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Biomedical subjects

M G Spillantini

Publications and source records attributed to M G Spillantini.

At least 91 records · Page 5Linked to original sources
PubMed1990

Localization of endo-oligopeptidase (EC 3.4.22.19) in the rat nervous tissue.

The subcellular and regional distribution of endo-oligopeptidase (EC 3.4.22.19), an enzyme capable of generating enkephalin by single cleavage from enkephalin-containing peptides, was determined by an enzymatic assay using metorphamide and by immunochemical techniques in the CNS of the rat. The rat CNS contains a membrane-associated form of endo-oligopeptidase, an enzyme predominantly associated with the soluble fraction of brain homogenates. Subcellular fractionation showed that approximately 17% of the total activity of the enzyme is associated with membrane fractions including synaptosomes. Synaptosomal membranes were prepared from neocortex, striatum, hypothalamus, medulla, spinal cord, and cerebellum. The amount of EC 3.4.22.19 activity solubilized by 3-[( 3-cholamidopropyl]dimethylammonio)-1-propanesulfonate from synaptosomal membranes was similar in neocortex, striatum, and hypothalamus, being three- to 10-fold greater than in spinal cord, cerebellum, and medulla. A polyclonal antibody exhibiting high affinity for endo-oligopeptidase was raised in rabbits against the purified rat brain enzyme and used to localize endo-oligopeptidase by Western blotting and by immunoperoxidase techniques. A strong band corresponding to the Mr of EC 3.4.22.19 was found in solubilized proteins obtained from synaptosomal membranes prepared from hypothalamus, neocortex, and striatum when subjected to Western blotting. The immunohistochemical localization of endo-oligopeptidase indicated that the immunoreactivity was confined to gray matter in regions known to be rich in peptide-containing neurons such as the striatum. In the cerebellum, a region poor in peptides, no staining could be detected. The nonuniform distribution of endo-oligopeptidase in rat brain suggests a role in neurotransmitter processing in the CNS.

Animals↗
PubMed1989

Distribution of beta-nerve growth factor receptors in the human basal forebrain.

The distribution of neurons expressing the receptor for beta-nerve growth factor has been examined immunohistochemically in serial coronal sections of basal forebrain from aged normal human subjects. Neurons expressing the receptor were observed in the nucleus of the diagonal band of Broca and in the anterior, the intermediate, and the posterior portions of the nucleus basalis of Meynert. Neurons could also be seen in the medial septal nucleus and embedded in myelinated fibre tracts such as those of the external capsule, cingulum, medullary laminae of the globus pallidus, ansa penduncularis, ansa lenticularis, and anterior commissure. In situ hybridization with a 35S cDNA probe to the human beta-nerve growth factor receptor confirms a neuronal location as the site of synthesis of beta-nerve growth factor receptors in the nucleus basalis of Meynert in a fifth brain. A high percentage of Nissl-stained hyperchromic magnocellular neurons expressed the receptor for beta-nerve growth factor, suggesting that most neurons in the human cholinergic magnocellular basal forebrain system express these receptors. Recent data suggest that beta-nerve growth factor functions as a neurotrophic factor in basal forebrain cholinergic neurons. In Alzheimer's disease there is known to be a reduction in cholinergic function and an apparent loss of neurons in the cholinergic nucleus basalis of Meynert. For this reason we have examined the distribution of receptors for beta-nerve growth factor in the normal human basal forebrain in order to form a basis for comparison to those with Alzheimer's disease.

Aged↗
PubMed1989

Thiorphan increases capsaicin-evoked release of substance P from slices of dorsal spinal cord of guinea pig.

Capsaicin-evoked release of substance P-like immunoreactivity (SP-LI) from dorsal horn slices of guinea pig spinal cord was unaffected by incubation with the converting enzyme inhibitor captopril (10 microM). However, incubation with the endopeptidase 24.11 inhibitor, thiorphan (10 microM), induced a 2.44-fold increase of capsaicin-evoked SP-LI release, leaving the capsaicin-evoked release of calcitonin gene-related peptide (CGRP)-LI unchanged. Endopeptidase-24.11 activity was higher in homogenates of the dorsal than ventral spinal cord. Endopeptidase-24.11 might be involved in the inactivation of SP released from central endings of primary sensory neurons.

Animals↗
PubMed1989

Cloning and sequencing of the cDNA encoding an isoform of microtubule-associated protein tau containing four tandem repeats: differential expression of tau protein mRNAs in human brain.

