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E Bronzetti

Publications and source records attributed to E Bronzetti.

At least 19 recordsLinked to original sources
PubMed1998

Density and localization of calcium channels of the L-type in human pulmonary artery.

The pharmacological profile and the anatomical localization of Ca2+ channels of the L-type were investigated in the human pulmonary artery to identify possible mechanisms involved in the regulation of the pulmonary vascular tone. Analysis was performed on slide-mounted frozen sections of human pulmonary artery using radioligand binding assay techniques associated with light microscope autoradiography. [3H]-Nicardipine was used as ligand. Human renal and right coronary arteries also were used as systemic reference arteries. Binding of [3H]-nicardipine to sections of human pulmonary artery was time-, temperature- and concentration-dependent, saturable and reversible. In the human pulmonary artery, the apparent equilibrium dissociation constant (Kd) was 0.12+/-0.02 nM and the maximum density of binding sites (Bmax) was 38.15+/-2.25 fmol/mg tissue. Kd values were 0.3+/-0.01 nM and 0.5+/-0.02 in the human renal artery and right coronary artery respectively. Bmax values were 248+/-16 fmol/mg tissue and 173+/-9.5 fmol/mg tissue in the human renal artery and right coronary artery respectively. The pharmacological profile of [3H]-nicardipine binding to sections of human pulmonary artery was consistent with the labeling of Ca2+ channels of the L-type. It was similar in the pulmonary artery and in the human renal and right coronary arteries. Light microscope autoradiography revealed a high density of [3H]-nicardipine binding sites within smooth muscle of the tunica media of human pulmonary artery as well as of human renal and right coronary arteries. A lower accumulation of the radioligand occurred in the tunica adventitia. No specific binding was noticeable in the tunica intima. Our data suggest that human pulmonary artery expresses Ca2+ channels of the L-type sensitive to dihydropyridines. These sites have similar affinity and lower density than those expressed by systemic arteries. The presence of Ca2+ channels of the L-type in human pulmonary artery suggests that their pharmacological manipulation may be considered in the treatment of pulmonary hypertension.

Aged↗
PubMed1997

Dopamine D4 receptor in human peripheral blood lymphocytes: a radioligand binding assay study.

The expression of dopamine D4 receptor was investigated in human peripheral blood lymphocytes with a radioligand binding assay technique, using [3H]clozapine as radioligand. [3H]Clozapine was specifically bound to human peripheral blood lymphocytes. The binding was time-, temperature-, and concentration-dependent and of high affinity, with a dissociation constant (K(d)) value of 0.34 +/- 0.02 nM and a maximum density of binding sites (B(max)) value of 27 +/- 1.4 fmol/10(6) cells. The pharmacological profile of [3H]clozapine binding to human peripheral blood lymphocytes was similar to that found in Chinese hamster ovary (CHO) cells transfected with the D4 clone (D4.2 variant). The above results are consistent with molecular biology studies demonstrating the expression of a dopamine D4 receptor in immune cells and in human peripheral blood lymphocytes. The availability of a rapid and sensitive radioligand binding assay technique for the dopamine D4 receptor in human peripheral blood lymphocytes may contribute to better define the role of this dopamine receptor subtype in neurological and psychiatric disorders.

Adult↗
PubMed1997

Use of [3H]-clozapine as a ligand of the dopamine D4 receptor subtype in peripheral tissues.

1. Molecular biology studies have documented the presence of peripheral dopamine D4 receptors. This site has not been characterized yet with classical radioligand binding assay techniques because of the lack of selective radioligands. 2. The atypical neuroleptic clozapine labelled with tritium ([3H]-clozapine) has been proposed and sold as a radioligand for brain dopamine D4 receptors. However, the selectivity of [3H]-clozapine for D4 receptor subtypes, and its specificity for brain dopamine receptors, have been questioned. 3. In this study dopamine D4 receptors were assayed in peripheral organs known to express them, such as rat atria and kidney, by using a radioligand binding assay technique with [3H]-clozapine as the radioligand. Parallel experiments were performed using Chinese hamster ovary (CHO) cells transfected with the D4 receptor clone (variant D4.2). 4. [3H]-Clozapine was bound to sections of rat atria and kidney. After appropriate blockade of sites other than dopamine receptors to which it can bind (i.e. muscarinic cholinergic, serotonergic and alpha-adrenergic receptors), the radioligand was bound to a site displaying a pharmacological profile similar to that expressed by CHO cells transfected with the D4 receptor. 5. The above findings indicate that with appropriate protocols, [3H]-clozapine may represent a radioligand for peripheral dopamine D4 receptors.

