Neuroprotective effect of cannabidiol, a non-psychoactive component from Cannabis sativa, on beta-amyloid-induced toxicity in PC12 cells

Abstract Alzheimer's disease is widely held to be associated with oxidative stress due, in part, to the membrane action of beta-amyloid peptide aggregates. Here, we studied the effect of cannabidiol, a major non-psychoactive component of the marijuana plant (Cannabis sativa) on beta-amyloid peptide-induced toxicity in cultured rat pheocromocytoma PC12 cells. Following exposure of cells to beta-amyloid peptide (1 micro g/mL), a marked reduction in cell survival was observed. This effect was associated with increased reactive oxygen species (ROS) production and lipid peroxidation, as well as caspase 3 (a key enzyme in the apoptosis cell-signalling cascade) appearance, DNA fragmentation and increased intracellular calcium. Treatment of the cells with cannabidiol (10(-7)-10(-4)m) prior to beta-amyloid peptide exposure significantly elevated cell survival while it decreased ROS production, lipid peroxidation, caspase 3 levels, DNA fragmentation and intracellular calcium. Our results indicate that cannabidiol exerts a combination of neuroprotective, anti-oxidative and anti-apoptotic effects against beta-amyloid peptide toxicity, and that inhibition of caspase 3 appearance from its inactive precursor, pro-caspase 3, by cannabidiol is involved in the signalling pathway for this neuroprotection.     

The genus Smittium (Trichomycetes, Harpellales) in the Iberian Peninsula

A study of larval Diptera (Chironomidae, Culicidae and Simuliidae) from Spain has been carried out to fulfill a catalogue of species of the genus Smittium (Harpellales: Legeriomycetaceae) present within these hosts. Among the reported taxa, eight are new species: Smittium brevisporum, S. bulbosporo-phorus, S. gracilis, S. hecatei, S. heterosporum, S. inex-pectans, S. prostratum and S. pseudodimorphum. We also report six previously described species, which are new for the Iberian Peninsula: S. alpinum, S. dipterorum, S. megazygosporum, S. pusillum, S. typhellum and S. fecundum. Three other species (S. simulii, S. culicis and S. culisetae) previously were reported from Spain. In two of them (S. fecundum and S. culicis), we describe for the first time the presence of zygospores. Some of the included species have been artificially cultured as well as ultrastructurally studied using scanning electron microscopy (SEM), with the purpose of observing the surface of both trichospores and the trichospore collar and the morphology of the trichospore appendage.     

Models of optimal foraging and resource partitioning: deep corollas for long tongues

We model the optimal foraging strategies for 2 nectarivore species,differing in the length of their proboscis, that exploit thenectar provided by 2 types of flowers, differing in the depthsof their corollas. When like flowers appear in clumps, nectarivoresmust decide whether to forage at a patch of deep or shallowflowers. If nectarivores forage optimally, at least one flowertype will be used by a single nectarivore species. Long-tonguedforagers will normally visit deep flowers and short-tonguedforagers shallow flowers, although extreme asymmetries in metaboliccosts may lead to the opposite arrangement. When deep and shallowflowers are randomly interspersed, nectarivores must decide,on encounter with a flower, whether to collect its nectar orcontinue searching. At low nectarivore densities, the optimalstrategy involves exploiting every encountered flower; however,as nectarivore densities increase and resources become scarce,long-tongued individuals should start concentrating on deepflowers and short-tongued individuals on shallow flowers. Therefore,regardless of the spatial distribution of flowers, corolla depthcan determine which nectarivore species exploit the nectar fromeach flower type in a given community. It follows that corollaelongation can evolve as a means to keep nectar thieves at bayif short-tongued visitors are less efficient pollinators thanlong-tongued visitors.     

Certainly can't live without this: SIRT6

Cellular metabolic rates might regulate aging by impinging on genomic stability through the DNA repair pathways. A new study published in Cell (Mostoslavsky et al., 2006) reports that deficiency in one of the mammalian Sir2 homologs, SIRT6, results in genome instability through the DNA base excision repair pathway and leads to aging-associated degenerative phenotypes.     

