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Effect of grape seed extract on puromycin-aminonucleoside-induced nephrosis in rats.

Recent studies indicate that an excessive production of oxidants plays an important role in the pathogenesis of glomerular disease. Grape seed extract (GSE) is a potent antioxidant, and the aim of this pilot study was to evaluate its effect on puromycin-aminonucleoside (PAN)-induced nephrosis in rats. Fifty Sprague-Dawley rats were divided into five groups. Groups 1 and 2 rats received water from day 0 to day 30. Rats in groups 3, 4, and 5 received GSE at 10 mg/100g of body weight (BW), which was started on day 0, 6, and 3 of the experiment, respectively. In group 5 animals the GSE dose was increased (40 mg/100g BW) on day 9. Intraperitoneal dextrose (group 1) or PAN 15 mg/100g BW (groups 2-5) was administered on day 3. Urine and blood specimens were collected at regular intervals, and the comparison between the various groups was made by analysis of variance (ANOVA). Rats in all study groups (groups 3-5) showed a decrease in urine protein and serum cholesterol and triglyceride levels, which was statistically significant in group 3 animals. No significant changes were noted in serum albumin and creatinine levels. In conclusion, GSE administration decreases urine protein excretion and serum cholesterol and triglyceride levels in rats with PAN-induced nephrosis.

Animals↗

Effect of a novel free radical scavenger, edaravone, on puromycin aminonucleoside induced nephrosis in rats.

Recent studies indicate that excessive production of oxidants plays a role in the pathogenesis of glomerular injury leading to proteinuria in patients with minimal-change nephrotic syndrome (MCNS). The novel free radical scavenger, edaravone (EDA), which was recently developed in Japan, is currently used in patients with stroke. We studied whether this new agent would be beneficial in patients with MCNS by its antioxidant activity and examined its effect on proteinuria in nephrosis induced by puromycin-aminonucleoside (PAN) in rats. Nineteen Wistar-Kyoto rats injected with PAN were assigned to four groups: group 1, without EDA (n=4); group 2, concomitant EDA injection from 1 day prior to PAN administration (n=5); group 3, concomitant EDA injection from 1 day after PAN administration (n=5); group 4, concomitant EDA injection from 3 days after PAN administration (n=5). Daily urinary excretions of protein and 8-hydroxy-2'-deoxyguanosine (8-OHdG), a new sensitive marker of oxidative DNA damage in vivo, were measured in each group from the 1st to the 30th day after PAN injection. In group 1 proteinuria developed from the 5th day and reached the peak level on the 9th day. In groups 2, 3, and 4 proteinuria did not appear until the 6th day. The excretions in urinary protein and 8-OHdG were significantly lower in groups 2, 3, and 4 than group 1 on days 5, 9, and 25. In conclusion, EDA could delay and ameliorate the urinary protein excretion in accordance with the urinary 8-OHdG excretion in PAN-induced nephrosis.

8-Hydroxy-2'-Deoxyguanosine↗

Inhibition by puromycin of transneuronal transport in the mouse accessory olfactory bulb.

Application of [3H]proline to the vomeronasal organ (VNO) in mice results in the transport of labelled material along the vomeronasal axons to their terminals in the glomerular layer of the accessory olfactory bulb (AOB). In addition labelled material leaves the vomeronasal nerve terminals and is found over the external plexiform layer (EPL), where a previous electron microscopic autoradiographic study showed that it is preferentially accumulated in mitral cells. Grain densities over the glomerular layer and the EPL were counted in light micrographs. After subtracting background, the overall density of grains in the EPL is about 10% of that over the glomerular layer at 6 h after administration of [3H]proline to the VNO (5 mice). In a further 7 mice, puromycin (or saline) was applied directly to the AOB at hourly intervals during the 6 h after [3H]proline administration. Under these circumstances the labelling in the EPL is only 2--4% of that in the glomerular layer (9% for the 2 saline controls). These observations are evidence that a major part of the transsynaptic transfer mechanism is dependent on protein synthesis, and also favour the view that free amino acids are an important component of the material transferred.

Animals↗

Effects of actinomycin D and puromycin on colchicine-induced endoreduplication in Chinese hamster cells in vitro.

