Personality and melanin-based colouration traits in barn owls, tawny owl and kestrels

Individuals need to adapt to their local environment in order to survive. When selection pressures differ in local populations, polymorphism can evolve. Colour polymorphism is one of the most obvious polymorphisms since it is readily observable. Different sources of colouration exist, but melanin-based colouration is one of the most common in birds. The melanocortin system produces this colouration and because the melanocortin system has pleiotropic effects on behavioural and physiological traits, it is a good candidate to be an underlying mechanism to explain the maintenance of colour polymorphism. In this thesis I studied three different raptors which all display melanin-based colouration; barn owls (Tyto alba), tawny owls (Strix aluco) and Eurasian kestrels (Falco tinnunculus). The main question was if there was a relationship between melanin-based colouration and individual behavioural differences. The underlying hypothesis is that colour could be a signal of certain adaptive traits. Our goal was to find evolutionary explanations for the persistence of colour polymorphism. I found that nestling kestrels and barn owls differ in anti-predatory behaviour, with respect to their melanic colouration (chapters 1 and 2). Darker individuals show less reaction to human handling, but in kestrels aggression and colouration are related in opposite ways than in barn owls. More reddish barn owls travel greater distances in natal dispersal and this behaviour is repeatable between parents and same sex offspring (chapter 3). Dark reddish tawny owls defend their nests more intensely against intruders and appear to suffer less from nest predation (chapter 4). Finally I show that polymorphism in the Melanocortin 1 receptor gene (MC1R), which is strongly correlated with reddish colouration in the barn owl, is related to natal dispersal distance, providing a first indication for a genetic basis of the relation between this behaviour and colouration (chapter 5). My results demonstrate a clear link between melanin-based colouration and animal personality traits. I demonstrated this relation in three different species, which shows there is most likely a general underlying mechanism responsible. Different predation pressures might have shaped the reactions to predation, but also differences in sex-related colouration. Male-like and female-like colouration might signal more or less aggressive behaviour. Fluctuating environmental conditions might cause different individual strategies to produce equal reproductive success. The melanocortin system with its pleiotropic effects might be an underlying mechanism, as suggested by the results from the genetic polymorphism, the similar results found in these three species and by the similar relations reported in other species. This thesis demonstrates that colouration and individual differences are correlated and it provides the first glimpse of an underlying system. We can now conduct a more directed search for underlying mechanisms and evolutionary explanations with the use of quantitative genetic methods.

Experimental infection of dogs with a Brazilian strain of Rickettsia rickettsii: clinical and laboratory findings

The bacterium Rickettsia rickettsii is the etiological agent of an acute, severe disease called Rocky Mountain spotted fever in the United States or Brazilian spotted fever (BSF) in Brazil. In addition to these two countries, the disease has also been reported to affect humans in Mexico, Costa Rica, Panama, Colombia and Argentina. Like humans, dogs are also susceptible to R. rickettsii infection. However, despite the wide distribution of R. rickettsii in the Western Hemisphere, reports of R. rickettsii-induced illness in dogs has been restricted to the United States. The present study evaluated the pathogenicity for dogs of a South American strain of R. rickettsii. Three groups of dogs were evaluated: group 1 (G1) was inoculated ip with R. rickettsii; group 2 (G2) was infested by R. rickettsii-infected ticks; and the control group (G3) was infested by uninfected ticks. During the study, no clinical abnormalities, Rickettsia DNA or R. rickettsii-reactive antibodies were detected in G3. In contrast, all G1 and G2 dogs developed signs of rickettsial infection, i.e., fever, lethargy, anorexia, ocular lesions, thrombocytopenia, anemia and detectable levels of Rickettsia DNA and R. rickettsii-reactive antibodies in their blood. Rickettsemia started 3-8 days after inoculation or tick infestation and lasted for 3-13 days. Our results indicate that a Brazilian strain of R. rickettsii is pathogenic for dogs, suggesting that canine clinical illness due to R. rickettsii has been unreported in Brazil and possibly in the other South American countries where BSF has been reported among humans.

Do Archaea and bacteria co-infection have a role in the pathogenesis of chronic chagasic cardiopathy?

