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G M Pasinetti

Publications and source records attributed to G M Pasinetti.

At least 55 records · Page 3Linked to original sources
PubMed1995

Association of apolipoprotein E genotype with brain levels of apolipoprotein E and apolipoprotein J (clusterin) in Alzheimer disease.

This study examines the relationship between the levels of apolipoprotein E (apoE) and apolipoprotein J (apoJ, also designated as clusterin) as a function of apoE genotype in the hippocampus and cortex of Alzheimer disease (AD) subjects. These two lipophilic proteins which are involved in the maintenance of lipid homeostasis are both synthesized in the brain by astrocytes. Results indicate a reduction of apoE levels in the hippocampus and frontal cortex that is proportional to the apoE4 allele dose. Conversely, apoJ (clusterin) levels were found to increase proportionately to the number of apoE4 allele dose. These results suggest a compensatory induction of apoJ (clusterin) in the brain of apoE4 AD subjects showing low brain levels of apoE.

Alzheimer Disease↗
PubMed1994

Purification and characterization of brain clusterin.

Clusterin, a 70-80 kDa sulfated glycoprotein found in numerous tissues, is also known as complement lysis inhibitor (CLI), apolipoprotein J, SP-40,40, TRPM-2, and SGP-2. In Alzheimer disease (AD), clusterin mRNA is increased, whereas clusterin protein is found in deposits of beta-amyloid (A beta). These studies characterized clusterin protein from human brain. In extracts from cortex and hippocampus, clusterin was about 40% higher in AD than in controls. Purified clusterin from human brain was slightly smaller than serum clusterin. Brain and serum clusterin were indistinguishable in the inhibition of complement-mediated hemolysis. Both serum and brain clusterin were indistinguishable in inhibiting the aggregation of A beta and promoting oxidative stress in rat pheochromocytoma PC12 cells (MTT assay). The inhibition of A beta aggregation and enhancement of A beta toxicity by clusterin suggest new mechanisms in AD.

Alzheimer Disease↗
PubMed1994

Expression of complement C1qB and C4 mRNAs during rat brain development.

This study examined the distribution of complement C1qB and C4 mRNAs during rat brain development by northern blot and in situ hybridization. Both C1q and C4 mRNAs were already present at embryonic day 14 (E14) and showed little change in abundance through six weeks postnatal. At E16, C1qB mRNA was present at high abundance in putative microglia/macrophages in cortical marginal and intermediate zones, and hippocampal analge, but not in the neurogenic ventricular or sub-ventricular zones. C4 mRNA had a broadly similar regional distribution, but was present at lower abundance in a larger number of cells, putatively neurons. The distribution pattern for C1qB and C4 mRNAs did not change appreciably as brain development proceeded. The lower prevalence of C mRNAs in neuroepithelial or subventricular zones suggests an inverse relationship of C mRNA to cell proliferation. The frequency of apoptotic nuclear profiles, which was as much as ten-fold higher at P7 vs. E17, did not correlate anatomically with C1qB or C4 mRNA levels. Thus, the widespread distribution and consistent presence of each C mRNA during development argues against a role for C in programmed cell death during brain development. We suggest that C1q and C4 components have novel roles during brain development that may be unrelated to normal cytotoxic actions of the activated classical C cascade.

Animals↗
PubMed1994

Clusterin (SGP-2): a multifunctional glycoprotein with regional expression in astrocytes and neurons of the adult rat brain.

