EuroDia: a beta-cell gene expression resource.

Type 2 diabetes mellitus (T2DM) is a major disease affecting nearly 280 million people worldwide. Whilst the pathophysiological mechanisms leading to disease are poorly understood, dysfunction of the insulin-producing pancreatic beta-cells is key event for disease development. Monitoring the gene expression profiles of pancreatic beta-cells under several genetic or chemical perturbations has shed light on genes and pathways involved in T2DM. The EuroDia database has been established to build a unique collection of gene expression measurements performed on beta-cells of three organisms, namely human, mouse and rat. The Gene Expression Data Analysis Interface (GEDAI) has been developed to support this database. The quality of each dataset is assessed by a series of quality control procedures to detect putative hybridization outliers. The system integrates a web interface to several standard analysis functions from R/Bioconductor to identify differentially expressed genes and pathways. It also allows the combination of multiple experiments performed on different array platforms of the same technology. The design of this system enables each user to rapidly design a custom analysis pipeline and thus produce their own list of genes and pathways. Raw and normalized data can be downloaded for each experiment. The flexible engine of this database (GEDAI) is currently used to handle gene expression data from several laboratory-run projects dealing with different organisms and platforms. Database URL: http://eurodia.vital-it.ch.

Distinct expression pattern of microtubule-associated protein-2 in human oligodendrogliomas and glial precursor cells.

Microtubule-associated protein 2 (MAP2), a protein linked to the neuronal cytoskeleton in the mature central nervous system (CNS), has recently been identified in glial precursors indicating a potential role during glial development. In the present study, we systematically analyzed the expression of MAP2 in a series of 237 human neuroepithelial tumors including paraffin-embedded specimens and tumor tissue microarrays from oligodendrogliomas, mixed gliomas, astrocytomas, glioblastomas, ependymomas, as well as dysembryoplastic neuroepithelial tumors (DNT), and central neurocytomas. In addition, MAP2-immunoreactive precursor cells were studied in the developing human brain. Three monoclonal antibodies generated against MAP2A-B or MAP2A-D isoforms were used. Variable immunoreactivity for MAP2 could be observed in all gliomas with the exception of ependymomas. Oligodendrogliomas exhibited a consistently strong and distinct pattern of expression characterized by perinuclear cytoplasmic staining without significant process labeling. Tumor cells with immunoreactive bi- or multi-polar processes were mostly encountered in astroglial neoplasms, whereas the small cell component in neurocytomas and DNT was not labeled. These features render MAP2 immunoreactivity a helpful diagnostic tool for the distinction of oligodendrogliomas and other neuroepithelial neoplasms. RT-PCR, Western blot analysis, and in situ hybridization confirmed the expression of MAP2A-C (including the novel MAP2+ 13 transcript) in both oligodendrogliomas and astrocytomas. Double fluorescent laser scanning microscopy showed that GFAP and MAP2 labeled different tumor cell populations. In embryonic human brains, MAP2-immunoreactive glial precursor cells were identified within the subventricular or intermediate zones. These precursors exhibit morphology closely resembling the immunolabeled neoplastic cells observed in glial tumors. Our findings demonstrate MAP2 expression in astrocytic and oligodendroglial neoplasms. The distinct pattern of immunoreactivity in oligodendrogliomas may be useful as a diagnostic tool. Since MAP2 expression occurs transiently in migrating immature glial cells, our findings are in line with an assumed origin of diffuse gliomas from glial precursors.

Differential expression of peroxisome proliferator-activated receptors (PPARs): tissue distribution of PPAR-alpha, -beta, and -gamma in the adult rat.

