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R Fusi

Publications and source records attributed to R Fusi.

8 recordsLinked to original sources
PubMed1995

Effects of acute n-hexane and 2,5-hexanedione treatment on the striatal dopaminergic system in mice.

In order to investigate the effect of n-hexane and its metabolites on the Central Nervous System (CNS), we treated mice with n-hexane and 2,5-hexanedione (2,5-HD) by intraperitoneal (i.p.) administration. Gascromatographic mass spectrometric (GCMS) analyses of striatum and cerebellum revealed a consistent increase of 2,5-HD concentration at 0.5 and 2 hours after treatment and a decline to baseline levels at 24 hours. Traces of 2,5-HD were detected in the brain of control animals. Biochemical analyses revealed a precocious, short lasting, significant increase of striatal dopamine (DA) and homovanillic acid (HVA) levels. A significant increase of striatal synaptosomal DA uptake, suggesting a DA releasing effect on the dopaminergic terminals, was also observed. These results support the hypothesis of a possible role of n-hexane and its metabolites in inducing parkinsonism in humans and animals.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

The effects of aging on MAO activity and amino acid levels in rat brain.

The possibility that age-related changes in amino acid levels in various rat brain areas might correlate with modifications of monoamine oxidase (MAO) activity, already found with aging, has been examined. Taurine, aspartic acid and glutamic acid levels were found to be unchanged or decreased with age, whereas GABA and glutamine concentrations increased or remained unchanged. Serine and glycine (except in pons-medulla) levels were found to be unaffected by age. The increase in total MAO activity with aging in some brain areas might contribute to the changes in amino acid levels. Likewise, the possible influence of age-induced changes in activity of various enzymes involved in H2O2 and NH3 detoxication and in amino acid biosynthesis on rat brain amino acid levels are considered. Oral administration of clorgyline or 1-deprenyl to young rats did not significantly modify the concentrations of most brain amino acids.

Aging↗
PubMed1987

Striatal cholinergic function reflects differences in D-2 dopaminergic receptor activation.

The ergot derivatives, bromocriptine, lisuride and quinpirole (Ly-171555), activators of D-2 receptors, increased striatal acetylcholine (ACh) content by about 40% and induced a 30% inhibition of ACh evoked release from striatal slices, similar to the effects of the dopaminergic agonist apomorphine. These actions were a consequence of dopaminergic activation since they were antagonized by pretreatment with the neuroleptic agent, pimozide. In contrast, pretreatment with L-sulpiride (100 mg/kg), a specific antagonist for the D-2 dopaminergic receptor only, prevented the rise of ACh levels induced by apomorphine or quinpirole but did not interfere with the lisuride- or bromocriptine- induced ACh increases. Similarly, inhibition of the ACh evoked release produced by lisuride (3 microM) was prevented by pimozide (1 mg/kg) but not by pretreatment with L-sulpiride. Addition of L-sulpiride (5 microM) to the Krebs solution had no effect on the inhibition of ACh-evoked release induced by lisuride, but a lower concentration (1 microM) antagonized the inhibition induced by quinpirole. Lisuride and bromocriptine responses were both insensitive to sulpiride. These results are discussed in terms of different interaction with the dopaminergic D-2 receptors by the drugs studied.

Acetylcholine↗
PubMed1987

D-1 receptor-linked mechanism modulates cholinergic neurotransmission in rat striatum.

