Hypothesis: spermine may be an important epidermal antioxidant

Effects of spermine on ileal physical barrier, antioxidant capacity, metabolic profile and large intestinal bacteria in piglets

Spermine, a polyamine, exerts important roles in alleviating oxidative damage, improving immunity, increasing antioxidant status and digestive enzyme activities, and promoting the development of small intestine. However, information is not available regarding the effects of spermine supplementation on gut barrier function, intestinal microbiota and metabolic profile in piglets. Therefore, this study was designed to explore the effect of spermine administration on these parameters. The experiment was conducted on twenty 12 day-old suckling piglets, which were allocated either to the group fed basal formula milk (control group) or to that fed a basal formula milk that contained spermine (0.4 mmol kg⁻¹ BW per day) for 3 days. Caecal and colonic digesta and ileal tissues were collected at the end of the three-day feeding experiment. The results were as follows: (1) supplementation with spermine increased glutathione S-transferase (GST) capacity by 27.84% and glutathione content by 18.68% in the ileum (P < 0.05). (2) Glutathione peroxidase 1 (GPx1), catalase (CAT), GST, nuclear factor erythroid 2-related factor 2 (Nrf2) and Kelch-like ECH-associated protein1 (Keap1) mRNA levels in ileum were increased in the spermine-supplemented group in contrast to those in the control group (P < 0.05). (3) The spermine-supplemented group increased zonula occludens-1 (ZO-1) (by 42.0%), ZO-2 (by 101.0%), occludin (by 84.0%), claudin 2 (by 98.0%), claudin 3 (by 121.0%), claudin 12 (by 47.0%), claudin 14 (by 68.0%) and claudin 16 (by 73.0%) mRNA levels in ileum relative to the control group (P < 0.05). (4) Supplementation with spermine increased ZO-2 and occludin mRNA levels in ileum by reducing myosin light chain kinase (MLCK) (by 23.0%) mRNA level. (5) Spermine supplementation increased choline, glycerolphosphocholine, creatine and serine levels, and decrease alanine, glutamate, lysine, phenylalanine, threonine, lactate, tyrosine levels in ileum (P < 0.05). (6) The population of Lactobacilli, Bifidobacteria and total bacteria increased, but the number of Escherichia coli decreased in the caecal and colonic digesta after spermine supplementation (P < 0.05). In summary, dietary spermine supplementation promotes ileal health by enhancing antioxidant properties, improving ileal barrier function, modulating metabolic profiles, and maintaining large intestinal microbial homeostasis.

Spermine, a polyamine, exerts important roles in alleviating oxidative damage, improving immunity, increasing antioxidant status and digestive enzyme activities, and promoting the development of small intestine.

Natural Polyamines and Their Biological Consequence in Mammals

The polyamines (putrescine, cadaverine, agmatine, spermidine and spermine), wide-spread in all organisms, have been shown to play a role in regulation of growth and differentiation of virtually all types of cells. Their role in many physiological and pathophysiological processes have been studied very intensively during the last two decades. Inhibitors of polyamine biosynthesis have potential clinical uses as antitumor and antiparasitic agents. The brief summary with regard to their biological consequences in mammals is discussed in this paper.

Supplementation with spermine during in vitro maturation of porcine oocytes improves early embryonic development after parthenogenetic activation and somatic cell nuclear transfer

Spermine plays an important role in protection from reactive oxygen species (ROS) in bacteria, yeast, and mammalian cells, but there are few studies on the effects of spermine on porcine oocyte maturation and subsequent embryo development. The aim of this study was to determine the effects of spermine on in vitro maturation (IVM) of porcine oocytes and their developmental competence after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT). We evaluated nuclear maturation, intracellular glutathione (GSH), and ROS levels in oocytes, and their subsequent embryonic development, as well as gene expression in mature oocytes, cumulus cells, and PA blastocysts. After treatment with various concentrations of spermine in IVM culture medium, there was no significant difference in nuclear maturation rate. However, spermine treatment groups (10- 500 µM) showed significantly increased intracellular GSH levels and decreased ROS levels compared to the control ( < 0.05). Furthermore, 10 µM spermine supported significantly higher blastocyst formation rates after PA than the control group ( < 0.05). According to the optimal condition from the PA results, we investigated the effects of 10 µM spermine on SCNT, and it also significantly improved blastocyst formation rates compared with the control group ( < 0.05). In evaluating the effects of 10 µM spermine on gene expression, there was significantly lower expression of a proapoptotic gene () and higher expression of an antiapoptotic gene () in cumulus cells ( < 0.05). was increased in spermine-treated oocytes. Levels of transcription for and were significantly increased in PA blastocysts. In conclusion, 10 µM spermine supplementation during IVM improved the development of porcine PA and SCNT embryos by increasing intracellular GSH, scavenging ROS levels, and regulating gene expression.