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily that can be activated by various xenobiotics and natural fatty acids. These transcription factors primarily regulate genes involved in lipid metabolism and also play a role in adipocyte differentiation. We present the expression patterns of the PPAR subtypes in the adult rat, determined by in situ hybridization using specific probes for PPAR-alpha, -beta and -gamma, and by immunohistochemistry using a polyclonal antibody that recognizes the three rat PPAR subtypes. In numerous cell types from either ectodermal, mesodermal, or endodermal origin, PPARs are coexpressed, with relative levels varying between them from one cell type to the other. PPAR-alpha is highly expressed in hepatocytes, cardiomyocytes, enterocytes, and the proximal tubule cells of kidney. PPAR-beta is expressed ubiquitously and often at higher levels than PPAR-alpha and -gamma. PPAR-gamma is expressed predominantly in adipose tissue and the immune system. Our results suggest new potential directions to investigate the functions of the different PPAR subtypes.

Aggregate cultures of foetal rat liver cells: development and maintenance of liver gene expression.

Rotation-mediated aggregate cultures of foetal rat liver cells were prepared and grown in a chemically defined medium. Their capacity for cellular organisation and maturation was studied over a culture period of 3 wk by using both morphologic and biochemical criteria. It was found that within each aggregate, distinct liver cell types were present and attained their normal, differentiated phenotype. Parenchymal cells formed small acini with a central lumen. Within the first 2 wk in culture, albumin and ferritin mRNA levels were maintained, while the alpha-fetoprotein mRNA levels decreased, and tyrosine aminotransferase (TAT) gene expression increased. No significant response to glucocorticoids was observed in early cultures, whereas after 3 wk a marked increase in TAT mRNA levels was elicited by dexamethasone and glucagon (additive stimulatory effects). The results show that foetal rat liver cells cultured in a chemically defined medium are able to rearrange themselves into histotypic structures, and display a developmental pattern of gene expression comparable to that of perinatal rat liver in vivo. This culture system offers therefore a useful model to study the development and function of liver cells.

Detection of promoter activity by flow cytometric analysis of GFP reporter expression.

Low efficiency of transfection is often the limiting factor for acquiring conclusive data in reporter assays. It is especially difficult to efficiently transfect and characterize promoters in primary human cells. To overcome this problem we have developed a system in which reporter gene expression is quantified by flow cytometry. In this system, green fluorescent protein (GFP) reporter constructs are co-transfected with a reference plasmid that codes for the mouse cell surface antigen Thy-1.1 and serves to determine transfection efficiency. Comparison of mean GFP expression of the total transfected cell population with the activity of an analogous luciferase reporter showed that the sensitivity of the two reporter systems is similar. However, because GFP expression can be analyzed at the single-cell level and in the same cells the expression of the reference plasmid can be monitored by two-color fluorescence, the GFP reporter system is in fact more sensitive, particularly in cells which can only be transfected with a low efficiency.

H-2D ligand expression by Ly49A+ natural killer (NK) cells precludes ligand uptake from environmental cells: implications for NK cell function.

To study the adaptation of natural killer (NK) cells to their major histocompatibility complex (MHC) class I environment we have established a novel mouse model with mosaic expression of H-2D(d) using a Cre/loxP system. In these mice, we noticed that NK cells expressing the inhibitory receptor for D(d), Ly49A, were specifically underrepresented among cells with low D(d) levels. That was due to the acquisition of D(d) molecules by the Ly49A+ NK cells that have lost their D(d) transgene. The uptake of H-2D molecules via the Ly49A receptor was restricted to strong ligands of Ly49A. Surprisingly, when Ly49A+ NK cells were D(d+), uptake of the alternative ligand D(k) was not detectable. Similarly, one anti-Ly49A mAb (A1) bound inefficiently when Ly49A was expressed on D(d+) NK cells. Concomitantly, functional assays demonstrated a reduced capacity of Ly49A to inhibit H-2(b)D(d) as compared with H-2(b) NK cells, rendering Ly49A+ NK cells in D(d+) mice particularly reactive. Minor reductions of D(d) levels and/or increases of activating ligands on environmental cells may thus suffice to abrogate Ly49A-mediated NK cell inhibition. The mechanistic explanation for all these phenomena is likely the partial masking of Ly49A by D(d) on the same cell via a lateral binding site in the H-2D(d) molecule.

Mating system and avpr1a promoter variation in primates.