Chronic cardiopathy (CC) in Chagas disease is a fibrotic myocarditis with C5b-9 complement deposition. Mycoplasma and Chlamydia may interfere with the complement response. Proteolytic enzymes and archaeal genes that have been described in Trypanosoma cruzi may increase its virulence. Here we tested the hypothesis that different ratios of Mycoplasma, Chlamydia and archaeal organisms, which are frequent symbionts, may be associated with chagasic clinical forms. MATERIALS AND METHODS: eight indeterminate form (IF) and 20 CC chagasic endomyocardial biopsies were submitted to in situ hybridization, electron and immunoelectron microscopy and PCR techniques for detection of Mycoplasma pneumoniae (MP), Chlamydia pneumoniae(CP), C5b-9 and archaeal-like bodies. RESULTS: MP and CP-DNA were always present at lower levels in CC than in IF (p < 0.001) and were correlated with each other only in CC. Electron microscopy revealed Mycoplasma, Chlamydia and two types of archaeal-like bodies. One had electron dense lipid content (EDL) and was mainly present in IF. The other had electron lucent content (ELC) and was mainly present in CC. In this group, ELC correlated negatively with the other microbes and EDL and positively with C5b-9. The CC group was positive for Archaea and T. cruzi DNA. In conclusion, different amounts of Mycoplasma, Chlamydia and archaeal organisms may be implicated in complement activation and may have a role in Chagas disease outcome.

Myxidium volitans sp. nov., a parasite of the gallbladder of the fish, Dactylopterus volitans (Teleostei: Triglidae) from the Brazilian Atlantic coast: morphology and pathology

Myxidium volitans sp. nov. (Myxozoa: Myxidiidae) parasitizing the hypertrophied green-brownish gallbladder of the teleost Dactylopterus volitans, collected in the Atlantic coast near Niterói, Brazil was described based on ultrastructural studies. The spores were fusiform, sometimes slightly crescent-shaped on average 21.7 ± 0.3 µm (mean ± standard deviation) (n = 50) long and 5.6 ± 0.4 µm (n = 30) wide. The spore wall was thin and smooth, comprising two equally-sized valves joined by a hardly visible sutural ridge. Spores containing two pyriform polar capsules (PC) (5.0 ± 0.4 × 2.3 ± 0.3 µm) (n = 30) are situated in each extremity of the spore. The PC wall was composed of hyaline layer (0.20-0.29 µm thick) and by a thin external granular layer. Each PC contains a polar filament (PF) with irregular arrangements that was projected from its apical region to the bases of PC and coiled laterally from bases to the tip of PC. Some regular striations and S-like structures in the periphery of the PFs with four-five irregular sections were observed. Based on the spore morphology, ultrastructural differences and the specificity of the host we describe this parasite as a new myxosporidian, named M. volitans sp. nov.

Molecular and immunological characterization of gluten proteins isolated from oat cultivars that differ in toxicity for celiac disease.

A strict gluten-free diet (GFD) is the only currently available therapeutic treatment for patients with celiac disease (CD). Traditionally, treatment with a GFD has excluded wheat, barley and rye, while the presence of oats is a subject of debate. The most-recent research indicates that some cultivars of oats can be a safe part of a GFD. In order to elucidate the toxicity of the prolamins from oat varieties with low, medium, and high CD toxicity, the avenin genes of these varieties were cloned and sequenced, and their expression quantified throughout the grain development. At the protein level, we have accomplished an exhaustive characterization and quantification of avenins by RP-HPLC and an analysis of immunogenicity of peptides present in prolamins of different oat cultivars. Avenin sequences were classified into three different groups, which have homology with S-rich prolamins of Triticeae. Avenin proteins presented a lower proline content than that of wheat gliadin; this may contribute to the low toxicity shown by oat avenins. The expression of avenin genes throughout the development stages has shown a pattern similar to that of prolamins of wheat and barley. RP-HPLC chromatograms showed protein peaks in the alcohol-soluble and reduced-soluble fractions. Therefore, oat grains had both monomeric and polymeric avenins, termed in this paper gliadin- and glutenin-like avenins. We found a direct correlation between the immunogenicity of the different oat varieties and the presence of the specific peptides with a higher/lower potential immunotoxicity. The specific peptides from the oat variety with the highest toxicity have shown a higher potential immunotoxicity. These results suggest that there is wide range of variation of potential immunotoxicity of oat cultivars that could be due to differences in the degree of immunogenicity in their sequences.

