Soluble factors, including TNF alpha, secreted by human T cells are both cytotoxic and cytostatic for medulloblastoma cells

We studied the effect of the treatment of a medulloblastoma cell line by human T cells derived soluble factors. Medulloblastoma is one of the more common aggressive solid neoplasms in children for which there is no adequate therapy. Cell lines established from such tumours may be helpful to test the effect of various molecules on cell proliferation. Previous studies have suggested that T cell-derived factors may be toxic for the medulloblastoma cell line Dev. Cytokines were thought to mediate this effect. In this paper, we described changes in morphology, survival and cell cycle induced in Dev cells cocultured with human T cell lines chronically infected with a retrovirus (HTLV-I) and known to secrete high level of cytokines TNF alpha, IL1alpha and IL6. Such cocultures resulted in the death of a part of Dev cells and in decreased proliferation of surviving cells, associated with morphological changes and increase in vimentin expression. Treatment with conditioned medium from infected Dev cells, containing virus induced cytokines, triggered the same effect. Reduction of these effects by TNF alpha deprivation of conditioned medium suggested that this cytokine may be implicated. Direct treatment of Dev cells with recombinant cytokines indicated that TNF alpha, but not IL1 or IL6, is associated with Dev cell alterations. TNF alpha was shown to induce the death of Dev cells by an apoptotic pathway. Furthermore, TNF alpha had a bimodal effect on the cell cycle of surviving Dev cells. These differential effects of such cytokines on medulloblastoma cells could be therefore of interest for immunotherapy of these tumours.

Retroviral vectors for the expression of two genes in human multipotent neural precursors and their differentiated neuronal and glial progeny

Retroviral vectors allow stable integration of exogenous DNA into genomic DNA and therefore gene transmission to progeny. Multipotent neural precursors and immortal cell lines prepared from them have been demonstrated to integrate into either adult or developing brain in a nontumorigenic, functional manner, without interfering with normal neurobiological processes. These cells thus appear to provide a Trojan horse ideally adapted to directing the expression of transgenes appropriately in a host brain. Here we investigated and optimized the transduction capacity of MuLV-based retroviral vectors in which internal ribosomal entry segments (IRESs) drive coexpression of two heterologous gene products from a single bicistronic mRNA in a human multipotent neural precursor cell line, "Dev," which was prepared from a medulloblastoma. For this, two vectors containing two different combinations of three viral IRESs were used and the capacity of different pseudotyped vectors to permit an efficient and stable transduction of Dev cells was compared. Our data show that (1) the best recombinant vectors for Dev cell transduction are those pseudotyped with the 10A1 MuLV envelope (40% of transduction) and (2) the initial coexpression of neo and plap, observed in transduced undifferentiated Dev cells, is maintained in differentiated Dev cells with a neuronal or glial phenotype. Therefore, these double-IRES vectors may provide an efficient means of transducing the coexpression of two proteins in undifferentiated human neural precursors that is maintained in their differentiated progeny. These data suggest that the double-IRES strategy is well adapted to potential therapeutic situations when coexpression of two different transgenes may be required in the same cell.

Human primitive neuroectodermal tumour cells behave as multipotent neural precursors in response to FGF2

Primitive neuroectodermal tumours (PNET) are thought to derive from the malignant transformation of pluripotent CNS precursors although this hypothesis has yet to be tested in vitro. Here we show that cells of a human PNET cell line 'Dev' express functional fibroblast growth factor (FGF) receptors (FGFR) and respond to FGF2 as multipotent CNS precursors. FGF2 induces tyrosine phosphorylation of FGFR-1 and FGFR-2 and many cellular substrates including MAP kinases and stimulates proliferation. Cells detach from plastic substrates and proliferate to form large clusters of undifferentiated cells. After adhesion to polylysine, cells migrate out from the clusters and differentiate. The majority of differentiated cells express neuronal phenotypes but distinct subpopulations express oligodendrocytic and astrocytic markers. Mature neural differentiation markers are not otherwise detected in Dev cells in defined medium. Identical results were obtained with 12 monoclonal subclones as well as the parent cell line, confirming that Dev cells are multipotent. This extends evidence that multipotent CNS precursors are the cellular substrate from which certain PNET develop and shows that FGF2 is a potent proliferation and differentiation inducer for PNET cells in vitro, suggesting that FGF2 may also modulate the evolution of PNET in vivo. Finally our results suggest that PNET cell lines may provide models to elucidate the biology of human multipotent CNS precursors.

