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G Nisticò

Publications and source records attributed to G Nisticò.

At least 37 records · Page 2Linked to original sources
PubMed1996

Melatonin affords protection against kainate-induced in vitro lipid peroxidation in brain.

Melatonin protection against in vitro kainic acid-induced oxidative damage in rat brain is shown. Brain disrupted cell homogenates were incubated with different concentrations of kainate and with or without different concentrations of melatonin. The concentration of malonaldehyde and 4-hydroxyalkenals was measured as an index of lipid peroxidation. When administered together with kainate, melatonin produced a concentration-dependent decrease in kainate-induced lipid peroxidation ranging from 20% to 100%. Moreover, when added to the reaction mixture alone, melatonin decreased the basal level of lipid peroxidation compared to controls.

Animals↗
PubMed1996

Paraquat toxicity and oxidative damage. Reduction by melatonin.

The ability of melatonin to protect against paraquat-induced oxidative damage in rat lung, liver, and serum was examined. Changes in the levels of malondialdehyde (MDA) plus 4-hydroxyalkenals (4-HDA) and reduced and oxidized glutathione concentrations were measured. Paraquat (50 mg/kg) was injected i.p. into either Sprague-Dawley or Wistar rats with or without the co-administration of 5 mg/kg melatonin. Paraquat alone increased MDA + 4-HDA levels in serum and lungs of both rat strains, with these increases being abolished by melatonin co-treatment. Paraquat also decreased reduced glutathione levels and increased oxidized glutathione concentrations in lung and liver; these changes were negated by melatonin. The effect of melatonin on paraquat-induced mortality was also studied. Paraquat at a dose of 79 mg/kg was lethal for 50% of animals within 24 hr; when administered together with melatonin, the LD50 for paraquat increased to 251 mg/kg.

Animals↗
PubMed1996

Nitric oxide-donor compounds inhibit lipoxygenase activity.

The nitric oxide (N0-releasing agents sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP) inhibit dioxygenase activity of lipoxygenase in human platelets and human CHP100 neuroblastoma cells, leading the latter to necrosis. The effect of both NO-donors on the dioxygenase reaction was investigated by using soybean lipoxygenase type II (LOX-2) as a model for the mammalian enzyme. SNP and SNAP were competitive inhibitors of LOX-2, with inhibition constants of 525 microM and 710 microM, respectively. Both compounds inactivated LOX-2 by reducing the catalytic iron to the inactive Fe(II) form and counteracted the H2O2-mediated activation of the LOX-2 catalyzed dioxygenase reaction. Similarly, the co-oxidative and per-oxidative activities of LOX-2 were also inhibited by the NO-releasing agents. These findings suggest that the biological role played by NO can be mediated, at least in part, by the inactivation of lipoxygenase, a key-enzyme for the arachidonic acid metabolism in human cells.

Blood Platelets↗
PubMed1996

Intracerebral injection of human immunodeficiency virus type 1 coat protein gp120 differentially affects the expression of nerve growth factor and nitric oxide synthase in the hippocampus of rat.

We have studied the neuropathological characteristics of the brain of rats receiving daily intracerebroventricular administration of freshly dissolved human immunodeficiency virus type 1 recombinant protein gp120 (100 ng per rat per day) given for up to 14 days. Histological examination of serial brain sections revealed no apparent gross damage to the cortex or hippocampus, nor did cell counting yield significant neuronal cell loss. However, the viral protein caused after 7 and 14 days of treatment DNA fragmentation in 10% of brain cortical neurons. Interestingly, reduced neuronal nitric oxide synthase (NOS) expression along with significant increases in nerve growth factor (NGF) were observed in the hippocampus, where gp120 did not cause neuronal damage. No changes in NGF and NOS expression were seen in the cortex, where cell death is likely to be of the apoptotic type. The present data demonstrate that gp120-induced cortical cell death is associated with the lack of increase of NGF in the cerebral cortex and suggest that the latter may be important for the expression of neuropathology in the rat brain. By contrast, enhanced levels of NGF may prevent or delay neuronal death in the hippocampus, where reduced NOS expression may be a reflection of a subcellular insult inflicted by the viral protein.

