Biomedical subjects

A Ricci

Publications and source records attributed to A Ricci.

At least 145 records · Page 8Linked to original sources

PubMed1995

Muscarinic cholinergic receptors in dorsal root ganglia of chick embryo: a radioligand binding and immunocytochemical study.

The presence and micro-anatomical localization of muscarinic cholinergic receptors were assessed in dorsal root ganglia of chick embryo during development using radioligand binding and immunocytochemical techniques, respectively. The non-selective muscarinic cholinergic receptor radioligand [3H]quinuclidinyl benzilate was specifically bound to sections of chick dorsal root ganglia with a dissociation constant value (Kd) of 0.75 +/- 0.02 nM and a maximum density of binding sites (Bmax) of 7.2 +/- 0.5 fmol/mg tissue. [3H]Quinuclidinyl benzilate binding was partially sensitive to pirenzepine displacement. This suggests that muscarinic cholinergic receptors expressed by dorsal root ganglia of chick embryo at least in part belong to the M1 muscarinic receptor subtype. Immunocytochemical analysis confirmed the presence of muscarinic receptors in the ganglia. These findings suggest that neurons of dorsal root ganglia, which are known to express cholinergic markers such as choline acetyltransferase, acetylcholinesterase and high affinity choline uptake, are also cholinoceptive.

Animals↗

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

Identification of age-related changes of dopamine D1-like receptors in the rat cerebellar cortex.

The present study was designed to characterize the pharmacological profile of dopamine D1-like receptors in the rat cerebellar cortex and to assess if these receptor sites undergo age-related changes. Cerebella of young (3 months), adult (12 months), and old (27 months) male Wistar rats were examined by using radioligand binding techniques and light microscope autoradiography. The non-selective dopamine D1-like radioligand [3H]SCH 23390 was specifically bound to sections of rat cerebellum. The findings that dopamine displaced [3H]SCH 23390 binding in the submicromolar range suggest that labelling of a dopamine D5 (or D1B) receptor subtype. The affinity of [3H]SCH 23390 for dopamine D1-like receptors was similar in the cerebellar cortex of the three animal groups investigated, whereas radioligand binding techniques revealed a gradual age-related reduction of the density of binding sites. Light microscope autoradiography showed the localization of [3H]SCH 23390 binding sites primarily in the molecular layer and to a lesser extent in the Purkinje neuron layer of the cerebellar cortex. Aging was accompanied by a loss of [3H]SCH 23390 binding sites affecting mainly the molecular layer. The age-dependent loss of dopamine D1-like receptors is more pronounced if detected with radioligand binding techniques than with light microscope autoradiography. This suggests that the decrease of dopamine D1-like receptors observed in aging rat cerebellar cortex may depend in part on changes in the receptor expression and in part on cortico-cerebellar structural changes.

Age Factors↗

PubMed1995

Chromium-induced sexual reproduction gives rise to a Cr-tolerant progeny in Scenedesmus acutus.

A clonal population of Scenedesmus acutus was treated for 3 months with 1 mg/liter Cr(VI) and then returned to Cr-free medium. After several months, the cells were treated with different Cr concentrations and then subjected to a series of morphological observations and metabolic tests. The results, compared with those obtained with a normal cell population treated in the same way, demonstrate that the progeny of algae subjected to the prolonged Cr treatment has acquired tolerance to the metal, as it can survive and grow in the presence of Cr concentrations that are lethal to normal cells. An ultrastructural description of gametes and zygotes is also given.

Chlorophyll↗

PubMed1995

Quantification of nucleolar organiser regions in canine perianal gland tumours.

The proliferative activity in 28 canine perianal gland tumours was examined by the quantitative evaluation of the nucleolar organiser regions associated with argyrophil proteins (AgNORs). These regions were stained with a specific silver stain and quantified directly by light microscopy and by computerised image analysis. The relationships between some of the parameters used (the number of AgNORs per nucleus, the area of AgNORs per nucleus and the ratio of the area of AgNORs to the area of the nucleus) were also examined in relation to the histopathological grades of the tumours. All the parameters showed a high correspondence with the tumours' proliferative activity, and the ratio of the area of AgNORs to the area of the nucleus was the most significantly correlated with the tumours' histological patterns.