Serotoninergic control of the activity and expression of glial GABA transporters in the rat cerebellum

Gamma-Aminobutyric acid (GABA) transporters (GAT-1, GAT-2, and GAT-3) play a key role in the termination of GABA transmission and the regulation of extracellular GABA concentrations. In the present study, pharmacological, cellular, and molecular analyses provide evidence for a modulatory effect of serotoninergic neurons on the activity and expression of glial GABA transporters in the rat cerebellum. Degeneration of serotoninergic neurons after in vivo 5,7-dihydroxytryptamine (5,7-DHT) treatment resulted in a significant decrease (-27%) in [3H]-GABA uptake into cerebellar punches. This decrease probably occurred via inhibition of GAT-2 or GAT-3 activity since their inhibitor, beta-alanine, induced a decrease in [3H]-GABA uptake in punches of sham-operated rats (-28%), but not in punches of 5,7-DHT-treated rats, demonstrating that serotonin terminal degeneration had already impaired the beta-alanine-sensitive component of GABA uptake. In contrast, nipecotic acid, a preferential inhibitor of GAT-1, induced comparable decreases in [3H]-GABA uptake comparable in punches of 5,7-DHT (-38%) versus sham-operated rats (-37%). The decreases in GAT-1 (-16%), GAT-2 (-34%), and GAT-3 (-32%) mRNA levels after 5,7-DHT treatment (detected by quantitative RT-PCR) are consistent with a serotoninergic control of GABA transporter expression at the transcriptional level. The cellular distribution of GAT-2 and GAT-3 mRNA, shown by in situ hybridization, suggests a glial localization of these transporters in the cerebellum and demonstrated a preferential anatomical localization of GAT-2 mRNA in the granular layer and of GAT-3 mRNA in the deep cerebellar nuclei. A direct serotoninergic control of glial GABA uptake was further demonstrated in vitro since serotonin stimulated the activity and mRNA expression of the GABA transporters in cerebellar astrocyte cultures.

POP66, a paraneoplastic encephalomyelitis-related antigen, is a marker of adult oligodendrocytes

Paraneoplastic neurological diseases are disorders of the central nervous system, associated with neuronal degeneration in patients with systemic cancer, but are not a direct result of the tumor mass or metastasis. The biological diagnosis of these syndromes is based mainly on the detection, in the patient's serum and cerebrospinal fluid, of autoantibodies (anti-Hu, anti-Yo, for example), suggesting an autoimmune origin for these disorders. Recently, we described novel autoantibodies (anti-CV2 autoantibodies) associated with paraneoplastic neurological disease, which recognize a 66 kDa brain protein. We named this antigen POP66, for Paraneoplastic Oligodendrocyte Protein of 66 kDa molecular weight, as in the adult human, rat, and mouse brain, it is specifically expressed by a subpopulation of oligodendrocytes. This cell type specificity was surprising given the fact that the cell loss in the brains of patients with anti-CV2 autoantibodies is neuronal. POP66-expressing oligodendrocytes are distributed along the longitudinal axis of the brain according to an increasing rostro-caudal gradient, with no positive oligodendrocytes being found in the forebrain and the greatest number found in the spinal cord. In addition, in transverse sections of the spinal cord, the distribution of POP66-positive oligodendrocytes follows an increasing dorsal-to-ventral gradient, which may be related to different oligodendrocyte precursor pools. In addition, the neuronal loss without demyelination seen in the brains of patients with anti-CV2 autoantibodies, together with the exclusive oligodendroglial expression of POP66 in the adult brain, raises the question of the possible involvement of POP66 in neuron survival via neuron/oligodendrocyte interactions.