Animals↗
PubMed1996

N-methyl-D-aspartate and non-N-methyl-D-aspartate receptors mediate seizures and CA1 hippocampal damage induced by dendrotoxin-K in rats.

The epileptogenic and neurodegenerative effects of dendrotoxin K, from Dendroaspis polylepis, a specific blocker of a non-inactivating, voltage-sensitive K+ channel, were studied after focal injection into one dorsal hippocampus in rats. Administration of 35 pmol dendrotoxin K elicited motor seizures and bilateral electrocortical discharges after a latent period (5.3 +/- 2.1 min), in all of the treated animals (n = 6). At 24 h, histological examination of brain (n = 5) coronal sections (10 microns; n = 6 per brain) detected bilateral damage to the hippocampal formation which extended 300 microns rostral and caudal to the injection tract. Quantitation of the damage revealed significant bilateral neuronal cell loss in the CA1 and CA4 pyramidal cell layer relative to the corresponding brain regions of rats (n = 3) injected with bovine serum albumin (105 pmol), which per se was ineffective in all respects. Dendrotoxin K (35 pmol) also caused a significant loss of CA3 pyramidal neurons and dentate gyrus granule cells ipsilateral to the site of toxin injection. In one out of six rats, a lower dose (3.5 pmol) of dendrotoxin K produced convulsive behaviour and electrocortical seizures but after a longer latency and these were accompanied by significant neuronal loss in the CA1, CA3 and CA4 pyramidal cell layer ipsilateral to the injected side. The lowest dose (0.35 pmol; n = 6 rats) of dendrotoxin K used failed to induce seizures and did not cause hippocampal damage (n = 6 rats). Systemic (i.p.) treatment with dizocilpine maleate (3 mg/kg) or LY 274614 (5 mg/kg i.p.), two N-methyl-D-aspartate receptor antagonists (given 15 min beforehand), prevented dendrotoxin K (35 pmol)-induced motor seizures and electrocortical epileptogenic discharges in 100% of the animals (n = 6 per group) treated. Similarly, these antagonists minimized the damage typically produced in the rat hippocampus, with no significant neuronal loss being observed. By contrast, NBQX (30 mg/kg, i.p. given 15 min previously), a non-N-methyl-D-aspartate antagonist, failed to prevent seizures normally evoked by dendrotoxin K (35 pmol; n = 6 rats); also, this treatment was unable to abolish CA1 pyramidal cell loss but minimized the loss in hippocampal sectors distant to the site of dendrotoxin K injection. However, complete protection against motor and electrocortical seizures and hippocampal damage was afforded by GYKI 52466 (10 mg/kg i.p.; n = 6 rats), a more effective non-N-methyl-D-aspartate receptor antagonist. These findings differ from the reported lack of protection by N-methyl-D-aspartate and non-N-methyl-D-aspartate receptor antagonists to rats receiving intra-hippocampal injection of alpha-dendrotoxin; this difference may stem from the ability of alpha-dendrotoxin to block predominantly a slowly inactivating K+ current whereas dendrotoxin K inhibits a non inactivating variant. In conclusion, the present data on dendrotoxin K, together with the previously described pattern of neurotoxicity for alpha-dendrotoxin, show that these homologues act via different mechanisms and, thus, can be used effectively as complementary tools to study seizures and neuronal cell death.

Animals↗
PubMed1996

Sound-evoked electrocortical desynchronization is inhibited by N omega-nitro-L-arginine methyl ester microinfused into the inferior colliculi in rats.

In previous experiments we have shown that systemic or intracerebroventricular administration of N omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthase, is able to significantly reduce sound-evoked electrocortical (ECoG) desynchronization in rats. The present experiments were aimed at identifying the site(s) of the brain through which these effects are mediated. L-NAME (200 and 300 nmol), oxyhaemoglobin (200 and 300 nmol), a NO-trapping agent, and methylene blue (100 and 150 nmol), an inhibitor of guanylate cyclase and NO synthase, given bilaterally into the inferior colliculi, but not in other relay stations of the acoustic pathway, prevented the reduction in ECoG amplitude induced by sound stimulation in rats. Significant reduction of sound-evoked ECoG desynchronization has also been observed in rats receiving injection of CGP37849 (125 and 500 pmol) and LY274614 (125 pmol), two competitive N-methyl-D-aspartate receptor antagonists into the inferior colliculi. The present results show that the inferior colliculus represents the main site where sound-evoked ECoG desynchronization is prevented by L-NAME and provide further support for the hypothesis that NO may play a role at this level in the control of the measured response.