Animals↗
PubMed1997

Dopamine D3 receptor in peripheral mononuclear cells of essential hypertensives.

Dopamine D3 receptor was studied in peripheral mononuclear cells of high-normal, stage 1, stage 2, and stage 3 essential hypertensives using a radioligand binding assay technique with [3H]-7-hydroxy-N,N-di-n-propyl-2-aminotetraline (7-OH-DPAT) as a radioligand. A group of de novo Parkinsonian patients was also examined as a reference group of impaired dopaminergic function. [3H]-7-OH-DPAT was bound specifically to human peripheral mononuclear cells in a manner consistent with the labeling of a dopamine D3 receptor. No changes in free dopamine, norepinephrine, epinephrine and aldosterone levels, renin activity, dissociation constant of [3H]-7-OH-DPAT binding, or the pharmacological profile of [3H]-7-OH-DPAT binding were found between normotensive control subjects and essential hypertensives or Parkinsonians. The density of peripheral mononuclear cell [3H]-7-OH-DPAT binding sites increased in essential hypertensives parallel to blood pressure value augmentation. A higher density of [3H]-7-OH-DPAT binding sites was found in Parkinsonians. In these patients, the density of [3H]-7-OH-DPAT binding sites was similar to that observed in high-normal subjects and in stage 1 essential hypertensives. The increased density of peripheral mononuclear cell dopamine D3 receptor in hypertension as well as in Parkinson's disease may represent an upregulation mechanism consequent to impaired dopaminergic function. In view of the difficulty in identifying markers of peripheral dopamine function, analysis of dopamine D3 receptor in peripheral mononuclear cells may help evaluate whether the dopaminergic system is involved in hypertension.

Adult↗
PubMed1996

Muscarinic cholinergic receptor subtypes in human peripheral blood lymphocytes.

The subtypes of muscarinic cholinergic receptors were studied in human peripheral blood lymphocytes with radioligand binding techniques and the non-selective muscarinic cholinergic receptor antagonist [3H]quinuclidinyl benzylate (QNB) as a ligand. [3H]QNB was bound to human peripheral lymphocytes in a manner consistent with the labelling of muscarinic cholinergic receptors. The dissociation constant (Kd) value was 0.60 +/- 0.08 nM and the maximum density of binding sites (Bmax) was 2.33 +/- 0.03 fmol/2.2 x 10(6) cells. The binding was time-, temperature- and concentration-dependent, belonging to a single class of high affinity sites. Analysis of the pharmacological profile of [3H]QNB binding in the presence of compounds specific for the different muscarinic receptor subtypes suggests that human peripheral blood lymphocytes express mainly muscarinic cholinergic M2 and M3 receptor subtypes and to a lesser extent muscarinic M4 receptors. The characterization of the subtypes of muscarinic cholinergic recognition sites expressed by human peripheral blood lymphocytes may represent a tool for investigating the possible relationships between immune and cholinergic systems in normal and pathologic conditions.

Adult↗
PubMed1996

Pharmacological characterisation of Ca2+ channels of the L-type in human peripheral blood lymphocytes.