Clusterin (SGP-2) is a newly described glycoprotein associated with several putative functions including responses to brain injury. This study reports the regional and cell type expression of clusterin mRNA and its encoded glycoprotein in the rat brain; a limited comparison was also done with the human brain. Using in situ hybridization combined with immunocytochemistry, we found that astrocytes and neurons may express clusterin mRNA in the normal adult brain. While astrocytes throughout the brain contained clusterin mRNA, there was regional selectivity for neuronal clusterin expression. In the striatum, clusterin mRNA was not detected in neurons. Only a subset of substantia nigra dopaminergic neurons or locus ceruleus noradrenergic neurons (tyrosine hydroxylase immunopositive) contained clusterin mRNA. However, neuronal clusterin mRNA was prevalent in pontine nuclei and in the red nucleus of the midbrain tegmentum. Similarly, clusterin mRNA was prevalent in both rat and human hippocampal neuron-specific enolase immunopositive pyramidal neurons, although rat CA1 neurons had less mRNA than CA2-CA3 neurons. Monotypic primary cell cultures from the neonatal rat showed clusterin mRNA in both neurons and astrocytes, but not in microglia. By immunocytochemistry, no clusterin immunopositive glia were observed in any region of the rat brain, confirming previous studies. However, clusterin immunopositive cells (putative neurons) were observed in the Purkinje cell layer of the cerebellum, medial and interposed cerebellar nuclei, trigeminal motor nucleus, and red nucleus. Finally, in vitro studies suggest that astrocytes, but not neurons, secrete clusterin, which is pertinent to clusterin immunodeposits found after experimental lesioning.

Alzheimer Disease↗
PubMed1994

Response of striatal astrocytes to neuronal deafferentation: an immunocytochemical and ultrastructural study.

This ultrastructural and light microscopic immunocytochemical study describes the time course of anatomical changes that occur in striatal astrocytes in response to neuronal deafferentation in young adult rats and the coordinate distribution of two astrocytic proteins involved in reactive synaptogenesis, glial fibrillary acidic protein and clusterin. We found that following a unilateral lesion of the cerebral cortex, striatal astrocytes undergo a rapid ultrastructural transformation from a protoplasmic to a reactive type of astroglia and are the primary cells involved in the removal of degenerating axon terminals, but not axons of passage, from the neuropil. In addition, at 10 and 27 days postlesion, processes of reactive astrocytes are also seen to occupy vacant postsynaptic spines after degenerating presynaptic terminals are removed, suggesting that they may also participate in the reinnervation of the deafferented neurons. By immunocytochemistry, reactive astrocytes were characterized by a significant increase in the intensity of glial fibrillary acidic protein staining beginning at three days postlesion and lasting for at least 27 days postlesion. Reactive astrocytes were characterized by cellular hypertrophy and an increase in the density of immunoreactive processes distributed throughout the deafferented striatum. However, our analysis of astrocyte cell number found no evidence of astrocyte proliferation in response to the deafferentation lesion. Although previous in situ hybridization studies have reported elevated clusterin messenger RNA in reactive astrocytes after decortication, clusterin immunoreactivity was not seen in the cell soma of reactive astrocytes but was distributed as punctate deposits, ranging from 1 to 2 microns in diameter, within the neuropil of the deafferented striatum. At 10 days postlesion, the distribution of clusterin staining appeared as large aggregates of immunoreactive deposits adjacent to neurons. However, by 27 days postlesion, the aggregates of clusterin reaction product were replaced by a fine scattering of individual punctate deposits distributed evenly over the dorsal part of the deafferented striatum. These data support the notion that reactive astrocytes serve multiple, time-dependent roles in response to brain injury and are involved in both the removal of degenerative debris from the lesion site as well as in reforming the synaptic circuitry of the damaged brain. Our data suggest that, in response to decortication, reactive astrocytes are the primary cells responsible for removing degenerating axon terminals, but not axons of passage, from the deafferented striatum and that the coordinate increase in glial fibrillary acidic protein may serve to stabilize the extension of reactive astrocytic processes during phagocytosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1994

Selective expression of clusterin (SGP-2) and complement C1qB and C4 during responses to neurotoxins in vivo and in vitro.