Animals↗
PubMed1995

Systemic administration of lithium chloride and tacrine but not kainic acid augments citrulline content of rat brain.

The effects of tacrine (5 mg/kg i.p.) in lithium chloride (LiCl; 12 mEq/kg i.p.)-pretreated (24 h beforehand) animals and of kainate (10 mg/kg i.p.) on brain citrulline, the co-product of nitric oxide (NO) synthesis, were studied in rats. High performance liquid chromatography analysis of whole brain tissue homogenates from rats treated with LiCl and tacrine revealed a significant increase in citrulline content before the onset of seizures. This effect was prevented in a stereoselective manner by N omega-nitro-L-arginine methyl ester (10 mg/kg i.p., given 20 min before tacrine), an inhibitor of NO synthase. By contrast, kainic acid (10 mg/kg i.p.) did not affect significantly brain citrulline during the pre-convulsive period. In conclusion, our data indicate that in rats seizures induced by LiCl and tacrine but not kainic acid are triggered by excessive NO production in the brain.

Animals↗
PubMed1995

Nitric oxide action on growth factor-elicited signals. Phosphoinositide hydrolysis and [Ca2+]i responses are negatively modulated via a cGMP-dependent protein kinase I pathway.

The role of nitric oxide (NO) in the phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis and intracellular Ca2+ release responses induced by epidermal, platelet-derived, and fibroblast growth factors was investigated in three cell lines, a clone of NIH-3T3 fibroblasts overexpressing epidermal growth factor receptors and the tumoral epithelial cells A431 and KB. In all three cell types, pretreatment with NO donors decreased growth factor-induced PIP2 and Ca2+ responses, whereas pretreatment with NO synthase inhibitors increased them. The Ca2(+)-dependent PIP2 hydroysis induced by micromolar concentrations of the Ca2+ ionophore, ionomycin, was also modulated negatively and positively by NO donors and synthase inhibitors, respectively. In contrast, the Ca2+ content of the intracellular stores was unaffected by the various pretreatments employed. NO donors and synthase inhibitors induced an increase and decrease, respectively, of the intracellular cGMP formation in all three cell lines investigated. All of the effects of the NO donors were mimicked by 8-bromo-cGMP administration and abolished by pretreatment with the specific blocker of the cGMP-dependent protein kinase I, KT5823, which by itself mimicked the effects of the synthase inhibitors. Together with previous observations on G protein-coupled receptors, the present results demonstrate that PIP2 hydrolysis and Ca2+ release occur under the feedback control of NO, independently of the phospholipase C (beta, gamma, or delta type) involved and of the mechanism of activation. Such a control, which appears to be effected by the cGMP-dependent protein kinase I acting at the level of the phospholipases C themselves, might ultimately contribute to the inhibitory role of NO on growth previously observed with various cell types.

Alkaloids↗
PubMed1995

HIV-1 gp120 produces DNA fragmentation in the cerebral cortex of rat.

In the present experiments we have used morphological techniques to study the neuropathological profile of the brain of rats after intracerebroventricular (i.c.v.) injection of recombinant HIV-1 gp 120. Using brain cryostat sections (10 microns) from rats treated with a single, daily dose of gp120 (100 ng/rat) given for 7 and 14 consecutive days, in situ DNA fragmentation was revealed in the neocortex but not in the hippocampus by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end-labelling (TUNEL). In these rats, dark degenerating neurones were observed in the neocortex but not in the hippocampus. Treatment with bovine serum albumin (300 ng/rat, i.c.v.) for up to 14 days did not produce DNA fragmentation nor did it yield neuropathological lesions of the neocortex or hippocampus. In conclusion, the present data demonstrate that gp 120 given i.c.v. produced DNA fragmentation in the neocortex, thus suggesting that apoptosis is the mechanism through which neurones of the neocortex are killed.