Ca2+ channels of the L-type were characterised in intact human peripheral blood lymphocytes using a radioligand binding technique and the dihydropyridine-type Ca2+ channel antagonist [3H](+)-PN 200-110 (isopropyl-4-(2,1,3-benzoxadiazol-4-yl)1,4-dihydro-5-methoxycarbon yl-2, 6-dimethyl-3-pyridine carboxylate) as a ligand. [3H](+)-PN 200-110 binding to human peripheral blood lymphocytes was time-, temperature-, concentration-dependent and of high affinity. The dissociation constant (Kd) value was 0.4 +/- 0.02 nM and the maximum binding capacity (Bmax) was 33.5 +/- 1.6 fmol/10(6) cells. Pharmacological analysis of [3H](+)-PN 200-110 binding to human peripheral blood lymphocytes was consistent with the labelling of a Ca2+ channel of the L-type. In fact, dihydropyridine derivatives were the most potent competitors of [3H](+)-PN 200-110 binding, whereas phenylalkylamine and benzothiazepine compounds or non-selective Ca2+ channel modulators were weak or ineffective displacers. These findings are the first observation that human peripheral blood lymphocytes express Ca2+ channels of the L-type. The possibility that Ca2+ channel antagonists may interfere with immune system function is discussed.

Adult↗
PubMed1996

Increased density of dopamine D5 receptor in peripheral blood lymphocytes of migraineurs: a marker for migraine?

The expression of dopamine D5 receptor was investigated in peripheral blood lymphocytes of 11 migraine patients and of ten healthy control subjects using a radioligand binding technique with [3H]SCH 23390 as a ligand. [3H]SCH 23390 is a benzazepine derivative with potent antagonist properties at the dopamine D1-like receptors. [3H]SCH 23390 was specifically bound to peripheral blood lymphocytes of migraineurs and control subjects in a manner consistent with the labelling of a dopamine D5 receptor. In migraineurs a statistically significant higher density of lymphocyte dopamine D5 receptor compared with controls was noticeable, whereas the affinity of the radioligand was unchanged. The increased density of dopamine D5 receptor in peripheral blood lymphocytes may reflect the dopaminergic hypersensitivity displayed by migraineurs and may represent a relatively simple and reliable peripheral marker of altered dopaminergic function.

Adult↗
PubMed1996

Distribution of p75 and trk-neurotrophin receptor proteins in adult human sympathetic ganglia.

We investigated the expression of immunoreactivity (IR) for low- (p75) and high-affinity (trk proteins) neurotrophin-receptor proteins in adult human paravertebral-sympathetic ganglion neurons. Mouse monoclonal antibodies against the pan-neurotrophin-receptor p75, and rabbit polyclonal antibodies against specific epitopes of the intracytoplasmic domain on trk neurotrophin-receptor proteins were used in fresh unfixed and formaldehyde-fixed paraffin-embedded sympathetic ganglia. All adult human paravertebral-sympathetic neurons displayed trkA neurotrophin-receptor-like protein IR, 10% express trkC neurotrophin-receptor-like protein IR, 37-44% show p75 IR, and no IR was obtained for trkB neurotrophin-receptor-like protein. The intensity of immunostaining was independent of the neuron size. Labelling of non-neuronal tissues, especially blood-vessel walls, was observed for p75, trkA and trkC neurotrophin-receptor proteins. These results indicate that overlapping exists in the expression of p75 and trk neurotrophin-receptor proteins in adult human paravertebral-sympathetic neurons, and suggest that neurotrophins might act on these neurons.

Adult↗
PubMed1996

Calretinin immunoreactivity in human sympathetic ganglia.

Calretinin is an "EF-hand" calcium-binding protein involved in the maintenance of intracellular calcium ion homeostasis. This study was undertaken to investigate the presence of calretinin in human lumbar paravertebral sympathetic ganglia from subjects of different ages (26-85 years) using immunohistochemical and immunoblotting methods. Calretinin-like immunoreactivity was found in a subpopulation of postganglionic sympathetic neurons, whose percentage decreased progressively with aging by about 50% (63% of immunoreactive neurons at < or = 40 years; 29% at > or = 81 years) whereas the neuronal density remained basically unchanged. Calretinin-like immunoreactivity showed a granular pattern of cytoplasmic distribution suggesting preferential localization of this protein associated with intracellular membranes. Occasionally diffuse cytosolic labelling was also observed. The immunoblotting demonstrated a protein band with an estimated molecular weight of 30 kDa, approximately. Present results provide, for the first time, evidence for the presence of calretinin in human paravertebral sympathetic ganglia. Since the number of calretinin-like immunoreactive neurons decreased significantly with aging our findings suggest an involvement of this protein in the age-dependent impairment of sympathetic function.