Glutamate-modulated production of GABA in immortalized astrocytes transduced by a glutamic acid decarboxylase-expressing retrovirus

Replication-defective Moloney murine leukemia virus expressing the GAD67 gene under the control of the GFAP promoter was produced using selected clones of a fibroblast-packaging cell line. A spontaneously immortalized astrocyte cell line was infected with this virus and cellular clones expressing GAD67 selected. Astrocyte and fibroblast clones expressed functional GAD (detected by glutamic acid decarboxylation), but only fibroblasts were able to also produce GABA in the extracellular medium. When exposed to 200 microM glutamate, despite an observed difference in the rates of glutamate accumulation in control and GAD67-expressing astrocytes, similar proportions of glutamate taken up were detected. In GAD67-expressing astrocytes, the glutamate was mainly converted into GABA, suggesting GAD transgene activity to be dominant over other glutamate metabolic pathways, such as glutamine synthetase and glutamate dehydrogenase. Moreover, rapid GABA release into the cell medium was also observed, suggesting the involvement of reverse GABA transporters. The use of the GFAP promoter might be able to take advantage of its activation in response to factors inducing reactive gliosis observed in pathological insults. GAD67-expressing astrocytes might therefore be used for future grafting in pathological situations in which an excess of glutamate results in neuronal dysfunction or cell death.

Tryptophan hydroxylase mRNAs analysis by RT-PCR: preliminary report on the effect of noradrenaline in the neonatal rat pineal gland

The levels of mRNAs coding for tryptophan hydroxylase (TPOH), the first enzyme in melatonin synthesis, have been investigated by quantitative reverse transcription of RNA, followed by polymerase chain reaction (RT-PCR), after stimulation of neonatal pineal organ cultures with Noradrenaline (NA). TPOH mRNAs were specifically amplified from various adult tissues, namely the pineal gland, raphe, retina, and kidney, but not the lung. PCR signals for TPOH were detected in the neonatal pineal gland in the absence of stimulation. Stimulation of neonatal pineal organ culture with 0.1 microM NA resulted in a significant increase (x2.5) in expression of TPOH mRNAs, whereas higher doses (1 and 10 microM) had no effect. All concentrations of NA enhanced melatonin secretion. Our results suggest that the level of TPOH mRNAs can be controlled by NA and that this effect might be implicated in the gene level regulation of the daily enzyme rhythm in the rat pineal gland.

Changes in astrocytic glutamate catabolism enzymes following neuronal degeneration or viral infection

Functional changes in astrocytes are among the earliest cellular responses to a wide variety of insults to the central nervous system (CNS). Such responses significantly contribute to maintaining CNS homeostasis. In this context, by controlling energetic metabolism and overall excitability of the CNS, the modulation of glutamate uptake and catabolism in astrocytes is crucial. Here, we review specific modulations of the expression of glutamate catabolizing enzymes (glutamate dehydrogenase and glutamine synthetase) in response to CNS insults (degeneration of serotonergic neurons or viral infection by a human retrovirus, HTLV-I). The cellular and molecular mechanisms involved in the control of the glutamate catabolism are discussed in relation to neurological disorders.

Transgene expression of plasmid DNAs directed by viral or neural promoters in the rat brain

The use of circular plasmid DNA may be an alternative method for the transfer of genes into the brain and is presumably easier to use than other vectors, such as viruses or genetically engineered cells. The effectiveness and time course of the expression of a reporter gene (LacZ), directed by appropriate promoters, was studied after stereotaxic injection of naked plasmid DNAs into the rat thalamus, cortex or cerebellum. The efficiencies of three different promoters, the human cytomegalovirus (HCMV) promoter and the glial fibrillary acidic protein (GFAP) and neuron-specific enolase (NSE) promoters (specific for astrocytes and neurons, respectively) to drive reporter gene expression were compared. Efficient expression of beta-gal, detected by X-gal histochemistry or immunochemistry, required the use of 50 microg of DNA and was detectable as early as 48 h after injection. Expression increased until day 8, remained stable until day 15, then decreased over 2 months, probably as a result of non-specific degradation of the plasmids within the transfected cells rather than from specific down-regulation of promoters, as the same time course was seen with all three promoters tested. Depending on the promoter used (GFAP or NSE), LacZ was preferentially expressed within astrocytes or neurons, respectively. The GFAP promoter was found to be as efficient as the HCMV promoter, possibly due to the reactive gliosis induced by plasmid injection which is known to up-regulate GFAP expression.

