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M Bentivoglio

Publications and source records attributed to M Bentivoglio.

At least 19 recordsLinked to original sources
PubMed1992

Connections of the thalamic reticular nucleus with the contralateral thalamus in the rat.

The occurrence of thalamic projections to the contralateral side of the thalamus, and the origin of these projections from the thalamic reticular nucleus, were demonstrated with fluorescent retrograde tracing. After a relatively large tracer injection in the anterior third of the thalamus (involving the reticular, anterior, intralaminar and ventrolateral nuclei), labeled cells were detected in the rostral portion of the contralateral reticular nucleus. The location within the reticular nucleus of the neurons retrogradely labeled in the contralateral thalamus was confirmed by means of the combination of tracing with immunocytochemistry, using antibodies against the calcium binding protein parvalbumin.

Animals↗
PubMed1992

Time course of nigrostriatal system changes after tract hemisection and effects of ganglioside treatment: a multiple retrograde fluorescent tracing study.

The postlesion phenomena of nigrostriatal neurons following partial tract hemisection have been studied with retrograde axonal transport of dyes in rats treated with saline or GM1 ganglioside (30 mg/kg, i.p., daily for varying times). The time course of the plastic changes in both experimental animal groups was determined by a double retrograde fluorescent tracing technique, utilizing Fast blue (FB) as prelesion tracer, and Diamidino yellow (DY) as postlesion tracer. The data show that the number of nigral cells retrogradely labeled by the prelesion intrastriatal injection of FB declined progressively to 50% of their initial number over 3 weeks. The ganglioside treatment did not significantly influence this temporal pattern of labeled cell loss. By DY-labeling, an almost complete block of the retrograde axonal transport was observed up to 1 week postlesion and only after 3 weeks a partial recovery was evident, positively influenced by the GM1 treatment. Therefore, together with the findings on nigrostriatal cell loss, these data indicate that ganglioside treatment favors and/or accelerates the recovery of axonal transport of surviving nigral neurons but does not significantly affect their degenerative rate in the first 3 weeks after the lesion.

Amidines↗
PubMed1992

Fine structural organization of the ependymal region of the paraventricular nucleus of the rat thalamus and its relation with projection neurons.

The ependymal lining of the diencephalic third ventricle is known to exhibit significant variation in zonal architecture and the relations of neurites to the ventricular surface in different regions remains obscure. The present study explores the fine structural organization of the ependymal region of the thalamic paraventricular nucleus. Methodology was developed for tracing neurites of cells retrogradely labelled with horseradish peroxidase based on our recent observation that paraventricular neurons projecting to the amygdaloid complex cluster near the ventricle and emit numerous dendrites extending toward the ependymal surface. A relatively uniform population of cuboidal 'pale' ependymocytes dominates the ventricular lining of the thalamic paraventricular nucleus, although a few 'dark' ependymocytes are interspersed. The subependymal region displays a variety of glial elements. Dendrites of thalamic paraventricular projection neurons terminate in proximity to the ependymal layer from which they are generally separated by thin cytoplasmic processes of putative astrocytes, and few indent the basal portion of ependymal cells. Thin 'terminal' (i.e., serially traced) horseradish peroxidase-labelled dendrites filled with lipid and lysosome-like dense bodies were often enveloped by astrocyte membrane whorls. This feature may constitute a reactive glial response in horseradish peroxidase-labelled dendritic terminals. A distinctive arrangement of tortuous astrocyte leaflets was insinuated between the basal portion of ependymocytes in a zone exhibiting numerous caveolae, apparently isolating neurites from direct contact with the cerebrospinal fluid. These findings indicate that the ependymal region of the thalamic paraventricular nucleus is not characterized by those features of the basal third ventricle suspected to confer neuroendocrine interaction between neurons and cerebrospinal fluid. The structural arrangement between ependymocytes and thalamic paraventricular projection cells indicate a specialized relation of these neurons with the ependymal interface, but apparently not directly with the overlying cerebrospinal fluid.