Adenocarcinoma↗

PubMed1995

Dopamine D1-like receptors in the thymus of aged rats: a radioligand binding and autoradiographic study.

Age-dependent changes in the density and pattern of dopamine D1-like receptors were studied in the thymus of young (3 months), adult (12 months) and aged (24 months) male Wistar rats using combined radioligand binding and autoradiographic techniques. [3H]SCH 23390, which was used as a ligand, was specifically bound to sections of the thymus in a manner consistent with the labelling of dopamine D5 receptor. The dissociation constant value was similar in the thymus of the three animal groups examined. The maximal density of binding sites, evaluated with conventional radioligand binding techniques, was significantly reduced in the thymus of adult in comparison with young rats and further reduced in aged animals. Silver grains which correspond to [3H]SCH 23390 binding sites were revealed by light microscope autoradiography primarily in the cortex of the thymus and in lesser amounts within thymic corpuscles. A progressive decrease in the density of silver grains more pronounced in the cortex than in thymic corpuscles was observed in the thymus of adult and old in comparison with young rats. The loss of silver grains revealed with autoradiography is more moderate than the decrease in the density of binding sites shown by radioligand binding. Silver grains developed per single cells (probably lymphocytes) of the thymic cortex were reduced between young and adult rats and further decreased in old rats. The above findings suggest that the age-related decline in the density of dopamine D5 receptor assayed in the thymus is due in part to the reduced thymic mass with aging.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1995

Radioligand binding characterization of putative dopamine D3 receptor in human peripheral blood lymphocytes with [3H]7-OH-DPAT.

The presence and the pharmacological profile of dopamine D3 receptor have been investigated in human peripheral blood lymphocytes using radioligand binding techniques and the selective dopamine D3 receptor agonist [3H]7-hydroxy-N,N-di-n-pro-pyl-2-aminotetralin ([3H]7-OH-DPAT) as a ligand. [3H]7-OH-DPAT binding to human peripheral blood lymphocytes was time-, temperature-, and concentration-dependent and of high affinity with a dissociation constant value (Kd) of 0.27 +/- 0.05 nM and a maximum binding density (Bmax) of 14.7 +/- 0.06 fmol/2 x 10(6) cells. Binding was also reversible. The rank order of potency of displacers of [3H]7-OH-DPAT binding to human peripheral blood lymphocytes resembled that found for dopamine D3 receptor in rat brain homogenates or in rat or human cell lines. Our findings, which are consistent with those of other authors performed with molecular biology techniques, suggest that human peripheral blood lymphocytes express dopamine D3 receptor. In the brain, dopamine D3 receptor probably mediates the anti-psychotic effect of neuroleptics. The availability of a rapid and reproducible technique for its assay may contribute to evaluate its status in brain disorders characterized by impaired dopaminergic neurotransmission.

Humans↗

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

Protective effect of nicardipine treatment on cerebrovascular microanatomical changes in spontaneously hypertensive rats.

1. The effect of long-term treatment with the dihydropyridine Ca2+ antagonist, nicardipine, on the morphology of different sized pial arteries was assessed in spontaneously hypertensive rats (SHR) using histological techniques associated with image analysis. 2. In control 20 week old SHR blood pressure values, the thickness of the tunica media, the media-to-lumen ratio and connective tissue content were significantly increased in comparison with reference normotensive Wistar-Kyoto (WKY) rats. 3. Treatment for 8 weeks with a daily dose of 3 mg/kg of nicardipine decreased blood pressure values in SHR and significantly reduced the area occupied by the tunica media and the media-to-lumen ratio. This effect was observed primarily in small sized pial arteries and to a lesser extent in medium sized pial arteries. Nicardipine administration was without effect on connective tissue content in the wall of cerebral arteries. 4. These results indicate that treatment with nicardipine reduces blood pressure elevation in SHR and exerts a protective effect on arteries controlling cerebrovascular resistance. The activity of the compound primarily on small sized pial arteries may protect the brain from generalized vasodilation which could cause cerebral hypoperfusion.