Antioxidative properties of natural polyamines and dimethylsilane analogues

Structural analogues of natural polyamines, which contain a -Si(CH3)2 group in the central carbon chain, have previously been found to be cytotoxic to various tumor cell lines in vitro and to inhibit tumor cell growth in experimentally grafted animals. In the present study, the antioxidative properties of dimethylsilane polyamine analogues were analyzed in comparison with the natural polyamines. Reactivities of these various polyamines against superoxide anions (generated from the hypoxanthine/xanthine oxidase reaction) and peroxyl radicals (produced from the thermal decomposition of water-soluble 2,2'-azo-bis-[2-amidinopropane] hydrochloride) were investigated. The dimethysilane analogues, and more particularly the hexamine derivative, exhibited the highest scavenging efficiency towards these two reactive oxygen species (ROS). Furthermore, analysis of their ability to prevent hydroxyl radical formation and to trap this ROS showed that the efficiency of the hexamine as a metal chelator and hydroxyl radical scavenger is similar to that of spermine. The higher antioxidant efficiency of the dimethylsilane polyamine analogues with respect to spermidine, together with their ability to displace this polyamine, essential for the promotion of cell growth, from its cellular anionic binding sites that are particularly prone to oxidation, could be biologically relevant and contribute to their in vivo cytotoxic effect and anti-tumor activity. Further experiments will be necessary to demonstrate clearly the relationship between their antioxidant properties and their antiproliferative effects.

Differential effects of polyamine on the cytosolic and mitochondrial NADP-isocitrate dehydrogenases

Two isozymes of NADP-dependent isocitrate dehydrogenases (EC 1.1.1.42) exist in mammalian tissues: mitochondrial (ICD1) and cytosolic (ICD2). Effects of polyamines such as spermine, spermidine, and putrescine on the cytosolic and mitochondrial NADP-isocitrate dehydrogenases were analyzed kinetically. Spermine activated ICD2, the cytosolic NADP-isocitrate dehydrogenase from rat liver with the increase in the maximal velocity and the decrease in the affinity for the substrates isocitrate and NADP. The activating action of spermine can be explained by "the uncompetitive effect," and the dissociation constant of spermine for the enzyme-substrate complex was determined to be 1.68 mM. Spermidine and putrescine showed little or no effect. ICD1, the mitochondrial form of NADP-isocitrate dehydrogenase from rat and porcine heart was inhibited by spermine effectively, and by spermidine and putrescine to a lesser extent. Spermine inhibited the enzyme competitively with respect to NADP, and noncompetitively with respect to isocitrate. K(i) value of the enzyme for spermine was 1.3 mM. These results suggest that activation by spermine of cytosolic NADP-isocitrate dehydrogenase can enhance the antioxidant activity by regeneration of GSH, and further is responsible for the stimulation of lipid biosynthesis in cytosol. Spermine may contribute to NADPH supply by enhancing transhydrogenase (EC1.6.1.2) activity through the spermine-dependent activation of Ca(2+) -incorporation to mitochondria.

Radiation protection following nuclear power accidents: a survey of putative mechanisms involved in the radioprotective actions of taurine during and after radiation exposure