Adult↗
PubMed1996

Muscarinic cholinergic receptor subtypes in the pigeon bursa of Fabricius: a radioligand binding and autoradiographic study.

The pharmacological profile and the anatomical localisation of muscarinic cholinergic receptor subtypes were studied in the pigeon bursa of Fabricius, using radioligand binding and autoradiographic techniques with [3H]quinuclidinyl benzilate (QNB) as a ligand. [3H]QNB was specifically bound to sections of bursa of Fabricius. The binding was time-, temperature- and concentration-dependent. The dissociation constant was 0.31 +/- 0.02 nM, and the maximum density of binding sites averaged 38 +/- 2.5 fmol/mg protein. The pharmacological profile of [3H]QNB binding to sections of pigeon bursa of Fabricius was consistent with the labelling of M2, M3 and M4 muscarinic receptor subtypes. Light microscope autoradiography showed the localisation of [3H]QNB binding sites in the medulla, in follicular septa, in the cortico-medullary border and in lesser amounts in the cortical layer. The functional significance of these receptors should be clarified in future studies.

Animals↗
PubMed1996

Age-dependent changes in the expression of dopamine receptor subtypes in human peripheral blood lymphocytes.

The pharmacological profile and the density of dopamine D3 and D5 receptor subtypes expressed by human peripheral blood lymphocytes of subjects of different ages (ranging from 20 to 75 years) were assessed using radioligand binding techniques. Dopamine D3 receptor was assayed with [3H]7-hydroxy-N,N-di-n-propyl-2-aminotetraline ([3H]7-OH-DPAT) as a ligand. Dopamine D5 receptor was assayed using [3HIR]-(+)-(-chloro-2,3,4,5, tetrahydro-5-phenyl-1H-3-benzazepin-al-hemimaleate) ([3H]SCH 23390) as a ligand. The affinity and the pharmacological profile of [3H]7-OH-DPAT and [3H]SCH 23390 at dopamine D3 and D5 receptor, respectively, were similar in subjects of different ages. The density of dopamine D3 receptor binding sites was slightly decreased in subjects of 30-39 years in comparison with younger individuals. A remarkable loss of dopamine D3 receptor was then found between 40 and 49 years of age in comparison with younger subjects. A further slight decrease was noticeable between 50 and 59 years of age. The number of [3H]7-OH-DPAT binding sites was then stabilized after 60 years of age. The density of dopamine D5 receptor binding sites did not show age-dependent changes. The above findings indicate the occurrence of a decline in the density of lymphocyte dopamine D3 but not D5 receptor between adult and mature subjects. The possibility that dopamine D3 receptor assay in peripheral blood lymphocytes may represent a tool for investigating dopamine receptor function in aging and age-related neurological disorders is discussed.

Adult↗
PubMed1995

Effect of long-term treatment with L-deprenyl on the age-dependent microanatomical changes in the rat hippocampus.