Animals↗

PubMed1995

Localisation of dopamine D1-like and D2-like receptors in the pulmonary vasculature.

The pharmacological profile and the anatomical localisation of dopamine receptor subtypes were investigated in the rabbit pulmonary vascular bed using combined radioligand binding and light microscope autoradiography techniques. Dopamine D1-like receptor sites, which probably belong to the dopamine D1 receptor subtype, were characterized in sections of lung using [3H]-SCH 23390 as a ligand. These sites were located within the tunica intima and the tunica media of large sized intrapulmonary artery branches and in the tunica media of medium sized intrapulmonary artery branches. Dopamine D2-like receptor sites, which probably belong to the dopamine D2 receptor subtype, were characterized using [3H]-spiroperidol as a ligand. These sites were located within the tunica adventitia of both extra- and intrapulmonary artery branches. Dopamine D2-like receptor sites were also found in the tunica adventitia of the human pulmonary artery, but not of the rat pulmonary artery. The different anatomical localization of dopamine D1 and D2 receptor subtypes in the pulmonary vasculature suggests that these sites are involved in the modulation of pulmonary vascular tone by interacting with different receptors unevenly distributed throughout the pulmonary vascular bed.

Animals↗

PubMed1995

Pharmacological characterisation and autoradiographic localisation of dopamine receptor subtypes in the cardiovascular system and in the kidney.

Combined radioligand binding and light microscope autoradiography techniques were used for investigating the pharmacological profile and the microanatomical localisation of dopamine receptor subtypes in the cardiovascular system and in the kidney. In superior mesenteric and renal arteries the predominant dopamine D1-like receptor belongs to the D5 (or D1b) subtype. This site is located within smooth muscle of the tunica media. The same receptor subtype predominates in the kidney, where it has a vascular and tubular localisation. The dopamine D2-like receptor subtype expressed by systemic arteries belongs to the D2 receptor subtype. It has a prejunctional and endothelial localisation. In the kidney the predominating dopamine D2-like receptor belongs to the dopamine D3 subtype. Atria but not ventricles express dopamine D2-like receptors belonging to the D4 receptor subtype. The above results suggest that in spite of the emerging complexity of the dopamine receptor profile demonstrated by molecular biology techniques, radioligand binding and autoradiographic techniques, if performed with appropriate radioligands and/or in the presence of compounds active on specific receptor subtypes, may represent a useful tool for better understanding the biological significance of peripheral dopamine receptors.

Animals↗

PubMed1995

Dopamine D5 receptor expression is unchanged in peripheral blood lymphocytes in essential hypertension.

The present study was designed to investigate possible changes in the expression of lymphocyte dopamine receptor in essential hypertension. The expression of dopamine D5 receptor was evaluated by radioligand binding techniques using [3H]-SCH 23390 as ligand. Plasma catecholamines, aldosterone levels and plasma renin activity were also measured. Eleven borderline hypertensive patients, 15 patient with the mild essential hypertension, 7 patients with moderate essential hypertension and 5 patients with severe essential hypertension were examined. Plasma catecholamine levels were assayed by high pressure liquid chromatography with electrochemical detection. Dopamine D5 receptor was measured by radioligand binding techniques. Plasma aldosterone levels and renin activity were determined by radio immunoassay. [3H]-SCH 23390 was specifically bound to human peripheral blood lymphocytes. The binding was time-, temperature- and concentration-dependent with a dissociation constant (Kd) value of 0.59 nM and a maximum density of binding sites (Bmax) of 223 pmol/10(6) cells. Dopamine competed with [3H]-SCH 23390 binding in the submicromolar range suggesting the labelling of a dopamine D5 receptor. No changes in the density of [3H]-SCH 23390 binding sites were observed in human peripheral blood lymphocytes between essential hypertensive patients and normotensive subjects. Also catecholamines, plasma renin activity and aldosterone levels were unchanged. In spite of the availability of a sensitive technique for measuring dopamine receptors in human peripheral lymphocytes, no change in their expression was noticeable in essential hypertension. This suggests that dopamine receptor analysis in essential hypertension is not a useful marker for investigating hypertension-dependent changes of the peripheral dopaminergic system.