Inhibition of tyrosine hydroxylase expression within the substantia nigra of mice infected with canine distemper virus

Experimental infection of mouse brain with a neuroadapted strain of canine distemper virus (CDV) leads to early acute encephalitis, followed by late neurological diseases such as motor pathologies (paralysis and turning behavior) or obesity syndrome. We have previously shown that, during the early stage of infection, CDV replicates transiently in selective structures of the brain including the substantia nigra, a structure known to play a critical role in motor control. In this study we demonstrate that CDV replication in the substantia nigra induces an early decrease in transcript level of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis. The CDV infection of neuroblastoma cell culture, constitutively expressing TH, results in downregulation of TH transcription in the absence of cell death. In the few surviving mice with motor deficiencies, a pronounced decrease in TH expression is associated with a loss of dopaminergic cell bodies in the absence of any viral transcripts and proteins, suggesting that the initial CDV infection was sufficient to trigger irreversible neurodegenerative processes.

Molecular cloning of a new unc-33-like cDNA from rat brain and its relation to paraneoplastic neurological syndromes

Anti-CV2-autoantibodies from patients with paraneoplastic neurological syndromes were used to purify protein(s) related to this disease. A novel cDNA, c-22, was obtained by PCR with primers based on amino-acid sequence of peptides obtained from this protein and rat brain cDNA as template. The deduced amino-acid sequence of c-22 shows homology to the Unc-33 gene from C. elegans in which mutations lead to defects in neuritic outgrowth and axonal guidance and cause uncoordinated movements of the nematode. Several consensus sites for putative protein kinase C phosphorylation were found, suggesting that the c-22 gene product may be a phosphoprotein. Northern hybridizations show that the apparently unique 3.8-kb mRNA of c-22 is present in rat brain tissue and its expression is developmentally regulated: the levels of C-22 mRNA, detectable in brain at embryonic day 17 (E17), increase up to post-natal day 7 (P7) and decline rapidly to an almost undetectable level in adult.

Specific potentialities of embryonic rat serotonergic neurons to innervate different periventricular targets in the adult brain

During the development of the central nervous system, neurons are directed by both genetic and environmental factors to differentiate and form connections with their targets. We took advantage of the abundant homogeneous serotonergic innervations of the ependyma forming the supra- and subependymal plexuses to investigate possible commitment of embryonic neurons to innervate specific targets during axogenesis in the rat. The origin of the supraependymal innervation was determined by retrograde transport of cholera toxin (CT) from the ventricles. The supraependymal plexuses of the fourth ventricle mainly originated from neurons in the dorsocaudal region of the raphe dorsalis (DRN), while the rostral DRN and raphe centralis (CRN) contained perikarya projecting into the third ventricle. This suggested the existence, along the rostrocaudal axis of the raphe, of different neuronal subsets able to form distinct supraependymal plexuses in the third or fourth ventricle. To determine whether serotonergic neurons were committed to innervate specific areas of the ependyma, different embryonic metencephalic segments (rostral, median, or caudal) from 14-day-old rat embryos were independently grafted into the third or fourth ventricle of an adult brain in which the serotonergic neurons had been previously destroyed. The distinctive patterns of re-innervation specific to each of grafted segments indicate that subsets of embryonic serotonergic neurons are indeed committed to innervate certain restricted ependymal areas of the adult brain, presumably in response to different neurotropic and/or neurotrophic cues.