Mutational screening of the CYP26A1 gene in patients with caudal regression syndrome

BACKGROUND: The retinoic acid (RA)-catabolizing enzyme Cyp26a1 plays an important role in protecting tailbud tissues from inappropriate exposure to RA. Cyp26a1-null animals exhibit caudal agenesis and spina bifida, imperforate anus, agenesis of the caudal portions of the digestive and urogenital tracts, and malformed lumbosacral skeletal elements. This phenotype closely resembles the most severe form of caudal agenesis in humans. In view of these findings, we investigated a potential involvement of the human CYP26A1 gene in the pathogenesis of caudal regression syndrome (CRS). METHODS: Mutational screening of 49 CRS patients and 132 controls was performed using denaturing high-performance liquid chromatography and sequencing. Differences in the genotype and allele frequency of each SNP were evaluated by chi(2) analysis. The biological significance of the intronic variants was investigated by transfection assays of mutant constructs and by analysis of the splicing patterns with RT-PCR. RESULTS: Mutational screening allowed us to identify 6 SNPs, 4 of which (447 C>G, 1134 G>A, IVS 1+10 G>C, and IVS 4+8 AG>GA) are new. In addition, we describe a novel 2-site haplotype consisting of the 2 intronic SNPs. Both single-locus and haplotype analyses revealed no association with increased risk for CRS. The consequences of the 2 intronic polymorphisms on the mRNA splicing process were also investigated. Moreover, using functional and computational methods we demonstrated that both of these intronic polymorphisms affect the intron splicing efficiency. CONCLUSIONS: Our research did not provide evidence that CYP26A1 has implications for the pathogenesis of human CRS. However, the relationship between CRS risk and the CYP26A1 genotype requires further study with a larger number of genotyped subjects.     

IL-1 beta breaks tolerance through expansion of CD25+ effector T cells

IL-1 is a key proinflammatory driver of several autoimmune diseases including juvenile inflammatory arthritis, diseases with mutations in the NALP/cryopyrin complex and Crohn's disease, and is genetically or clinically associated with many others. IL-1 is a pleiotropic proinflammatory cytokine; however the mechanisms by which increased IL-1 signaling promotes autoreactive T cell activity are not clear. Here we show that autoimmune-prone NOD and IL-1 receptor antagonist-deficient C57BL/6 mice both produce high levels of IL-1, which drives autoreactive effector cell expansion. IL-1beta drives proliferation and cytokine production by CD4(+)CD25(+)FoxP3(-) effector/memory T cells, attenuates CD4(+)CD25(+)FoxP3(+) regulatory T cell function, and allows escape of CD4(+)CD25(-) autoreactive effectors from suppression. Thus, inflammation or constitutive overexpression of IL-1beta in a genetically predisposed host can promote autoreactive effector T cell expansion and function, which attenuates the ability of regulatory T cells to maintain tolerance to self.     

Exclusive frugivory and seed dispersal of Rhamnus alaternus in the bird breeding season

We studied avian frugivory and seed dispersal in a dioecious shrub, Rhamnus alaternus, focusing on the quantitative and qualitative components of effectiveness. The study took place at three locations in the northeast of the Iberian Peninsula, and examined bird behaviour, intensity of feeding, and the consequences for seedling emergence. The coincidence between the bird breeding season and fruit ripening of R. alaternus in the absence of other ripe fruit, generates a monospecific interaction. The extant frugivorous species were mainly legitimate seed dispersers and their abundance was low. Sylvia melanocephala and S. undata were the most important at one site whereas S. atricapilla, Erithacus rubecula and Turdus merula predominated at the other two sites. Fruit handling took place directly on the branches. Bird species used microhabitats differently as first post-feeding perch, which usually was a short distance away. The low density of frugivorous birds in all localities, among others factors, resulted in satiation of the disperser community and many mature fruits unconsumed. Both adults and juveniles feed upon the plants and their foraging patterns are similar. Adults of S. melanocephala were observed to feed fruit to nestlings and consequently a second phase of dispersal potentially arises from the transport of fecal sacs. Pulp removal and passage through the digestive tract increased the probability of seedling emergence. This plant-dispersal interaction has important consequences, both positive and negative for the plant. Positively, the fruiting of R. alaternus at a time when other ripe fruits are not available avoids interspecific competition for seed dispersers. In addition, a low density of seed rain may reduce intraspecific competition. Negatively, the low density and small size of the breeding frugivorous bird community limit fruit handling and removal away from the parent plants, while the territorial behaviour of birds at that time of the year reduces the potential distances of seed dispersal.     

