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Biomedical subjects

E Bronzetti

Publications and source records attributed to E Bronzetti.

At least 55 records · Page 3Linked to original sources
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 localization of neurotrophin receptor proteins in human skin.

The target organs of neurotrophin-dependent sympathetic and sensory neurons, including the skin, synthesize and release neurotrophins, primarily NGF. Neurotrophins undergo retrograde axonal transport, and exert specific function in the perikarya of the responsive neurons. Moreover, evidence exists for an autocrine and/or paracrine function of neurotrophins in the skin. This study analyses the immunohistochemical localization of low (gp75) and high-affinity (gp140 trkA, gp145trkB and gp145trkC) neurotrophin receptor proteins in the human glabrous skin. We consider that the expression of neurotrophin receptors may be indicative of neurotrophin activity. Specific gp75 and gp140trkA-like immunoreactivity (IR) were observed highly co-localized in (1) epidermis, primarily in the basal keratinocytes; 2) sweat glands; (3) blood vessel walls, mainly in the muscular layer; (4) Schwann and perineurial cells of nerve trunks; (5) periaxonic cells forming sensory nerve formations (Meissner's and Pacini's corpuscles); (6) large axons of nerve bundles and of sensory corpuscles; gp145trkB-like and gp145trkC-like were found labelling nerve fibers and sensory nerve formations, as well as blood vessels and sweat glands, but not epidermic cells. The results suggest that, in addition to the well known neurotrophic functions, neurotrophins may also regulate unknown functions in non-nervous cutaneous cells, which are targets for neurotrophin-dependent sympathetic and sensory neurons.

Humans↗
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↗
PubMed1994

Choline acetyltransferase and acetylcholinesterase in the hippocampus of aged rats: sensitivity to choline alphoscerate treatment.

The influence of aging on the acetylcholine synthesising and the degrading enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) was studied in the hippocampus of male Wstar rats at 2 months (young), 12 months (adult) and 27 months (old) of age using biochemical, immunocytochemical and histochemical techniques. The influence of treatment for 6 months with a daily dose of 100 mg/kg of choline alphoscerate (L-alpha-glycerylphosphorylcholine) on the parameters examined was also investigated in old rats. Biochemical analysis of ChAT and AChE revealed the highest of the enzymatic activities in the hippocampus of adult rats and no significant differences between young and old animals. Immunocytochemical analysis of ChAT immunoreactivity revealed the highest immunostaining in adult rats followed in descending order by young then old animals. Histochemical evaluation of AChE reactivity revealed the highest expression in adult rats followed in descending order by old then young animals. Biochemical analysis of the effects of choline alphoscerate did not reveal any effect on ChAT activity and in increased expression of AChE activity. Moreover, the compound restored, in part, ChAT immunoreactivity in the hippocampus of old rats and increased the expression of AChE reactivity primarily in the CA3 sub field in old rats. The above results suggest that appropriate quantitative immunocytochemical and histochemical techniques may represent a useful tool for assessing age-dependent changes in cholinergic neurotransmission markers. The functional and pharmacological significance of the effects of choline alphoscerate on the expression of ChAT and AChE in the hippocampus of aged rats should be clarified in future studies.

Acetylcholinesterase↗
PubMed1994

Behavioral and electrophysiological correlates of the quinolinic acid rat model of Huntington's disease in rats.

The influence of bilateral intrastriatal injection of quinolinic acid (QA, 300 nmol) was studied in male Wistar rats. Behavioral and electrophysiological experiments were conducted in 15 lesioned plus 15 vehicle-injected (control) animals. With respect to control animals, QA-lesioned rats showed marked, statistically significant alterations from both the behavioral (greater motor activation in response to d-amphetamine, place-learning deficit in the Morris water maze), and the electroencephalographic (reduced voltage amplitude and EEG power at the level of frontal cortex) points of view. In addition, a significant loss in body weight and a marked striatal gliosis (GFAP staining) were observed in lesioned rats. Conversely, QA-lesioned rats did not show modifications in posttetanic potentiation (P.T.P.) or long-term potentiation (L.T.P.) in CA1 hippocampal area. The present results confirm that QA lesions of rat striatum may be regarded as a suitable model of Huntington's disease (HD).

Animals↗
PubMed1994

Interactions between calcium channel blockers and alpha-adrenoceptors in the human coronary and mammary arteries: a radioligand binding study.