Animals↗
PubMed1991

Nerve growth factor differentially modulates the expression of its receptor within the CNS.

The effect of nerve growth factor on the expression of nerve growth factor receptor in the central nervous system of newborn and adult rats was studied by means of immunohistochemistry with the monoclonal antibody 192-IgG. Both during development and in adulthood, the intracerebroventricular administration of nerve growth factor elicited a pronounced increase of nerve growth factor receptor-like immunoreactivity in the cell bodies and neural processes of the basal forebrain cholinergic nuclei, as compared to cytochrome c-treated rats (controls). A pronounced nerve growth factor-induced increase of nerve growth factor receptor-like immunoreactivity was also observed in central regions innervated by trigeminal and spinal ganglia. A moderate to a marked increase of nerve growth factor receptor-like immunoreactivity was evident in some mesencephalic visual system-related structures and thalamic nuclei expressing nerve growth factor receptor. In contrast, NGF treatment did not induce appreciable modification of nerve growth factor receptor-like immunoreactivity in cerebellar, brainstem, and spinal motor structures of newborn rats. In adult nerve growth factor-treated rats, a decrease of nerve growth factor receptor-like immunoreactivity was detected in the cerebellum, whereas no re-expression of nerve growth factor receptor-like immunoreactivity occurred in the motor structures that had expressed it in the first postnatal week. Finally, nerve growth factor was also found to enhance, in both adult and newborn rats, nerve growth factor receptor-like immunoreactivity associated with ependymal and subependymal cellular elements of the lateral and third ventricles, as well as with the leptomeninges overlying the superior colliculus and supraoptic area. The present results indicate that endogenous nerve growth factor or nerve growth factor-like molecules may play a dynamic role in a variety of cell populations of both the developing and mature mammalian central nervous system. We thus propose the nerve growth factor ability to modulate its receptor in vivo as a novel criterion to define nerve growth factor or nerve growth factor-like molecules, sensitive neuronal, and non-neuronal cells. Whereas this criterion does not intrinsically possess absolute physiological validity, its pharmacological concomitants might be relevant in view of the proposed therapeutical use of this trophic factor.

Aging↗
PubMed1991

Postnatal development of calbindin and parvalbumin immunoreactivity in the thalamus of the rat.

The maturation of the calcium binding proteins calbindin-D28k (CB) and parvalbumin (PV) during the first 3 postnatal weeks was studied in the rat thalamus using immunohistochemistry. These two proteins display a non-homogeneous distribution in the adult thalamus. In the rat, CB is mainly localized in the neurons and neuropil of the thalamic midline, intralaminar, and ventromedial nuclei, as well as in the posterior complex. At birth, CB-immunoreactive cell bodies were evident in thalamic midline structures, and especially in the nucleus reuniens. The number of thalamic CB-positive cell bodies, as well as the intensity of the neuropil immunostaining, increased progressively in the first postnatal weeks. This quantitative increase was first apparent in the midline structures and then in the other thalamic territories which are CB-positive in adulthood, and followed a mediolateral gradient. The mature pattern was achieved by the end of the third postnatal week. In the adult rat thalamus the neurons of the reticular nucleus display PV-immunostaining and PV-positive fibers densely innervate most of the dorsal thalamic domains. PV-immunoreactivity was clearly evident at birth in the cell bodies of the reticular nucleus. The density of PV-containing fibers increased progressively after birth in the dorsal thalamus, with a lateromedial gradient. At the end of the third postnatal week the ventroposterior (VP) complex appeared heavily innervated by PV-positive fibers, whose density in more medial structures was still lower than in the adult thalamus. A transient hyperinnervation of PV-immunoreactive fibers, displaying a dishomogenous organization in distinct segments, was observed in VP, and especially in the ventroposteromedial nucleus, during the second postnatal week. Altogether these findings indicate that the maturation of CB and PV requires postnatally a relatively prolonged period of time. The possible involvement of these proteins in different functional aspects of thalamic neuronal maturation is discussed.