We have isolated cDNA clones encoding a 383-amino acid isoform of the human microtubule-associated protein tau. It differs from previously determined tau sequences by the presence of an additional repeat of 31 amino acids, giving four, rather than three, tandem repeats in its carboxy-terminal half. The extra repeat is encoded by a separate exon. Probes derived from cDNA clones encoding the three (type I) and four repeat (type II) tau protein isoforms detected mRNAs for both forms in all adult human brain areas examined. However, in foetal brain only type I mRNA was found. Type I and type II mRNAs were present in pyramidal cells in cerebral cortex. In the hippocampal formation, type I mRNA was found in pyramidal and granule cells; type II mRNA was detected in most, though not all, pyramidal cells but not in granule cells. These observations indicate that tau protein mRNAs are expressed in a stage- and cell-specific manner. Tau protein is found in the protease-resistant core of the paired helical filament, the major constituent of the neurofibrillary tangle in Alzheimer's disease. Taken in conjunction with previous findings, the present results indicate that both the three and four repeat-containing tau protein isoforms are present in the core of the paired helical filament.

Amino Acid Sequence↗
PubMed1989

Expression and cellular localization of amyloid beta-protein precursor transcripts in normal human brain and in Alzheimer's disease.

Two classes of amyloid beta-protein precursors which differ by the presence of a serine protease inhibitor domain have been described. We have used synthetic oligonucleotide probes to investigate the tissue distribution and cellular localization of mRNAs encoding the two classes of amyloid beta-protein precursors. RNA blot analysis showed that transcripts encoding the protease inhibitor sequence are ubiquitously expressed in peripheral and central tissues. By contrast, transcripts lacking the protease inhibitor domain were only found in the central nervous system. By in situ hybridization on cerebral cortex and hippocampal formation both types of transcripts were present exclusively in nerve cells and they appeared to be produced by the same cells. A reduction in the transcript lacking the protease inhibitor domain was observed in frontal cortex from Alzheimer's disease patients. The present results indicate that there exists no correlation between the distribution of amyloid amyloid beta-protein precursor mRNAs and the tissue and cellular pathology of Alzheimer's disease; they also suggest that an overproduction of amyloid beta-protein precursor mRNA is unlikely to be responsible for amyloid beta-protein deposition in Alzheimer's disease.

Aged↗
PubMed1989

Multiple isoforms of human microtubule-associated protein tau: sequences and localization in neurofibrillary tangles of Alzheimer's disease.

We have determined the sequences of isoforms of human tau protein, which differ from previously reported forms by insertions of 29 or 58 amino acids in the amino-terminal region. Complementary DNA cloning shows that the insertions occur in combination with both three and four tandem repeats. RNAase protection assays indicate that transcripts encoding isoforms with the insertions are expressed in an adult-specific manner. Transcripts encoding four tandem repeats are also expressed in an adult-specific manner, whereas mRNAs encoding three tandem repeats are expressed throughout life, including in fetal brain. The levels of transcripts encoding the 29 or 58 amino acid inserts were not significantly changed in cerebral cortex from patients with Alzheimer's disease. Antisera raised against synthetic peptides corresponding to these different human tau isoforms demonstrate that multiple tau protein isoforms are incorporated into the neurofibrillary tangles of Alzheimer's disease.

Alzheimer Disease↗
PubMed1989

Nerve growth factor mRNA and protein increase in hypothalamus in a mouse model of aggression.

The effects of intermale aggressive behavior induced by social isolation on the level of nerve growth factor (NGF) mRNA and protein were investigated in central and peripheral mouse tissues. A large increase in NGF mRNA and protein was observed in hypothalamus, with no changes in cerebral cortex, hippocampus, and cerebellum. No change in NGF mRNA levels was found in heart, spleen, vas deferens, and submaxillary salivary gland. The cellular localization of NGF mRNA in the central nervous system was investigated by in situ hybridization. Numerous nerve cells were specifically labeled in preoptic and ventrolateral nuclei of the hypothalamus, as well as in the cornu ammonis region of the hippocampus and throughout all layers of the cerebral cortex, with the highest concentration in layer III. The present results firmly establish that nerve cells constitute the major source in NGF in the brain. They also open the way to understanding the regulation of NGF biosynthesis in the central nervous system.

Aggression↗
PubMed1988

Biochemical, anatomical and functional correlates of postnatal development of the capsaicin-sensitive innervation of the rat urinary bladder.