Adult↗

PubMed1995

Autoradiographic localization of dopamine D2-like receptors in the rat adrenal gland.

The pharmacological profile and the anatomical localization of dopamine D2-like receptors were studied in sections of the rat adrenal gland using combined radioligand binding and autoradiographic techniques with [3H]-spiroperidol as a ligand. [3H]-Spiroperidol was bound to sections of the rat adrenal gland in a manner consistent with the labelling of dopamine D2-like receptor sites. The binding was time-, temperature- and concentration-dependent and of high affinity with a dissociation constant (Kd) value of 1.6 +/- 0.04 nM and a maximum density of binding sites (Bmax) of 60 +/- 3.6 fmol/mg tissue. Experiments on the pharmacological specificity of [3H]-spiroperidol binding to sections of the rat adrenal gland suggest the labelling of dopamine D3 and/or D4 receptors. The presence of dopamine D3 and D4 receptors in the rat adrenal gland was confirmed by the demonstration of a specific binding for the D3 radioligand [3H]-7-hydroxy-N,N-di-n-propyl-2-aminotetralin (DPAT) and for the D4 radioligand [3H]-clozapine. Light microscope autoradiography showed the highest accumulation of silver grains which correspond to [3H]-spiroperidol binding sites in the rat adrenal medulla. In the adrenal cortex, where density of silver grains is about 40% lower than in the medulla, the radioligand is accumulated primarily in the zona glomerulosa and to a lesser extent in the zona reticularis. These findings suggest that dopamine D2-like receptor sites in the rat adrenal gland cortex are primarily involved in the modulation of catecholamine secretion from the medulla and of aldosterone secretion from the cortex. The possible relevance of the occurrence of dopamine D3 and D4 receptor subtypes in the adrenal gland is discussed.

Adrenal Glands↗

PubMed1995

DNA ploidy in testicular germ cell tumors: can an atypical seminoma be identified?

Recent immunohistochemical and DNA ploidy analyses indicate that seminoma serves as a precursor to nonseminomatous germ cell tumors. It is believed that tumor progression from classical seminoma to nonseminoma is accompanied by inactivation and deletion of genetic material, and that these deletions are reflected in DNA ploidy. Twenty-three primary testicular germ cell tumors were studied by DNA flow cytometry to investigate whether a proposed histologic intermediate "atypical seminoma" (AS) could be separated from classical seminoma by ploidy analysis. The mean DNA indices (DI) for classical seminoma (N = 16), atypical seminoma (N = 5), and nonseminoma (N = 2; both embryonal carcinoma) were 1.53, 1.34, and 1.35, respectively. When a single "outlier" case of atypical seminoma was removed from consideration the mean DI for the AS rose to 1.45. This data is consistent with the interpretation of atypical seminoma as an intermediate between classical seminoma (CS) and embryonal carcinoma (ES). It suggests that genetic deletions characterizing progression from CS to nonseminoma may, in part, already be extant in atypical seminoma.

Adult↗

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

Localisation of dopamine D2-like receptors in pulmonary artery of the human and rabbit but not of the rat.

The present study was designed to investigate the presence of dopamine D2-like receptor sites in the main trunk of the human, rabbit and rat pulmonary artery using combined radioligand binding and light microscope autoradiography techniques. [3H]Spiroperidol was used as a ligand. The presence and the localisation of the sympathetic neuroeffector plexus were also studied using catecholamine histofluorescence techniques. Radioligand binding experiments demonstrated the labelling of a population of dopamine D2-like receptors in sections of human and rabbit pulmonary arteries by [3H]spiroperidol. No specific binding occurred in sections of the rat pulmonary artery. Light microscope autoradiography showed the development of specific silver grains within the tunica adventitia, including the adventitia-media border, of the human and rabbit pulmonary arteries. No specific silver grains were found in sections of the rat pulmonary artery. Studies on the pharmacological characterisation of [3H]spiroperidol binding sites in the human and rabbit pulmonary arteries showed that they are sensitive primarily to domperidone, haloperidol, (-)-sulpiride or bromocriptine, and to a lesser extent to n-propylnorapomorphine, quinpirole or clozapine displacement. This suggests that [3H]spiroperidol binding sites in the pulmonary artery probably belong to the dopamine D2 receptor subtype. Catecholamine histofluorescence techniques revealed a rich plexus of fluorescent adventitial and adventitial-medial nerve fibres in the human and to a lesser extent in the rabbit pulmonary artery. Comparison of the localisation of dopamine D2-like receptor sites and of the sympathetic neuroeffector plexus in the pulmonary artery, suggests a possible prejunctional localisation of these sites.