Chronic treatment with L-deprenyl increases both mean and maximum life span and improves cognitive functions in the aged rat. The present study was designed to evaluate whether long-term treatment with L-deprenyl at a dosage not inhibiting the monoamine oxidase-B (MAO-B) (1.25 mg/kg/day) or inhibiting the enzyme activity (5 mg/kg/day) had any effect on the age-dependent microanatomical changes in the rat hippocampus. The hippocampus was chosen in view of its key role in learning and memory functions. Treatment with L-deprenyl started at 19 months and lasted until the 24th month of age. Age-matched untreated rats were used as a control, whereas 11-month-old rats were used as an adult reference group. The number of nerve cell and glial fibrillary acidic protein-immunoreactive astrocyte profiles in the CA1 and CA3 fields of the hippocampus and in the dentate gyrus was decreased and increased, respectively in aged compared with adult rats. Treatment with 5 mg/kg/day, but not with 1.25 mg/kg/day L-deprenyl increased the number of neuronal profiles and decreased the number of astrocytes in the hippocampus of aged rats. The density of zinc stores in the associative intrahippocampal pathway of mossy fibres, which was decreased in aged animals, was increased after treatment with the two doses of L-deprenyl. Lipofuscin accumulation within the cytoplasm of pyramidal neurons of the hippocampus was reduced dose dependently by L-deprenyl treatment. These results suggest that long-term treatment with L-deprenyl is able to counter the expression of age-dependent microanatomical changes in the rat hippocampus. These effects seem only partially correlated with the MAO-B inhibitory activity of L-deprenyl.

Aging↗
PubMed1995

Age-related changes of the noradrenergic and acetylcholinesterase reactive nerve fibres innervating the pigeon bursa of Fabricius.

Age-dependent changes in the innervation of the pigeon (Columba livia, L.) bursa of Fabricius, from hatching to 120 days of age, were studied by fluorescence-histochemical and neurochemical methods for demonstrating noradrenergic and acetylcholinesterase (AChE)-reactive nerve fibres respectively. The distribution of both nerve fibre types was largely perivascular. Furthermore, a few isolated nerve fiber profiles were observed beneath the bursal epithelium, in the interfollicular septa and in the follicular cortex. No nerve fibre profiles reaching the medulla of the lymphoid follicles were observed. In addition to nerve fibres, AChE reactive neuron-like cells were encountered within the capsule and interfollicular septa. AChE reactivity was also found in dendritic-like cells localized in the cortical and cortico-medullary border. No changes in the density of perivascular noradrenergic innervation were noticeable during the ages studied, whereas the density of AChE-reactive fibres supplying vessels reached the adult pattern at 30 days, and then remained unvaried. The density of non-perivascular nerve fiber profiles, specially the AChE reactive type, increased until 30 days, remained unchanged until 75 days and then increased with aging (90-120 days). The interrelationship between the autonomic nervous system and the immune system is discussed.

Acetylcholinesterase↗
PubMed1995

Immunohistochemical characteristics of cutaneous Herbst corpuscles from beak and rictus in domestic pigeon.

Herbst corpuscles are the avian equivalent to the mammalian Pacinian corpuscles. In this study we used indirect peroxidase-anti peroxidase (PAP) immunohistochemistry to analyze the distribution in the pigeon cutaneous Herbst corpuscles, of several markers which are known to specifically label the axon, the Schwann-related and perineurial-related cells in Pacinian corpuscles. The distribution of the assessed antigens on Herbst corpuscles was as follows: i) the central axon displayed positive immunoreactivity for neurofilament proteins and neuron specific enolase; ii) the lamellar cells forming the inner-core were positive for S-100 protein and vimentin, whereas fibroblast surrounding them were vimentin and epithelial membrane antigen positive; iii) the capsule was focally immunolabelled for vimentin, and regularly for epithelial membrane antigen. No immunoreactivity was found neither for cytokeratins nor for glial fibrillary acidic protein. These observations demonstrate that the immunohistochemical profile of cutaneous (beak skin and rictus) Herbst corpuscles in pigeon is similar to that of the mammalian Pacinian corpuscles.

Animals↗
PubMed1995

Immunohistochemical evidence for sympathetic denervation and reinnervation after necrotic injury in rat myocardium.