Animals↗
PubMed1991

GABAergic interneurons and neuropil of the intralaminar thalamus: an immunohistochemical study in the rat and the cat, with notes in the monkey.

Immunohistochemistry using antibodies to glutamic acid decarboxylase (GAD) was used to investigate the intralaminar nuclei of the thalamus in rat, cat and monkey. Antibodies to gamma aminobutyric acid (GABA) were also used in the cat. Intralaminar immunoreactive cell bodies were not detected in the rat, but were clearly present in cat and monkey. In the latter species, GABA- or GAD-immunopositive perikarya were distributed throughout the anterior intralaminar nuclei, whereas in the posterior intralaminar complex they prevailed in the lateral part of the centre median nucleus and around the fasciculus retroflexus. Measurements of the area of immunostained intralaminar cell bodies in cat and monkey indicated that they are represented by small neurons. Experiments in the cat, based on retrograde tracers injections involving large sectors of the frontal and parietal cortices and the head of the caudate nucleus, revealed that the GABA- or GAD-immunoreactive cells and the retrogradely labeled projection neurons represented two separate intralaminar cell populations, although the latter also included small cells. Considerable differences were observed in the immunoreactive GABAergic neuropil of the anterior and posterior intralaminar nuclei. Clusters of densely packed bouton-like immunoreactive elements were detected in the former structures in the rat, cat and monkey, and were especially evident in the central lateral nucleus; immunopositive varicose fibers and puncta were diffusely distributed in the posterior intralaminar structures. Taken together with data from the literature, the present findings indicate that in cat and monkey local circuit inhibitory cells regulate not only the activity of principal thalamic nuclei which project densely upon restricted cortical fields, but also of the intralaminar structures which are widely connected with the cerebral cortex and the striatum. Regional variations in the distribution of GABAergic fibers and terminals suggest major differences in the organization of inhibitory circuits and synaptic arrangements of the anterior and posterior intralaminar thalamus.

Animals↗
PubMed1991

[Recent findings on the physiopathology of hypertension].

The numerous pathophysiological theories in the field of essential hypertension are often conflicting, and till now a comprehensive model is not available. The aetiology of human hypertension is probably multifactorial, the control mechanisms of hypertension are strictly interdependent, and the alteration of one induces readjustment of the others, so that it is very difficult to discriminate the "primum movens" from its consequences. In this review the recent acquisitions in the aetiology and the pathophysiology of arterial hypertension are analysed, with particular regard to the role of inheritance, of renal mechanisms of sodium retention, ions transport, humoral factors, central nervous system and of enhanced vascular reactivity. The activation of some of these pathophysiological factors induces the rise in peripheral vascular resistance, which is the final common pathway in the development of essential hypertension.

Biological Transport↗
PubMed1990

Thalamic midline cell populations projecting to the nucleus accumbens, amygdala, and hippocampus in the rat.

