Peripheral-type benzodiazepine receptor ligands: mitochondrial permeability transition induction in rat cardiac tissue

Strong evidence is emerging that mitochondrial permeability transition (MPT) may be important in certain physiological conditions and, above all, in the processes of cell damage and death. Reversible MPT, triggered by inducing agents in the presence of calcium ions, has resulted in the opening of a dynamic multiprotein complex formed in the inner mitochondrial membrane and has caused large-amplitude mitochondrial swelling. In the present work, the exposure of de-energized rat cardiac mitochondria to peripheral benzodiazepine receptor (PBR) ligands (1-(2-chlorophenyl-N-methyl-1-methylpropyl)-3-isoquinolinecarboxamide (PK 11195), 7-chloro-5-(4-chlorophenyl)-1,3-dihydro-1-methyl-2H-1,4-benzodiazepin-2-one (Ro5-4864), and diazepam) produced a dose-dependent and cyclosporin A (CSP)-sensitive loss of absorbance, which was indicative of mitochondrial swelling. By contrast, the addition of a high-affinity central benzodiazepine receptor ligand (clonazepam) was ineffective, even at the highest concentration tested. The ultrastructural changes associated with swelling were similar in mitochondria exposed either to PK 11195 or to calcium. Supporting the apoptotic role of PK 11195-induced swelling, supernatants from mitochondria that had undergone permeability transition caused apoptotic changes in isolated cardiac nuclei. In addition, ultrastructural abnormalities were observed in rat cardiac tissue following in vivo PK 11195 administration, with these abnormalities being prevented by CSP co-administration. These data indicate that PBR ligands induce mitochondrial permeability transition and ultrastructural alterations in isolated cardiac mitochondria as well as in myocardiocytes, suggesting a novel strategy for studying the implication of PBR ligands as apoptosis inducers, through a probable effect on the MPT pore.

The genetic network of prototypic planarian eye regeneration is Pax6 independent

We report the presence of two Pax6-related genes, Pax6A and Pax6B, which are highly conserved in two planarian species Dugesia japonica and Girardia tigrina (Platyhelminthes, Tricladida). Pax6A is more similar to other Pax6 proteins than Pax6B, which is the most divergent Pax6 described so far. The planarian Pax6 homologs do not show any clear orthology to the Drosophila duplicated Pax6 genes, eyeless and twin of eyeless, which suggests an independent Pax6 duplication in a triclad or platyhelminth ancestor. Pax6A is expressed in the central nervous system of intact planarians, labeling a subset of cells of both cephalic ganglia and nerve cords, and is activated during cephalic regeneration. Pax6B follows a similar pattern, but shows a lower level of expression. Pax6A and Pax6B transcripts are detected in visual cells only at the ultrastructural level, probably because a limited amount of transcripts is present in these cells. Inactivation of both Pax6A and Pax6B by RNA-mediated gene interference (RNAi) inhibits neither eye regeneration nor eye maintenance, suggesting that the genetic network that controls this process is not triggered by Pax6 in planarians.

Severe ultrastructural mitochondrial changes in lymphoblasts homozygous for Huntington disease mutation

Mutated huntingtin is expressed in nervous and non nervous system included lymphoblasts. Eneregetic metabolism is impaired in Huntington's disease (HD) and other neurodegenerative diseases. Human HD lymphoblasts have provided clear-cut data on mitochondnal disruption. Here we report morphological, morphometric and membrane potential differences in mitochondria from lymphoblasts obtained from patients homozygous and heterozygous for the CAG mutation, and controls. Homozygotes, who despite a similar age at onset show a more aggressive phenotype than heterozygotes, had giant mitochondria and a reduced membrane potential. We argue that early mitochondrial impairment at basal level may affect the severity of HD progression in patients.

A3 adenosine receptors in human astrocytoma cells: agonist-mediated desensitization, internalization, and down-regulation

A(3) adenosine receptor activation has been previously demonstrated to result in both neuroprotective and neurodegenerative effects, depending upon specific pathophysiological conditions. This dual effect may depend on receptor regulation mechanisms that are able to change receptor availability and/or function. In the present study, we investigated desensitization, internalization, and down-regulation of native A(3) adenosine receptors in human astrocytoma cells after exposure to the agonist 2-chloro-N6-(3-iodobenzyl)-N-methyl-5'-carbamoyladenosine (Cl-IBMECA). Cl-IBMECA induced a concentration-dependent inhibition of adenylyl cyclase activity with an EC(50) value of 2.9 +/- 0.1 nM. The effect was suggested to be mediated by A(3) adenosine receptor subtype by the use of selective adenosine receptor antagonists. Cell treatment with pertussis toxin abolished Cl-IBMECA-mediated inhibition of adenylyl cyclase activity, evidencing an A(3) receptor coupling to inhibitory G protein. Short-term exposure to the agonist Cl-IBMECA (100 nM) caused rapid receptor desensitization, within 15 min. Agonist-induced desensitization was accompanied by receptor internalization: A(3) adenosine receptor internalized with rapid kinetics, within 30 min, after cell exposure to 100 nM Cl-IBMECA. The localization of A(3) adenosine receptors on the plasma membrane and in intracellular compartments was directly revealed by immunogold electron microscopy. After desensitization, the removal of agonist led to the restoration of A(3) adenosine receptor functioning through receptor recycling to the cell surface within 120 min. Prolonged agonist exposure (1-24 h) resulted in a marked down-regulation of A(3) adenosine receptors that reached 21.9 +/- 2.88% of control value after 24 h. After down-regulation, the recovery of receptor functioning was slow (24 h) and associated with the restoration of receptor levels close to control values. In conclusion, our results demonstrated that A(3) receptors, in astrocytoma cells, are regulated after short- and long-term agonist exposure.