This study concerns expression of the genes encoding three multifunctional proteins: clusterin and two complement cascade components, C1q and C4. Previous work from this and other laboratories has established that clusterin, Clq and C4 messenger RNAs are elevated during Alzheimer's disease, and in response to deafferenting and excitotoxic brain lesion. This study addresses hippocampal clusterin, ClqB and C4 expression in response to neurotoxins that caused selective neuron death. Kainate, which preferentially kills hippocampal CA3 pyramidal neurons but not dentate gyrus granule neurons induced clusterin immunoreactivity in CA1 and CA3 pyramidal neurons and adjacent astrocytes, but not in dentate gyrus granule neurons. In contrast, colchicine, which preferentially kills the dentate gyrus granule neurons, induced clusterin immunoreactivity in the local neuropil as punctate deposits, but not in the surviving or degenerating dentate gyrus granule neurons. Clusterin messenger RNA was increased in astrocytes. ClqB and C4 messenger RNAs increased within 48 h after kainate injections, particularly in the CA3 pyramidal layer, less in the dentate gyrus-CA4, and less in CA1. Clq immunoreactivity was detected in CA1 pyramidal neurons and also as small punctate deposits in the CA1 region at eight and 14 days after kainate. The increase of both clusterin and ClqB messenger RNAs after kainate injections was blocked by barbiturates that prevented seizures and neurodegeneration. In primary hippocampal neuronal cultures treated with glutamate, a subpopulation of cultured neurons that survived glutamate toxicity also had parallel elevations of clusterin and ClqB messenger RNA. In conclusion, cytotoxins that target selective hippocampal neurons increase the expression of both clusterin and ClqB in vivo and in vitro. These results show that elevations of clusterin messenger RNA or protein can be dissociated from each other and from cell death. These increased messenger RNAs were associated with immunoreactive deposits that differed by cell type and intra- versus extracellular locations. These results suggest that the complement system is involved in brain responses to injury.

Animals↗
PubMed1993

TGF-beta 1 is an organizer of responses to neurodegeneration.

TGF-beta 1 mRNA and protein were recently found to increase in animal brains after experimental lesions that cause local deafferentation or neuron death. Elevations of TGF-beta 1 mRNA after lesions are prominent in microglia but are also observed in neurons and astrocytes. Moreover, TGF-beta 1 mRNA autoinduces its own mRNA in the brain. These responses provide models for studying the increases of TGF-beta 1 protein observed in beta A/amyloid-containing extracellular plaques of Alzheimer's disease (AD) and Down's syndrome (DS) and in brain cells of AIDS victims. Involvement of TGF-beta 1 in these human brain disorders is discussed in relation to the potent effects of TGF-beta 1 on wound healing and inflammatory responses in peripheral tissues. We hypothesize that TGF-beta 1 and possibly other TGF-beta peptides have organizing roles in responses to neurodegeneration and brain injury that are similar to those observed in non-neural tissues. Work from many laboratories has shown that activities of TGF-beta peptides on brain cells include chemotaxis, modification of extracellular matrix, and regulation of cytoskeletal gene expression and of neurotrophins. Similar activities of the TGF-beta's are well established in other tissues.

Animals↗
PubMed1993

TGF-beta 1 mRNA increases in macrophage/microglial cells of the hippocampus in response to deafferentation and kainic acid-induced neurodegeneration.

This study examined TGF-beta 1 mRNA levels and cellular localization in the F344 rat hippocampus following deafferentation or kainic acid (KA)-induced neurodegeneration. By RNA solution hybridization, TGF-beta 1 transcripts were at low prevalence in intact adult rat hippocampus (0.02 pg/microgram total RNA). Four days after unilateral entorhinal cortex lesioning (ECL), TGF-beta 1 mRNA increased threefold in the ipsilateral hippocampus. This increase was localized to the outer molecular layer of the dentate gyrus, where gliosis, synapse loss, and synaptic reorganization occur. TGF-beta 1 mRNA also increased in the hippocampus after KA-induced limbic seizures, particularly in the areas of the hippocampus undergoing neurodegeneration. Microglia [OX-42 immunoreactive (IR) cells] responded to these two lesions with distinct morphological changes. Combined immunocytochemistry-in situ hybridization showed that TGF-beta 1 mRNA was localized to reactive microglia (OX-42-IR, with blunt processes), but not to resting ramified microglia (OX-42-IR, with numerous fine processes) or to astrocytes (GFAP-IR). After ECL, round macrophage-like cells (OX-42-IR with TGF-beta 1 mRNA) were seen at the wound site. Thus, brain macrophage/microglial cells produce TGF-beta 1 mRNA in the hippocampus in response to deafferentation and neurodegeneration.