It has been suggested that primate mating and social behaviours may be influenced by variation in promoter region repetitive DNA of the vasopressin receptor 1a gene (avpr1a). We show that male mating behaviour does not covary in a simple way with promoter repetitive DNA in 12 Old World primates. We found that one microsatellite (-553 bp upstream) was present in all species, irrespective of their behaviour. By contrast, two microsatellites (-3956 and -3625 bp upstream) were present only in some species, yet this variation did not correlate with behaviour. These findings agree with a recent comparative analysis of voles and show that the variation in repetitive DNA in the avpr1a promoter region does not generally explain variation in male mating behaviour. Phylogenetic analysis revealed a GAGTA motif that has been independently deleted three times and involved in another larger deletion. Importantly, the presence/absence of this GAGTA motif leads to changes in predicted transcription factor-binding sites. Given the repeated loss of this motif, we speculate that it might be of functional relevance. We suggest that such non-repetitive variation, either in indels or in sequence variation, are likely to be important in explaining interspecific variation in avpr1a expression.

Role of the hypocretin system in cocaine- and alcohol-related behaviors : evidence from hypocretin-deficient mice

RésuméL'addiction aux drogues est une maladie multifactorieile affectant toutes les strates de notre société. Cependant, la vulnérabilité à développer une addiction dépend de facteurs environnementaux, génétiques et psychosociaux. L'addiction aux drogues est décrite comme étant une maladie chronique avec un taux élevé de rechutes. Elle se caractérise par un besoin irrépressible de consommer une drogue et une augmentation progressive de la consommation en dépit des conséquences néfastes. Les mécanismes cérébraux responsables des dépendances aux drogues ne sont que partiellement élucidés, malgré une accumulation croissante d'évidences démontrant des adaptations au niveau moléculaire et cellulaire au sein des systèmes dopaminergique et glutamatergique. L'identification de nouveaux facteurs neurobiologiques responsables de la vulnérabilité aux substances d'abus est cruciale pour le développement de nouveaux traitements thérapeutiques capables d'atténuer et de soulager les symptômes liés à la dépendance aux drogues.Au cours des dernières années, de nombreuses études ont démontré qu'un nouveau circuit cérébral, le système hypocrétinergique, était impliqué dans plusieurs fonctions physiologiques, tel que l'éveil, le métabolisme énergétique, la motivation, le stress et les comportements liés aux phénomènes de récompense. Le système hypocrétinergique est composé d'environ 3000-4000 neurones issus de l'hypothalamus latéral projetant dans tout ie cerveau. Des souris transgéniques pour le gène des hypocrétines ont été générées et leur phénotype correspond à celui des animaux sauvages, excepté le fait qu'elles soient atteintes d'attaques de sommeil similaires à celles observées chez les patients narcoleptiques. H semblerait que les hypocrétines soient requises pour l'acquisition et l'expression de la dépendance aux drogues. Cependant, le mécanisme précis reste encore à être élucidé. Dans ce rapport, nous rendons compte des comportements liés aux phénomènes de récompense liés à l'alcool et à la cocaine chez les souris knock-out (KO), hétérozygotes (HET) et sauvages (WT).Nous avons, dans un premier temps, évalué l'impact d'injections répétées de cocaïne (15 mg/kg, ip) sur la sensibilisation locomotrice et sur le conditionnement place préférence. Nous avons pu observer que les souris WT, HET et KO exprimaient une sensibilisation locomotrice induite par une administration chronique de cocaïne, cependant les souris déficientes en hypocrétines démontraient une sensibilisation retardée et atténuée. Π est intéressant de mentionner que les mâles