Expression of non-TLR pattern recognition receptors in the spleen of BALB/c mice infected with Plasmodium yoelii and Plasmodium chabaudi chabaudi AS

The spleen plays a crucial role in the development of immunity to malaria, but the role of pattern recognition receptors (PRRs) in splenic effector cells during malaria infection is poorly understood. In the present study, we analysed the expression of selected PRRs in splenic effector cells from BALB/c mice infected with the lethal and non-lethal Plasmodium yoelii strains 17XL and 17X, respectively, and the non-lethal Plasmodium chabaudi chabaudi AS strain. The results of these experiments showed fewer significant changes in the expression of PRRs in AS-infected mice than in 17X and 17XL-infected mice. Mannose receptor C type 2 (MRC2) expression increased with parasitemia, whereas Toll-like receptors and sialoadhesin (Sn) decreased in mice infected with P. chabaudi AS. In contrast, MRC type 1 (MRC1), MRC2 and EGF-like module containing mucin-like hormone receptor-like sequence 1 (F4/80) expression decreased with parasitemia in mice infected with 17X, whereas MRC1 an MRC2 increased and F4/80 decreased in mice infected with 17XL. Furthermore, macrophage receptor with collagenous structure and CD68 declined rapidly after initial parasitemia. SIGNR1 and Sn expression demonstrated minor variations in the spleens of mice infected with either strain. Notably, macrophage scavenger receptor (Msr1) and dendritic cell-associated C-type lectin 2 expression increased at both the transcript and protein levels in 17XL-infected mice with 50% parasitemia. Furthermore, the increased lethality of 17X infection in Msr1 -/- mice demonstrated a protective role for Msr1. Our results suggest a dual role for these receptors in parasite clearance and protection in 17X infection and lethality in 17XL infection.

Coxiella burnetii, the agent of Q fever in Brazil: its hidden role in seronegative arthritis and the importance of molecular diagnosis based on the repetitive element IS1111 associated with the transposase gene

Coxiella burnetii is the agent of Q fever , an emergent worldwide zoonosis of wide clinical spectrum. Although C. burnetii infection is typically associated with acute infection, atypical pneumonia and flu-like symptoms, endocarditis, osteoarticular manifestations and severe disease are possible, especially when the patient has a suppressed immune system; however, these severe complications are typically neglected. This study reports the sequencing of the repetitive element IS1111 of the transposase gene of C. burnetii from blood and bronchoalveolar lavage (BAL) samples from a patient with severe pneumonia following methotrexate therapy, resulting in the molecular diagnosis of Q fever in a patient who had been diagnosed with active seronegative polyarthritis two years earlier. To the best of our knowledge, this represents the first documented case of the isolation of C. burnetii DNA from a BAL sample.

Equine herpesvirus-2 E10 gene product, but not its cellular homologue, activates NF-kappaB transcription factor and c-Jun N-terminal kinase.

We have previously reported on the death effector domain containing E8 gene product from equine herpesvirus-2, designated FLICE inhibitory protein (v-FLIP), and on its cellular homologue, c-FLIP, which inhibit the activation of caspase-8 by death receptors. Here we report on the structure and function of the E10 gene product of equine herpesvirus-2, designated v-CARMEN, and on its cellular homologue, c-CARMEN, which contain a caspase-recruiting domain (CARD) motif. c-CARMEN is highly homologous to the viral protein in its N-terminal CARD motif but differs in its C-terminal extension. v-CARMEN and c-CARMEN interact directly in a CARD-dependent manner yet reveal different binding specificities toward members of the tumor necrosis factor receptor-associated factor (TRAF) family. v-CARMEN binds to TRAF6 and weakly to TRAF3 and, upon overexpression, potently induces the c-Jun N-terminal kinase (JNK), p38, and nuclear factor (NF)-kappaB transcriptional pathways. c-CARMEN or truncated versions thereof do not appear to induce JNK and NF-kappaB activation by themselves, nor do they affect the JNK and NF-kappaB activating potential of v-CARMEN. Thus, in contrast to the cellular homologue, v-CARMEN may have additional properties in its unique C terminus that allow for an autonomous activator effect on NF-kappaB and JNK. Through activation of NF-kappaB, v-CARMEN may regulate the expression of the cellular and viral genes important for viral replication.