Experiments were carried out to study the events through which the process of endoreduplication occurs after treatment with colchicine in Chinese hamster cells cultivated in vitro, and to analyse the differences between the processes leading to normal mitosis and those leading to endoreduplication. Chinese hamster cells (line C-125) were treated with colchicine (10(-4) M) for 1 h, in order to induce endoreduplication. Before and after colchicine treatment the cultures were treated at various intervals with actinomycin D and puromycin. For preparation of mitosis specific RNA synthesis is required, and also synthesis of a specific protein, which is not required for endoreduplication. Moreover this suggests not only that the cells that endoreduplicate do not need new RNA and protein synthesis, but that inhibition of their synthesis apparently favours the processes of endoreduplication.

Cell Division↗

Angiotensin I-converting enzyme activity in puromycin aminonucleoside-nephrotic syndrome.

Puromycin aminonucleoside (PAN)-nephrotic rats have high serum angiotensin I-converting enzyme (ACE) activity. We studied ACE activity in serum, urine, and tissues from PAN-nephrotic rats on days 2, 6, 11, and 16 after PAN injection. Proteinuria and hypoproteinemia were evident on days 6 and 11. Though significantly decreased, proteinuria was still evident on day 16. Serum ACE activity increased on days 2, 6, and 11. Urinary ACE activity became evident on days 6, 11, and 16 and correlated positively with proteinuria, suggesting that the source of urine ACE is the blood serum. ACE activity increased in testis on days 2 and 6, in lungs and aorta on days 6 and 11, in adrenal glands and small intestine on day 11, and in kidney on days 11 and 16. Heart ACE activity decreased on days 2 and 6, and increased on day 16; brain ACE activity decreased on day 6 and increased on day 11. These data implicate that changes in tissue ACE content may contribute to elevate serum ACE in PAN-nephrotic rats.

Animals↗

Protein synthesis inhibitors and catalytic RNA. Effect of puromycin on tRNA precursor processing by the RNA component of Escherichia coli RNase P.

RNase P and ribosomes must interact with similar substrate molecules, tRNA precursors in the case of RNase P and aminoacyl-, peptidyl- or free tRNAs in the case of ribosomes. In order to compare the substrate recognition mechanisms between ribosomes and RNase P, protein synthesis inhibitors have been assayed for their effect on the catalytic activity of the RNA component of Escherichia coli RNase P (M1 RNA). Puromycin has an inhibitory effect that could be related to similar substrate recognition mechanisms by rRNA in the ribosome and by M1 RNA in RNase P.

Catalysis↗

Tissue lipoperoxidation and glutathione peroxidase activity in puromycin aminonucleoside injected rats.

1. Lipoperoxidation (LPx) and glutathione peroxidase (GPx) activity were measured in kidney, liver, heart, lung, brain and testis from control and puromycin aminonucleoside (PAN) injected rats on days 1-6, 8, 10, 16 and 22 after vehicle or PAN injection. 2. PAN-injected rats developed proteinuria on day 3. 3. In PAN-injected rats: (a) LPx increased in kidney, liver, lung, brain and testis before day 3 and in heart on day 3; (b) GPx activity increased in kidney, liver, heart, lung and testis and diminished in brain on day 3 or after.

Animals↗

Puromycin: two distinct behavioral effects with different temporal parameters in the pigeon.

Pigeons were injected intracerebrally with either puromycin (PM) or control saline solution following training for one 12-min session on a visual discrimination. Injections were made either immediately following training, 1 hr later or 24 hr later. Retention testing 3 days after training showed that PM produced marked amnesia in the first two groups, but had no effect in the 24 hr condition. However, all PM groups were retarded subsequently in the number of days required to reach a 90% discimination criterion. This differentiation of two separate behavioral effects with different temporal gradients suggests that PM may be working through two distinct physiological mechanisms.

Animals↗

Distribution, survival and biological effects in mice of a behaviorally active, enzymatically stable peptide: pharmacokinetics of cyclo(Leu-Gly) and puromycin-induced amnesia.