HET exprimaient une sensibilisation comportementale intermédiaire. Après normalisation des données, toutes les souris exprimaient une amplitude de sensibilisation similaire, excepté les souris mâles KO qui affichaient, le premier jour de traitement, une sensibilisation locomotrice réduite et retardée, reflétant un phénotype hypoactif plutôt qu'une altération de la réponse aux traitements chroniques de cocaïne. Contre toute attente, toutes les souris femelles exprimaient un pattern similaire de sensibilisation locomotrice à la cocaïne. Nous avons ensuite évalué l'effet d'un conditionnement comportemental à un environnement associé à des injections répétées de cocaine (15 mg / kg ip). Toutes les souris, quelque soit leur sexe ou leur génotype, ont manifesté une préférence marquée pour l'environnement apparié à la cocaïne. Après deux semaines d'abstinence à la cocaïne, les mâles et les femelles déficientes en hypocrétines n'exprimaient plus aucune préférence pour le compartiment précédemment associé à la cocaïne. Alors que les souris WT et HET maintenaient leur préférence pour le compartiment associé à la cocaïne. Pour finir, à l'aide d'un nouveau paradigme appelé IntelliCage®, nous avons pu évaluer la consommation de liquide chez les femelles WT, HET et KO. Lorsqu'il n'y avait que de l'eau disponible, nous avons observé que les femelles KO avaient tendance à moins explorer les quatre coins de la cage. Lorsque les souris étaient exposées à quatre types de solutions différentes (eau, ImM quinine ou 0.2% saccharine, alcool 8% et alcool 16%), les souris KO avaient tendance à moins consommer l'eau sucrée et les solutions alcoolisées. Cependant, après normalisation des données, aucune différence significative n'a pu être observée entre les différents génotypes, suggérant que la consommation réduite d'eau sucrée ou d'alcool peut être incombée à l'hypoactivité des souris KO.Ces résultats confirment que le comportement observé chez les souris KO serait dû à des compensations développementales, puisque la sensibilisation locomotrice et le conditionnement comportemental à la cocaïne étaient similaires aux souris HET et WT. En ce qui concerne la consommation de liquide, les souris KO avaient tendance à consommer moins d'eau sucrée et de solutions alcoolisées. Le phénotype hypoactif des souris déficientes en hypocrétine est probablement responsable de leur tendance à moins explorer leur environnement. Il reste encore à déterminer si l'expression de ce phénotype est la conséquence d'un état de vigilance amoindri ou d'une motivation diminuée à la recherche de récompense. Nos résultats suggèrent que les souris déficientes en hypocrétine affichent une motivation certaine à la recherche de récompense lorsqu'elles sont exposées à des environnements où peu d'efforts sont à fournir afin d'obtenir une récompense.AbstractDrug addiction is a multifactorial disorder affecting human beings regardless their education level, their economic status, their origin or even their gender, but the vulnerability to develop addiction depends on environmental, genetic and psychosocial dispositions. Drug addiction is defined as a chronic relapsing disorder characterized by compulsive drug seeking, with loss of control over drug intake and persistent maladaptive decision making in spite of adverse consequences. The brain mechanisms responsible for drug abuse remain partially unknown despite accumulating evidence delineating molecular and cellular adaptations within the glutamatergic and the dopaminergic systems. However, these adaptations do not fully explain the complex brain disease of drug addiction. The identification of other neurobiological factors responsible for the vulnerability to substance abuse is crucial for the development of promising therapeutic treatments able to alleviate signs of drug dependence.For the past few years, growing evidence demonstrated that a recently discovered brain circuit, the hypocretinergic system, is implicated