN)6(2+)-Ac2O-H2O2, and the transition state model between oxoiron and thymine.

Oxidative thymine damage was investigated using a new non-heme oxygenation model, Fe(MeCN)6(2+)-H2O2-Ac2O, based on high-spin Fe(MeCN)6(2+) in a non-aqueous solution, Ac2O-MeCN. Thymine and 1,3-dimethylthymine oxidized by the system gave the corresponding trans-thymine glycol derivatives in good yield. Thymineglycol is equivalent to an oxidative product as a measure of oxidative DNA damage in living cells.

Development of new double-stranded phenylalanyl chelators using eta-chi diagrams and binding constants for chelators and lanthanide ions.

We examined the interaction between several ligands and alkaline (M(+)) or lanthanide (Ln(3+)) ions using eta-chi diagrams. eta and chi represent absolute hardness and absolute electronegativity, respectively. Based on the diagrams, new double-stranded amino acid chelators (1) conjugated to Cat (catechol) were synthesized.

Inhibition of nucleoside transport and synergistic potentiation of methotrexate cytotoxicity by cimicifugoside, a triterpenoid from Cimicifuga simplex.

Cimicifugoside, a triterpenoid isolated from Cimicifuga simplex, which has been used as a traditional Chinese medicine due to its anti-inflammatory, analgesic or anti-pyretic action, was examined for inhibition of nucleoside transport and synergistic potentiation of methotrexate cytotoxicity. Cimicifugoside inhibited uptake of uridine, thymidine and adenosine in human leukemia U937 cells with the low nanomolar IC(50) values, but did not affect that of uracil, leucine or 2-deoxyglucose at cimicifugenin (aglycon of cimicifugoside)>bugbanoside B>cimicifugenin A, O-methyl cimicifugenin and bugbanoside A.

Effect of memantine on the levels of neuropeptides and microglial cells in the brain regions of rats with neuropathic pain.

Neuropathic pain induced by sciatic nerve injury not only causes peripheral dysfunctions but also affects the cortical and subcortical regions of the brain. It is still unknown whether neuropathic pain could relate to behavioral and neurochemical alterations in the central nervous system. This paper deals with the effect of peripheral neuropathic pain on mechanical allodynia, neuropeptide levels, neuropeptide-degrading enzyme activities, and microglial cells in the brain regions of rats by applying chronic constriction injury, a partial sciatic nerve injury.

Interleukin-6 induces prostaglandin E(2) synthesis in mouse astrocytes.

The physiological function of interleukin-6 within the central nervous system (CNS) is complex; interleukin-6 exerts neurotrophic and neuroprotective effects and yet can also function as a mediator of inflammation, demyelination, and astrogliosis depending on the cellular context. However, the roles of interleukin-6 in astrocytes are poorly understood. In the present study, we investigated the effect of the pro-inflammatory cytokine interleukin-6 on the production of the inflammatory mediator prostaglandin E(2) in mouse astrocytes.

Up-regulation of hepatic heme oxygenase-1 expression by locally induced interleukin-6 in rats administered carbon tetrachloride intraperitoneally.

We previously reported that interleukin-6 (IL-6) was locally produced in the early period after intraperitoneal (i.p.) or subcutaneous carbon tetrachloride (CCl4) administration, but not after oral (p.

4-Hydroxy-2-nonenal-modified glyceraldehyde-3-phosphate dehydrogenase is degraded by cathepsin G.

Degradation of oxidized or oxidatively modified proteins is an essential part of the antioxidant defenses of cells. 4-Hydroxy-2-nonenal (HNE), a major reactive aldehyde formed by lipid peroxidation, causes many types of cellular damage. It has been reported that HNE-modified proteins are degraded by the ubiquitin-proteasome pathway or, in some cases, by the lysosomal pathway.

Interleukin-6 production by peritoneal mesothelial cells and its regulation by inflammatory factors in rats administered carbon tetrachloride intraperitoneally.

We previously reported that a high level of interleukin-6 (IL-6), which is protective against CCl(4)-induced hepatotoxicity, is produced in the peritoneal cavity in the early period after ip carbon tetrachloride (CCl(4)) administration. The objective of this study was to identify the tissues and cells involved in IL-6 production and clarify the mechanisms underlying its regulation. IL-6 mRNA levels increased significantly in the serous membranes of the mesentery and peritoneum, but not in the parenchymal organs including liver, kidney and spleen, 3 h after ip CCl(4) administration.

Early induced, high-level interleukin-6 expression in the rat peritoneal cavity into which a hepatotoxicant carbon tetrachloride was administered.

IL-6 induction depending on the mode of carbon tetrachloride (CCl4) administration was investigated in rats. After the intraperitoneal (i.p.

Suppressive effect of clozapine but not haloperidol on the increases of neuropeptide-degrading enzymes and glial cells in MK-801-treated rat brain regions.

MK-801, a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, produces neurotoxicity in adult rodent brain, and causes schizophrenia-like psychosis and cognitive dysfunction. Since neuropeptides and neuropeptide-degrading enzymes play important roles in cognitive function, we examined whether or not MK-801-induced schizophrenia-like psychosis is co-related with the changes of these enzymes in rat brain regions. In the present study, we investigated the effect of systemic treatment with MK-801 (0.

Axonal transports of tripeptidyl peptidase II in rat sciatic nerves.

Axonal transport of tripeptidyl peptidase II, a putative cholecystokinin inactivating serine peptidase, was examined in the proximal, middle, and distal segments of rat sciatic nerves using a double ligation technique. Enzyme activity significantly increased not only in the proximal segment but also in the distal segment 12-72h after ligation, and the maximal enzyme activity was found in the proximal and distal segments at 72h. Western blot analysis of tripeptidyl peptidase II showed that its immunoreactivities in the proximal and distal segments were 3.

