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F Cattabeni

Publications and source records attributed to F Cattabeni.

At least 109 records · Page 6Linked to original sources
PubMed1993

The impaired long-term potentiation in the CA1 field of the hippocampus of cognitive deficient microencephalic rats is restored by D-serine.

Rat embryos exposed on gestational day 15 to methyl-azoxymethanol acetate develop a microencephaly characterized primarily by a hypoplasia of the neocortex and CA fields of the hippocampus that in adulthood is associated with disturbances in learning. In brain slices prepared from microencephalic rats, we have examined the field excitatory postsynaptic potentials and population spike in the CA1 field of the hippocampus evoked by stimulation of the stratum radiatum. These parameters did not differ from those obtained in slices from control rats. High frequency stimulation of the stratum radiatum afferent fibres, which readily induced long-term potentiation of the field excitatory postsynaptic potentials and population spike in the CA1 field of the hippocampus of control rats, failed to induce long-term potentiation in that of microencephalic rats. High frequency stimulation of the perforant path readily elicited long-term potentiation in the dentate gyrus of both control and microencephalic rats. Picrotoxin had no apparent effect on field excitatory postsynaptic potentials and population spike in the CA1 field of the microencephalic rats, indicating that little GABAergic inhibition was present in slices from these rats. D-2-Amino-phosphonovalerate suppressed the field potentials in slices from microencephalic rats by more than 50%, suggesting that N-methyl-D-aspartate receptors contributed markedly to the synaptic responses evoked by single stimuli. D-Serine, but not picrotoxin, restored long-term potentiation in the CA1 field of the microencephalic rats. The D-serine effect was prevented by pretreating the slices with either 7-chloro-kynurenate or D-2-amino-phosphonovalerate. The failure to induce long-term potentiation, if also found in vivo, may be among the factors related to the learning deficits displayed by these rats.

2-Amino-5-phosphonovalerate↗
PubMed1992

L-glutamine prevents the L-histidine-mediated enhancement of hydrogen peroxide-induced cytotoxicity.

Results presented in this study demonstrate that L-glutamine, a competitive inhibitor of L-histidine uptake, inhibits in a concentration-dependent fashion the L-histidine-mediated enhancement of H2O2-induced cytotoxicity. L-Glutamine also prevents the induction of DNA double strand breaks (DSB) but does not affect the enhancing effect of L-histidine on DNA single strand break induction by H2O2. Taken together, these data demonstrate that L-histidine, in order to allow the formation of DNA double strand breakage and increase the toxicity elicited by the oxidant, has to enter the cell. In addition, these results indicate that the enhancement of DNA single strand breakage is a consequence of the action of the amino acid at the extracellular level and/or outer surface of the plasma membrane and does not appear related to the mechanism whereby L-histidine increases the cytotoxic response to H2O2. The latter mechanism very likely involves the formation of DNA DSB.

Animals↗
PubMed1992

Cellular expression of somatostatin in MAM-induced microencephaly in the rat.

Methylazoxymethanol acetate (MAM) is a mitotic inhibitor that has been used to selectively destroy neuroblasts at specific times during gestation. The administration of MAM results in a dose-dependent microencephaly. Following MAM treatment at 15 days of gestation, we have noted an increase in the level of SS immunoreactivity in the neocortex, as determined by radioimmunoassay. Northern blot analysis for preproSS mRNA revealed an increase in MAM-treated cortex. The cellular distribution of SS has been determined using in situ hybridization and immunocytochemistry. There was a 30% increase in the density of SS-immunoreactive neurons in the cortex of the MAM-treated animals. These data suggest that SS neurons in the cortex are spared following MAM treatment at GD 15.

Animals↗
PubMed1992

Prolonged in vitro exposure of rat brain slices to adenosine analogues: selective desensitization of adenosine A1 but not A2 receptors.