The postnatal development of substance P-like immunoreactivity (SP-LI) in the urinary bladder (assayed by radioimmunoassay and immunohistochemistry) was investigated in rats and compared with changes in the contractile response to acetylcholine, SP or capsaicin. In adult rats, bladder SP-LI was depleted by systemic capsaicin desensitization or extrinsic bladder denervation indicating that it is completely stored in sensory nerves. Bladder SP-LI was not detected in rat fetuses nor in newborn rats until day 3 of postnatal life (P3). SP-LI increased thereafter to reach, at P20, values approaching 60% of the SP-LI observed in the adult rat. By immunohistochemistry, SP-LI positive varicose fibers were not observed until P13. The contractile response to capsaicin was absent at P0, both in vivo (topical application) and in vitro. In adult rats, the capsaicin-induced bladder contraction was abolished by extrinsic denervation and is produced by release of transmitters from sensory nerves. The amplitude of the capsaicin-induced contraction in the postnatal rat bladder was significantly correlated with SP-LI concentration in the organ. Bladders excised from newborn (P0) or adult rats were equally sensitive to exogenous SP which, in both cases, produced a concentration-related contraction. It is concluded that the postnatal development of the 'efferent' function mediated by capsaicin-sensitive nerves of the rat bladder is strictly related to development of peptidergic sensory innervation.

Acetylcholine↗
PubMed1988

Measurement of catecholamines, met-enkephalin, somatostatin and substance P-like immunoreactivities in 12 human pheochromocytomas.

The present study was designed to evaluate the simultaneous presence of epinephrine (E), norepinephrine (NE), met-enkephalin (ME)-, somatostatin (SRIF)- and substance P (SP)- like immunoreactivities (LI) in extracts of 12 pheochromocytomas obtained at the time of surgery from 10 patients. Moreover, catecholamines and ME-LI levels were measured in peripheral plasma of each patient. Each pheochromocytoma was characterized by a high variability of ME-LI, SRIF-LI, SP-LI, E and NE levels. The highest E concentrations were found in tumors from patients with Multiple Endocrine Adenomatosis (MEA) IIa syndrome, whereas in sporadic pheochromocytomas NE was the main catecholamine. Among the neuropeptides ME-LI showed the highest intratumoral concentration, and SP-LI the lowest. No correlations were found between intratumoral levels of catecholamines and any of the neuropeptides or between any of the different neuropeptides measured. Plasma catecholamine levels were not correlated with intratumoral catecholamine levels. Plasma ME-LI was higher than normal in only one patient. No correlation was observed between tumoral CA or peptide content and the clinical picture. Our study confirms that human pheochromocytoma cells can synthetize different neuropeptides. The variability of the clinical picture very likely depends on the biochemical and biological heterogeneity of this chromaffin tumor.

Adrenal Gland Neoplasms↗
PubMed1988

Increase in substance P levels in the lung of old rats.

Substance P levels in the lung of young (3-month-old), adult (12-month-old), senescent (20-month-old) and aged (28-month-old) male Wistar rats were determined by radioimmunoassay. Levels of substance P were constant until 28 months of age when these become significantly higher (approximately more than 2 times, p less than 0.001) than the values found in younger rats. Whether the increase of substance P content in the lung of old rats may reflect changes in the density of substance P containing nerve fibres or in the content of the peptide in single nerve fibres is discussed.

Aging↗
PubMed1987

The correlation between sensory-efferent functions mediated by the capsaicin-sensitive neurons and substance P content of the rat urinary bladder.

The substance P-like immunoreactivity (SP-LI) of the urinary bladder of adult rats was depleted by capsaicin desensitization (50 mg/kg, s.c., 4 days before) or extrinsic denervation (pelvic ganglionectomy) thus indicating its neurogenic sensory origin. SP-LI levels were inversely proportional to the volume threshold for micturition but not to the amplitude of micturition contraction. Moreover SP-LI levels were directly related to the amplitude of the capsaicin- but not field stimulation-induced contraction of the rat isolated bladder. These findings indicate that the SP-LI level of the rat bladder is a useful index for monitoring the dual sensory-efferent functions of the capsaicin-sensitive innervation of this organ.

Animals↗
PubMed1987

Substance P-like immunoreactivity in capsaicin-sensitive structures of the rat thymus.

Unlike in mouse and hamster, the thymus of rats or guinea pigs contains measurable amounts of substance P-like immunoreactivity (SP-LI), which, in a HPLC system, eluted as authentic SP or SP sulfoxide. Ontogenetic study showed that in rats the SP-LI content of the thymus increased up to 60 days from birth, and decreased thereafter. Capsaicin, but not 6-hydroxydopamine (6-OHDA) pretreatment completely depleted thymic SP-LI content in both newborn and adult rats. Animals treated with capsaicin as newborns, but not as adults, showed lower thymus weights as compared to controls. Rats pretreated with capsaicin as adults underwent partial time-dependent recovery of thymic SP-LI content. Somatostatin-like immunoreactivity (SST-LI) of rat thymus, eluting in part as authentic SST, was unaffected both by capsaicin or 6-OHDA pretreatment. Taken together, these findings demonstrate the existence of capsaicin-sensitive structures containing SP in the rat thymus. The possible function(s) that capsaicin-sensitive structures could exert in the thymus, among which a trophic action, mediated by the efferent function of sensory neurons, remain(s) to be established.