There are several animal experiments showing that high doses of ionizing radiation lead to strongly enhanced leakage of taurine from damaged cells into the extracellular fluid, followed by enhanced urinary excretion. This radiation-induced taurine depletion can itself have various harmful effects (as will also be the case when taurine depletion is due to other causes, such as alcohol abuse or cancer therapy with cytotoxic drugs), but taurine supplementation has been shown to have radioprotective effects apparently going beyond what might be expected just as a consequence of correcting the harmful consequences of taurine deficiency per se. The mechanisms accounting for the radioprotective effects of taurine are, however, very incompletely understood. In this article an attempt is made to survey various mechanisms that potentially might be involved as parts of the explanation for the overall beneficial effect of high levels of taurine that has been found in experiments with animals or isolated cells exposed to high doses of ionizing radiation. It is proposed that taurine may have radioprotective effects by a combination of several mechanisms: (1) during the exposure to ionizing radiation by functioning as an antioxidant, but perhaps more because it counteracts the prooxidant catalytic effect of iron rather than functioning as an important scavenger of harmful molecules itself, (2) after the ionizing radiation exposure by helping to reduce the intensity of the post-traumatic inflammatory response, and thus reducing the extent of tissue damage that develops because of severe inflammation rather than as a direct effect of the ionizing radiation per se, (3) by functioning as a growth factor helping to enhance the growth rate of leukocytes and leukocyte progenitor cells and perhaps also of other rapidly proliferating cell types, such as enterocyte progenitor cells, which may be important for immunological recovery and perhaps also for rapid repair of various damaged tissues, especially in the intestines, and (4) by functioning as an antifibrogenic agent. A detailed discussion is given of possible mechanisms involved both in the antioxidant effects of taurine, in its anti-inflammatory effects and in its role as a growth factor for leukocytes and nerve cells, which might be closely related to its role as an osmolyte important for cellular volume regulation because of the close connection between cell volume regulation and the regulation of protein synthesis as well as cellular protein degradation. While taurine supplementation alone would be expected to exert a therapeutic effect far better than negligible in patients that have been exposed to high doses of ionizing radiation, it may on theoretical grounds be expected that much better results may be obtained by using taurine as part of a multifactorial treatment strategy, where it may interact synergistically with several other nutrients, hormones or other drugs for optimizing antioxidant protection and minimizing harmful posttraumatic inflammatory reactions, while using other nutrients to optimize DNA and tissue repair processes, and using a combination of good diet, immunostimulatory hormones and perhaps other nontoxic immunostimulants (such as beta-glucans) for optimizing the recovery of antiviral and antibacterial immune functions. Similar multifactorial treatment strategies may presumably be helpful in several other disease situations (including severe infectious diseases and severe asthma) as well as for treatment of acute intoxications or acute injuries (both mechanical ones and severe burns) where severely enhanced oxidative and/or nitrative stress and/or too much secretion of vasodilatory neuropeptides from C-fibres are important parts of the pathogenetic mechanisms that may lead to the death of the patient. Some case histories (with discussion of some of those mechanisms that may have been responsible for the observed therapeutic outcome) are given for illustration of the likely validity of these concepts and their relevance both for treatment of severe infections and non-infectious inflammatory diseases such as asthma and rheumatoid arthritis.

Nitric oxide and polyamine pathway-dependent modulation of neutrophil free amino- and α-keto acid profiles or host defense capability

We have examined the effects of N(omega)-nitro-L-arginine-methylester-hydrochloride [L-NAME; inhibitor of nitric oxide synthase], S-nitroso-N-acetyl-penicillamine [SNAP; nitric oxide donor], alpha-difluoro-methyl-ornithine [DFMO; inhibitor of ornithine decarboxylase] arginine or ornithine as well as the combination of arginine or ornithine with L-NAME, SNAP or DFMO on intracellular free amino- and alpha-keto acid profiles and the immune function markers superoxide anion and hydrogen peroxide generation as well as released myeloperoxidase activity in neutrophils (PMN). Although the underlying mechanisms still remain unclear, we believe from our results that nitric oxide as well as polyamine-dependent pathways are involved in the signal transmission of free radical molecule, beneficial nutritional therapy or maleficient pharmacological stress-induced alterations in PMN nutrient composition. Relevant changes in intragranulocyte free amino- and alpha-keto acid homeostasis and metabolism, especially, may be one of the determinants in PMN nutrition that positively or negatively influences and modulate neutrophil host defence capability and immunocompetence.