in many physiological functions, including arousal, energy metabolism, motivation, stress and reward-related behaviors. The hypocretin system is composed of a few thousands neurons arising from the lateral hypothalamus and projecting to the entire brain. Hypocretin- deficient mice have been generated, and unexpectedly, their phenotype resembles that of wild type mice excepting sleep attacks strikingly similar to those of human narcolepsy patients. Evidence suggesting that hypocretins are required for the acquisition and the expression of drug addiction has also been reported; however the precise mechanism by which hypocretins modulate drug seeking behaviors remains a matter of debate. Here, we report alcohol and cocaine reward-related behaviors in hypocretin-deficient mice (KO), as well as heterozygous (HET) and wild type (WT) littermates.We first evaluated the impact of repeated cocaine injections (15 mg/kg, ip) on locomotor sensitization and conditioned place preference. We observed that WT, HET and KO mice exhibited behavioral sensitization following repeated cocaine administrations, but hypocretin deficient males displayed a delayed and attenuated response to chronic cocaine administrations. Interestingly, HET males exhibited an intermediate pattern of behavioral sensitization. However, after standardization of the post-injection data versus the period of habituation prior to cocaine injections, all mice displayed similar amplitudes of behavioral sensitization, except a reduced response in KO males on the first day, suggesting that the delayed and reduced cocaine-induced locomotor sensitization may reflect a hypoactive phenotype and probably not an altered response to repeated cocaine administrations. Unexpectedly, all female mice exhibited similar patterns of cocaine-induced behavioral sensitization. We then assessed the behavioral conditioning for an environment repeatedly paired with cocaine injections (15 mg/kg ip). All mice, whatever their gender or genotype, exhibited a robust preference for the environment previously paired with cocaine administrations. Noteworthy, following two weeks of cocaine abstinence, hypocretin-deficient males and females no longer exhibited any preference for the compartment previously paired with cocaine rewards whereas both WT and HET mice continued manifesting a robust preference. We finally assessed drinking behaviors in WT, HET and KO female mice using a novel paradigm, the IntelliCages®. We report here that KO females tended to less explore the four cage comers where water was easily available. When exposed to four different kinds of liquid solutions (water, ImM quinine or saccharine 0.2%, alcohol 8% and alcohol 16%), KO mice tended to less consume the sweet and the alcoholic beverages. However, after data standardization, no significant differences were noticed between genotypes suggesting that the hypoactive phenotype is most likely accountable for the trend regarding the reduced sweet or alcohol intake in KO.Taken together, the present findings confirm that the behavior seen in Hcrt KO mice likely reflects developmental compensations since only a slightly altered cocaine-induced behavioral sensitization and a normal behavioral conditioning with cocaine were observed in these mice compared to HET and WT littermates. With regards to drinking behaviors, KO mice barely displayed any behavioral changes but a trend for reducing sweet and alcoholic beverages. Overall, the most striking observation is the constant hypoactive phenotype seen in the hypocretin-deficient mice that most likely is accountable for their reduced tendency to explore the environment. Whether this hypoactive phenotype is due to a reduced alertness or reduced motivation for reward seeking remains debatable, but our findings suggest that the hypocretin-deficient mice barely display any altered motivation for reward seeking in environments where low efforts are required to access to a reward.