Metabolic and structural rearrangement during dark-induced autophagy in soybean (Glycine max L.) nodules: an electron microscopy and 31P and 13C nuclear magnetic resonance study.

The effects of dark-induced stress on the evolution of the soluble metabolites present in senescent soybean (Glycine max L.) nodules were analysed in vitro using (13)C- and (31)P-NMR spectroscopy. Sucrose and trehalose were the predominant soluble storage carbons. During dark-induced stress, a decline in sugars and some key glycolytic metabolites was observed. Whereas 84% of the sucrose disappeared, only one-half of the trehalose was utilised. This decline coincides with the depletion of Gln, Asn, Ala and with an accumulation of ureides, which reflect a huge reduction of the N(2) fixation. Concomitantly, phosphodiesters and compounds like P-choline, a good marker of membrane phospholipids hydrolysis and cell autophagy, accumulated in the nodules. An autophagic process was confirmed by the decrease in cell fatty acid content. In addition, a slight increase in unsaturated fatty acids (oleic and linoleic acids) was observed, probably as a response to peroxidation reactions. Electron microscopy analysis revealed that, despite membranes dismantling, most of the bacteroids seem to be structurally intact. Taken together, our results show that the carbohydrate starvation induced in soybean by dark stress triggers a profound metabolic and structural rearrangement in the infected cells of soybean nodule which is representative of symbiotic cessation.

Function of TRADD in tumor necrosis factor receptor 1 signaling and in TRIF-dependent inflammatory responses.

Tumor necrosis factor receptor 1 (TNFR1) and Toll-like receptors (TLRs) regulate immune and inflammatory responses. Here we show that the TNFR1-associated death domain protein (TRADD) is critical in TNFR1, TLR3 and TLR4 signaling. TRADD deficiency abrogated TNF-induced apoptosis, prevented recruitment of the ubiquitin ligase TRAF2 and ubiquitination of the adaptor RIP1 in the TNFR1 signaling complex, and considerably inhibited but did not completely abolish activation of the transcription factor NF-kappaB and mitogen-activated protein kinases 'downstream' of TNFR1. TRIF-dependent cytokine production induced by the synthetic double-stranded RNA poly(I:C) and lipopolysaccharide was lower in TRADD-deficient mice than in wild-type mice. Moreover, TRADD deficiency inhibited poly(I:C)-mediated RIP1 ubiquitination and activation of NF-kappaB and mitogen-activated protein kinase signaling in fibroblasts but not in bone marrow macrophages. Thus, TRADD is an essential component of TNFR1 signaling and has a critical but apparently cell type-specific function in TRIF-dependent TLR responses.

Control of pancreatic β-cell mass and function by gluco-incretin hormones : identification of novel regulatory mechanisms for the treatment of diabetes