Agonist-induced desensitization of adenosine A1 and A2 receptors was studied in rat striatum slices maintained in carbo-oxygenated Krebs buffer. Slices were exposed to adenosine analogues (either cyclo-pentyl-adenosine or N-ethyl-carboxamido-adenosine) for selected time periods (15-60 min) and repeatedly washed at the end of agonist exposure. Agonist-induced changes of adenosine receptors were then evaluated in P2 fractions prepared from slices by measuring A1 and A2 receptor-regulated adenylate cyclase. A1 receptors were rapidly desensitized by agonist exposure, as shown by a gradual loss of A1 receptor-mediated inhibition of basal cyclase activity and cAMP formation, which was evident within 15-30 min after addition of the adenosine analogue. Agonist-induced desensitization of A1 receptors was dose- and time-dependent, and seemed quicker in onset with cyclo-pentyl-adenosine, according to the higher A1 selectivity of this receptor agonist, with respect to N-ethyl-carboxamido-adenosine. Binding of the A1-selective agonist [3H]cyclo-hexyl-adenosine was unaffected by the desensitization procedure at any of the exposure periods utilized, suggesting that an uncoupling of A1 receptors from their transduction system is indeed responsible for the loss of functional activity. Loss of A1 receptor function was accompanied by a time-dependent amplification of A2 receptor-mediated stimulation of adenylate cyclase activity, likely due to an 'unmasking' of A2 stimulatory receptor function as a consequence of the desensitization of A1 inhibitory receptors. All these effects could be completely counteracted by the concomitant exposure to an adenosine receptor antagonist, and specifically involved the coupling mechanisms of adenosine receptors with their effector system.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1992

Measurement of relative amounts of phospho- and dephospho-B-50(GAP-43) peptides by fast atom bombardment-mass spectrometry.

The biological role of phosphoproteins depends upon their degree of phosphorylation in vivo. Methods currently available to measure the degree of phosphorylation of a protein involve indirect procedures to detect the 32P-phosphate incorporation. We report here a direct method to measure relative amounts of phospho- and dephospho-forms of peptides based upon a mass spectrometric technique. The intensities of the molecular ions corresponding to the two forms of the peptides are proportional to their relative amounts. This is demonstrated for a peptide fragment of the protein B-50(GAP-43) and for kemptide, respectively substrates for protein kinases C and A, and demonstrates the applicability of fast atom bombardment-mass spectrometry to quantitate peptides bearing post-translational modifications.

Amino Acid Sequence↗
PubMed1992

Cholinergic hyperinnervation in the cerebral cortex of microencephalic rats does not result in muscarinic receptor down-regulation or in alteration of receptor-stimulated phosphoinositide metabolism.

Administration of methylazoxymethanol (MAM; 25 mg/kg) to pregnant rats at gestational day 15 (GD 15) induces a marked reduction of telencephalic areas of the offspring brain. Previous neurochemical studies demonstrated a marked cholinergic hyperinnervation in the cerebral cortex of microencephalic rats. In this study we have evaluated whether this cholinergic hyperinnervation could result in altered functionality of muscarinic receptors. Acetylcholinesterase activity (AChE) was increased by 69% in the cerebral cortex of MAM treated rats, confirming a relative hyperinnervation, whereas in the hippocampus and striatum no significant changes were observed. Despite the marked hyperinnervation, in the cerebral cortex of microencephalic rats neither muscarinic receptor-stimulated phosphoinositide metabolism nor muscarinic receptor density were altered. No differences in receptor density were also observed in the hippocampus and striatum. Chronic diisopropylfluorophosphate (DFP) administration induced a marked decrease of AChE activity and down-regulation of muscarinic receptors whereas atropine administration resulted in receptor up-regulation in cerebral cortex, striatum and hippocampus of both control and MAM rats. The results confirm a relative cholinergic hyperinnervation in the cerebral cortex of microencephalic rats and demonstrate that the regulation of muscarinic receptor-stimulated phosphoinositide metabolism and muscarinic receptor plasticity is not modified in a condition of increased cholinergic presynaptic terminals.

Abnormalities, Drug-Induced↗
PubMed1992

Induction/repair of strand breakage in mature and nascent DNA of cultured Chinese hamster ovary cells exposed to hydrogen peroxide.

Treatment of cultured mammalian cells with hydrogen peroxide results in the production of extensive DNA damage. Strand breakage was produced at the level of either nascent or mature DNA and the former target appeared slightly more resistant than the latter. Although inhibitors of the enzyme poly(ADP-ribose) polymerase similarly retarded the repair of such lesions, removal of DNA strand breaks was much slower for the newly synthesized DNA as compared to mature DNA.

Animals↗
PubMed1992

Diabetes-induced alterations of central nervous system G proteins. ADP-ribosylation, immunoreactivity, and gene-expression studies in rat striatum.