Angiotensinergic neurotransmission in the peripheral autonomic nervous system.

Angiotensin (Ang) II has for long been identified as a neuropeptide located within neurons and pathways of the central nervous system involved in the control of thirst and cardio-vascular homeostasis. The presence of Ang II in ganglionic neurons of celiac, dorsal root, and trigeminal ganglia has only recently been described in humans and rats. Ang II-containing fibers were also found in the mesenteric artery and the heart, together with intrinsic Ang II-containing cardiac neurons. Ganglionic neurons express angiotensinogen and co-localize it with Ang II. Its intraneuronal production as a neuropeptide appears to involve angiotensinogen processing enzymes other than renin. Immunocytochemical and gene expression data suggest that neuronal Ang II acts as a neuromodulatory peptide and co-transmitter in the peripheral autonomic, and also sensory nervous system. Neuronal Ang II probably competes with humoral Ang II for effector cell activation. Its functional role, however, still remains to be determined. Angiotensinergic neurotransmission in the autonomic nervous system is a potential new target for therapeutic interventions in many common diseases such as essential hypertension, heart failure, and cardiac arrhythmia.

Immunological system and Schistosoma mansoni: co-evolutionary immunobiology. What is the eosinophil role in parasite-host relationship?

Schistosomes, ancestors and recent species, have pervaded many hosts and several phylogenetic levels of immunity, causing an evolutionary pressure to eosinophil lineage expression and response. Schistosoma mansoni adult worms have capitalized on the apparent adversity of living within the mesenteric veins, using the dispersion of eggs and antigens to other tissues besides intestines to set a systemic activation of several haematopoietic lineages, specially eosinophils and monocytes/macrophages. This activation occurs in bone marrow, spleen, liver, lymph nodes, omental and mesenteric milky spots (activation of the old or primordial and recent or new lymphomyeloid tissue), increasing and making easy the migration of eosinophils, monocytes and other cells to the intestinal periovular granulomas. The exudative perigranulomatous stage of the periovular reaction, which present hystolitic characteristics, is then exploited by the parasites, to release the eggs into the intestinal lumen. The authors hypothesize here that eosinophils, which have a long phylogenic story, could participate in the parasite - host co-evolution, specially with S. mansoni, operating together with monocytes/ macrophages, upon parasite transmission.

The expression of nuclear 3,5,3' triiodothyronine receptors is induced in Schwann cells by nerve transection.

The effects of thyroid hormones on the nervous system are mediated by the presence of nuclear T3 receptors (NT3R). In this study, the expression of NT3R was investigated in spinal cord, dorsal root ganglia (DRG), or sciatic nerve of adult rats after immunostaining with a 2B3-NT3R monoclonal antibody which recognizes both alpha and beta types of NT3R. The specificity of this monoclonal antibody was confirmed by Western blots. The 2B3-NT3R monoclonal antibody recognized one band corresponding to a molecular weight of 57 kDa in extract of spinal cord or DRG. No staining was observed on immunoblot of intact sciatic nerve. In the spinal cord, the nuclei of the neurons and glial cells including both astrocytes and oligodendrocytes exhibited 2B3-NT3R immunoreactivity. While all the nuclei of the DRG sensory neurons expressed the NT3R, all the nuclei of the satellite and Schwann cells were devoid of any immunoreaction. In the sciatic nerve, the nuclei of the Schwann cells also lacked 2B3-NT3R-immunoreactivity. After sciatic nerve transection in vivo, Schwann cell nuclei, which never expressed NT3R in intact nerves of adult rats, displayed a clear 2B3-NT3R immunoreaction in proximal and distal stumps adjacent to the section. Double immunostaining with antibodies raised to 3-sulfogalactosylceramide or S100 confirmed that most of the NT3R containing nuclei belong to Schwann cells. In dissociated cell cultures grown in vitro from sciatic nerves, Schwann cells exhibited 2B3-NT3R immunoreactivity. These data suggest that the inhibition of NT3R expression in Schwann cells ensheathing axons in intact nerve is reversed when the axons are degenerating or lacking.(ABSTRACT TRUNCATED AT 250 WORDS)

Down-regulation of NOSII gene expression by iontophoresis of anti-sense oligonucleotide in endotoxin-induced uveitis.

Transcorneoscleral iontophoresis was used to enhance ocular penetration of a 21-bp NH(2) protected anti-NOSII oligonucleotides (ODNs) (fluorescein or infrared-41 labeled) in Lewis rats. Both histochemical localization and acrylamide sequencing gels were used. To evaluate the potential to down-regulate NOSII expression in the rat model of endotoxin-induced uveitis (EIU), anti-sense NOSII ODN, scrambled ODN or saline were iontophorezed into these animals' eyes. Iontophoresis facilitated the penetration of intact ODNs into the intraocular tissues of the rat eye and only the eyes receiving ODNs and electrical current demonstrated intact ODNs within the ocular tissues of both segments of the eye. Iontophoresis of anti-NOSII ODN significantly down-regulated the expression of NOSII expression in iris/ciliary body compared to the saline or scrambled ODN treated eyes. Nitrite production was also significantly reduced in the anti-NOSII applied eyes compared to those treated with saline. Using this system, intraocular delivery of ODNs can be significantly enhanced increasing the potential for successful gene therapy for human eye diseases.

Mls--a retrovirus exploits the immune system.

