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G Sancesario

Publications and source records attributed to G Sancesario.

At least 19 recordsLinked to original sources
PubMed2006

Oligodendrocytes express P2Y12 metabotropic receptor in adult rat brain.

In the CNS, nucleotide receptors termed P2 receptors are identified on neurons and glial cells, mediating neuron-neuron, glia-glia and glia-neuron communication. In the present work, we qualify in vivo in the adult rat CNS the cellular/subcellular distribution of P2Y12 receptor protein in cerebral cortex, white matter and subcortical nuclei (striatum and substantia nigra), by means of immunofluorescence-confocal, electron microscopy and Western blot analysis. P2Y12 receptor immunoreactivity colocalizes neither with markers such as neuronal nuclei, neurofilament light chain, calbindin and tyrosine hydroxylase, nor with glial fibrillary acidic protein and isolectin B4, but with myelin basic protein and the oligodendrocyte marker RIP, in both cell bodies and processes, indicating therefore oligodendrocyte localization. Electron microscopy identifies P2Y12 receptors in both the perikaryon and under the plasmalemma of oligodendrocyte cell bodies and radiating processes, until the paranodal region of fibers. By Western blot analysis, P2Y12 receptor shows a specific band of 42-44 kDa, matching the molecular mass predicted from amino acid sequencing. Since in platelets P2Y12 receptor is known to regulate adhesion/activation and thrombus growth/stability, from our results we could speculate by analogy that, in oligodendrocytes, P2Y12 receptor signaling might contribute to the migration and adhesion of the glial processes to axons to be myelinated.

Animals↗
PubMed2006

Helicobacter pylori eradication and l-dopa absorption in patients with PD and motor fluctuations.

OBJECTIVE: To investigate if Helicobacter pylori (HP) eradication could make an effective and long-lasting improvement in the pharmacokinetic and clinical response to l-dopa in patients with Parkinson disease (PD) and motor fluctuations. METHODS: In a group of 34 HP-infected, motor-fluctuating patients with PD, the short-term (1-week) and long-term (3-month) beneficial effect of HP eradication (n = 17) was investigated in a double-blind fashion in comparison with a generic antioxidant treatment (n = 17), by means of pharmacokinetic, clinical, and gastrointestinal assessments. Results were compared with placebo treatment. RESULTS: Differently from the antioxidant-treated patients, the HP-eradicated patients showed a significant increase of l-dopa absorption, which was coupled with a significant improvement of clinical disability and with a prolonged "on-time" duration, whereas gastritis/duodenitis scores significantly decreased in line with a better l-dopa pharmacokinetics. CONCLUSIONS: These data demonstrate a reversible Helicobacter pylori (HP)-induced interference with l-dopa clinical response related to the impaired drug absorption, probably due to active gastroduodenitis. Therefore, the authors suggest that HP eradication may improve the clinical status of infected patients with Parkinson disease and motor fluctuations by modifying l-dopa pharmacokinetics.

Aged↗
PubMed2006

Metal changes in CSF and peripheral compartments of parkinsonian patients.

BACKGROUND: Involvement of metals in the risk of developing Parkinson's disease (PD) has been suggested. In the present study, concentration of metals in cerebrospinal fluid (CSF), blood, serum, urine and hair of 91 PD patients and 18 controls were compared. METHODS: Blood and hair were microwave digested, while CSF, serum and urine were water-diluted. Elements quantification was achieved by Inductively Coupled Plasma Atomic Emission Spectrometry and Sector Field Inductively Coupled Plasma Mass Spectrometry. RESULTS: Some metal imbalances in PD were observed: i), in CSF, lower Fe and Si; ii), in blood, higher Ca, Cu, Fe, Mg and Zn; iii), in serum, lower Al and Cu; iv), in urine, lower Al and Mn, higher Ca and Fe; and v), in hair, lower Fe. The ROC analysis suggested that blood Ca, Fe, Mg and Zn were the best discriminators between PD and controls. In addition, hair Ca and Mg were at least 1.5 times higher in females than in males of patients and controls. A decrement with age of patients in hair and urine Ca and, with less extent, in urine Si was observed. Magnesium concentration in CSF decreased with the duration and severity of the disease. Elements were not influenced by the type of antiparkinsonian therapy. CONCLUSIONS: Variation in elements with the disease do not exclude their involvement in the neurodegeneration of PD.