Clozapine but not haloperidol suppresses the changes in the levels of neuropeptides in MK-801-treated rat brain regions.

Noncompetitive NMDA receptor antagonist (+)MK-801 is known to induce neurotoxicity and schizophrenia-like symptomatology where atypical neuroleptic clozapine is effective in contrast to typical neuroleptic, haloperidol. Although neuropeptides are implicated in memory and cognition, their roles in schizophrenia are not well understood. In the present study, we therefore examined the possible roles of neuropeptides, cholecystokinin (CCK) and somatostatin (SS) in the posterior cingulate/retrosplenial cortices (PC/RSC), frontal cortex, and hippocampus of a MK-801-induced schizophrenia-like model rat brain.

Pentylenetetrazol-induced seizures affect the levels of prolyl oligopeptidase, thimet oligopeptidase and glial proteins in rat brain regions, and attenuation by MK-801 pretreatment.

The regulatory mechanisms of neuropeptide-metabolizing enzymes often play a critical role in the pathogenesis of neuronal damage. A systemic administration of pentylenetetrazol (PTZ), an antagonist of GABA(A) receptor ion channel binding site, causes generalized epilepsy in an animal model. In the present study, we examined the involvement of prolyl oligopeptidase (POP), thimet oligopeptidase/neurolysin (EP 24.

Degradation of glyceraldehyde-3-phosphate dehydrogenase triggered by 4-hydroxy-2-nonenal and 4-hydroxy-2-hexenal.

Lipid peroxidation products such as 4-hydroxy-2-nonenal (HNE) may be responsible for various pathophysiological events under oxidative stress, since they injure cellular components such as proteins and DNA. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which is a key enzyme of glycolysis and has been reported to be a multifunctional enzyme, is one of the enzymes inhibited by HNE. Previous studies showed that GAPDH is degraded when incubated with acetylleucine chloromethyl ketone (ALCK), resulting in the liberation of a 23-kDa fragment.

Improved determination of bovine glutaminyl cyclase activity using precolumn derivatization and reversed-phase high-performance liquid chromatography with ultraviolet detection.

A sensitive, rapid and reproducible assay for the determination of glutaminyl cyclase activity is reported. This method is based on the monitoring of the absorption of l-pyroglutamic acid beta-naphthylamide at 235 nm, enzymatically formed from the substrate l-glutaminyl-beta-naphthylamide, after separation by high-performance liquid chromatography using a C-18 reversed-phase column by isocratic elution. The detection limit of this method is at a level as low as 0.

Conformational change of glyceraldehyde-3-phosphate dehydrogenase induced by acetylleucine chloromethyl ketone is followed by unique enzymatic degradation.

We have previously reported that acetylleucine chloromethyl ketone (ALCK), an inhibitor of acylpeptidehydrolase, induces the inhibition and degradation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the U937 cell extract. In the present study, the process of ALCK-induced GAPDH degradation was investigated. A kinetic study revealed that GAPDH was irreversibly inhibited by ALCK.

Dose-dependent effect of MK-801 on the levels of neuropeptides processing enzymes in rat brain regions.

The appropriate levels of neuropeptides and their processing enzyme activities are required to continue a normal cell life, and the dysfunction of these peptides and enzymes are responsible for many neuronal abnormalities. Systemic administration of (+) MK-801 (dizocilpine maleate), a noncompetitive N-methyl-[D]-aspartate (NMDA) receptor antagonist, causes both neuroprotective and neurotoxic activities depending on doses and conditions. In the present study, we investigated the dose dependent effect of (+) MK-801 on prolyl endopeptidase (PEP), endopeptidase EC 24.

Changes in the levels of neuropeptides and their metabolizing enzymes in the brain regions of nucleus basalis magnocellularis-lesioned rats.

The regulation mechanism of the interrelation between neuropeptides and their metabolizing enzymes in in vivo tissues is still not clear. In the present report, we attempted to measure the levels of neuropeptides and their enzymes in the frontal cortex, hippocampus, and striatum of the rat that had been bilaterally lesioned by the infusion of ibotenic acid or amyloid beta-peptide 25 - 35 (Abeta25 - 35) into the nucleus basalis magnocellularis. In the drug-treated rats, at two weeks after the infusion, the decrease of somatostatin-like immunoreactivity (SS-LI) and the increase of cholecystokinin-8S-LI were found in some brain regions relative to vehicle-treated rats.

Characterization of muscarinic receptor subtypes in the rostral ventrolateral medulla and effects on morphine-induced antinociception in rats.

The present study investigated the role of muscarinic receptor subtypes in the nucleus reticularis gigantocellularis/nucleus reticularis gigantocellularis alpha of the rat rostral ventrolateral medulla in morphine-induced antinociception. The antinociceptive effects of morphine were evoked by systemic administration or microinjection into the nucleus reticularis gigantocellularis/nucleus reticularis gigantocellularis alpha. Administration of morphine produced antinociception for hot plate and tail immersion responses to noxious heat stimuli.

Anterograde axonal transport of endopeptidase 24.15 in rat sciatic nerves.

Axonal transport of endopeptidase 24.15 (EP24.15), a putative neuropeptide degrading-enzyme, was examined in the proximal, middle, and distal segments of rat sciatic nerves using a double ligation technique.

Effect of monensin on the levels of tachykinins and their processing enzyme activity in rat dorsal root ganglia.

Th effect of monensin, which inhibits trans-Golgi function, on the levels of tachykinins and their processing enzyme activity was examined in organ-cultured rat dorsal root ganglia (DRG). Using an enzyme immunoassay method, we measured neurokinin A and substance P immunoreactivity in the DRG cultured for 72 h with and without 0.1 microM monensin.