Previous studies from our laboratory have suggested that diabetes-associated central nervous system abnormalities are characterized by progressive alterations of neurotransmitters and of transductional Gi/Go proteins. In this study, we have further characterized these abnormalities in the striatum of alloxan-diabetic rats by means of adenosine 5'-diphosphate (ADP)-ribosylation, and Western and Northern blotting techniques. Fourteen weeks after diabetes induction, pertussis-toxin (PTX) catalyzed ADP-ribosylation of Gi/Go proteins was markedly reduced in diabetic animals, as shown by a clear decrease of 32P-ADPribose incorporation into G protein alpha subunits. In agreement with our previous pharmacological studies that showed a reduction of Gi-mediated modulation of adenylate cyclase activity only at this stage of diabetes, no changes in PTX-mediated ADP-ribosylation were observed earlier (5-wk diabetes). Immunoblotting studies performed by using antibodies selectively raised against Gi-2, Go, and Gs proteins did not reveal any differences between control and diabetic animals at any stage of diabetes. Similarly, the mRNAs corresponding to the alpha subunits of Gi-2, Go, and Gs proteins did not show any marked changes in chronic diabetic rats with respect to control animals. It is therefore concluded that diabetes is associated with development of a time-related alteration of cerebral Gi/Go proteins and that this defect is not owing to gross changes in either content of G proteins or mRNA level, but probably reflects modifications of G protein's structure or physiological status affecting the coupling with membrane effector systems and the sensitivity to PTX.

Adenosine Diphosphate Ribose↗
PubMed1992

Differential effect of the amino acid cystine in cultured mammalian and bacterial cells exposed to oxidative stress.

The effect of cystine in the cytotoxic response of cultured Chinese hamster ovary and Escherichia coli cells to challenge with hydrogen peroxide has been investigated. It was found that this amino acid could either protect or sensitize cells, depending on the cellular system. In fact, although a reduction in the growth-inhibitory effect of hydrogen peroxide was observed in mammalian cells, a marked increase in the susceptibility to oxidative stress was induced by cystine in bacteria. None of the amino acid precursors of glutathione, e.g., glutamate, glycine or cysteine, afforded protection in the mammalian cell system, whereas cysteine, but not glycine or glutamate, markedly sensitized bacteria to hydrogen peroxide-induced cell killing. In mammalian cells, methionine, an amino acid which is converted to cysteine, was also unable to modify the oxidative response. The results presented indicate that cystine displays differential effects in oxidatively injured mammalian or bacterial cells and suggest that the mechanism whereby the amino acid modulates the lethal action of hydrogen peroxide differs in the two cellular systems.

Animals↗
PubMed1992

The phosphorylation state of DARPP-32, a third messenger for dopamine, is regulated by in vivo pharmacological treatments.

It has been recently proposed that DARPP-32 participates, as third messenger, in the mediation of effects induced by dopamine at the cellular level. DARPP-32 is indeed localized almost exclusively on dopaminoceptive neurons bearing the D1 receptor subtype and it is phosphorylated by cAMP-dependent protein kinase. In its phospho-form, DARPP-32 acts as an inhibitor of protein phosphatase-1. In vivo pharmacological treatment with selective D1 agonists and antagonists induces changes in the phosphorylation state of DARPP-32 that can be correlated to changes in cAMP, mediated in turn by D1 and D2 receptors. These data demonstrate that the measurement of the phosphorylation state of DARPP-32 with the back-phosphorylation assay can represent a useful biochemical tool to gain further insight into the sequence of events elicited by specific dopaminergic drugs in vivo.

Animals↗
PubMed1992

Distribution of nicotinic receptors in cynomolgus monkey brain and ganglia: localization of alpha 3 subunit mRNA, alpha-bungarotoxin and nicotine binding sites.