Cytokines secreted by glial cells infected with HTLV-I modulate the expression of matrix metalloproteinases (MMPs) and their natural inhibitor (TIMPs): possible involvement in neurodegenerative processes

Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) known to be fundamental to normal physiological processes, also contribute to several pathologies associated with uncontrolled tissue degradation. Recent observation of MMPs and TIMPs in the central nervous system suggest they could play a role in the neurodegenerative process following viral infection. We have investigated the expression of these molecules in human and rat glial cells infected with retrovirus HTLV-I, the causative agent of HTLV-I associated myelopathy (TSP/HAM). We report that cytokines secreted by infected glial cells are responsible for the increased expression of MMP-3, MMP-9 and TIMP-3, while MMP-2, TIMP-1 and TIMP-2 remained stable. The role of dysregulated MMPs/TIMPs in the pathogenesis of TSP/HAM may be related to various functions of these proteases, namely degradation of the blood-brain barrier, myelin constituent cleavage and conversion of inactive TNF-precursor to active form.

Imbalanced expression of glutamate-glutamine cycle enzymes induced by human T-cell lymphotropic virus type 1 Tax protein in cultivated astrocytes

Human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent involved in the disease HTLV-1-associated myelopathy, or tropical spastic paraparesis (HAM/TSP). The pathogenesis of HAM/TSP is poorly understood, but it is probable that viral infection has an indirect, deleterious effect on neural function. In this regard, dysfunction in astrocytes may be severely detrimental, as they supply neurons with metabolic precursors, control the extracellular levels of ion and excitatory neurotransmitters, and are electrically coupled with oligodendrocytes. In a model in vitro, we demonstrate that HTLV-1 induces an imbalance in the expression of two astrocyte enzymes, at both the transcriptional and translational levels. In both human astrocyte precursors and rat glial cells, the levels of expression of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) were increased and decreased, respectively, after coculture with HTLV-1 T cells. The enhancement of GS expression may result from the action of the protein Tax, which is demonstrated to transactivate the GS gene promoter, while the decreased expression of GDH seems to reflect some compensatory mechanism in response to GS induction. GS and GDH are involved in the conversion of glutamate into glutamine or alpha-ketoglutarate, which then acts as a precursor for glutamatergic and gamma-aminobutyric acid (GABA)-ergic neurons. Metabolism in astrocytes altered by Tax protein may lead to deleterious effects if it modifies the extracellular levels of glutamine, glutamate, and GABA and thus modulates neuronal excitability and osmotic equilibrium in the central nervous system of HTLV-1-infected patients.

GABA uptake and phenotypic characteristics of the subcommissural ependymocytes of the semi-desertic rodent, Meriones shawi: correlation with serotoninergic innervation

Many studies have emphasized species differences in the serotoninergic innervation and phenotypic characteristics of the subcommissural organ in mammals. The post-natal distribution patterns of serotonin-containing fibers, the onset of gamma-aminobutyric acid uptake, and glial markers have been studied in the subcommissural organ of the semi-desertic rodent, Meriones shawi, by using immunohistochemical and autoradiographic techniques. Abundant serotoninergic fibers can be observed in the subcommissural organ of the newborn Meriones, some of them running among the ependymocytes and reaching the apical part of this organ. During the first 2 post-natal weeks of development, the subcommissural organ displays a progressive increase of serotonin fiber density throughout the organ, including the apical part. The existence of a dense serotonin-containing basal plexus concomitantly with a high apical innervation in this organ is a specific characteristic of Meriones. Ependymocytes of this organ have the ability to take up gamma-aminobutyric acid at birth. This uptake decreases and completely disappears from the 2nd week. The reappearance of gamma-aminobutyric acid accumulation in ependymocytes of the adult subcommissural organ after destruction of the serotonin innervation by a neurotoxin (5-7 dihydroxytryptamine) suggests an inhibitory effect of the serotonin innervation on this accumulation. Immunohistochemical studies of the phenotype of the ependymocytes with respect to glial markers during ontogeny show the transitory expression of glial fibrillary acidic protein, the presence of vimentin and the absence of S100 protein expression. No correlation has been found between the serotonin innervation and the expression of the glial markers.