Age Factors↗
PubMed2005

Temporal lobe epileptic activity mimicking dementia: a case report.

Epileptic activity is an underdiagnosed cause that can determine a disruption of memory and cognitive performance, leading an incorrect diagnosis of dementia. We report a 68-year-old man, referred with a 5-year history of subtle behavioral changes and a subjective memory impairment, who was admitted to our department because of recurrent episodes of confusional state lasting from 1 week. Neuropsychological evaluation demonstrated a marked impairment of all cognitive domains examined. Electroencephalogram (EEG) recording showed frequent almost continuous sharp waves localized on the bilateral posterior temporal regions with mild right side predominance. Treatment with phenytoin reversed his cognitive dysfunction and behavioral disturbances. We presume that ictal temporal lobe epileptiform activity is the cause of his confusional episodes and cognitive dysfunction, showing an electroclinical picture of complex partial status epilepticus. However, we hypothesize that the interictal discharges and ictal and postictal effects of subclinical seizures could be involved in the behavioral changes and memory impairment complained by our patient in the last years.

Aged↗
PubMed2004

Immunolocalization of CB1 receptor in rat striatal neurons: a confocal microscopy study.

Several lines of evidence indicate that cannabinoids, among other functions, are involved in motor control. Although cannabinoid receptors (CB(1)) mRNA has been observed in medium-sized spiny neurons of the striatum, a description of the precise localization of CB(1) at a protein level among striatal cells is still lacking. Therefore, we performed immunohistochemical studies with light and confocal microscopy to identify neuronal subpopulations that express CB(1) and to assess the distribution of the receptor within these neurons. In our single label light microscopy study, CB(1) was observed in most medium-sized neurons of the caudate-putamen. However, CB(1) was also present in large-sized neurons scattered throughout the striatum. Our dual-label study showed that 89.3% of projection neurons in matrix contain CB(1), and that 56.4% of projection neurons in patch are labeled for CB(1). To investigate the presence of CB(1) among the different subclasses of striatal interneurons we performed a double-labeling study matching CB(1) and each of the striatal interneuron markers, namely, choline acetyl-transferase, parvalbumin, calretinin, and nitric oxide synthase. Our double-label study showed that most parvalbumin immunoreactive interneurons (86.5%), more than one-third (39.2%) of cholinergic interneurons, and about one-third (30.4%) of the NOS-positive neurons are labeled for CB(1). Calretinin-immunolabeled neurons were devoid of CB(1).

Animals↗
PubMed2004

Trace and major elements in whole blood, serum, cerebrospinal fluid and urine of patients with Parkinson's disease.

Quantifications of Al, Ca, Cu, Fe, Mg, Mn, Si and Zn were performed in urine, serum, blood and cerebrospinal fluid (CSF) of 26 patients affected by Parkinson's disease (PD) and 13 age-matched controls to ascertain the potential role of biological fluids as markers for this pathology. Analyses were performed by Inductively Coupled Plasma Atomic Emission Spectrometry and Sector Field Inductively Coupled Plasma Mass Spectrometry. The serum oxidant status (SOS) and anti-oxidant capacity (SAC) were also determined. Results showed a decreasing trend for Al in all the fluids of PD patients, with the strongest evidence in serum. Calcium levels in urine, serum and blood of PD patients were significantly higher than in controls. Copper and Mg concentrations were significantly lower in serum of PD patients. Levels of Fe in urine, blood and CSF of patients and controls were dissimilar, with an increase in the first two matrices and a decrease in CSF. No significant difference was found in levels of Mn between patients and controls. Urinary excretion of Si was significantly higher in PD subjects than in controls. No clear difference between Zn levels in the two groups was found for serum, urine or CSF, but an increase in Zn levels in the blood of PD patients was observed. The SOS level in PD was significantly higher while the corresponding SAC was found to be lower in patients than in controls, in line with the hypothesis that oxidative damage is a key factor in the pathogenesis of PD. The results on the whole indicate the involvement of Fe and Zn (increased concentration in blood) as well as of Cu (decreased serum level) in PD. The augmented levels of Ca and Mg in the fluids and of Si in urine of patients may suggest an involuntary intake of these elements during therapy.