The identity of minor lymphocytes stimulating (Mls) antigens, endogenous superantigens that can activate, or induce the deletion of, large portions of the T-cell repertoire, has recently been revealed: they are encoded by mouse mammary tumor viruses (MMTV) that have integrated into the germ line as DNA proviruses. As Hans Acha-Orbea and Ed Palmer point out, Mls-mediated modulation may be only the tip of the retrovirus iceberg; already murine leukemia virus (MuLV), with similar superantigen properties, has been discovered.

The Body Action and Posture Coding System (BAP): Development and Reliability

Several methods are available for coding body movement in nonverbal behavior research, but there is no consensus on a reliable coding system that can be used for the study of emotion expression. Adopting an integrative approach, we developed a new method, the Body Action and Posture (BAP) coding system, for the time-aligned micro description of body movement on an anatomical level (different articulations of body parts), a form level (direction and orientation of movement), and a functional level (communicative and self-regulatory functions). We applied the system to a new corpus of acted emotion portrayals, examined its comprehensiveness and demonstrated intercoder reliability at three levels: a) occurrence, b) temporal precision and c) segmentation. We discuss issues for further validation and propose some research applications.

Gene expression mapping in neuropathic pain : molecular plasticity in nociceptors and superficial dorsal horn

RESUME : La douleur neuropathique est le résultat d'une lésion ou d'un dysfonctionnement du système nerveux. Les symptômes qui suivent la douleur neuropathique sont sévères et leur traitement inefficace. Une meilleure approche thérapeutique peut être proposée en se basant sur les mécanismes pathologiques de la douleur neuropathique. Lors d'une lésion périphérique une douleur neuropathique peut se développer et affecter le territoire des nerfs lésés mais aussi les territoires adjacents des nerfs non-lésés. Une hyperexcitabilité des neurones apparaît au niveau des ganglions spinaux (DRG) et de la corne dorsale (DH) de la moelle épinière. Le but de ce travail consiste à mettre en évidence les modifications moléculaires associées aux nocicepteurs lésés et non-lésés au niveau des DRG et des laminae I et II de la corne dorsale, là où l'information nociceptive est intégrée. Pour étudier les changements moléculaires liés à la douleur neuropathique nous utilisons le modèle animal d'épargne du nerf sural (spared nerve injury model, SNI) une semaine après la lésion. Pour la sélection du tissu d'intérêt nous avons employé la technique de la microdissection au laser, afin de sélectionner une sous-population spécifique de cellules (notamment les nocicepteurs lésés ou non-lésés) mais également de prélever le tissu correspondant dans les laminae superficielles. Ce travail est couplé à l'analyse à large spectre du transcriptome par puce ADN (microarray). Par ailleurs, nous avons étudié les courants électriques et les propriétés biophysiques des canaux sodiques (Na,,ls) dans les neurones lésés et non-lésés des DRG. Aussi bien dans le système nerveux périphérique, entre les neurones lésés et non-lésés, qu'au niveau central avec les aires recevant les projections des nocicepteurs lésés ou non-lésés, l'analyse du transcriptome montre des différences de profil d'expression. En effet, nous avons constaté des changements transcriptionnels importants dans les nocicepteurs lésés (1561 gènes, > 1.5x et pairwise comparaison > 77%) ainsi que dans les laminae correspondantes (618 gènes), alors que ces modifications transcriptionelles sont mineures au niveau des nocicepteurs non-lésés (60 gènes), mais important dans leurs laminae de projection (459 gènes). Au niveau des nocicepteurs, en utilisant la classification par groupes fonctionnels (Gene Ontology), nous avons observé que plusieurs processus biologiques sont modifiés. Ainsi des fonctions telles que la traduction des signaux cellulaires, l'organisation du cytosquelette ainsi que les mécanismes de réponse au stress sont affectés. Par contre dans les neurones non-lésés seuls les processus biologiques liés au métabolisme et au développement sont modifiés. Au niveau de la corne dorsale de la moelle, nous avons observé des modifications importantes des processus immuno-inflammatoires dans l'aire affectée par les nerfs lésés et des changements associés à l'organisation et la transmission synaptique