Summary : Control of pancreatic ß-cell mass and function by gluco-incretin hormones: Identification of novel regulatory mechanisms for the treatment of diabetes The ß-cells of islets of Langerhans secrete insulin to reduce hyperglycemia. The number of pancreatic islet ß-cells and their capacity to secrete insulin is modulated in normal physiological conditions to respond to the metabolic demand of the organism. A failure of the endocrine pancreas to maintain an adequate insulin secretory capacity due to a reduced ß-cell number and function underlies the pathogenesis of both type 1 and type 2 diabetes. The molecular mechanisms controlling the glucose competence of mature ß-cells, i.e., the magnitude of their insulin secretion response to glucose, ß-cell replication, their differentiation from precursor cells and protection against apoptosis are poorly understood. To investigate these mechanisms, we studied the effects on ß-cells of the gluco-incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) which are secreted by intestinal endocrine cells after food intake. Besides acutely potentiating glucose-stimulated insulin secretion, these hormones induce ß-cell differentiation from precursor cells, stimulate mature ß-cell replication, and protect them against apoptosis. Therefore, understanding the molecular basis for gluco-incretin action may lead to the uncovering of novel ß-cell regulatory events with potential application for the treatment or prevention of diabetes. Islets from mice with inactivation of both GIP and GLP-1 receptor genes (dK0) present a defect in glucose-induced insulin secretion and are more sensitive than control islets to cytokine-induced apoptosis. To search for regulatory genes, that may control both glucose competence and protection against apoptosis, we performed comparative transcriptomic analysis of islets from control and dK0 mice. We found a strong down-regulation of the IGF1 Rexpression in dK0 islets. We demonstrated in both a mouse insulin-secreting cell line and primary islets, that GLP-1 stimulated IGF-1R expression and signaling. Importantly, GLP-1induced IGF-1R-dependent Akt phosphorylation required active secretion, indicating the presence of an autocrine activation mechanism. We further showed that activation of IGF-1R signaling was dependent on the secretion of IGF-2 and IGF-2 expression was regulated by nutrients. Finally, we demonstrated that the IGF-Z/IGF-1R autocrine loop was required for GLP-1 i) to protect ß-cells against cytokine-induced apoptosis, ii) to enhance their glucose competence and iii) to increase ß-cell proliferation. Résumé : Contrôle de la masse des cellules ß pancréatiques et de leur fonction par les hormones glucoincrétines: Identification de nouveaux mécanismes régulateurs pour le traitement du diabète Les cellules ß des îlots de Langerhans sécrètent l'insuline pour diminuer l'hyperglycémie. Le nombre de cellules ß et leur capacité à sécréter l'insuline sont modulés dans les conditions physiologiques normales pour répondre à la demande métabolique de l'organisme. Un échec du pancréas endocrine à maintenir sa capacité sécrétoire d'insuline dû à une diminution du nombre et de la fonction des cellules ß conduit au diabète de type 1 et de type 2. Les mécanismes moléculaires contrôlant la compétence au glucose des cellules ß matures, tels que, l'augmentation de la sécrétion d'insuline en réponse au glucose, la réplication des cellules ß, leur différentiation à partir de cellules précurseurs et la protection contre l'apoptose sont encore peu connus. Afin d'examiner ces mécanismes, nous avons étudié les effets sur les cellules ß des hormones gluco-incrétines, glucose-dépendent insulinotropic polypeptide (G1P) et glucagon-like peptide-1 (GLP-1) qui sont sécrétées par les cellules endocrines de l'intestin après la prise alimentaire. En plus de potentialiser la sécrétion d'insuline induite par le glucose, ces hormones induisent la différentiation de cellules ß à partir de cellules précurseurs, stimulent leur prolifération et les protègent contre l'apoptose. Par conséquent, comprendre les mécanismes d'action des gluco-incrétines permettrait de découvrir de nouveaux processus régulant les cellules ß avec d'éventuelles applications dans le traitement ou la prévention du diabète. Les îlots de souris ayant une double inactivation des gènes pour les récepteurs du GIP et du GLP-1 (dK0) présentent un défaut de sécrétion d'insuline stimulée par le glucose et une sensibilité accrue à l'apoptose induite par les cytokines. Afin de déterminer les gènes régulés, qui pourraient contrôler à la fois la compétence au glucose et la protection contre l'apoptose, nous avons effectué une analyse comparative transcriptomique sur des îlots de souris contrôles et dKO. Nous avons constaté une forte diminution de l'expression d'IGF-1R dans les îlots dKO. Nous avons démontré, à la fois dans une lignée cellulaire murine sécrétant l'insuline et dans îlots primaires, que le GLP-1 stimulait l'expression d'IGF-1R et sa voie de signalisation. Par ailleurs, la phosphorylation d'Akt dépendante d'IGF1-R induite parle GLP-1 nécessite une sécrétion active, indiquant la présence d'un mécanisme d'activation autocrine. Nous avons ensuite montré que l'activation de la voie de signalisation d'IGF-1R était dépendante de la sécrétion d'IGF-2, dont l'expression est régulée par les nutriments. Finalement, nous avons démontré que la boucle autocrine IGF-2/IGF-1R est nécessaire pour le GLP-1 i) pour protéger les cellules ß contre l'apoptose induite par les cytokines, ii) pour améliorer la compétence au glucose et iii) pour augmenter la prolifération des cellules ß. Résumé tout public : Contrôle de la masse des cellules ß pancréatiques et de leur fonction par les hormones gluco-incrétines: Identification de nouveaux mécanismes régulateurs pour le traitement du diabète Chez les mammifères, la concentration de glucose sanguine (glycémie) est régulée et maintenue à une valeur relativement constante d'environ 5 mM. Cette régulation est principalement contrôlée par 2 hormones produites par les îlots pancréatiques de Langerhans: l'insuline sécrétée par les cellules ß et le glucagon sécrété par les cellules a. A la suite d'un repas, l'augmentation de la glycémie entraîne la sécrétion d'insuline ce qui permet le stockage du glucose dans le foie, les muscles et le tissu adipeux afin de diminuer le taux de glucose circulant. Lors d'un jeûne, la diminution de la glycémie permet la sécrétion de glucagon favorisant alors la production de glucose par le foie, normalisant ainsi la glycémie. Le nombre de cellules ß et leur capacité sécrétoire s'adaptent aux variations de la demande métabolique pour assurer une normoglycémie. Une destruction complète ou partielle des cellules ß conduit respectivement au diabète de type 1 et de type 2. Bien que l'augmentation de la glycémie soit le facteur stimulant de la sécrétion d'insuline, des hormones gluco-incrétines, principalement le GLP-1 (glucagon-like peptide-1) et le GIP (glucose-dependent insulinotropic polypeptide) sont libérées par l'intestin en réponse aux nutriments (glucose, acides gras) et agissent au niveau des cellules ß, potentialisant la sécrétion d'insuline induite par le glucose, stimulant leur prolifération, induisant la différentiation de cellules précurseurs en cellules ß matures et les protègent contre la mort cellulaire (apoptose). Afin d'étudier plus en détail ces mécanismes, nous avons généré des souris déficientes pour les récepteurs du GIP et du GLP-l. Les îlots pancréatiques de ces souris présentent un défaut de sécrétion d'insuline stimulée par le glucose et une sensibilité accrue à l'apoptose par rapport aux îlots de souris contrôles. Nous avons donc cherché les gènes régulés pas ces hormones contrôlant la sécrétion d'insuline et la protection contre l'apoptose. Nous avons constaté une forte diminution de l'expression du récepteur à l'IGF-1 (IGF-1R) dans les îlots de souris déficientes pour les récepteurs des gluco-incrétines. Nous avons démontré dans un model de cellules ß en culture et d'îlots que le GLP-1 augmentait l'expression d'IGF-1R et la sécrétion de son ligand (IGF-2) permettant l'activation de la voie de signalisation. Finalement, nous avons montré que l'activation de la boucle IGF-2/IGF-1R induite par le GLP-1 était nécessaire pour la protection contre l'apoptose, l'augmentation de la sécrétion et la prolifération des cellules ß.