Agonist-induced internalization and recycling of the human A(3) adenosine receptors: role in receptor desensitization and resensitization

A(3) adenosine receptors have been proposed to play an important role in the pathophysiology of cerebral ischemia with a regimen-dependent nature of the therapeutic effects probably related to receptor desensitization and down-regulation. Here we studied the agonist-induced internalization of human A(3) adenosine receptors in transfected Chinese hamster ovary cells, and then we evaluated the relationship between internalization and signal desensitization and resensitization. Binding of N(6)-(4-amino-3-[(125)I]iodobenzyl)adenosine-5'-N-methyluronamide to membranes from Chinese hamster ovary cells stably transfected with the human A(3) adenosine receptor showed a profile typical of these receptors in other cell lines (K:(D) = 1.3+/-0.08 nM; B(max) = 400+/-28 fmol/mg of proteins). The iodinated agonist, bound at 4 degrees C to whole transfected cells, was internalized by increasing the temperature to 37 degrees C with a rate constant of 0.04+/-0.034 min(-1). Agonist-induced internalization of A(3) adenosine receptors was directly demonstrated by immunogold electron microscopy, which revealed the localization of these receptors in plasma membranes and intracellular vesicles. Moreover, short-term exposure of these cells to the agonist caused rapid desensitization as tested in adenylyl cyclase assays. Subsequent removal of the agonist led to restoration of the receptor function and recycling of the receptors to the cell surface. The rate constant of receptor recycling was 0.02+/-0.0017 min(-1). Blockade of internalization and recycling demonstrated that internalization did not affect signal desensitization, whereas recycling of internalized receptors was implicated in the signal resensitization.

Mechanisms involved in the formation of dopamine-induced intracellular bodies within striatal neurons

Recent studies demonstrated that methamphetamine (METH) produces intracellular bodies which are reminiscent of those occurring during degenerative disorders. In vivo studies demonstrate the occurrence of these morphological alterations both in the dopamine (DA) neurons of the substantia nigra and striatal cells. These consist of neuronal bodies staining for a variety of antigens belonging to the ubiquitin-proteasome pathway. The formation of these intracellular bodies both in the substantia nigra and PC12 cells depends on the presence of endogenous DA. In the present study, we analyze the mechanisms which lead to METH-induced intracellular bodies within non-dopaminergic striatal neurons. We found that METH is no longer able to produce inclusions in vivo, in striatal cells, when striatal DA is lost. Similarly, in vitro, in primary striatal cell cultures which do not possess DA, METH administration does not produce inclusions. On the other hand, administration of DA to striatal cell cultures produces neuronal inclusions and cell death, which are both related to the inhibition of the ubiquitin-proteasome system and activation of specific-DA receptors. In line with this, we produced subcellular alterations by administering dopamine agonists.

DNA damage and ubiquitinated neuronal inclusions in the substantia nigra and striatum of mice following MDMA (ecstasy)

RATIONALE

3,4-Methylenedioxymethamphetamine (MDMA) is an amphetamine derivative, which is neurotoxic to both serotonin (5HT) and dopamine (DA) nerve terminals. Previous reports, carried out in rodents and non-human primates, demonstrated neurotoxicity to monoamine axon terminals, although no study has analyzed nigral and striatal cell bodies at the sub-cellular level.

OBJECTIVE

In this study, we examined intrinsic nigral and striatal cells, and PC12 cell cultures to evaluate whether, in mice, MDMA might affect nigral and striatal cell bodies.

METHODS

After administering MDMA, we analyzed effects induced in vivo and in vitro using high-performance liquid chromatography (HPLC) analysis, light- and electron microscopy with immunocytochemistry, and DNA comet assay.

RESULTS

We found that MDMA (5 mg/kg x4, 2 h apart), besides a decrease of nigrostriatal DA innervation and 5HT loss, produces neuronal inclusions within nigral and intrinsic striatal neurons consisting of multi-layer ubiquitin-positive whorls extending to the nucleus of the cell. These fine morphological changes are associated with clustering of heat shock protein (HSP)-70 in the nucleus, very close to chromatin filaments. In the same experimental conditions, we could detect oxidation of DNA bases followed by DNA damage. The nature of inclusions was further investigated using PC12 cell cultures.