Aged↗
PubMed2003

Activation of beta1-adrenoceptors excites striatal cholinergic interneurons through a cAMP-dependent, protein kinase-independent pathway.

The role of noradrenergic neurotransmission was analyzed in striatal cholinergic interneurons. Conventional intracellular and whole-cell patch-clamp recordings were made of cholinergic interneurons in rat brain slice preparations. Bath-applied noradrenaline (NA) (1-300 microm) dose-dependently induced both an increase in the spontaneous firing activity and a membrane depolarization of the recorded cells. In voltage-clamped neurons, an inward current was induced by NA. This effect was not prevented by alpha-adrenoceptor antagonists, whereas it was mimicked by the beta-adrenoceptor agonist isoproterenol and blocked by the beta1 antagonists propranolol and betaxolol. Interestingly, forskolin, activator of adenylate cyclase, mimicked and occluded the membrane depolarization obtained at saturating doses of both dopamine and NA. Accordingly, SQ22,536, a selective adenylate cyclase inhibitor, reduced the response to NA. Analysis of the reversal potential of the NA-induced current did not provide homogeneous results, indicating the involvement of multiple membrane conductances. Because cAMP is known to modulate Ih, the effects of ZD7288, a selective inhibitor of Ih current, were examined on the NA-induced membrane depolarization/inward current. ZD7288 mostly reduced the response to NA. However, both KT-5720 and H-89, selective protein kinase A (PKA) blockers, failed to prevent the excitatory action of NA. Likewise, calphostin C, antagonist of PKC, genistein, inhibitor of tyrosine kinase, and 8-Bromo-cGMP, blocker of PKG, did not affect the response to NA. Finally, double-labeling experiments combining beta1-adrenoceptor and choline acetyltransferase immunocytochemistry by means of confocal microscopy revealed a strong beta1-adrenoceptor labeling on cholinergic interneurons. We conclude that NA depolarizes striatal cholinergic interneurons via beta1-adrenoceptor activation, through a cAMP-dependent but PKA-independent mechanism.

Adenylyl Cyclases↗
PubMed2003

Enkephalin, neurotensin, and substance P immunoreactivite neurones of the rat GP following 6-hydroxydopamine lesion of the substantia nigra.

The ascending dopaminergic tract influences the activity of GP neurones in normal conditions. Its lesion may lead to an up-regulation of activity in this nucleus that is contrary to what would be expected based on the current model of the basal ganglia function. In this study we investigated the occurrence of enkephalin, neurotensin, and substance P immunoreactivity of the rat globus pallidus (GP) following lesion of the nigrostriatal pathway induced by the injection of the toxin 6-hydroxydopamine into the substantia nigra. Since 60-65% of GP neurones are immunopositive for parvalbumin, the immunoreactivity for peptides was evaluated, considering the different content in parvalbumin of pallidal neurones types, at early and chronic phases of denervation. Our results showed that a lesion of the nigrostriatal pathway induced the expression of enkephalin, neurotensin, and substance P immunoreactivity in numerous pallidal cell bodies. Each subgroup of neurones showed a different pattern of distribution. These modifications equally involved the two main subclasses of neurones. However parvalbumin-negative neurones were modified to a larger extent than the parvalbumin-positive ones. These data indicate that nigrostriatal lesion induces in a wide and unexpected peptide synthesis at least in three different subgroups of GP neurones. These modifications might be useful to further histochemically characterise neurones of the GP.