The distribution of nicotinic receptors in the brain and ganglia of the Cynomolgus monkey was studied by in situ hybridization and receptor autoradiography. A 35S-labeled antisense riboprobe for the mRNA of the alpha 3 subunit of the human nicotinic receptor, [3H]L-nicotine and [125]alpha-bungarotoxin were used as markers. The highest levels of alpha 3-mRNA were observed in the hippocampus, the medial habenula, the lateral geniculate, the granular layer of the cerebellum, as well as in the pineal gland; moderate levels were found in other nuclei of the thalamus and in the deeper layers of the cerebral cortex. High-affinity binding sites for [3H]L-nicotine were observed mainly in the thalamus. The distribution of [125I]alpha-bungarotoxin binding sites was different from that observed for alpha 3-mRNA and [3H]L-nicotine; they were most abundant in a few specific thalamic nuclei, in the medial habenula and in lamina I of the cerebral cortex. The localization of these three markers was also investigated in the sympathetic, parasympathetic and sensory ganglia of the monkey. Intense labeling was observed for alpha 3-mRNA and for [125I]alpha-bungarotoxin in the sympathetic and parasympathetic ganglia, whereas no positive signal was seen in the ganglion of Gasser. [3H]L-nicotine binding was not detected in any of the ganglia examined. High levels of mRNA for the alpha 3 subunit of the nicotinic receptor were also detected in human sympathetic ganglia. Comparison between alpha 3-mRNA distribution and [3H]L-nicotine binding suggests that in the Cynomolgus monkey brain, the alpha 3 subunit may participate in the formation of more than one nicotinic receptor subtype: a high-affinity binding site for [3H]L-nicotine in the thalamus, and other sites with low affinity for nicotine in the medial habenula and cerebral cortex. Both the alpha 3-mRNA and the [125I]alpha-bungarotoxin are highly expressed in the sympathetic ganglia; however, since no information is presently available on the intraneuronal cellular localization, it cannot be established whether or not they are both present at synaptic sites.

Animals↗
PubMed1992

Adenosine receptors in rat basophilic leukaemia cells: transductional mechanisms and effects on 5-hydroxytryptamine release.

1. The presence of adenosine receptors linked to adenylate cyclase activity and their functional role in calcium-evoked 5-hydroxytryptamine (5-HT) release was investigated in rat basophilic leukaemia (RBL) cells, a widely used model for studying the molecular mechanisms responsible for stimulus-secretion coupling. 2. In [3H]-5-HT-loaded cells triggered to release by the calcium ionophore A23187, a biphasic modulation of 5-HT secretion was induced by adenosine analogues, with inhibition of stimulated release at nM and potentiation at microM concentrations, suggesting the presence of adenosine receptor subtypes mediating opposite effects on calcium-dependent release. This was also confirmed by results obtained with other agents interfering with adenosine pharmacology, such as adenosine deaminase and the non-selective A1/A2 antagonist 8-phenyl-theophylline. 3. Similar biphasic dose-response curves were obtained with a variety of adenosine analogues on basal adenylate cyclase activity in RBL cells, with inhibition and stimulation of adenosine 3':5'-cyclic monophosphate (cyclic AMP) production at nM and microM concentrations, respectively. The rank order of potency of adenosine analogues for inhibition and stimulation of adenylate cyclase activity and the involvement of G-proteins in modulation of cyclic AMP levels suggested the presence of cyclase-linked A1 high-affinity and A2-like low-affinity adenosine receptor subtypes. However, the atypical antagonism profile displayed by adenosine receptor xanthine antagonists on cyclase stimulation suggested that the A2-like receptor expressed by RBL cells might represent a novel cyclase-coupled A2 receptor subtype.4. Micromolar concentrations of adenosine analogues could also increase inositol phospholipid hydrolysis and inositol tris-phosphate formation in both unstimulated cells and in cells triggered to release by the calcium ionophore. The stimulation was constant, small and additive to that exerted by the calcium ionophore.5. It is concluded that RBL cells express both A1 and A2-like adenosine receptors which exert opposite effects on 5-HT release and intracellular cyclic AMP levels. However, besides modulation of cyclic AMP levels, additional transduction pathways, such as modulation of phospholipase C activity, may contribute to the release response evoked by adenosine analogues in this cell-line.

Adenylyl Cyclases↗
PubMed1992

The role of extracellular medium components and specific amino acids in the cytotoxic response of Escherichia coli and Chinese hamster ovary cells to hydrogen peroxide.