Animals↗
PubMed1995

Nitric oxide modulates agonist-evoked Ca2+ release and influx responses in PC12-64 cells.

Nitric oxide (NO) is a signalling molecule involved in events crucial to neuronal cell function such as neurotransmitter release, gene transcription, and neurotoxicity. In these, as well as in many other neuronal processes, a key role may be played by the increases of the intracellular Ca2+ concentration ([Ca2+]i) occurring in response to activation of plasma membrane receptors coupled to phosphatidylinositol 4,5-bisphosphate hydrolysis. Such a [Ca2+]i increases are sustained by release of the cation from intracellular stores and stimulation of influx through specific Ca2+ channels. We have investigated the role of NO in modulating the two above Ca2+ processes occurring subsequently to muscarinic receptor activation in a selected clone (PC12-64) of PC12 cells, a neurosecretory/neuronal cell model. Analysis of [Ca2+]i variations in fura-2-loaded cells, exposed to different NO synthase inhibitors or NO donors, showed that Ca2+ release from intracellular stores was moderately inhibited and stimulated by these two groups of drugs, respectively, while Ca2+ influx through the channels directly coupled to muscarinic receptors was found to be insensitive to NO action. In contrast, Ca2+ influx activated by muscarinic receptor-induced store depletion (investigated also by Mn2+ quenching of the fura-2 signal) was increased by NO generation and inhibited by NO synthase blockade. Incubation of the cells with 8-bromo cGMP did not mimick the action of NO, suggesting that the effect of the messenger on Ca2+ influx is exerted through a signalling pathway different from cGMP generation.

Amino Acid Oxidoreductases↗
PubMed1995

Lack of involvement of nitric oxide in the mechanisms of seizures and hippocampal damage produced by kainate and ouabain in rats.

The gross behavioural, electrocortical and neuropathological effects of kainate (10 mg/kg i.p,) and ouabain (1 micrograms, given into one dorsal hippocampus) were studied in rats. The effects of these treatments on nitric oxide synthase (NOS) activity in homogenates of hippocampus and cortex were also studied. Administration of kainate or ouabain produced motor and electrocortical seizures similar for latency to onset (approximately 15 min) and intensity (in all instances 80-100% of the treated rats showed behavioural and electrographic seizures). These effects were accompanied at 24 h by severe damage to all subsectors of the hippocampal formation and this concerned a similar proportion of the treated rats (n = 4-8 per treatment). No significant changes in nitric oxide synthase (NOS) activity were noted in the cerebral cortex and hippocampus of rats receiving injections of kainate and ouabain. In addition, pretreatment with N omega-Nitro-L-arginine methyl ester (300 micrograms, given into one lateral cerebral ventricle 15 min previously) was ineffective in preventing the effects of kainate and ouabain. In conclusion, present data suggest that excessive production of NO is not involved in the mechanisms triggering seizures and neurodegeneration produced by kainate or ouabain.

Amino Acid Oxidoreductases↗
PubMed1995

Release of nitric oxide from astroglial cells: a key mechanism in neuroimmune disorders.

Astrocytes are glial cells able to release nitric oxide (NO) under basal conditions as well as following different neurochemical stimuli including cytokines, endotoxins and soluble antigens, thereby participating in neuroimmune responses. In particular, the inducible isoform of NO synthase seems to be activated during co-incubation of this cell type with cytokines as well as in the presence of the HIV coating gp120 glycoprotein, an effect which is associated with an enhancement of prostanoid release. This seems also to occur via activation of cyclooxygenase by NO. Thus, the L-arginine-NO pathway found in astrocytes may represent a novel approach in the treatment of neuroimmune disorders such as multiple sclerosis, Alzheimer's disease and AIDS.

Animals↗
PubMed1995

Death of cultured human neuroblastoma cells induced by HIV-1 gp120 is prevented by NMDA receptor antagonists and inhibitors of nitric oxide and cyclooxygenase.