Several neuronal and axonal types form long intrinsic connections in the cat primary auditory cortical field (AI).

Intrinsic connections in the cat primary auditory field (AI) as revealed by injections of Phaseolus vulgaris leucoagglutinin (PHA-L) or biocytin, had an anisotropic and patchy distribution. Neurons, labelled retrogradely with PHA-L were concentrated along a dorsoventral stripe through the injection site and rostral to it; the spread of rostrally located neurons was greater after injections into regions of low rather than high characteristic frequencies. The intensity of retrograde labelling varied from weak and granular to very strong and Golgi-like. Out of 313 Golgi like retrogradely labelled neurons 79.6% were pyramidal, 17.2% multipolar, 2.6% bipolar, and 0.6% bitufted; 13.4% were putatively inhibitory, i.e. aspiny or sparsely spiny multipolar, or bitufted. Individual anterogradely labelled intrinsic axons were reconstructed for distances of 2 to 7 mm. Five main types were distinguished on the basis of the branching pattern and the location of synaptic specialisations. Type 1 axons travelled horizontally within layers II to VI and sent collaterals at regular intervals; boutons were only present in the terminal arborizations of these collaterals. Type 2 axons also travelled horizontally within layers II to VI and had rather short and thin collateral branches; boutons or spine-like protrusions occurred in most parts of the axon. Type 3 axons travelled obliquely through the cortex and formed a single terminal arborization, the only site where boutons were found. Type 4 axons travelled for some distance in layer I; they formed a heterogeneous group as to their collaterals and synaptic specializations. Type 5 axons travelled at the interface between layer VI and the white matter; boutons en passant, spine-like protrusions, and thin short branches with boutons en passant were frequent all along their trajectory. Thus, only some axonal types sustain the patchy pattern of intrinsic connectivity, whereas others are involved in a more diffuse connectivity.