To study the short and long term effects of myocardial injury on sympathetic nerve fibers, a necrotizing lesion was performed on the diaphragmatic side of rat myocardium by freeze-thawing. Animals were sacrificed at 2, 6, 18, 28 and 105 days after the surgical procedure and paraffin-embedded hearts were subjected to peroxidase immunohistochemistry. According to previous studies cardiac nerves were visualized by staining their surrounding Schwann cells with an anti-S100 protein antibody. Catecholaminergic axons were specifically identified by an anti-tyrosine hydroxylase antibody. No S-100 positive structures were found in 2-day lesions (denervation). Starting from day 6,S-100 positive structures became progressively more evident (reinnervation) and persisted up to day 105. Many of these newly formed nerve fibers were positive for tyrosine hydroxylase, indicating that a necrotic injury of rat myocardium causes a disappearance of sympathetic innervation which is followed by a phase of sympathetic reinnervation.

Animals↗
PubMed1995

Nucleus basalis magnocellularis lesions decrease histochemically reactive zinc stores in the rat brain: effect of choline alphoscerate treatment.

The effects of monolateral lesioning of the nucleus basalis magnocellularis (NBM) and of choline alphoscerate treatment on histochemically reactive vesicular zinc stores were assessed in the rat brain using the sulphide-silver histochemical technique. Histochemically reactive zinc stores are located primarily within association fibres of the neuropil of the cerebral cortex as well as in the mossy fibres of the hippocampus. The density of cortical and hippocampal sulphide-silver positive fibres, which might have a role in cognitive and mnemonic processes, parallels the density of zinc-containing presynaptic buttons. Unilateral lesions of NBM caused a remarkable decrease of sulphide-silver positive fibres from the 4th week after lesioning in the neuropil of the ipsilateral fronto-parietal cortex and from the 3rd week in the mossy fibres of the ipsilateral hippocampus. Treatment with choline alphoscerate, which is a precursor in the biosynthesis of brain phospholipids that increases the bioavailability of acetylcholine in the nervous tissue, restored, in part, the density and pattern of sulphide-silver positive fibres in the fronto-parietal cortex and in the hippocampus. The data suggest that, analogously to reports from Alzheimer's disease patients, lesions of the NBM cause a decrease of zinc stores in the rat brain. Choline alphoscerate treatment is able to counter the expression of this phenomenon which accompanies experimental lesions of the NBM.

Animals↗
PubMed1994

Influence of long-term treatment with L-deprenyl on the age-dependent changes in rat brain microanatomy.

The present study was designed to assess whether treatment with the monoamine oxidase-B (MAO-B) inhibitor L-deprenyl, which has been documented to increase both mean and maximum survival in aged rats as well as sexual performance and cognitive function, has any effect on the age-related microanatomical changes occurring in the rat brain. Male Sprague-Dawley rats received a subcutaneous injection of 0.25 mg/kg L-deprenyl every other day from the 19th to the 24th month of age. Age-matched control rats were injected with saline, whereas 11-month-old untreated rats were used as an adult reference group. Both body and brain weight were increased as a function of age, and they were unaffected by treatment with L-deprenyl. The density of nerve cell profiles in the frontal cortex, in the CA-1 and CA-3 subfields of the hippocampus, in the dentate gyrus and in the cerebellar cortex were decreased in aged rats in comparison with adult rats. The density of nerve cell profiles in the above brain areas of L-deprenyl-treated rats was not significantly higher in comparison with age-matched control animals with the exception of Purkinje neuron profiles. The intensity of Nissl's staining, which may be related to the protein synthetic capabilities of nerve cells, is reduced within pyramidal neurons of the hippocampus and Purkinje neurons of the cerebellar cortex of aged rats. The intensity of Nissl's staining in L-deprenyl-treated rats was not different from adult rats. Lipofuscin deposition was significantly increased within the cytoplasm of pyramidal neurons of the frontal cortex, of the CA-3 subfield of the hippocampus and of Purkinje neurons of the cerebellar cortex. L-Deprenyl administration decreased lipofuscin accumulation within the cytoplasm of the above mentioned nerve cell types. The density of sulphide-silver staining in the intrahippocampal pathway of mossy fibres, which participate in the elaboration of passive avoidance responses, is decreased in aged rats. Treatment with L-deprenyl counters this age-related reduction. The above results suggest that long-term treatment with L-deprenyl is able to counter the expression of some microanatomical changes typical of aging brain.

Aging↗