The organization of the thalamic midline efferents to the amygdaloid complex, hippocampal formation, and nucleus accumbens was investigated in the rat by means of multiple retrograde fluorescent tracing. The present findings indicate that these connections derive from separate cell populations of the thalamic midline, with a low degree of divergent collateralization upon more than one of the targets examined. The neural populations projecting to the amygdala, hippocampus, or accumbens are highly intermingled throughout the thalamic midline, but display some topographical prevalence. Midline thalamo-hippocampal cells are concentrated in the nucleus reuniens; thalamo-accumbens neurons prevail in the ventral portion of the paraventricular nucleus, and in the central medial nucleus. Thalamo-amygdaloid cells display a topographical prevalence in the rostral third of the thalamic midline and are concentrated in the dorsal part of the paraventricular nucleus and in the medial part of the nucleus reuniens. Both dorsally in the paraventricular nucleus and ventrally in the nucleus reuniens, thalamo-amygdaloid cells are located closer to the ependymal lining than the neurons projecting to the hippocampus or nucleus accumbens. Further, thalamo-amygdaloid cells, especially in the paraventricular nucleus, extend their dendritic processes in the vicinity of the ependymal lining, where they arborize profusely. These features indicate a close topographical relationship of neurons projecting to the amygdala with ependymal cells. The fairly discrete origin of midline outputs to the amygdala, hippocampus, and accumbens indicates that the flow of information is conveyed through separate channels from the thalamic midline to limbic and limbic-related targets. Together with the literature on the limbic afferents to the thalamus, these findings emphasize the relationships between the thalamus and the limbic system subserved by parallel input-output routes. However, because of the overlap of the projection cell populations, the thalamic midline may represent a locus of interaction among neurons connected with different parts of the limbic system. The functional implications of these findings are discussed in relation to the "nonspecific" thalamic system, as well as to the circuits involved in memory formation.

Amnesia↗
PubMed1990

Photoconversion of fluorescent retrograde tracers.

Photoconversion of fluorescent dyes, retrogradely transported through axons to their parent cell bodies, into a stable diaminobenzidine (DAB) reaction product was tested in the nigrostriatal and thalamocortical systems of rats. Satisfactory results were obtained with Propidium Iodide (PI), Fluoro-Gold (FG), Fast Blue (FB), Diamidino Yellow (DY), and rhodamine-labeled latex microspheres (RLM); some photoconversion was also observed in Evans Blue (EB)-labeled neurons. The red fluorescent tracers PI, EB and RLM were photoconverted under the excitation wavelength appropriate for eliciting their fluorescent emission. With the yellow or blue fluorescent tracers FG, FB, and DY satisfactory results could instead be obtained using an excitation wavelength which did not elicit visible fluorescent emission. This finding indicates that the latter is not a critical factor for obtaining photoconversion. The features and subcellular localization of photoconverted DAB were different from those of the fluorescent labeling: photoconversion resulted in the appearance of brown granules of DAB reaction products in the cytoplasm, independently from the occurrence of fluorescent labeling in the neuronal cytoplasm or nucleus. Photoconversion may enable new applications of fluorescent retrograde tracing and, in particular, its electron microscopic visualization.

Animals↗
PubMed1990

Verapamil 240 SR versus verapamil 120 SR in arterial hypertension. A randomized double-blind, placebo-controlled study with 24-hour ambulatory blood pressure monitoring.

Fifteen patients (6 males, 9 females), age range 36-70 years, were enrolled in a randomized, double-blind, placebo-controlled study according to a Latin-square design, with the aim of comparing 24-hour blood pressure profiles after three 15-day treatment periods with placebo, verapamil SR 120 mg (V120 SR) given twice daily (bid), and verapamil SR 240 mg (V240 SR) given once daily (od). All of the patients were diagnosed as mild or moderate essential hypertensives on the basis of standard casual recordings. Noninvasive 24-hour ambulatory blood pressure (BP) monitoring was performed with an ICR Spacelab 5200 automatic device. In comparison with placebo, a clinically and statistically significant reduction in both systolic and diastolic BP over 24 hours was obtained with both active treatments. Comparison of the two active treatments shows that V240 SR led to a greater reduction in systolic and diastolic BP than V120 SR. No changes in heart rate were observed. Both treatments were well tolerated. In conclusion, both verapamil regimens proved to be effective and safe in treating essential hypertensives, with V240 SR giving better 24-hour BP control.

Adult↗
PubMed1990

Neuronal cell types in the thalamic intralaminar central lateral nucleus of the cat.