Aging↗
PubMed1987

Acute oral captopril inhibits angiotensin converting enzyme activity in human cerebrospinal fluid.

Angiotensin converting enzyme (ACE) activity in human plasma and cerebrospinal fluid (CSF), was measured by a fluorimetric method, following an acute oral dose (75 mg) of captopril. A decrease of approximately 60% in enzyme activity was observed in CSF, suggesting that the drug penetrates the blood/brain barrier (BBB) in sufficient amounts to inhibit the ACE in CSF. The activity of CSF enkephalinase, an enzyme present in human brain and inhibited in vitro by an elevated concentration of captopril, was, however, unaffected by the acute drug administration. It is proposed that the antihypertensive effect of captopril in humans may be due, at least in part, to the inhibition of ACE contained within brain structures.

Administration, Oral↗
PubMed1986

In vivo 'enkephalinase' inhibition by acetorphan in human plasma and CSF.

Thiorphan, the potent inhibitor of 'enkephalinase', has shown some analgesic properties in experimental animals and in man. The possibility that the intravenous infusion of acetorphan, a prodrug of thiorphan (26 micrograms/kg per min for 60 min), can inhibit plasma and cerebrospinal fluid (CSF) enkephalinase in man in vivo was investigated. A decrease of approximately 65% in enzyme activity was observed in both plasma and CSF. Acetorphan did not induce any significant variation of plasma angiotensin-converting enzyme activity.

Amino Acids, Sulfur↗
PubMed1986

[Plasma beta endorphin in man during partial immersion in water using the therapeutic method].

The following study was designed to evaluate plasma beta-endorphin (beta-EP) variations in healthy volunteers during thermoneutral head-out water immersion while prevalently in the standing position. The type of immersion was similar to that currently adopted for therapeutic rehabilitation. Plasma beta-EP was evaluated by RIA previous beta-lipotropin stripping and Sep-Pack cartridge methanol extraction. Plasma beta-EP levels significantly decreased during water immersion from a value of 12.71 +/- 2.04 pmol/l to 7.46 +/- 1.09 pmol/l at 15 min (P less than 0.05) and to 6.08 +/- 1.87 pmol/l at 30 min (P less than 0.01). Thirty min after the end of immersion, plasma beta-EP levels showed a slight increase to 6.98 +/- 1.88 pmol/l but were still significantly below the basal level (P less than 0.05). These results are consistent with the previously demonstrated decrease of ACTH and prolactin and the increase of plasma dopamine and decrease of norepinephrine, suggesting that thermoneutral head-out water immersion is not a stressful condition in healthy subjects. Further studies are necessary in order to clarify the mechanism involved in beta-EP decrease in normal subjects during thermoneutral head-out water immersion.

Adrenocorticotropic Hormone↗
PubMed1986

Inhibition of penicillin-induced EEG discharges by low doses of morphine or naloxone in the rabbit. Evidence for a possible non-opioid receptor-mediated mechanism at the sensorimotor cortex.

In rabbits, pretreatment by intravenous (IV) and intracortical (IC) routes with low doses of morphine (250 micrograms/kg IV or 60 pmoles/rabbit IC) and naloxone (1-50 micrograms/kg IV or 0.3 pmoles/rabbit IC) antagonizes the EEG and behavioural seizures due to the IC injection of penicillin (150 Units) at the level of the sensorimotor cortex. Pretreatment with naloxone (20 micrograms/kg IV) did not alter the anticonvulsant effect of morphine (250 micrograms/kg IV). The similar anticonvulsant effect of the two drugs together with the absence of any antagonism by naloxone on the effect of morphine seem to suggest that both drugs act through a non-opioid receptor-mediated mechanism. Further, in light of the low effective doses of the drugs and of the absence of any additive effect after their combined administration, one might speculate that morphine and naloxone do not act through different pharmacological receptors. However, the presence of distinct EEG patterns with either morphine or naloxone, injected IC and IV, in animals fully protected against penicillin-induced seizures, does not seem to be in favour of the latter possibility.

Animals↗
PubMed1986

Hypernociceptive syndromes and pharmacological inhibition of endogenous opioid degradation.

Endogenous opioid peptides, by modulating the release of sympathetic transmitters, may play a role in the pathogenesis of migraine and related headaches which are considered hypernociceptive syndromes. Hypoendorphinaemia has been demonstrated in migraine attack. Captopril, a drug able to potentiate morphine analgesia in rats and inhibit enkephalinase in animals and in man, improves the clinical course of migraine. In the present research the cerebrospinal fluid and plasma beta-endorphin (beta-EP) levels have been evaluated following a single oral dose of captopril. The drug increased plasma beta-EP levels in migraine sufferers, and these data may be relevant in the mechanism of action of this drug in migraine and related headaches.

Captopril↗