au niveau de l'aire des nerfs non-lésés. L'analyse approfondie des canaux sodiques a démontré plusieurs changements d'expression, principalement dans les neurones lésés. Les analyses fonctionnelles n'indiquent aucune différence entre les densités de courant tétrodotoxine-sensible (TTX-S) dans les neurones lésés et non-lésés même si les niveaux d'expression des ARNm des sous-unités TTX-S sont modifiés dans les neurones lésés. L'inactivation basale dépendante du voltage des canaux tétrodotoxine-insensible (TTX-R) est déplacée vers des potentiels positifs dans les cellules lésées et non-lésées. En revanche la vitesse de récupération des courants TTX-S et TTX-R après inactivation est accélérée dans les neurones lésés. Ces changements pourraient être à l'origine de l'altération de l'activité électrique des neurones sensoriels dans le contexte des douleurs neuropathiques. En résumé, ces résultats suggèrent l'existence de mécanismes différenciés affectant les neurones lésés et les neurones adjacents non-lésés lors de la mise en place la douleur neuropathique. De plus, les changements centraux au niveau de la moelle épinière qui surviennent après lésion sont probablement intégrés différemment selon la perception de signaux des neurones périphériques lésés ou non-lésés. En conclusion, ces modulations complexes et distinctes sont probablement des acteurs essentiels impliqués dans la genèse et la persistance des douleurs neuropathiques. ABSTRACT : Neuropathic pain (NP) results from damage or dysfunction of the peripheral or central nervous system. Symptoms associated with NP are severe and difficult to treat. Targeting NP mechanisms and their translation into symptoms may offer a better therapeutic approach.Hyperexcitability of the peripheral and central nervous system occurs in the dorsal root ganglia (DRG) and the dorsal horn (DH) of the spinal cord. We aimed to identify transcriptional variations in injured and in adjacent non-injured nociceptors as well as in corresponding laminae I and II of DH receiving their inputs.We investigated changes one week after the injury induced by the spared nerve injury model of NP. We employed the laser capture microdissection (LCM) for the procurement of specific cell-types (enrichment in nociceptors of injured/non-injured neurons) and laminae in combination with transcriptional analysis by microarray. In addition, we studied functionál properties and currents of sodium channels (Nav1s) in injured and neighboring non-injured DRG neurons.Microarray analysis at the periphery between injured and non-injured DRG neurons and centrally between the area of central projections from injured and non-injured neurons show significant and differential expression patterns. We reported changes in injured nociceptors (1561 genes, > 1.5 fold, >77% pairwise comparison) and in corresponding DH laminae (618 genes), while less modifications occurred in non-injured nociceptors (60 genes) and in corresponding DH laminae (459 genes). At the periphery, we observed by Gene Ontology the involvement of multiple biological processes in injured neurons such as signal transduction, cytoskeleton organization or stress responses. On contrast, functional overrepresentations in non-injured neurons were noted only in metabolic or developmentally related mechanisms. At the level of superficial laminae of the dorsal horn, we reported changes of immune and inflammatory processes in injured-related DH and changes associated with synaptic organization and transmission in DH corresponding to non-injured neurons. Further transcriptional analysis of Nav1s indicated several changes in injured neurons. Functional analyses of Nav1s have established no difference in tetrodotoxin-sensitive (TTX-S) current densities in both injured and non-injured neurons, despite changes in TTX-S Nav1s subunit mRNA levels. The tetrodotoxin-resistant (TTX-R) voltage dependence of steady state inactivation was shifted to more positive potentials in both injured and non-injured neurons, and the rate of recovery from inactivation of TTX-S and TTX-R currents was accelerated in injured neurons. These changes may lead to alterations in neuronal electrogenesis. Taken together, these findings suggest different mechanisms occurring in the injured neurons and the adjacent non-injured ones. Moreover, central changes after injury are probably driven in a different manner if they receive inputs from injured or non-injured neurons. Together, these distinct and complex modulations may contribute to NP.