Aged↗

PubMed1994

Neuroanatomy of aging brain. Influence of treatment with L-deprenyl.

The present study was designed to assess the influence of long term L-deprenyl treatment on some microanatomical parameters of aging rat frontal cortex and hippocampus. Male Sprague-Dawley rats of 19 months of age were divided into three groups. Rats of the first group received an oral daily dose of 1.25 mg/kg L-deprenyl; animals of the second group were treated with an oral daily dose of 5 mg/kg L-deprenyl, whereas rats of the third group were left untreated and used as control. Treatment lasted for 5 months, and rats were sacrificed at 24 months. At this age they were considered to be old. Another group of 11-month-old rats was used as an adult reference group. The density of nerve cell profiles and of glial fibrillary acidic protein (GFAP) immunoreactive astrocytes was decreased and increased respectively in the frontal cortex and in the different portions of the hippocampus in old in comparison with adult rats. A decrease in the intensity of sulfide silver staining in the mossy fibers of the hippocampus was also observed in old rats. Moreover, a cytoplasmatic accumulation of lipofuscin was noticeable in old rats as well as a significant increase of the monoamine-oxidase (MAO) B reactivity both in the frontal cortex and in the hippocampus. A higher density of nerve cell profiles, of sulfide silver staining, and fewer astrocyte profiles were noticeable in the frontal cortex and in the hippocampus of old rats treated with 5 mg/kg/day of L-deprenyl. This dose of the compound also significantly reduced lipofuscin accumulation and MAO-B reactivity in old rats. However, the lower dose of the compound did not cause any statistically significant effect on the microanatomical parameters investigated with the exception of sulfide silver staining and lipofuscin accumulation, which were increased and decreased respectively after 1.25 mg/kg per day of L-deprenyl. The above results suggest that long-term treatment with L-deprenyl is able to counter some microanatomical changes typical of the aging frontal cortex and hippocampus in the rat. These changes seem to be in part related to the MAO-B inhibitory activity of L-deprenyl.

Aging↗

PubMed1994

Autoradiographic localization of dopamine D1-like receptors in the rabbit pulmonary circulation.

The pharmacological characteristics and the anatomical localization of dopamine D1-like receptors were studied in sections of rabbit lung using [3H]SCH 23390 as a ligand. [3H]SCH 23390 was bound to sections of rabbit lung in a manner consistent with the labelling of dopamine D1-like receptors. The binding was time-, temperature-, and concentration-dependent belonging to a single class of high affinity sites. The dissociation constant value (Kd) was 2.05 nM, whereas the maximum density of binding sites (Bmax) averaged 85 +/- 4 fmol/mg tissue. The pharmacological profile of [3H]SCH 23390 binding to sections of rabbit lung is consistent with the labelling of dopamine D1 receptors. Light microscope autoradiography revealed the development of silver grains which correspond to [3H]SCH 23390 binding sites within the tunica intima and the tunica media of large intrapulmonary artery branches. The presence of silver grains was also observed in the tunica media, but not in the tunica intima of medium-sized pulmonary artery branches. No silver grains were observed in small-sized pulmonary artery branches or in the pulmonary veins. Dopamine D1-like receptors localized in the rabbit pulmonary circulation probably mediate vasodilatation. Further work is necessary to clarify the functional significance of the non-homogeneous distribution of dopamine D1-like receptor sites in the pulmonary circulation.

Animals↗