The cytotoxic effects of the human immunodeficiency virus type 1 (HIV-1) coat protein gp120 were studied in human CHP100 neuroblastoma cell cultures. Incubation of neuroblastoma cultures with gp120 (1 pM-10 nM) induces cell death which is not concentration-related. The significant cell death evoked by 10 pM gp120 was prevented by neutralization of the viral protein with a monoclonal anti-gp120 (IgG) antibody. In addition, gp120-induced cytotoxicity was inhibited by [DL-(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid] (CGP37849; 100 microM), [(+/-)-3R*, 4as*, 6R*, 8aR*-6-(phosphonomethyl) decahydro-isoquinoline-3-carboxylic acid] (LY274614; 100 microM), MK801 (dizocilpine; 200 nM) and 7-chloro kynurenic acid (100 microM), selective antagonists of the NMDA receptor complex; by contrast, (6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 100 microM), a non-NMDA antagonist, was ineffective. Prevention of the lethality elicited by the HIV-1 coat protein was also obtained by incubating neuroblastoma cells with gp120 in Ca(2+)-free medium. The lethal effects induced by gp120 involve activation of L-arginine-nitric oxide (NO) pathway since these were prevented by haemoglobin (10 microM), a NO-trapping agent, and by D-arginine (1 mM), the less active enantiomer of the endogenous precursor of NO synthesis. Cytoprotection was also afforded by N omega-nitro-L-arginine methyl ester (L-NAME; 200 microM), an inhibitor of NO synthase, and this was reversed by L-arginine (1 mM). Interestingly, indomethacin and flufenamic acid (10 microM), two inhibitors of cyclooxygenase, protected neuroblastoma cells from death induced by gp120. Furthermore, indomethacin prevented the neuroblastoma cell death evoked by exposure of cultures to sodium nitroprusside (SNP; 0.2-1.6 mM), a NO donor. Finally significant cytotoxic effects were observed after incubation of neuroblastoma cells with prostaglandin E2 (0.1-10 microM). In conclusion, the present data suggest that death of human CHP100 neuroblastoma cells in culture produced by gp120 involves NO and PGE2 production.

Antineoplastic Agents↗
PubMed1995

Nitric oxide modulation of agonist-evoked intracellular Ca2+ release in neurosecretory PC-12 cells: inhibition of phospholipase C activity via cyclic GMP-dependent protein kinase I.

Nitric oxide is a signaling molecule involved in events crucial to neuronal cell function, such as neurotransmitter release, gene transcription, and neurotoxicity, i.e., a number of processes in which a key role appears to be played by increases in intracellular Ca2+ concentration. In the neurosecretory/neuronal cell line PC-12, we have investigated the role of nitric oxide in the modulation of Ca2+ release from intracellular stores elicited by activation of three different receptors coupled to phosphatidyl-inositol-4,5-bisphosphate hydrolysis, i.e., the purinergic P2U, muscarinic M3, and bradykinin B2 receptors. The results obtained show that nitric oxide donors have an inhibitory effect on agonist-evoked Ca2+ release. This effect is not due to nitric oxide-induced modifications of Ca2+ storage, because the total releasable Ca2+ pool, measured as the radioactivity released by thapsigargin and ionomycin in cells loaded at equilibrium with 45Ca2+, was unchanged. In contrast, nitric oxide donors decreased agonist-evoked inositol-1,4,5-trisphosphate generation and total inositol phosphate accumulation. Similarly, nitric oxide inhibited total inositol phosphate accumulation stimulated by either aluminium fluoride or Ca2+. All of these effects were mimicked by the cGMP analogue 8-bromo-cGMP. When cells were incubated with nitric oxide synthase inhibitors, the results observed were opposite those produced by nitric oxide donors. All of the effects of nitric oxide were abolished when cells were treated with the cGMP-dependent protein kinase I inhibitor KT5823. Furthermore, KT5823 mimicked the effects of nitric oxide synthase inhibitors. We conclude that nitric oxide and Ca2+ signaling pathways are interconnected in PC-12 cells. Modulation of inositol phosphate generation and Ca2+ release by nitric oxide appears to be exerted primarily at the level of phospholipase C functioning and to be mediated by the activation of cGMP-dependent protein kinase I.