SCH 23390, a D-1 dopaminergic antagonist, was examined for its effects on the cholinergic system in rat brain. The compound raised the content of acetylcholine selectively in striatum and not in other brain areas including the hippocampus, nucleus accumbens, hemispheric residuum and midbrain-hindbrain, mirroring the action of dopaminomimetic drugs. That the increase in acetylcholine content reflected a depression of striatal cholinergic neuronal activity was substantiated by the drug's ability to inhibit sodium-dependent high affinity choline uptake, to reduce the electrically evoked release of [3H]acetylcholine from striatal slices in vitro and to reduce acetylcholine release from striatum in freely moving rats in vivo. The increase in striatal acetylcholine was prevented by the D-1 dopaminergic agonist, SK 38393-A, but not by the D-2 agonist, LY 171555. Inhibition of dopamine synthesis by DL alpha-methyltyrosine methyl ester HCI or the selective degeneration of nigrostriatal dopaminergic terminals by the neurotoxin 6-hydroxydopamine HBr prevented the acetylcholine increasing effect of SCH 23390 completely, suggesting that presynaptic dopamine is important in the action of the dopaminergic antagonist. In agreement with these findings, SCH 23390 amplified the action of amphetamine, a dopamine releaser, on striatal cholinergic neurons. Furthermore, blockade of D-2 receptors by pimozide or sulpiride did not suppress the cholinergic effect of SCH 23390. When combined with a subthreshold dose of LY 171555, SCH 23390 did not potentiate the action of the D-2 dopaminergic agonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1985

An approach using lecithin treatment for olivopontocerebellar atrophies.

A therapeutic trial with two different lecithins, with 32 and 7% phosphatidylcholine respectively, was performed for 3 months on 11 patients with clinical diagnosis of dominant, recessive and sporadic olivopontocerebellar atrophies. The correlation between plasma choline levels and the clinical picture shows a clinical worsening with very high choline levels and a slight improvement with smaller increases of plasma choline levels. The possible role in these disorders of phosphatidylcholine and linoleic acid - both present in lecithin - is discussed, with relationship to these findings.

Adult↗
PubMed1984

In vitro and in vivo evidence for the existence of presynaptic muscarinic cholinergic receptors in the rat hippocampus.

The intrahippocampal injection of kainic acid cleared 50% of muscarinic receptors and favored the detection of a further 20% loss in hippocampal presynaptic muscarinic receptors produced by electrolytic lesion of the medial septal nucleus as determined by Scatchard analysis of the saturation isotherms of [3H]dexetimide binding. In accordance, a decrease of about 20% in the in vivo accumulation of [3H]dexetimide in the hippocampus was found in animals lesioned in the medial septal nucleus. This effect occurred at both the dose of 5 micrograms/kg and at the saturating dose of 100 micrograms/kg of [3H]dexetimide. The results suggest that the loss was due to decreased receptor number rather than decreased receptor affinity.

Animals↗
PubMed1982

Neurochemical effects of buspirone, a novel psychotropic drug, on the central cholinergic system.

Buspirone, a novel psychotropic anxioselective agent, produced a dose-dependent decrease in the level of acetylcholine in the striatum of the rat. The maximum effect of about 25-30% was produced at the dose of 20 mg kg-1. A smaller decrease of 10% was also found in the n. accumbens-olfactory tubercle while other brain regions were unaffected. The drug did not alter striatal choline acetyltransferase or acetylcholinesterase activities and was feeble in displacing [3H]dexetimide from its specific muscarinic binding sites. The effect of buspirone in lowering acetylcholine content was more marked and longer lasting in the striatum of female than male rats. Buspirone proved to be weak as a blocker of the dopamine receptor agonist, apomorphine, and it appears that only a small proportion of the decrease in striatal acetylcholine content can be attributed to the blockade of dopamine receptors. Rapid homologous tolerance to an acute challenge with buspirone on striatal acetylcholine was achieved within seven days of its chronic administration, and, unlike clozapine, a cross tolerance of buspirone to chronic haloperidol treatment was also observed. Other data indicating that the drug differed from haloperidol both qualitatively and quantitatively on dopaminergic neurochemical parameters, and the fact that it is not cataleptogenic, suggest that buspirone cannot be considered a typical neuroleptic agent. The possibility that buspirone may act as an agonist at certain presynaptic dopamine receptors, which could translate into a fall in striatal acetylcholine content, is discussed.

Acetylcholine↗