A concentration of H2O2 resulting in mode one killing of Escherichia coli is more toxic when exposure to the oxidant is performed in complete medium (K medium), as compared to a saline (M9 salts). Inorganic salts (MgSO4 and CaCl2), thiamine or glucose, when added separately, or combined, to M9 salts had no effect on the cytotoxic response to H2O2. In contrast, the lethality of the oxidant was highly dependent on the presence of the amino acids in the incubation medium. The addition of glucose further enhanced this response. Among the seventeen amino acids which are present in the complete amino acid mixture, only two, i.e. L-histidine and L-cystine, were found to increase the toxicity of H2O2. Again, glucose augmented this response. The effect of these amino acids on the growth inhibitory action of hydrogen peroxide was also tested in Chinese Hamster Ovary cells. It was found that L-histidine was capable of increasing the toxicity of the oxidant whereas all the other amino acids did not affect the toxicity of the oxidant. Glucose only slightly augmented this effect of L-histidine. DNA single strand breakage produced by H2O2 was increased by L-histidine and was not significantly modified by the other amino acids. DNA double strand breakage was also shown to occur in cells exposed to H2O2-L-histidine, and this effect was independent on the presence of glucose. These results demonstrate that the cytotoxic response of bacterial and mammalian cells to challenge with H2O2 is highly dependent on the composition of the extracellular milieu.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1992

Effects of L-histidine on hydrogen peroxide-induced DNA damage and cytotoxicity in cultured mammalian cells.

L-Histidine markedly increased the growth- and DNA synthesis-inhibitory effects elicited by hydrogen peroxide in cultured Chinese hamster ovary cells. DNA single-strand breakage was also higher in the presence of the amino acid and, in addition, these breaks were characterized by a slower rate of repair, compared with that of the breaks generated by the oxidant alone. In the presence of L-histidine, hydrogen peroxide also produced DNA double-strand breakage, a lesion that cannot be detected in cells treated with even exceedingly high concentrations of the oxidant alone. Data reported herein suggest that the L-histidine-mediated increase of the cytotoxic response of cultured Chinese hamster ovary cells to hydrogen peroxide may be at least partially dependent on the formation of DNA double-strand breaks.

Animals↗
PubMed1991

Microencephaly reduces the phosphorylation of the PKC substrate B-50/GAP43 in rat cortex and hippocampus.

The administration of the antimitotic agent methylazoxymethanol (MAM) to rats at day 15 of gestation results in a consistent loss of intrinsic neurons primarily in cortex and hippocampus. These animals when adult, show a cognitive impairment, if tested in specific behavioural tasks. B-50/GAP43 is a neuronal phosphoprotein, specific substrate for protein kinase C (PKC) and involved in the development and plasticity of synaptic connections. Since B-50/GAP43 has been implicated in functional modulation of synapses and in the molecular mechanism underlying cognitive processes, we studied the phosphorylation of B-50 in cortex and hippocampus of control and MAM-treated rats. Here we report that B-50 in MAM-treated rats shows a marked reduction in the phosphate incorporation in the areas affected by the prenatal treatment. In situ hybridization studies demonstrate that the mRNA levels for B-50 are not altered in MAM-treated rats and that the relative amount of the protein, as revealed by Western blot analysis, is also not affected in microencephalic rats. These results suggest that microencephalic animals might represent a useful experimental model to study biochemical correlates of cognitive impairment and synaptic plasticity.

Animals↗
PubMed1991

Cytocidal and filamentous response of Escherichia coli cells exposed to low concentrations of hydrogen peroxide and hydroxyl radical scavengers.

The hydroxyl radical scavengers thiourea, ethanol, and dimethyl sulfoxide significantly reduced the killing of Escherichia coli elicited by low concentrations of H2O2 (resulting in mode 1 killing) when treatments with the oxidant and the scavengers were performed in a complete growth medium (K medium) but not in M9 salts. In addition, thiourea efficiently prevented the toxic response to high concentrations of H2O2 (resulting in mode 2 killing) under both exposure conditions. Sod A cells, which do not respond with a bimodal pattern of toxicity when challenged with increasing concentrations of H2O2, were markedly protected by thiourea against the lethal action of various levels of the oxidant (which in the wild-type strain result in either mode 1 or mode 2 killing) under conditions of treatments in both K medium and M9 salts. In some experiments, wild-type cells were challenged with a low concentration of H2O2 (in the absence or presence of hydroxyl radical scavengers) and then postincubated in fresh K medium for various time intervals. It was found that scavengers were able to inhibit the filamentous response generated by exposure to the oxidant in K medium. Both the length and the number of filaments were markedly reduced. Treatment in M9 salts resulted in a limited number of very short filaments, and this response was slightly reduced by the scavengers.

Dimethyl Sulfoxide↗