Animals↗
PubMed2003

Up-regulation of P2X2, P2X4 receptor and ischemic cell death: prevention by P2 antagonists.

In the present work we examined the involvement of selected P2X receptors for extracellular ATP in the onset of neuronal cell death caused by glucose/oxygen deprivation. The in vitro studies of organotypic cultures from hippocampus evidenced that P2X2 and P2X4 were up-regulated by glucose/oxygen deprivation. Moreover, we showed that ischemic conditions induced specific neuronal loss not only in hippocampal, but also in cortical and striatal organotypic cultures and the P2 receptor antagonists basilen blue and suramin prevented these detrimental effects. In the in vivo experiments we confirmed the induction of P2X receptors in the hippocampus of gerbils subjected to bilateral common carotid occlusion. In particular, P2X2 and P2X4 proteins became significantly up-regulated, although to different extent and in different cellular phenotypes. The induction was confined to the pyramidal cell layer of the CA1 subfield and to the transition zone of the CA2 subfield and it was coincident with the area of neuronal damage. P2X2 was expressed in neuronal cell bodies and fibers in the CA1 pyramidal cell layer and in the strata oriens and radiatum. Intense P2X4 immunofluorescence was localized to microglia cells. Our results indicate a direct involvement of P2X receptors in the mechanisms sustaining cell death evoked by metabolism impairment and suggest the use of selected P2 antagonists as effective neuroprotecting agents.

Animals↗
PubMed2002

P2 receptor modulation and cytotoxic function in cultured CNS neurons.

In this study we investigate the presence, modulation and biological function of P2 receptors and extracellular ATP in cultured cerebellar granule neurons. As we demonstrate by RT-PCR and western blotting, both P2X and P2Y receptor subtypes are expressed and furthermore regulated as a function of neuronal maturation. In early primary cultures, mRNA for most of the P2 receptor subtypes, except P2X(6), are found, while in older cultures only P2X(3), P2Y(1) and P2Y(6) mRNA persist. In contrast, P2 receptor proteins are more prominent in mature neurons, with the exception of P2Y(1). We also report that extracellular ATP acts as a cell death mediator for fully differentiated and mature granule neurons, for dissociated striatal primary cells and hippocampal organotypic cultures, inducing both apoptotic and necrotic features of degeneration. ATP causes cell death with EC(50) in the 20-50 microM range within few minutes of exposure and with a time lapse of at most two hours. Additional agonists for P2 receptors induce toxic effects, whereas selected antagonists are protective. Cellular swelling, lactic dehydrogenase release and nuclei fragmentation are among the features of ATP-evoked cell death, which also include direct P2 receptor modulation. Comparably to P2 receptor antagonists previously shown preventing glutamate-toxicity, here we report that competitive and non-competitive NMDA receptor antagonists inhibit the detrimental consequences of extracellular ATP. Due to the massive extracellular release of purine nucleotides and nucleosides often occurring during a toxic insult, our data indicate that extracellular ATP can now be included among the potential causes of CNS neurodegenerative events.

Adenosine Triphosphate↗
PubMed2001

A synaptic mechanism underlying the behavioral abnormalities induced by manganese intoxication.