Cytokines are increased in the rat hippocampus after serotonergic neuron degeneration and upregulate the expression of GDH, an enzyme involved in glutamate detoxification

The degeneration of serotonergic neurons increases the expression of glutamate dehydrogenase (GDH) in hippocampal astrocytes. This process was demonstrated to be independent of the serotonin level. At the same time, upregulation of tumor necrosis factor (TNF) alpha and interleukin (IL)-1 alpha mRNA were observed, whereas levels of transforming growth factor (TGF) beta 1 mRNA remained unchanged. The level of GDH mRNA was increased in primary cultures of hippocampal astrocytes treated with TNF alpha and IL-1 alpha suggesting that these cytokines act on the GDH metabolism. TNF alpha and IL-1 alpha induced an increase in GDH promoter activity in C8S (an astrocytic cell line) transfected with constructs containing 5' flanking genomic sequences of GDH driving the expression of a reporter gene. These observations suggest that cytokines may be signals that upregulate the astrocytic GDH expression in response to the degeneration of serotonergic terminals in the hippocampus.

Antibodies to a subpopulation of glial cells and a 66 kDa developmental protein in patients with paraneoplastic neurological syndromes

BACKGROUND

Paraneoplastic neurological syndromes (PNS) are inflammatory disorders that probably depend on autoimmune processes. Several autoantibodies (anti-Hu, anti-Ri, and anti-Yo) have been characterised in PNS and proved to be helpful in the diagnosis. However, these do not account for all the cases and the possibility that other types of antibodies could be detected was investigated.

METHODS AND RESULTS

Of 45 patients with PNS whose serum was probed on paraformaldehyde fixed rat brain sections, 11 patients were identified whose serum samples recognised a cytoplasmic antigen in a subpopulation of glial cells in the white matter of adult rat brainstem, cerebellum, and spinal cord that were double labelled with a monoclonal antibody specific for oligodendrocytes. All serum samples reacted with a 66 kDa protein of newborn rat brain on western blot analysis. These antibodies were designated as anti-CV2 antibodies. Only one of the 11 patients had one of the well characterised autoantibodies (anti-Hu). Five patients had cerebellar degeneration, three had limbic encephalitis, two had encephalomyelitis, and one had Lambert-Eaton myasthenic syndrome. The tumours were small cell lung cancer or undifferentiated mediastinal cancer in seven patients, uterine sarcoma in two, and malignant thymoma in two. Among 1061 control serum samples, only two patients had anti-CV2 antibodies. One had small cell lung cancer and the other malignant thymoma.

CONCLUSIONS

The detection of anti-CV2 antibodies in patients with neurological disorders should be considered as an indication of the presence of an occult cancer.

Nycthemeral expression of tryptophan hydroxylase mRNAs in the rat pineal gland

The expression of mRNAs coding for tryptophan hydroxylase (TPOH), the first enzyme involved in melatonin synthesis, has been studied in the rat adult pineal gland at four different circadian time points by in-situ hybridization using an oligonucleotide probe. TPOH mRNAs were detected at all chosen time-points. The lowest level was seen at 13:00 h. Quantification of the hybridization signals demonstrated a significant increase in expression (+16.5%) between 13:00 h and 19:30 h, with the values at 23:30 h and 09:00 h being similar to that of 19:30 h. These results coincide with the nycthemeral rhythm of TPOH activity. Day/night rhythms in the rat pineal gland are controlled by noradrenaline release at lights-off, which results in an increase in cAMP levels and in gene activation. This study suggests that the TPOH gene might be one such gene whose activation is stimulated in this way.