The existence of Golgi type II neurons was verified in the anterior intralaminar central lateral (CL) nucleus of the cat thalamus, and its projection cell types were identified, by means of Golgi impregnation. CL principal neurons were found to display a large- or medium-sized cell body and a radiate dendritic pattern. Their primary dendrites were limited in number, and had a rather long course; they were poorly ramified. The axons of principal neurons were impregnated only occasionally and for a short distance. Projection neurons of the 'bushy' or tufted type, described in the main thalamic sensory nuclei, were not identified in the CL in the present study. Typical Golgi type II neurons were found throughout CL. They were mainly small-sized, and displayed a rich dendritic arborization characterized by dendritic appendages. The axons of Golgi type II neurons were seen to give rise to extensive local arborizations. The present findings indicate that in the cat CL, principal cells are mainly represented by radiate neurons. Typical local circuit neurons also are evident in CL, suggesting that the activity of anterior intralaminar structures is regulated by intrinsic mechanisms similar to those operating in the main thalamic relay nuclei.

Animals↗
PubMed1990

[Simvastatin versus gemfibrozil in the treatment of primary hypercholesterolemia in hypertensive patients treated with hydrochlorothiazide].

Recent pharmacological studies confirmed the role of hypercholesterolemia in the pathogenesis of coronary atherosclerosis. A 10% reduction in cholesterol levels can reduce the risk of coronary heart disease by 15%. However many hypercholesterolemic patients often suffer from arterial hypertension and drugs such as thiazide diuretics cause an imbalance in lipid metabolism. The efficacy and the tolerability of simvastatin (a inhibitor of HGM-CoA reductase) with that of gemfibrozil (a fibric acid derivative, which can reduce the VLDL level) were compared in a placebo-controlled study in 2 groups of patients with primary hypercholesterolemia and mild-to-moderate essential hypertension treated with hydrochlorothiazide. After 10 weeks standard hypolipidemic diet and hydrochlorothiazide (25 mg od) therapy, 30 patients whose cholesterol levels were still greater than or equal to 250 mg/100 ml and whose diastolic blood pressure was less than 95 mmHg were randomized to one of the following treatments: simvastatin, 20 mg od, gemfibrozil, 600 mg bid or placebo, while continuing dietetic and diuretic treatment. After 24 weeks treatment, simvastatin induced a 37% reduction in cholesterol plasma levels, a 9% increase of HDL and a 16% reduction of LDL. APO-A1 showed a 4% increase, while APO-B showed a 3% reduction. Gemfibrozil induced a 20% reduction in plasma triglycerides and a 13% decrease in plasma cholesterol, with a significant 19% increase in HDL and a 11% reduction in LDL. No significant variations in any of the lipid parameters monitored were observed in the placebo group. Treatment with simvastatin or gemfibrozil in hypertensive patients in hydrochlorothiazide monotherapy can reduce total cholesterol and LDL-cholesterol plasma levels, while significantly increasing HDL plasma levels compared to placebo. Simvastatin, however, resulted more efficient than gemfibrozil on total cholesterol or cholesterol fractions.

Adult↗
PubMed1989

[Doppler echocardiography in atrial myxoma].

Two-dimensional echocardiography is the technique of choice for the diagnosis of atrial myxoma. In fact the Echo study allows the recognition of the presence of the tumor, and can show its dimensions, shape, implantation site and motility. However, it is not clear the role of Doppler echocardiography in the evaluation of atrial myxoma. This technique could be useful to recognize patients with more severe obstruction to atrioventricular flow due to large tumors. In 4 patients with large atrial myxomas (3 left and 1 right atrial myxoma) Doppler analysis of atrioventricular flow showed an apparent correlation between variation of trans-mitral or trans-tricuspid diastolic flow and symptoms (syncopal attacks). Only patients with an obstruction to atrioventricular flow and severely restricted calculated mitral or tricuspid orifice had syncopal attacks, at variance with patients without flow obstruction. Further studies on larger population will verify this apparent relation between atrioventricular flow obstruction and clinical symptoms in patients with large atrial myxoma.

Adult↗