Cyclo(Leu-Gly), the enzymatically resistant diketopiperazine formally derived from the C-terminal dipeptide sequence of oxytocin, exhibits activity in several behavioral systems. The distribution of cyclo(Leu-14C(U)Gly) in brain, and the time course of the disappearance of this labeled peptide from brain and plasma after subcutaneous injection into mice have been studied. The intact peptide was distributed equally in the five cerebral areas studied, for up to 96 hours after injection. Two exponential components were determined for peptide disappearance rates in plasma and brain; peptide half-lives in plasma up to 10 hr and from 24--96 hr after injection were, respectively, 0.8 and 33 hr; in brain, 1.0 and 42 hr. The peptide was found to accumulate in brain intracellular space to some degree. The time course of distribution of labeled cyclo(Leu-Gly) in subcellular fractions of mouse brain was also examined, and the concentration of peptide in the synaptosomal fraction was significantly correlated with the degree of protection against puromycin-induced amnesia of a maze-learning test. The results obtained not only confirm that cyclo(Leu-Gly) penetrates brain tissue intact and remains intact after peripheral administration in order to exert its behavioral effects, but, moreover, suggest an intriguing dynamic relationship between peptide concentration in the synaptosomal fraction and behavioral activity.

Amnesia↗

Roles of active oxygen species in glomerular epithelial cell injury in vitro caused by puromycin aminonucleoside.

The mechanism of puromycin aminonucleoside (PAN)-induced nephrosis has not yet been well defined. In the present study, we examined the protective effect of active oxygen scavengers on the PAN-induced injury of cultured rat glomerular epithelial cells (GECs) and the generation of active oxygen species in PAN-treated GECs. When exposed to PAN (greater than or equal to 25 micrograms/ml), cellular damage occurred in a time- and dose-dependent manner as evaluated by both the LDH release and MTT colorimetric assays. Concomitant addition of either the hydrogen peroxide (H2O2) scavenger, catalase, or the iron chelating agent, deferoxamine, to the culture medium caused a striking reduction of cellular injury. This suggested a role for H2O2 and for hydroxyl radicals (OH.) generated via the iron-catalyzed breakdown of H2O2 in PAN nephrosis. Using the scopoletin fluorescence assay, the release of H2O2 into the culture medium by GECs exposed to PAN (greater than or equal to 50 micrograms/ml) was shown to increase dose-dependently (greater than or equal to 57 +/- 11 pmol/4.4 x 10(6) cells per h, P less than 0.01) as compared with control cells (14 +/- 2 pmol/4.4 x 10(6) cells per h). These results strongly suggested that active oxygen species, especially H2O2 and OH., might play an important role in PAN-induced GEC injury in vitro as well as in vivo.

Animals↗

Puromycin-induced argyrophilia as an alternative to Golgi methods: reliable impregnations of hypothalamic cell groups following lateral ventricular injections in rats.

Parenchymal injections of puromycin were known to induce Golgi-like silver impregnations upon treatment with the cupric-silver method. We have found lateral ventricular injections (5 microliter, 0.1 M) also effective. Such injections consistently led to detailed Golgi-like profiles of cells in a number of hypothalamic regions including one, the paraventricular nucleus, which traditionally is quite recalcitrant to Golgi methods. It is concluded that this technique is a reliable alternative to Golgi methods for the study of many hypothalamic regions.

Animals↗

Cycloheximide or puromycin can substitute for PDGF in inducing cellular DNA synthesis in quiescent 3T3 cells.

A brief exposure of quiescent (Go) Swiss 3T3 mouse fibroblasts to inhibitors of protein synthesis can replace platelet-derived growth factor in the stimulation of cellular DNA synthesis. When 3T3 cells, after a 6 hr exposure to either cycloheximide or puromycin, are incubated with platelet-poor plasma, a significant percentage of cells enters DNA synthesis. Either inhibition of protein synthesis, or platelet poor plasma by themselves are totally ineffective. A possible mechanism by which inhibitors of protein synthesis may initiate cell cycle progression is through the activation of the c-myc gene.

Animals↗

Two genes in Streptomyces alboniger puromycin biosynthesis pathway are closely linked.