Afferent Pathways↗
PubMed1993

Astrocytic messenger RNA responses to striatal deafferentation in male rat.

This investigation describes the schedule and regional distribution of astrocytic responses in striatum following deafferentation by unilateral frontal cortex ablation. In the ipsilateral deafferented striatum, glial fibrillary acidic protein and clusterin (sulfated glycoprotein-2) messengerRNA showed peak elevations by 10 days postlesioning (Northern blots). Vimentin messengerRNA responded faster, with a transient elevation by three days postlesioning. The messengerRNA for glial fibrillary acidic protein, clusterin and vimentin returned toward control levels by 27 days postlesioning. However, the neuronal marker growth-associated protein messengerRNA, was decreased at all postlesion times. By in situ hybridization, the increased glial fibrillary acidic protein messengerRNA and clusterin messengerRNA signals were localized mainly to the dorsal half of the ipsilateral deafferented striatum and followed the same schedule as found by Northern blots. Glial fibrillary acidic protein messengerRNA was widely diffused in the dorsal striatum and was excluded from fascicles of the internal capsule; a similar distribution was found for glial fibrillary acidic protein-immunopositive astrocytes. While clusterin messengerRNA signal showed a distinct clustering, its immunoreactivity appeared as deposits in the deafferented striatal neuropil; Western blots confirmed the immunocytochemical results. By in situ hybridization, vimentin messengerRNA was mostly localized to the cortical wound cavity dorsal to the deafferented striatum and overlapped the distribution of vimentin-immunopositive cells. These findings suggest a coordination of striatal astrocytic messengerRNA responses with the degeneration of corticostriatal afferents. We also compared these same parameters with those from published reports on the hippocampus after deafferenting lesions. Certain astrocyte molecular responses to deafferentation are detected about five days earlier in the hippocampus than in the striatum. This different schedule in response to decortication may pertain to differences in synaptic remodeling in the hippocampus vs striatum.

Animals↗
PubMed1993

Transforming growth factor beta 1 and fibronectin messenger RNA in rat brain: responses to injury and cell-type localization.

Transforming growth factor-beta 1 rapidly increases in adult rat brain in response to experimental lesions. This study characterized the schedule of changes, regional distribution, and cellular localization of striatal transforming growth factor-beta 1 messenger RNA and fibronectin messenger RNA following partial striatal deafferentation by frontal cortex ablation. Frontal cortex ablation induced striatal transforming growth factor-beta 1 messenger RNA elevations that coincided temporally and overlapped anatomically with the course of degeneration of cortico-striatal afferent fibers. Within three days post-lesioning, transforming growth factor-beta 1 messenger RNA was localized at the cortical wound. By 10 days, the anatomical site of transforming growth factor-beta 1 messenger RNA expression shifted to the dorsal half of the deafferented striatum and co-localized with OX-42+ immunostained microglia-macrophage at the site of degenerating afferent terminals. Similarly, fibronectin messenger RNA also shifted from the cortical wound to the deafferented striatum by 10 days post-lesioning. Fibronectin messenger RNA was localized to glial fibrillary acidic protein+ immunostained astrocytes surrounding degenerating corticostriatal afferents. Infusion of transforming growth factor-beta 1 peptide elevated striatal and cortical fibronectin messenger RNA. These findings suggest that microglia-macrophage associated with degenerating afferent fibres can upregulate transforming growth factor-beta 1 messenger RNA and may influence fibronectin messenger RNA synthesis in reactive astrocytes. This study suggests that transforming growth factor-beta 1 has a role in controlling extracellular matrix synthesis following brain injury, which is analogous to that in peripheral wound healing.