Effects of peritoneal aluminum overload on polyamines and nitric oxide contents of testes and epididymis in the mice

Polyamines are involved in cellular growth, differentiation and regulation of oxidative stress. The present investigation was to determine the effect of aluminum (Al) toxicity on the nitric oxide products (NO(x)) and metabolism of polyamines in mouse testes and epididymis. Aluminum chloride, AlCl(3,) was administered intraperitoneally to CD-1 adult male mice at dosages of 0, 7 or 35mg Al/kg body weight/day for 14 days (C, LAL and HAL groups). Results obtained show that the weights of epididymis in HAL animals are significantly decreased due to Al administration. Al treatment significantly induced higher Al concentrations in serum, testis and epididymis tissue. In addition, the serum and testicular and epididymal NO(x) production in HAL and testicular NO(x) in LAH groups were increased remarkably compared to the control animals. On the contrary, the contents of putrescine and spermine in testis were significantly lower than the values of controls and LAL groups. The epididymal spermine levels of HAL animal also decreased significantly. It is suggested that the polyamine biosynthesis in the mouse testis and epididymis can be affected by Al, which is associated with the NO(x) production in the male reproductive toxicity.

Inhibition by L-arginine and spermidine of hemoglobin glycation and lipid peroxidation in rats with induced diabetes

The effect of L-arginine and spermidine on hemoglobin glycation and lipid peroxidation in serum of normal and diabetic rats was studied. Five groups of 40 rats were studied during 20 days and compared with a control group (Group I) that consisted of normal rats (N = 6) not treated with L-arginine or spermidine. Group II, diabetic rats (alloxan 120 mg/kg, i.p. at the day 0 and alloxan 60 mg/kg, i.p. at the day 10) were considered as diabetic control. Group III, diabetic rats treated with 10 mM L-arginine (i.p.). Group IV, diabetic rats treated with 10 microM spermidine (i.p.). Group V, normal rats treated with 10 mM L-arginine (i.p.). Group VI, normal rats treated with 10 microM spermidine (i.p.). The rats of each group were divided in subgroups of four each. Rats were anesthetized and blood was taken from aorta to determine glucose, triglycerides (TGs), total cholesterol (TC), low- and high-density lipoproteins (LDL and HDL), glycated hemoglobin (HbA(1C)), and thiobarbituric acid-reactive substances (TBARS). We observed that the alloxan concentrations used in this study reproduced the clinical manifestations of disease including hyperglycemia (from 116 +/- 7 mg/dl to 435 +/- 80 mg/dl) in 96 hours. As a consequence the levels of TGs, TC, LDL, TBARS, and HbA(1C) were increased, whereas HDL diminished. HbA(1C) concentration was significantly correlated with the concentration of TBARS. The L-arginine and spermidine injection tended to normalize the glycemia from 24 hours, similarly, hyperlipidemia, TBARS, and HbA(1C). From these results, we conclude that l-arginine and spermidine exerted an inhibitory effect of hemoglobin glycation and lipid peroxidation in vivo, which may be relevant in preventing diabetic complications.

Alternative antiglycation mechanisms: are spermine and fructosamine-3-kinase part of a carbonyl damage control pathway?

Spermine is an ubiquitous molecule that bears unique structural features of regularly spaced positive charges interrupted by hydrophobic methylene bridges. In previous studies we have shown significant antiglycation effects of physiological concentrations of spermine and spermidine. The effect is apparent in four different protein models, two targeting structural changes on histones and ubiquitin, and two targeting impairment of catalytic activities of AT III and plasminogen. We hypothesize that polyamines inhibit glycation and that might be one of their elusive molecular functions. A mammalian fructosamine-3-kinase (FN-3-K), which phosphorylates fructoselysine (FL) residues on glycated proteins, to FL-3-phosphate has been isolated and cloned by two independent groups. This enzyme may function as a deglycating enzyme. Being its Km for FL two orders of magnitude lower than for its protein substrate, we propose the enzyme has a dual role and also functions as a recycler of spermine-carbonyl adducts. Spermine and FN-3-K may be part of a carbonyl damage control pathway. Thirdly, due to critically functional lysine residues, we underscore the vulnerability to glycation of ornithine decarboxylase, the main enzyme in spermine biosynthesis. If glycation is modulated by polyamines and glycation itself impairs polyamine synthesis, a dangerous loop of excessive spermine consumption and slower spermine biosynthesis might ensue in chronic hyperglycemic conditions. In this perspective, small changes in flow rates in the spermine (where ODC and antizyme are key players) and/or FN-3-K pathway could contribute to enhance the effects of hyperglycemia and explain why there are diabetic subjects with higher glycation phenotypes and incidence of complications. They could have altered steady state levels of polyamines and/or decreased FN-3-K expression or activity.

