Biomedical subjects
M Trabucchi
Publications and source records attributed to M Trabucchi.
Chronic lead exposure differentially affects dopamine transport in rat striatum and nucleus accumbens.
Dopamine release and uptake were investigated in striatum and nucleus accumbens slices of rats chronically exposed to lead. No indication of altered endogenous dopamine release under basal or depolarized conditions was observed in both areas. On the other hand lead intoxication inhibited striatal dopamine uptake while stimulating it at the mesolimbic level. Cocaine binding, that is related to the uptake system, appeared to be down-regulated in the striatum and unaffected in the nucleus accumbens. The results suggest that chronic lead might interfere with dopaminergic transmission at the presynaptic level through specific and differential interactions with the uptake process depending on the area examined.
Afferent fibers mediate the increase of met-enkephalin elicited in rat spinal cord by localized pain.
Met-enkephalin levels were measured in various spinal cord regions of rats chronically suffering from the inflammation of a single paw following a treatment with Freund's adjuvant. The results indicate that chronic localized pain induces a selective increase of met-enkephalin immunoreactive material (ME-IR) in the dorsal horn of the spinal cord segment which receives a direct projection from the inflamed paw. In order to gain information on the functional meaning of these data, either the plexus brachialis or the sciatic nerve were sectioned peripherally before inducing inflammation. Denervation prevented the increase of ME-IR concentration induced by the injection of Freund's adjuvant. Our observations suggest that chronic localized pain in a limb induces a change in ME-IR content which is selective for the spinal cord segment receiving a direct projection from the inflamed paw. This increase depends on an intact innervation.
Chronic lead treatment affects dopaminergic control of prolactin secretion in rat pituitary.
The effect of lead exposure on dopaminergic mechanisms regulating prolactin (PRL) secretion was studied in rats by measuring dopamine (DA) and dihydroxyphenylacetic acid hypothalamic concentrations and DA receptor density in the hypothalamus and pituitary of lead-exposed animals. [3H]Sulpiride was used as dopamine receptor ligand. A decrease of dihydroxyphenylacetic acid (DOPAC) hypothalamic concentrations and a decrease of DA receptor density in the pituitary are shown. The decreased [3H]sulpiride binding in the pituitary is consistent with the elevated serum PRL concentrations previously described in lead-exposed rats.
Chronic dihydroergotoxine treatment affects the number of dopamine recognition sites in rat striatum.
Ergot derivatives have been proposed to have ameliorative effects in various pathological conditions where dopaminergic transmission is believed to be impaired, namely Parkinson's disease, amenorrhea-galactorrhea syndrome, and in the treatment of behavioural disturbances of the elderly. To get more insight into a possible involvement of a direct action of ergot derivatives on dopamine receptors we studied the effect of acute and chronic dihydroergotoxine (DHT) treatment on 3H-Spiroperidol and 3H-N-Propylnorapomorphine (3H-NPA) binding to rat striatal membrane preparations. The results are in favor of an interaction of ergot derivatives with dopamine recognition sites both after acute and chronic treatment.
Caerulein peripheral injection: a study on the correlation with dopaminergic metabolism.
Immunocytochemical and electrophysiological studies indicate the existence of a functional relationship between Cholecystokinin (CCK) and dopaminergic transmission. In order to gain more information on this relationship, the effect of Caerulein, a CCK stable analogue, on rat spontaneous locomotor activity and on biochemical markers of dopaminergic transmission were measured simultaneously. The concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC) and the spontaneous or K+ evoked release of dopamine were studied in rat striatum and nucleus accumbens immediately after testing for motor activity. An almost complete reduction in locomotor activity but not significant changes in DOPAC content and dopamine release were observed in rats injected with the peptide (0.25/microgram/Kg, intraperitoneally). DOPAC concentrations were slightly (30%) decreased by increasing 200 folds caerulein dose. In addition, a very minute dose of haloperidol (25 /microgram/Kg) potentiated the caerulein (0.25/microgram/Kg) induced hypomotility, while the parameters of dopaminergic metabolism were unaffected. Our results indicate the existence of a relevant pharmacological interaction between caerulein and dopamine antagonists, although it is not clear whether this interaction takes place at the dopamine terminals level.
Medical education of the elderly.