In the present study we have characterized a rat model of manganese (Mn) intoxication leading to behavioral disinhibition in the absence of major motor alterations. These behavioral changes were associated with significantly increased brain Mn levels but were uncoupled to anatomical lesions of the striatum or to morphological and cytochemical changes of the nigrostriatal dopaminergic pathway. The analysis of this model at cellular level showed an enhanced dopaminergic inhibitory control of the corticostriatal excitatory transmission via presynaptic D2-like dopamine (DA) receptors in slices obtained from Mn-treated rats. Conversely, the use of agonists acting on presynaptic purinergic, muscarinic, and glutamatergic metabotropic receptors revealed a normal sensitivity. Moreover, membrane responses recorded from single dopaminergic neurons following activation of D2 DA autoreceptors were also unchanged following Mn intoxication. Thus, our findings indicate a selective involvement of the D2-like DA receptors located on glutamatergic corticostriatal terminals in this pathological condition and suggest that the behavioral symptoms described in the "early" clinical phase of manganism may be caused by an abnormal dopaminergic inhibitory control on corticostriatal inputs. The identification of the synaptic mechanism underlying the "early" phase of Mn intoxication might have a critical importance to understand the causes of the progression of this pathological condition towards an "established" phase characterized by motor abnormalities and anatomical lesions of the basal ganglia.

Animals↗
PubMed2001

Reduced L-dopa absorption and increased clinical fluctuations in Helicobacter pylori-infected Parkinson's disease patients.

We report that the area under the curve of L-dopa plasma concentration, following the administration of a single 250 mg L-dopa dose, is augmented after Helicobacter pylori (HP) eradication in six Parkinson's disease (PD) patients showing high IgG antibody titer against HP. A prolongation of L-dopa clinical benefit was also observed. We suggest that HP infection-activated gastric alterations may be responsible, at least in part, for the reported erratic efficacy of oral L-dopa therapy in some advanced PD patients. Given the high percentage of HP-positivity in the age cohorts including the largest prevalence of PD patients, we propose that HP eradication be recommended in all PD patients under L-dopa therapy.

Aged↗
PubMed2001

Hypoglycaemia-induced cell death: features of neuroprotection by the P2 receptor antagonist basilen blue.

Our previous work in neuronal cultures has shown that several antagonists of P2 ATP receptors prevent cell death evoked by hypoglycaemia, chemical hypoxia, mitochondria dysfunction, as well as glutamate-dependent excitotoxicity and low potassium-induced apoptosis. Experiments are now designed to examine which biological pathway contributes to cell death/survival under glucose starvation. We show here that, consequently to hypoglycaemic insults, cerebellar granule neurones undergo a combination of apoptosis and necrosis both inhibited by the P2 receptor antagonist basilen blue. This is demonstrated by morphological and biochemical features, such as TdT-mediated dUTP-biotin nick end-labelling, fluorescent staining of nuclear chromatin using Hoechst 33258, direct counting of intact viable nuclei and extracellular releasing of the cytosolic enzyme LDH. Furthermore, we show that hypoglycaemia induces outflow of cytochrome c from mitochondria and it up-regulates heat-shock proteins HSP70, but not HSP90, glucose-regulated proteins GRP75 and GRP78, as well as expression and activity of the enzyme caspase-2. Basilen blue can modulate only some of these effects. Our data contribute to dissect the role played by P2 receptor antagonism in sustaining neuroprotection against metabolic stresses.

Animals↗
PubMed2001

Glucose deprivation and chemical hypoxia: neuroprotection by P2 receptor antagonists.

In this work we investigate cell survival after glucose deprivation and/or chemical hypoxia and we analyse the neuroprotective properties of selected antagonists of P2 ATP receptors. We find that in rat cerebellar granule neurones, the antagonist basilen blue prevents neuronal death under hypoglycaemia. Basilen blue acts through a wide temporal range and it retains its efficacy under chemically induced hypoxic conditions, in the presence of the respiratory inhibitors of mitochondria electron transport chain complexes II (3-nitropropionic acid) and III (antimycin A). In spite of the presence of these compounds, basilen blue maintains normal intracellular ATP levels. It furthermore prevents neuronal death caused by agents blocking the mitochondrial calcium uptake (ruthenium red) or discharging the mitochondrial membrane potential (carbonyl cyanide m-chlorophenylhydrazone). Inhibition of poly (ADP-ribose) polymerase, modulation of the enzyme GAPDH and mitochondrial transport of mono-carboxylic acids are not conceivable targets for the action of basilen blue. Survival is sustained by basilen blue also in CNS primary cultures from hippocampus and in PNS sympathetic-like neurones. Partial neuroprotection is furthermore provided by three additional P2 receptor antagonists: suramin, pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid 4-sodium and 4,4'-diisothiocyanatostilbene-2,2'disulphonic acid. Our data suggest the exploitation of selected P2 receptor antagonists as potential neuroprotective agents.