Extracellular matrix-remodeling metalloproteinases and infection of the central nervous system with retrovirus human T-lymphotropic virus type I (HTLV-I)

Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) are involved in physiological processes and contribute to the phenotype of several pathological conditions associated with uncontrolled tissue degradation. In the central nervous system (CNS), MMPs are thought to play a role in cell migration and synaptic plasticity. We have investigated the expression, regulation and possible role of MMPs and TIMPs during infection of glial cells with human T-lymphotropic virus type I (HTLV-I), the causative agent of a progressive chronic myelopathy, TSP/HAM. The major alteration consists in a high increase in MMP-9 secretion and TIMP-2 mRNA expression. Cytokines TNF alpha and IL1 alpha, induced in glial cells during HTLV-I infection, promote the upregulation of MMP-9. In addition, cerebrospinal fluid from TSP/HAM patients contain high MMP-9 level. The exact role of dysregulated MMPs/TIMPs in the pathogenesis of TSP/HAM is not known; however, functions of these proteases in physiological processes should provide valuable clues. MMPs can affect the blood-brain barrier and the intercellular connectivity by degrading the extracellular matrix of endothelial and neural cells. They can be involved in autoimmunity by generating preformed specific peptides from myelin components. Finally, they can direct and prolong TNF activity in the CNS by converting its inactive precursor into active molecules.

Glucocorticoid upregulation of glutamate dehydrogenase gene expression in vitro in astrocytes

Glutamate, the major excitatory neurotransmitter, is preferentially catabolized in astrocytes by glutamate dehydrogenase (GDH). Treatment of an astrocytic cell line with hydrocortisone (10(-5) M) resulted in increased expression of GDH mRNA. Transfection of the cells with truncated parts of the GDH promoter showed that genomic responsive elements activated by hydrocortisone are localized in the -557/+1 region of the promoter. This control of GDH expression by glucocorticoids may be involved in their protective effect against glutamate excitotoxicity.

Selective induction of cytokines in mouse brain infected with canine distemper virus: structural, cellular and temporal expression

We have previously shown that, in experimentally inoculated mice, canine distemper virus (CDV), a neurotropic virus, selectively infects certain brain structures (hypothalamus, hippocampus, monoaminergic nuclei, etc). Here we demonstrate that tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta and IL-6 transcripts are selectively expressed in these CDV-targeted structures, except in the dentate gyrus, where cytokines are induced without prior CDV replication. The time-course of TNF-alpha expression vs. viral replication in the hypothalamus was different from that in hippocampus. In addition, we show that a substantial number of neurons express TNF-alpha and IL-6. These findings provide new insights into the possible participation of cytokines in the neurological disorders triggered by CDV infection.

Association between intra-abdominal fat and hypertension in android obese diabetics

We have examined the relationship between visceral fat measured by MRI on a transverse cut through L3, insulin sensitivity assessed by the somatostatin-insulin-glucose test, and arterial blood pressure in 18 obese (11 women and 7 men), non insulin-dependent diabetic patients with android body fat distribution. Extent of visceral fat and insulin sensitivity were not different between women and men. Insulin sensitivity correlated significantly with visceral fat (r = -0.54, p < 0.05) but not with body mass index, L3 subcutaneous fat, or with waist to hip circumference ratio. Moreover, insulin sensitivity was lower in hypertensive compared to normotensive diabetic patients (Steady State Plasma Glucose = 18.8 +/- 3 mmol/l vs 15.1 +/- 3.3 mmol/l p < 0.05) and L3 visceral fat was greater (238 +/- 70 cm2 vs 106 +/- 36 cm2 p < 0.01), although there were no differences in body mass index, L3 subcutaneous fat, waist to hip circumference ratio or age. In conclusion, visceral fat quantity correlates with insulin sensitivity and blood pressure in android obese diabetics with similar morphotype (comparable body mass index and waist to hip circumference ratio).

Rapid in situ hybridization using digoxigenin probe and microwave oven

In situ hybridization has been developed with probes labelled with a non-radioactive nucleotide, especially digoxigenin-coupled nucleotides. These non-radioactive probes significantly reduce safety problems and experimentation time. In this paper, we have studied by in situ hybridization the messenger RNA (mRNA) of the neuropeptide pro-opiomelanocortin (POMC), in the rat pituitary gland using digoxigenin labelled oligonucleotide and a microwave oven. Our protocol permitted us to visualize POMC mRNA in all cells of the intermediate lobe and a few corticotroph cells in the anterior lobe, as it has been already demonstrated and to complete the experiment in less than 24 hrs.