Polyamine modulation of iron uptake in CHO cells

Polyamines are ubiquitous molecules, which, like iron, are essential for cell growth. All eukaryotic cells are equipped with a specific polyamine transport system (PTS). Polyamines have primary and secondary amino groups which chelate bivalent metal cations such as Fe and Cu. In the present study, we investigated the potential contribution of naturally occurring polyamines and their active transport system to iron uptake. In presence of subtoxic Fe(III) (10microM), treatment of CHO cells with spermine, and to a lesser extent with spermidine (10-100microM), resulted in a marked cytotoxic effect. This cytotoxicity was prevented by the addition of an iron-chelator, deferioxamine, and was not observed in CHO-MG cells, a mutant cell line devoid of polyamine transport activity. Experiments using 14C-polyamines and 55Fe(III) revealed that these toxic effects were related to polyamine-modulation of iron uptake, and were dependent on the presence of the active PTS. These results demonstrated active uptake of polyamine-iron complexes via the PTS. The number of amino groups affected the efficacy of the studied natural polyamines to transport iron via the PTS. Spermine, a tetramine, was more efficient than the triamine spermidine. Co-transport of iron by the diamine putrescine was not observed. These results demonstrate that the cell polyamine transport system is a potential cell entry pathway for iron. The studied polyamines, spermine and spermidine, may be components of the pool of transferrin-independent iron-chelating vectors, which have recently attracted the attention of many investigators.

The polyamines spermine and spermidine protect proteins from structural and functional damage by AGE precursors: a new role for old molecules?

Due to the importance of glycation in the genesis of diabetic complications, an intense search for synthetic new antiglycation agents is ongoing. However, a somewhat neglected avenue is the search for endogenous compounds that may inhibit the process and be a source of protodrugs. Based on their ubiquity, their polycationic nature, their essential role in growth, their relatively high concentrations in tissues, and their high concentrations in sperm, we hypothesized that polyamines inhibit glycation and that might be one of their so far elusive functions. In this study we demonstrate a potent antiglycation effect of physiological concentrations of the polyamines spermine and spermidine. We employed two approaches: in the first, we monitored structural changes on histones and ubiquitin in which polyamines inhibit glycation-induced dimer and polymer formation. In the second we monitored functional impairment of catalytic activity of antithrombin III and plasminogen. Protection is afforded against glycation by hexoses, trioses and dicarbonyls AGE precursors and is comparable to those of aminoguanidine and carnosine.

Decreased ornithine decarboxylase activity in the kidneys of Dahl salt-sensitive rats

To assess the roles of polyamines (putrescine, spermidine, and spermine) and ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine synthesis, in the development of salt-sensitive hypertension, we evaluated activity and expression of ODC, urinary polyamine excretion, and antizyme (endogenous ODC inhibitor protein) expression in Dahl salt-sensitive (SS) and salt-resistant (SR) rats after they were fed on a low (0.3%) or high (4%) salt diet for 4 weeks. We also examined the effects of spermidine and difluoromethylornithine (DFMO: a specific inhibitor of ODC) on the systolic blood pressure and ODC protein expression in SS rats fed a high salt diet. Renal ODC activity and urinary polyamine excretion in SS rats were lower than those in SR rats after 4 weeks treatment with a low or high salt diet. The renal ODC protein expression of SS rats was paradoxically increased as compared to the SR group. A high salt diet did not alter ODC activity but increased ODC protein only in SS rats. ODC mRNA and antizyme protein expressions were not significantly different among the four groups. Spermidine supplementation attenuated and DFMO exaggerated hypertension in SS rats fed a high salt diet. Spermidine down-regulated and DFMO up-regulated renal ODC protein in SS rats on a high salt diet. ODC activity was decreased but protein was paradoxically increased in kidneys of SS rats. ODC protein was suggested to increase in compensation for the inhibition of its activity. Impaired ODC activity and polyamine production in the kidney may exaggerate salt-sensitive hypertension in SS rats.