Amino Acid Oxidoreductases↗
PubMed1995

Growth factor-induced Ca2+ responses are differentially modulated by nitric oxide via activation of a cyclic GMP-dependent pathway.

Nitric oxide (NO) plays a modulatory role on cell growth and differentiation, biological processes that occur under the control of various signal transduction mechanisms, including those triggered by activation of membrane receptors for polypeptide growth factors. The increases in intracellular Ca2+ concentration elicited by the activation of these receptors are sustained by release of the cation from intracellular stores and by stimulation of this influx from the extracellular medium. Using NIH 3T3 cells overexpressing the human epidermal growth factor receptor, we investigated both of these processes stimulated by the administration of epidermal and platelet-derived growth factors as the receptor agonists. Pharmacological and functional analyses carried out on Fura-2-loaded cells showed that Ca2+ influx elicited by both growth factors is the summation of two distinct pathways, with the major pathway dependent on and the minor pathway independent of store depletion. Exposure of the cells to either No donors or NO synthase inhibitors induced increase and inhibition, respectively, of the two components of Ca2+ influx. When Ca2+ release was investigated, the above drugs were also active but in the opposite direction. The effects of NO were mimicked by the cGMP analogue 8-Br-cGMP and abolished by two cGMP-dependent protein kinase I inhibitors, whereas the cAMP analogue 8-Br-cAMP and two protein kinase A inhibitors had no appreciable effects. In addition, growth factors induced an increase in cGMP formation, an effect that was prevented by NO synthase inhibitors. In conclusion, NO appears to exert a feedback modulatory control on CA2+ responses to growth factor administration. Such a control might contribute to the inhibitory effect of NO on growth previously reported with various cell types.

3T3 Cells↗
PubMed1994

NMDA-dependent NGF mRNA expression by human astrocytoma cells is mediated by nitric oxide.

The aim of this study was to investigate the role of NO-cGMP pathway in NMDA-induced NGF mRNA expression by T67 astrocytoma cells. Levels of nitrite, a breakdown product of NO, in supernatants of NMDA-treated astrocytoma cells were significantly higher compared with control cells, this effect being reversed by the specific NO synthase inhibitor L-NAME. Furthermore, NGF mRNA expression was induced by NMDA treatment, this effect being inhibited by pretreating cells with L-NAME. Moreover, methylene blue, an inhibitor of NO biological activity at guanylate cyclase level, inhibited NMDA-induced NGF mRNA expression and this effect was reversed by dbt2-cGMP. These findings suggest that NO-cGMP pathway mediates the synthesis of NGF mRNA.

Astrocytoma↗
PubMed1994

Intracerebral injection of human immunodeficiency virus type 1 coat glycoprotein GP120 does not produce neurodegeneration in rats.

The human immunodeficiency virus type 1 (HIV-1) coat glycoprotein, GP120 has been reported to cause death of several neuronal cell types maintained in vitro. In the present experiments the gross behavioural, electrocortical (ECoG) and neuropathological effects of GP120 were studied in rats chronically microinfused into one lateral cerebral ventricle (i.c.v.) via mini-osmotic pumps. Treatment with GP120 (100 ng/day) for 1, 7 and 14 consecutive days lacked postural, motor and ECoG effects nor did it produce any apparent brain damage. In addition, acute i.c.v. injection of a subconvulsive dose (500 ng) of N-methyl-D-aspartate (NMDA) did not produce motor and ECoG epileptogenic discharges in rats which received 1 h beforehand a dose of GP120 (900 ng) into the dorsal hippocampus ipsilateral to the injected ventricle; per se this dose of GP120 was ineffective. In conclusion, the present experiments demonstrate that acute or chronic microinfusion of GP120 into the rat cerebral ventricular system does not produce neurotoxic effects. In addition, they demonstrate that intrahippocampal GP120 does not sensitize rats to the excitotoxic effects of a subconvulsive dose of NMDA.

Animals↗