Fas-associated death domain protein (FADD) and caspase-8 mediate up-regulation of c-Fos by Fas ligand and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) via a FLICE inhibitory protein (FLIP)-regulated pathway.

Fas, a death domain-containing member of the tumor necrosis factor receptor family and its ligand FasL have been predominantly studied with respect to their capability to induce cell death. However, a few studies indicate a proliferation-inducing signaling activity of these molecules too. We describe here a novel signaling pathway of FasL and the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) that triggers transcriptional activation of the proto-oncogene c-fos, a typical target gene of mitogenic pathways. FasL- and TRAIL-mediated up-regulation of c-Fos was completely dependent on the presence of Fas-associated death domain protein (FADD) and caspase-8, but caspase activity seemed to be dispensable as a pan inhibitor of caspases had no inhibitory effect. Upon overexpression of the long splice form of cellular FADD-like interleukin-1-converting enzyme (FLICE) inhibitory protein (cFLIP) in Jurkat cells, FasL- and TRAIL-induced up-regulation of c-Fos was almost completely blocked. The short splice form of FLIP, however, showed a rather stimulatory effect on c-Fos induction. Together these data demonstrate the existence of a death receptor-induced, FADD- and caspase-8-dependent pathway leading to c-Fos induction that is inhibited by the long splice form FLIP-L.

Role of the cannabinoid system in the effects induced by nicotine on anxiety-like behaviour in mice

Rationale: Acute behavioural effects and motivational responses induced by nicotine can be modulated by the endocannabinoid system supporting the existence of a physiological interaction between these two systems. Objectives: The present study was designed to examine the possible involvement of the cannabinoid system in the anxiolytic- and anxiogenic-like responses induced by nicotine in mice. Methods: Animals were only exposed once to nicotine. The acute administration of low (0.05, sc) or high (0.8 mg/kg, sc) doses of nicotine produced opposite effects in the elevated plus-maze, i.e., anxiolytic- and anxiogenic-like responses, respectively. The effects of the pretreatment with the CB1 cannabinoid receptor antagonist, rimonabant (0.25, 0.5 and 1 mg/kg, ip), and the cannabinoid agonist, 9-tetrahydrocannabinol (0.1 mg/kg, ip), were evaluated on the anxiolytic- and anxiogenic-like responses induced by nicotine. Results: Rimonabant completely abolished nicotine-induced anxiolytic-like effects and increased the anxiogenic-like responses of nicotine, suggesting an involvement of CB1 receptors in these behavioural responses. On the other hand, 9-tetrahydrocannabinol failed to modify nicotine anxiolytic-like responses, but attenuated its anxiogenic-like effects. In addition the association of non-effective doses of 9-tetrahydrocannabinol and nicotine produced clear anxiolytic-like responses. Conclusions: These results demonstrate that the endogenous cannabinoid system is involved in the regulation of nicotine anxiety-like behaviour in mice, and provide new findings to support the use of cannabinoid antagonists in the treatment of tobacco addiction.

CB1 cannabinoid receptor modulates MDMA acute responses and reinforcement

Background: 3, 4-methylenedioxymethamphetamine (MDMA) is a popular recreational drug widely abused by young people. The endocannabinoid system is involved in the addictive processes induced by different drugs of abuse. However, the role of this system in the pharmacological effects of MDMA has not been yet clarified.Methods: Locomotion, body temperature and anxiogenic-like responses were evaluated after acute MDMA administration in CB1 knockout mice. Additionally, MDMA rewarding properties were investigated in the place conditioning and the intravenous self-administration paradigms. Extracellular levels of DA in the nucleus accumbens were also analyzed after a single administration of MDMA by in vivo microdialysis. Results: Acute MDMA administration increased locomotor activity, body temperature and anxiogenic-like responses in wild type mice, but these responses were lower or abolished in knockout animals. MDMA produced similar conditioned place preference and increased dopamine extracellular levels in the nucleus accumbens in both genotypes. Nevertheless, CB1 knockout mice failed to self-administer MDMA at any of the doses used. Conclusions: These results indicate that CB1 cannabinoid receptors play an important role in the acute prototypical effects of MDMA, and are essential in the acquisition of an operant behavior to self-administer this drug.