Norepinephrine induces calcium spikes and proinflammatory actions in human hepatic stellate cells

Catecholamines participate in the pathogenesis of portal hypertension and liver fibrosis through alpha1-adrenoceptors. However, the underlying cellular and molecular mechanisms are largely unknown. Here, we investigated the effects of norepinephrine (NE) on human hepatic stellate cells (HSC), which exert vasoactive, inflammatory, and fibrogenic actions in the injured liver. Adrenoceptor expression was assessed in human HSC by RT-PCR and immunocytochemistry. Intracellular Ca2+ concentration ([Ca2+]i) was studied in fura-2-loaded cells. Cell contraction was studied by assessing wrinkle formation and myosin light chain II (MLC II) phosphorylation. Cell proliferation and collagen-alpha1(I) expression were assessed by [3H]thymidine incorporation and quantitative PCR, respectively. NF-kappaB activation was assessed by luciferase reporter gene and p65 nuclear translocation. Chemokine secretion was assessed by ELISA. Normal human livers expressed alpha(1A)-adrenoceptors, which were markedly upregulated in livers with advanced fibrosis. Activated human HSC expressed alpha(1A)-adrenoceptors. NE induced multiple rapid [Ca2+]i oscillations (Ca2+ spikes). Prazosin (alpha1-blocker) completely prevented NE-induced Ca2+ spikes, whereas propranolol (nonspecific beta-blocker) partially attenuated this effect. NE caused phosphorylation of MLC II and cell contraction. In contrast, NE did not affect cell proliferation or collagen-alpha1(I) expression. Importantly, NE stimulated the secretion of inflammatory chemokines (RANTES and interleukin-8) in a dose-dependent manner. Prazosin blocked NE-induced chemokine secretion. NE stimulated NF-kappaB activation. BAY 11-7082, a specific NF-kappaB inhibitor, blocked NE-induced chemokine secretion. We conclude that NE stimulates NF-kappaB and induces cell contraction and proinflammatory effects in human HSC. Catecholamines may participate in the pathogenesis of portal hypertension and liver fibrosis by targeting HSC.     

TRPV1+ sensory neurons control beta cell stress and islet inflammation in autoimmune diabetes

In type 1 diabetes, T cell-mediated death of pancreatic beta cells produces insulin deficiency. However, what attracts or restricts broadly autoreactive lymphocyte pools to the pancreas remains unclear. We report that TRPV1(+) pancreatic sensory neurons control islet inflammation and insulin resistance. Eliminating these neurons in diabetes-prone NOD mice prevents insulitis and diabetes, despite systemic persistence of pathogenic T cell pools. Insulin resistance and beta cell stress of prediabetic NOD mice are prevented when TRPV1(+) neurons are eliminated. TRPV1(NOD), localized to the Idd4.1 diabetes-risk locus, is a hypofunctional mutant, mediating depressed neurogenic inflammation. Delivering the neuropeptide substance P by intra-arterial injection into the NOD pancreas reverses abnormal insulin resistance, insulitis, and diabetes for weeks. Concordantly, insulin sensitivity is enhanced in trpv1(-/-) mice, whereas insulitis/diabetes-resistant NODxB6Idd4-congenic mice, carrying wild-type TRPV1, show restored TRPV1 function and insulin sensitivity. Our data uncover a fundamental role for insulin-responsive TRPV1(+) sensory neurons in beta cell function and diabetes pathoetiology.