Animals↗
PubMed1992

Complement C1qB and C4 mRNAs responses to lesioning in rat brain.

These data show the presence of mRNAs for two complement components (C) in the adult rat brain and describe their responses to experimental lesions. Cortical deafferentation caused elevations in striatal C1qB and C4 mRNAs that coincided temporally and overlapped anatomically with the course of degeneration of corticostriatal afferent fibers. By in situ hybridization, C1qB mRNA in the lesioned striatum was colocalized to cells immunoreactive for CR3, a complement receptor found on microglia-macrophages. The mRNA for SGP-2, a putative C inhibitor in rat, showed parallel changes. Similarly, in hippocampus and other brain regions, kainic acid lesions increased C1qB mRNA. The data suggest that microglia-macrophages and possibly other cells in rat brain rapidly up-regulate C-mRNAs in response to deafferentation and local neuron injury. These experimental responses provide models to analyze changes in C components during Alzheimer's disease and other chronic neurodegenerative conditions.

Animals↗
PubMed1992

Amyloid precursor protein mRNA encoding the Kunitz protease inhibitor domain is increased by kainic acid-induced seizures in rat hippocampus.

A 168-nucleotide exon, found in alternatively spliced amyloid precursor protein (APP) mRNAs, encodes a Kunitz protease inhibitor (KPI) domain. Kainic acid (ip) caused a selective increase of KPI mRNA in rat hippocampus. By in situ hybridization, KPI mRNA was induced in the neuronal layers of the hippocampus 11-12 h after the onset of kainate-induced seizures. The kainate-induced elevation of the KPI-containing APP-770 mRNA was blocked by pretreatment with the anticonvulsant pentobarbital. These data suggest that kainate-induced seizures cause alterations in APP RNA stability and/or processing in rat hippocampal neurons.

Amino Acid Sequence↗
PubMed1992

Slow changes of tyrosine hydroxylase gene expression in dopaminergic brain neurons after neurotoxin lesioning: a model for neuron aging.

Slow neuron regression develops during the adult phase of life in select brain systems of mammals. We describe a model in adult rats that resolves several phases in a slow atrophic process that differentially influences levels of mRNA and protein for tyrosine hydroxylase (TH). Responses of striatal dopaminergic markers to 6-hydroxydopamine (6-OHDA) lesions in rats indicated that the striatal terminals maintained TH protein, despite greater than 3-fold loss of TH mRNA in the substantia nigra pars compacta (SNC) cell bodies whose axons project to the striatum. The loss of TH mRNA/cell was progressive up to 9 months, whereas SNC cell body shrinkage stabilized by 3 months post-lesioning. Consideration of possible mechanisms in protein turnover motivated a search for PEST motifs in the TH of rats and other vertebrates that could be a point of regulation by altering the rate of TH protein turnover.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Regionally specific and rapid increases in brain-derived neurotrophic factor messenger RNA in the adult rat brain following seizures induced by systemic administration of kainic acid.

In situ hybridization techniques were used to analyse the spatiotemporal pattern of brain-derived neurotrophic factor messenger RNA elevation associated with kainic acid-induced seizure activity in the rat. Pronounced increases in hippocampal brain-derived neurotrophic factor messenger RNA levels were observed as early as 30 min following the onset of behavioral seizures. The greatest increase (10-fold) occurred in the dentate granule cell layer, while pyramidal layers CA1, CA3, and CA4 exhibited increases of two- to six-fold. Peak elevation of brain-derived neurotrophic factor messenger RNA in CA1 hippocampal region was evident at 4 h in CA3, and in the dentate granule layer at 30 min postseizure. Elevations persisted in the dentate and hilar regions to four days, while the increases in CA1 and CA3 returned to control levels by 16 h following seizure. Significant increases in brain-derived neurotrophic factor messenger RNA were also observed in the superficial layers of cortex (II and III) and in the piriform cortex which reached peak elevations by 8 h. No detectable changes were observed in the dorsomedial thalamus. Although histologically defined pyramidal and granule cell layers displayed relatively uniform increases in brain-derived neurotrophic factor messenger RNA in response to kainate, a closer examination of the labeling patterns using emulsion autoradiography revealed discrete areas of high grain densities overlapping uniform, moderate hybridization densities in the dentate granule cell layer and CA3, suggesting that the capacity to upregulate brain-derived neurotrophic factor messenger RNA in these regions may differ among individual neurons. In conclusion, our studies revealed that brain-derived neurotrophic factor messenger RNA induction in response to systemic kainate administration differs in hippocampal and cortical areas, in magnitude, time of onset and duration. The observed temperospatial pattern does not correspond in a simple way to increases in metabolic or electrical activity associated with seizures or neuronal vulnerability coincident with the seizures.