The study was designed to assess whether Ca2+ channel blockers of the dihydropyridine family (felodipine, nicardipine, nifedipine, nimodipine, nitrendipine and nisoldipine), and of the phenylalkylamine family (verapamil) have any effect on alpha-adrenoceptor binding to sections of the human right coronary and mammary arteries, measured using [3H]-dihydroergocryptine (DHT) as a ligand. Increasing concentrations of nicardipine, verapamil and nitrendipine competed with [3H]-DHT binding to sections of the human coronary and mammary arteries. The other compounds tested were without effect. Among the competitors of [3H]-DHT binding, nicardipine was the most powerful, with a 50% inhibition (IC50) value of approximately 10 nM. The pharmacological profile of competition with [3H]-DHT binding by nicardipine, in the presence or in the absence of guanosine triphosphate and NaCl, is consistent with antagonist activity of the dihydropyridine derivative at the alpha-adrenoceptor. This property may account for the lower sympathetic stimulatory activity elicited by nicardipine, in comparison with other Ca2+ channel blockers used in cardiovascular therapy.

Adolescent↗
PubMed1993

Effect of ipsilateral lesioning of the nucleus basalis magnocellularis and of L-alpha-glyceryl phosphorylcholine treatment on choline acetyltransferase and acetylcholinesterase in the rat fronto-parietal cortex.

The present study assesses the effect of unilateral lesions of the nucleus basalis magnocellularis (NBM) and of treatment with L-alpha-glyceryl phosphorylcholine (GFC, choline alfoscerate) on the acetylcholine-synthesizing (choline acetyltransferase (ChAT)), and acetylcholine-degradating (acetylcholinesterase (AChE)) enzymes in the rat fronto-parietal cortex ipsilateral to the lesion. Ibotenic acid injections in the right NBM area caused a significant decrease of both ChAT and AChE activities as well as of histochemically reactive stores of AChE in the right fronto-parietal cortex. Treatment with GFC restored in part the loss of ChAT and AChE activities. Moreover, AChE reactivity is restored in the fronto-parietal cortex of NBM-lesioned rats treated with GFC. GFC is a precursor in the biosynthesis of brain phospholipids which increases the bioavailability of acetylcholine in the nervous tissue. The possible relevance of the restoration of the marker enzymes of cholinergic neurotransmission by GFC in an animal model of cholinergic hypofunction is considered.

Acetylcholinesterase↗
PubMed1993

Muscarinic cholinoceptor subtypes in the rat frontoparietal cortex after ipsilateral lesions of the nucleus basalis magnocellularis.

Muscarinic cholinoceptor subtypes (M1 and M2) were studied in membrane particles of the rat frontoparietal cortex 72 h and 1, 2, 3, and 4 weeks after ipsilateral lesioning of the nucleus basalis magnocellularis (NBM). The affinity of the ligand used to characterize muscarinic cholinoceptors, 3H-quinuclidinyl benzilate did not significantly change in lesioned compared with sham-operated rats as well as the density of high affinity (M1) sites. Low affinity muscarinic cholinoceptors (M2 sites) were significantly decreased in NBM-lesioned rats 72 h and 1 week after lesioning. The density of M2 sites did not significantly differ in lesioned rats 2 or 3 weeks after NBM lesioning, but increased, in comparison with sham-operation 4 weeks after NBM lesioning. These findings suggest that frontoparietal M2 muscarinic cholinoceptors, which probably have a presynaptic localization, are sensitive to NBM lesions. Their changes at different times after NBM lesioning suggest the occurrence of loss, compensation and upregulation of cholinergic projections arising to the neocortex from the NBM.

Animals↗
PubMed1992

Oral choline alfoscerate counteracts age-dependent loss of mossy fibres in the rat hippocampus.