Several recombinant plasmids, derived from the Streptomyces vector pIJ702 and carrying different stretches of Streptomyces alboniger DNA encoding the gene (pac) for puromycin N-acetyl transferase [Vara et al., Gene 33 (1985) 197-206] were found to also include the gene (dmpM) for the O-demethylpuromycin O-methyl transferase enzyme. Both genes are present on the same 2.4-kb DNA fragment. Coupled transcription-translation experiments suggested that the dmpM gene product is a 44-kDa polypeptide and that both dmpM and pac might belong to different transcriptional units. The level of expression of the dmpM gene was dependent upon the orientation of insertion in the vector.

Acetyltransferases↗

Effect of zelandopam, a dopamine D1-like receptor agonist, in puromycin aminonucleoside nephrosis rats.

The present experiment was designed to investigate the role of peripheral dopamine D1-like receptors and to evaluate the prophylactic effect of zelandopam, a dopamine D1-like receptor agonist, on puromycin aminonucleoside (PA)-induced nephrosis in rats. Rats were divided into six groups (n=10 per group): 0.9% saline-injected rats (control); PA-injected rats (PAN); PA-injected rats treated with the selective dopamine D1-like receptor agonist zelandopam (30, 100, 300 mg/kg p.o. twice a day); PA-injected rats treated with prednisolone (1 mg/kg p.o. once a day). Nephrosis was induced in rats with a single intravenous injection of PA at a dose of 50 mg/kg. The effects of zelandopam and prednisolone in PA nephrosis rats were evaluated before injection of PA and at 7 and 14 days after injection. PA-induced nephrosis was characterized by an increase in urinary protein excretion (proteinuria) and plasma total cholesterol. Zelandopam dose-dependently attenuated the increase in proteinuria and total cholesterol. Prednisolone significantly attenuated the increase in proteinuria and total cholesterol and resulted in a significant decrease in body weight. The present study demonstrates for the first time that zelandopam, a selective dopamine D1-like receptor agonist, is effective in blunting the development of PA-induced nephrosis, and that the effects of zelandopam are dose dependent.

Animals↗

Altered expression of NDST-1 messenger RNA in puromycin aminonucleoside nephrosis.

Sulfated portions of glycosaminoglycan (GAG) side chains in heparan sulfate proteoglycan (HSPG) are thought to play an important role in charge-dependent selectivity of glomerular filtration against plasma proteins. Heparan sulfate N-acetylglucosamine N-deacetylase/adenosine 3'-phosphate 5'-phosphosulfate: unsubstituted glucosamine N-sulfotransferase (NDST) is the key enzyme regulating sulfation of GAG chains. In this study we investigated transcriptional expression of NDST-1, 1 of 4 isozymes of NDST, in glomeruli of rats with puromycin aminonucleoside (PAN) nephrosis. Nephrosis was induced in rats with a single intraperitoneal injection of 150 mg/kg PAN. On days 10 and 35, expression of NDST-1 messenger RNA (mRNA) in glomeruli was analyzed with the use of Northern-blot analysis. Immunohistochemical studies were also performed with the use of monoclonal antibodies that react specifically with the N-sulfated portion of the GAG chain of HSPG and agrin, a major core protein of HSPG in glomerular basement membrane (GBM). In addition, we studied the expression of NDST-1 mRNA in cultured glomerular epithelial cells (GECs) and glomerular mesangial cells in the presence of PAN. On day 10, when significant proteinuria developed, the ratios of glomerular expression of NDST-1 mRNA against glyceraldehyde-phosphate dehydrogenase mRNA in PAN-treated rats were decreased to 48% +/- 6% of those in controls (P<.05). Immunohistochemical studies revealed that staining for N-sulfated GAG chains of HSPG on GBM was markedly reduced on day 10 in PAN-treated rats but that staining for agrin was unchanged. In contrast, on day 35, when PAN-treated rats recovered from proteinuria, we noted no differences in glomerular expression of NDST-1 mRNA and staining intensity for N-sulfated GAG chains on GBM between PAN-treated rats and controls. Incubation of GECs for 24 hours in the presence of 50 ng/mL PAN resulted in the reduction of the expression of NDST-1 mRNA (67% +/- 12% of those in controls, P<.05). In summary, we found alteration of the expression of NDST-1 mRNA, accompanying a loss of N-sulfated GAG chains of HSPG on GBM without changes in the core protein agrin, in the course of PAN nephrosis. These data suggest an important role for this enzyme in heparan sulfate assembly in GBM and GEC and in the pathogenesis of proteinuria in PAN nephrosis.