Adenosine Triphosphate↗
PubMed2000

Selective vulnerability of pallidal neurons in the early phases of manganese intoxication.

Prolonged exposure to manganese in mammals may cause an extrapyramidal disorder characterized by dystonia and rigidity. Gliosis in the pallidal segments underlies the well-established phase of the intoxication. The early phase of the intoxication may be characterized by psychic, nonmotor signs, and its morphological and electrophysiological correlates are less defined. In a rat model of manganese intoxication (20 mg/ml in drinking water for 3 months), neither neuronal loss nor gliosis was detected in globus pallidus (GP). However, a striking vulnerability of manganese-treated GP neurons emerged. The majority of GP neurons isolated from manganese-treated rats died following brief incubation in standard dissociation media. In addition, patch-clamp recordings in the whole-cell configuration were not tolerated by surviving GP neurons. Neither coeval but untreated GP neurons nor striatal ones manifested analogous susceptibility. Using the perforated-patch mode of recording we attempted at identifying the functional hallmarks of GP vulnerability: in particular, voltage-gated calcium currents and glutamate-induced currents were examined. Manganese-treated GP neurons exhibited calcium currents similar to control cells aside from a slight reduction in the dihydropyridine-sensitive current facilitation. Strikingly, manganese-treated GP cells--but not striatal ones--manifested peculiar responses to glutamate, since repeated applications of the excitatory amino acid, at concentrations which commonly promote desensitizing responses, produced instead an irreversible cell damage. Possible mechanisms are discussed.

Animals↗
PubMed2000

Synaptic transmission in the striatum: from plasticity to neurodegeneration.

Striatal neurones receive myriad of synaptic inputs originating from different sources. Massive afferents from all areas of the cortex and the thalamus represent the most important source of excitatory amino acids, whereas the nigrostriatal pathway and intrinsic circuits provide the striatum with dopamine, acetylcholine, GABA, nitric oxide and adenosine. All these neurotransmitter systems interact each other and with voltage-dependent conductances to regulate the efficacy of the synaptic transmission within this nucleus. The integrative action exerted by striatal projection neurones on this converging information dictates the final output of the striatum to the other basal ganglia structures. Recent morphological, immunohistochemical and electrophysiological findings demonstrated that the striatum also contains different interneurones, whose role in physiological and pathological conditions represents an intriguing challenge in these years. The use of the in vitro brain slice preparation has allowed not only the detailed investigation of the direct pre- and postsynaptic electrophysiological actions of several neurotransmitters in striatal neurones, but also the understanding of their role in two different forms of corticostriatal synaptic plasticity, long-term depression and long-term potentiation. These long-lasting changes in the efficacy of excitatory transmission have been proposed to represent the cellular basis of some forms of motor learning and are altered in animal models of human basal ganglia disorders, such as Parkinson's disease. The striatum also expresses high sensitivity to hypoxic-aglycemic insults. During these pathological conditions, striatal synaptic transmission is altered depending on presynaptic inhibition of transmitter release and opposite membrane potential changes occur in projection neurones and in cholinergic interneurones. These ionic mechanisms might partially explain the selective neuronal vulnerability observed in the striatum during global ischemia and Huntington's disease.

Animals↗