Polyamines and central nervous system injury: spermine and spermidine decrease following transient focal cerebral ischemia in spontaneously hypertensive rats

Polyamines (putrescine, spermidine and spermine) are ubiquitous cellular components, but their specific role in central nervous system (CNS) injury has yet to be characterized. CNS injury results in increased activities of ornithine decarboxylase and spermidine/spermine-N(1)-acetyltransferase, and accumulation of putrescine. The present study determined the polyamine profile in three models of CNS injury, in two different species (gerbil and rat) and two strains of rats (Sprague-Dawley and spontaneously hypertensive): (1) transient focal cerebral ischemia in spontaneously hypertensive rats (SHR); (2) traumatic brain injury in Sprague-Dawley rats; and (3) transient forebrain ischemia in gerbils. While there was a significant increase in putrescine in all three models, spermine and spermidine levels were unaltered in forebrain ischemia and traumatic brain injury. However, transient focal cerebral ischemia shows depletion of spermine and spermidine levels in injured hemisphere compared to contralateral region. Exogenous spermine significantly restored the spermine as well as spermidine levels in the ipsilateral hemisphere after transient focal cerebral ischemia, but did not alter putrescine levels or the ratio of spermidine to spermine. The loss of spermine in particular, may have several consequences that contribute to ischemic injury, including destabilization of chromatin, decreased mitochondrial Ca(2+) buffering capacity, and increased susceptibility to oxidative stress. Based on our and other studies, we propose a tentative antioxidant mechanism of spermine neuroprotection.

Imbalance of antioxidant defense in mice lacking cellular prion protein

Prion diseases are fatal neurodegenerative disorders resulting from conformational changes in the prion protein from its normal cellular isoform, PrPC, to the infectious scrapie isoform, PrP(Sc). In spite of many studies, the physiological function of PrPC remains unknown. Recent work shows that PrPC binds Cu2+, internalizing it into the cytoplasm. Since many antioxidant enzymes depend on Cu2+ (e.g., Cu/ZnSOD), their function could be affected in prion diseases. Here we investigate a possible relationship between PrP(C) and the cellular antioxidant systems in different structures isolated from PrPC knockout and wild-type mice by determining oxidative damage in protein and lipids and activity of antioxidant enzymes (CAT, SOD) and stress-adaptive enzymes (ODC). Our results show that, in the absence of PrPC, there is an increased oxidation of lipid and protein in all structures investigated. Decreased SOD activity and changes in CAT/ODC activities were also observed. Taking into account these results, we suggest that the physiological function of PrP(C) is related to cellular antioxidant defenses. Therefore, during development of prion diseases, the whole organism becomes more sensitive to ROS injury, leading to a progressive oxidative disruption of tissues and vital organs, especially the central nervous system.

Role of spermine in amyloid beta-peptide-associated free radical-induced neurotoxicity

The polyamines, relatively low-molecular-weight aliphatic compounds, are the main inducers of eukaryotic cell growth and proliferation. Although polyamine requirements for cell growth are well defined, their role is still enigmatic. We have previously reported that amyloid beta-peptide (A beta), the main constituent of senile plaques in Alzheimer's disease (AD) brain, is toxic to neurons through a free radical-dependent oxidative stress mechanism and that A beta(1--42), the principal form of A beta in AD brain, causes an increase in polyamine metabolism manifested by up-regulated polyamine uptake and increased ornithine decarboxylase (ODC) activity. Both effects were prevented by the free radical scavenger vitamin E. Spermine has been reported to function directly as a free radical scavenger. In the current study, we aimed to address whether up-regulation of polyamine metabolism is a defense against, or a result of, A beta-induced oxidative stress by investigating the capability of spermine to quench A beta-associated free radicals in solution and to assert a protective function of spermine in neuronal culture against A beta. Pretreatment of cultured neurons with spermine prior to A beta exposure failed to prevent A beta-induced cell death. Indeed, A beta plus spermine added to cultured neurons was even more neurotoxic than either agent alone. Additionally, inhibition of the polyamine synthesis by difluoromethylornithine (DFMO) did not protect cells from A beta-induced free radical toxicity, and stimulation of the synthesis of putrescine and spermine by the aminopropyltransferase inhibitor S-adenosyl-1,8-diamino-thiooctane (AdoDATO), rather, further enhanced A beta-induced toxicity. Although spermine is capable of scavenging free radicals generated by A beta in solution as measured by electron paramagnetic resonance (EPR) spectroscopy, the up-regulated transport of exogenously added spermine together with A beta may lead to overaccumulation of a cellular spermine pool, with resulting enhanced neurotoxicity.