Amidohydrolases↗

Soy protein diet ameliorates renal nitrotyrosine formation and chronic nephropathy induced by puromycin aminonucleoside.

It has been shown that reactive oxygen species are involved in chronic puromycin aminonucleoside (PAN) induced nephrotic syndrome (NS) and that a 20% soy protein diet reduces renal damage in this experimental model. The purpose of the present work was to investigate if a 20% soy protein diet is able to modulate kidney nitrotyrosine formation and the activity of renal antioxidant enzymes (catalase, glutathione peroxidase, Cu,Zn- or Mn-superoxide dismutase) which could explain, at least in part, the protective effect of the soy protein diet in rats with chronic NS induced by PAN. Four groups of rats were studied: (1) Control rats fed 20% casein diet, (2) Nephrotic rats fed 20% casein diet, (3) Control rats fed 20% soy protein diet, and (4) Nephrotic rats fed 20% soy protein diet. Chronic NS was induced by repeated injections of PAN and rats were sacrificed at week nine. The soy protein diet ameliorated proteinuria, hypercholesterolemia, and the increase in serum creatinine and blood urea nitrogen observed in nephrotic rats fed 20% casein diet. Kidney nitrotyrosine formation increased in nephrotic rats fed 20% casein diet and this increase was ameliorated in nephrotic rats fed 20% soy protein diet. However, the soy protein diet was unable to modulate the antioxidant enzymes activities in control and nephrotic rats fed 20% soy protein diet. Food intake was similar in the two diet groups. The protective effect of a 20% soy protein diet on renal damage in chronic nephropathy induced by PAN was associated with the amelioration in the renal nitrotyrosine formation but not with the modulation of antioxidant enzymes.

Animals↗

Analysis of conserved residues of the human puromycin-sensitive aminopeptidase.

The puromycin-sensitive aminopeptidase (ApPS) is a zinc metallopeptidase involved in the degradation of neuropeptides. Putative catalytic residues of the enzyme, Cys146, Glu338, and Lys396 were mutated, and the resultant mutant enzymes characterized. ApPS C146S exhibited normal catalytic activity, ApPS E338A exhibited decreased substrate binding, and ApPS K396I exhibited decreases in both substrate binding and catalysis. ApPS K396I and ApPS Y394F were analyzed with respect to transition state inhibitor binding. No effect was seen with the K396I mutation, but ApPS Y394F exhibited a 3.3-fold lower affinity for RB-3014, a transition state inhibitor, indicating that Tyr394 is involved in transition state stabilization.

Amino Acid Sequence↗

Low molecular weight heparin in the treatment of puromycin-induced nephrosis.

Heparin may have a beneficial effect in proteinuric renal diseases, where negative charges of the glomerular capillary membrane are compromised. We evaluated the role of low molecular weight heparin (LMWH - 3000 Da) in puromycin aminonucleoside (PAN)-induced focal and segmental glomerulosclerosis in male Wistar rats: Controls (C) n=7, LMWH-treated group, n=9, subcutaneously (SC), 6 mg/kg every day. The PAN group (n=7) received 7 doses on weeks 0, 1, 2, 4, 6, 8, 10 (SC - 2mg/100g), and a group PAN+LMWH (n=6). After 12 weeks, cholesterol and triglycerides were higher in nephrotic groups, as well as proteinuria and urinary IgG. Kidney weight, glomerular volume, and glomerular sclerosis index were higher in the PAN-treated groups. Glomerular capillary length density (L(Vcap)) and glomerular capillary surface density (S(Vcap)) were lower in the PAN group, and mesangial fractional volume was higher. Fibronectin immunostaining was more intense in the PAN group, and collagens I and III were absent in the studied glomeruli. Thus, LMWH prevented mesangial expansion and capillaries changes, showing antiproliferative properties, despite worsening glomerular permeability changes in the PAN model. In conclusion, LMWH interferes in the complications of PAN model, but not through inhibition of the proteinuria.

Animals↗