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Differential effects of caffeine on dihydroxyphenylacetic acid concentrations in various rat brain dopaminergic structures.
The behavioural and neurochemical effects of caffeine were examined in rats. The intraperitoneal administration of different doses of caffeine significantly decreased DOPAC concentrations in striatum, hypothalamus and frontal cortex, but increased them in nucleus accumbens. These observations suggest that the effects of caffeine on the central nervous system (cns) are at least partially mediated through an interaction with the dopaminergic system.
Motor behaviour modifications after a stroke in a patient with Huntington's disease.
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Brain microvessel receptor function during aging.
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Chronic ethanol treatment changes the number of beta-receptors in rat brain microvessels.
The effect of chronic ethanol consumption on the binding (125I)-iodohydroxybenzylpindolol to beta-adrenergic receptors in rat brain microvessels has been studied. The results show that chronic ethanol treatment increases the number of beta-receptors present in brain microvessels without changing the binding affinity of the binding site for the beta-adrenoceptor ligand. This effect is apparently not associated with changes in peripheral adrenergic tone, since no differences in platelet epinephrine or norepinephrine concentrations were found between ethanol-treated and control animals. An increase in beta-receptor density in brain microvessels might contribute to the alterations of cerebral blood flow and oxygen consumption reported during chronic ethanol intoxication.
Cyclic nucleotides in human cerebral tumors: role of the protein kinase system.
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Lisuride in extrapyramidal disorders: a possible mechanism of action.
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Immunoreactive met-enkephalin plasma concentrations in chronic alcoholics and in children born from alcoholic mothers.
Several experimental and clinical observations indicate that ethanol ingestion induces specific neurochemical modifications in the Central Nervous System. In particular, an involvement of endogenous opiates has been suggested in the case of alcohol addiction. In this light, the plasma concentrations of met-enkephalin immunoreactive peptides (ME-IR) have been measured in selected groups of chronic alcoholics and in children whose mothers were ethanol addicts. Both groups revealed a marked reduction of ME-IR plasma concentrations when compared with sex and age matched controls.
Plasma prolactin concentrations in a large population of healthy old people.
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Effect of chronic ethanol treatment on adenylate cyclase activity in rat striatum.
Chronic ethanol consumption induces an increase in striatal adenylate cyclase enzymatic activity but is unable to further potentiate the dopamine stimulated production of cyclic-AMP. In striatal membranes obtained from chronic ethanol-treated rats, apomorphine exerts a more potent inhibition of [3H]spiperone binding when compared with controls, demonstrating that ethanol increases the affinity of the dopaminergic receptors associated with adenylate cyclase activity. In addition, GTP is unable to modify the agonist component of dopamine receptor in membrane exposed 'in vivo' to ethanol. Data are discussed in terms of a derangement of receptor-adenylate cyclase coupling system produced by chronic ethanol treatment.
Age related changes of enkephalin in rat spinal cord.
Met-enkephalin immunoreactive material content was found to be decreased in the cervical and thoracic segments of the spinal cord from rats aged 25 months as compared to young, 3-month-old, rats. No age-related variations were detectable at the lumbar level. Bio-Gel P 30 column chromatography of thoracic segment extracts indicates that the composition of the immunoreactive material is similar in the two age-groups investigated. At the thoracic level opiate receptor binding was also measured. Opiate receptor number is increased in the thoracic segments of the spinal cord from older rats. These age-related changes in immunoreactive Met-enkephalin content and opiate receptor number at spinal levels may contribute to determine an altered pain sensitivity during aging.
Acute treatment of Huntington's chorea with lisuride.
The authors studied the effects of lisuride hydrogen maleate (lisuride) on the hyperkinesias of 11 patients suffering from Huntington's chorea (HC). In all patients, acute injection of 150 micrograms of the drug induced a marked temporary improvement of the abnormal involuntary movements; the favourable drug-effect was more pronounced in the patients with a less severe degree of hyperkinesia. The antichoreic activity of the drug was prevented by pretreatment with haloperidol (2 mg) or sulpiride (400 mg), both injected intramuscularly 30 min before lisuride administration. The authors suggest the improvement of the motor disturbance induced in HC by lisuride may be explained on the basis of its preferential action on a subset of brain dopaminergic receptor.