Retinol-induced elevation of ornithine decarboxylase activity in cultured rat Sertoli cells is attenuated by free radical scavenger and by iron chelator

We investigated retinol effects in ornithine decarboxylase activity in Sertoli cells. We also tested the hypothesis that free radical scavengers and iron chelators may attenuate the effect of retinol. Sertoli cells isolated from 15-day-old Wistar rats were previously cultured for 48 h and then treated with retinol by 24 h with or without mannitol (1 mM) or 1,10 phenanthroline (100 microM). We measured ornithine decarboxylase and catalase activities and malondialdehyde concentrations in response to retinol treatment. In response to 7 microM retinol treatment ornithine decarboxylase activity increased 30%. Retinol-induced ornithine decarboxylase activity was significantly decreased by addition of free radical scavenger (mannitol) or iron chelator (1,10 phenanthroline). In addition the same effect was observed in catalase increased activity and in malondialdehyde concentrations. These results suggest that retinol treatment induced ornithine decarboxylase and catalase activity and increased malondialdehyde concentration. These effects appear to be mediate by ROS.

Phorbol ester (12-O-tetradecanoylphorbol 13-acetate) prevents ornithine decarboxylase inhibition and apoptosis and L1210 leukemic cells exposed to TGF-beta 1

Previous studies have shown that growth suppression and apoptosis of leukemic cells exposed to TGF-beta 1 is associated with the inhibition of ornithine decarboxylase (ODC)--the key enzyme of polyamine pathway. The aim of the present study was to evaluate the influence of 12-O-tetradecanoylphorbol 13-acetate (TPA)--a potent ODC inducer on antiproliferative and apoptotic effects of TGF-beta 1 in L1210 leukemic cells. Cells were incubated in 2% FCS/RPMI-1640 medium, supplemented with TGF-beta 1 (2 ng/ml). TPA (100 ng/ml) or alpha-difluoromethylornithine (DFMO) (5 mM). Cell proliferation, apoptosis and necrosis were evaluated using [methyl-3H] thymidine, electron microscopy, electrophoresis of DNA and trypan blue exclusion. Expression and activity of ODC were determined by RT-PCR and measurement of 14CO2 release from L-1-14C ornithine, respectively. TGF-beta 1 inhibited proliferation and induced apoptotic and necrotic cell death in L1210 leukemic cells. The above effects were associated with the inhibition of ODC expression and activity, measured 2 and 4 hr after TGF-beta 1 administration, respectively. The presence of DFMO, an irreversible inhibitor of ODC, led to apoptotic fragmentation of DNA, similar to that observed in TGF-beta 1-treated cultures. Administration of TPA simultaneously with TGF-beta 1 significantly reduced antiproliferative, apoptotic and necrotic effects of TGF-beta 1, and prevented its inhibitory action of ODC expression and activity. It is concluded that: down-regulation of ODC expression may be one of the early events associated with TGF-beta 1-evoked suppression of growth and apoptosis; ODC is involved in the mechanism of protective action of TPA on TGF-beta 1-related growth inhibition of L1210 leukemic cells.

Spermine partially normalizes in vivo antioxidant defense potential in certain brain regions in transiently hypoperfused rat brain

Activities of the antioxidant enzymes such as superoxide dismutase (Cu,Zn-SOD), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R) as well as the level of reduced glutathione and the concentration of thiobarbituric acid-reactive substance (TBARS) in brain regions in transiently hypoperfused rat brain with or without intravenous infusion of spermine were evaluated. Cerebral hypoperfusion was induced by temporary occlusion of common carotid arteries for 30 min and subsequently, by reperfusion for 60 min. Infusion of spermine reversed the decrease in SOD activity in the cerebral cortex, striatum, hippocampus, hypothalamus and midbrain, and amounted to 50.1 U, 61.5 U, 50.3 U, 30.0 U, 38.0 U, respectively, while GSH-Px restored to normal values only in the cerebral cortex and striatum and amounted to 100 U and 110 U, respectively. During hypoperfusion/reperfusion and after use of spermine no changes in GSSG-R were seen in the hypothalamus and midbrain. The activity of GSSG-R was in accordance with the control for the striatum and amounted to 39.0 IU after using spermine. GSH content returned to normal values in the striatum and midbrain after i.v. use of spermine and amounted to 210 and 240 nmol/g of wet tissue, respectively. In addition, the production of TBARS dropped markedly (P < 0.05) in the hippocampus and midbrain and amounted to 100 and 105 mumol/g of wet tissue, respectively. Partially beneficial effect of spermine could result from the inhibition of free radical generation and capability of chelate formation with iron ions.