Mossy fibres represent a major intrahippocampal associative pathway. They consist of axons of granule cells of the dentate gyrus and show an age-dependent loss as do the granule cells of the dentate gyrus. The present study was designed to assess whether long-term treatment of rats with choline alfoscerate in their drinking water would be effective in countering the loss of mossy fibres and of granule cells occurring with aging. Choline alfoscerate is a precursor in the biosynthesis of brain phospholipids and increases the bioavailability of choline in nervous tissue. Male Sprague-Dawley rats of 18 months of age were divided into two groups. One group received a daily dose of 100 mg/kg choline alfoscerate for 6 months; the other group was used as an untreated control. Twelve-month-old untreated animals were used as a reference group. The area occupied by mossy fibres, as well as their density, was significantly reduced in 24-month-old control rats in comparison with 12-month-old rats. The same is true for the density granule cells of the dentate gyrus which was decreased by about 20% in the oldest animals. In choline alfoscerate-treated rats both the area occupied by mossy fibres and their density were significantly higher than in age-matched controls. Moreover, the number of granule neurons of the hippocampus was higher by about 7% in choline alfoscerate-treated than in control 24-month-old rats. The above data suggest that choline alfoscerate treatment counteracts some anatomical changes of the rat hippocampus occurring in old age.

Administration, Oral↗
PubMed1992

Hippocampal long-term potentiation in nucleus basalis magnocellularis-lesioned rats.

The probability of hippocampal long-term potentiation induction in the mossy fiber CA3 and commissural/associational CA3 responses and the cortical levels of choline acetyltransferase (ChAT) activity were compared in right nucleus basalis magnocellularis (NBM)-lesioned rats. A 50% reduction in the right cortical ChAT activity was demonstrated 4 weeks after an ibotenic acid lesion of the NBM. No significative differences were found in the probability of LTP induction of right hippocampal slices in sham-operated rats from 10 to 40 days after the injection into the right NBM. On the contrary, a progressive and significative increase in the probability of LTP induction was shown in right hippocampal slices of NBM-lesioned rats from 10 to 40 days after the injection of ibotenic acid into the right NBM. The results demonstrated the appearance of a paradoxical increase of hippocampal synaptic plasticity when the cortical cholinergic biochemical alterations are still present. This finding might be responsible for a behavioural recovery, in NBM-lesioned rats.

2-Amino-5-phosphonovalerate↗
PubMed1992

Effect of nicardipine treatment upon cardiac hypertrophy in spontaneously hypertensive rats: a morphometric and ultrastructural study.

OBJECTIVE: The present study was designed to investigate the effect of nicardipine administration upon systolic blood pressure (SBP) and cardiac hypertrophy in spontaneously hypertensive rats (SHR). DESIGN: SBP, heart: and left ventricle: body weight ratios, the cross-sectional area of cardiocytes, and the ultrastructure of the left ventricle were evaluated. METHODS: Ten-week old male SHR and age-matched normotensive Wistar-Kyoto rats were studied for 12 weeks. One group of SHR was treated for 12 weeks with a daily oral dose of 1 mg/kg nicardipine and another group with 1 mg/kg hydralazine; Wistar-Kyoto rats were used as a normotensive control group. Light and electron microscope techniques associated with image analysis and morphometry were used. RESULTS: Nicardipine administration normalized SBP values and significantly reduced the heart: and left ventricle: body weight ratios. Moreover, administration reduced the cross-sectional area of cardiocytes by approximately 38% in subendocardium and by 24% in subepicardium. Hydralazine administration significantly reduced SBP values but had no effect upon heart: or left ventricle: body weight ratios or the cross-sectional area of cardiocytes. Electron microscopy showed that nicardipine treatment was able to reduce the hypertension-dependent changes in cardiac ultrastructure consisting of alternations to intercalated discs and line Z morphology as well as in the decrease of the mitochondria: myofibrils ratio. CONCLUSIONS: The above data indicate that nicardipine administration is able to reduce SBP and to counter the development of structural and ultrastructural changes in cardiac morphology which represent a common complication of arterial hypertension.

Animals↗
PubMed1992

Autoradiographic localization of the gamma-aminobutyric acid type A receptor agonist 3H-muscimol in the rat superior cervical ganglion.

The anatomical localization of gamma-aminobutyric acid type A (GABA-A) receptor sites in the rat superior cervical ganglion was studied using combined radioreceptor binding and autoradiographic techniques. 3H-Muscimol was used as a ligand of GABA-A receptor sites. The binding was consistent with the labelling of GABA-A sites. The dissociation constant value was 6.4 nmol/l, and the maximum density of binding sites was 146 +/- 7.8 fmol/mg tissue. Light microscope autoradiography revealed the accumulation of 3H-muscimol mainly in superior portions of the ganglion. Binding sites are located primarily in the neuropil rather than within ganglionic neurons. It is probable that the sites revealed by autoradiography are involved in the inhibition of acetylcholine release from ganglionic neurons.

Animals↗