Animals↗
PubMed1992

Decortication and striatal mRNA: increases of mRNA for fibronectin, but not of NCAM or alpha-1 tubulin.

Ipsilateral frontal cortex lesions damaged the corticostriatal input. Northern hybridization analysis showed increases in fibronectin (FN) mRNA, but not changes in mRNA for neural cell adhesion molecule (NCAM), neuro-filament-68 (NF-68) or alpha-tubulin (alpha-1T) 72 h post-lesion. In situ hybridization resolved a different spatial-temporal distribution. The superficial cell layer beneath the wound cavity showed transient elevations of FN mRNA that peaked at 72 h post-lesion. However, in the ipsilateral striatum, FN mRNA was maximal at later times than in the wound cavity, at 240 h post-lesion. Changes in NCAM and alpha-tubulin mRNAs in response to decortication occur only around the wound cavity but not in the deafferentated striatum. The different time courses of mRNA revealed by Northern blot analysis and in situ hybridization are most probably due to contamination of the ipsilateral striatum at dissection with superficial tissue adjacent to the wound cavity. These results suggest that cellular responses to ipsilateral decortication consist of two phases: (i) a wound healing process; and (ii) striatal responses to deafferentation.

Animals↗
PubMed1991

Striatal responses to decortication. I. Dopaminergic and astrocytic activities.

Unilateral ablation of the frontal cortex induced 30%-50% decrease of dopamine (DA) concentration in the ipsilateral striatum at 10 and 27 days after lesioning. There were increased ratios of dihydroxyphenylacetic acid (DOPAC): DA and homovanillic acid (HVA): DA by 20%-60% at 10 days post-lesioning, which suggest compensatory increases of DA metabolism. While no change in total striatal tyrosine hydroxylase (TH) polypeptide concentration was found at any post-lesion time, TH catalytic activity was decreased slightly (-25%) at 10 days. Among individual rats, at 3, 10 and 27 days post-lesioning, striatal DA concentration was inversely related to striatal glial fibrillary acidic protein (GFAP) concentration, a marker of astrocytic activity. The loss of DA was observed whether or not DA was normalized to striatal protein, which suggests that DA loss cannot be simply attributed to increased astrocytic proteins. These data suggest reciprocal relationships between the extent of astrocytic reactions after cortical deafferentation and striatal DA loss, which could involve local remodelling without primary damage to the nigro-striatal terminals.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

Sulfated glycoprotein-2 (SGP-2) mRNA is expressed in rat striatal astrocytes following ibotenic acid lesions.

A combination of in situ hybridization and immunocytochemistry (ICC) was used to identify the cells that contained mRNA for sulfated glycoprotein-2 (SGP-2) in adult male rats after striatal ibotenic acid (IA) lesioning. Astrocytic responses were monitored by ICC for glial fibrillary acidic protein (GFAP). IA lesioning that caused death of striatal neurons also stimulated astrocytic responses as monitored by GFAP and SGP-2. The SGP-2 immunoreactivity showed punctate deposits in the lesioned striatum without any apparent cellular localization. By in situ hybridization combined with ICC, SGP-2 mRNA was localized in astrocytes that were GFAP-immunopositive. These data suggest that reactive astrocytes may express SGP-2 which may be eventually secreted.

Animals↗