CONCLUSIONS

The present findings lead to re-consideration of the neurotoxic consequences of MDMA administration. In fact, occurrence of ubiquitin-positive neuronal inclusions and DNA damage both in nigral and striatal cells sheds new light into the fine alterations induced by MDMA, also suggesting the involvement of nuclear and cytoplasmic components of the ubiquitin-proteasome pathway in MDMA toxicity.

Fine ultrastructure and biochemistry of PC12 cells: a comparative approach to understand neurotoxicity

The PC12 cell line is commonly used as a tool to understand the biochemical mechanisms underlying the physiology and degeneration of central dopamine neurons. Despite the broad use of this cell line, there are a number of points differing between PC12 cells and dopamine neurons in vivo which are missed out when translating in vitro data into in vivo systems. This led us to compare the PC12 cells with central dopamine neurons, aiming at those features which are predictors of in vivo physiology and degeneration of central dopamine neurons. We carried out this comparison, either in baseline conditions, following releasing or neurotoxic stimuli (i.e. acute or chronic methamphetamine), to end up with therapeutic agents which are suspected to produce neurotoxicity (l-DOPA). Although the neurotransmitter pattern of PC12 cells is close to dopamine neurons, ultrastructural morphometry demonstrates that, in baseline conditions, PC12 cells possess very low vesicles density, which parallels low catecholamine levels. Again, compartmentalization of secretory elements in PC12 cells is already pronounced in baseline conditions, while it is only slightly affected following catecholamine-releasing stimuli. This low flexibility is caused by the low ability of PC12 cells to compensate for sustained catecholamine release, due both to non-sufficient dopamine synthesis and poor dopamine storage mechanisms. This contrasts markedly with dopamine-containing neurons in vivo lending substance to opposite findings between these compartments concerning the sensitivity to a number of neurotoxins.

Compartment-dependent mitochondrial alterations in experimental ALS, the effects of mitophagy and mitochondriogenesis

Amyotrophic lateral sclerosis (ALS) is characterized by massive loss of motor neurons. Data from ALS patients and experimental models indicate that mitochondria are severely damaged within dying or spared motor neurons. Nonetheless, recent data indicate that mitochondrial preservation, although preventing motor neuron loss, fails to prolong lifespan. On the other hand, the damage to motor axons plays a pivotal role in determining both lethality and disease course. Thus, in the present article each motor neuron compartment (cell body, central, and peripheral axons) of G93A SOD-1 mice was studied concerning mitochondrial alterations as well as other intracellular structures. We could confirm the occurrence of ALS-related mitochondrial damage encompassing total swelling, matrix dilution and cristae derangement along with non-pathological variations of mitochondrial size and number. However, these alterations occur to a different extent depending on motor neuron compartment. Lithium, a well-known autophagy inducer, prevents most pathological changes. However, the efficacy of lithium varies depending on which motor neuron compartment is considered. Remarkably, some effects of lithium are also evident in wild type mice. Lithium is effective also in vitro, both in cell lines and primary cell cultures from the ventral spinal cord. In these latter cells autophagy inhibition within motor neurons in vitro reproduced ALS pathology which was reversed by lithium. Muscle and glial cells were analyzed as well. Cell pathology was mostly severe within peripheral axons and muscles of ALS mice. Remarkably, when analyzing motor axons of ALS mice a subtotal clogging of axoplasm was described for the first time, which was modified under the effects of lithium. The effects induced by lithium depend on several mechanisms such as direct mitochondrial protection, induction of mitophagy and mitochondriogenesis. In this study, mitochondriogenesis induced by lithium was confirmed in situ by a novel approach using [2-³H]-adenosine.

Nigrostriatal damage with 6-OHDA: validation of routinely applied procedures

The 6-hydroxydopamine (6-OHDA) model of Parkinson's disease in the rat represents a fundamental tool for investigating the pathophysiology of dopamine denervation. Nevertheless, 6-OHDA can induce also noradrenergic lesions; therefore desmethylimipramine (DMI) is co-administrated as a selective inhibitor of noradrenergic reuptake to protect noradrenaline (NA) fibers neighboring DA neurons and/or axons. The neurotoxin 6-OHDA must be microinfused selectively into the substantia nigra pars compacta (SNpc) or into the medial forebrain bundle (MFB) to determine the nigrostriatal lesion. However, this experimental procedure is invasive and always produces a certain amount of mechanical damage that cannot be prevented by pharmacological approaches. For this reason, we have compared two types of experimental design in which we tested critical steps of the procedures, such as the flow rate. We microinfused rats in MFB with 8 microL of total volume of a solution containing the neurotoxin (infusion rate 2 microL/min in 4 min) according with general practice, and rats microinfused with an amount of 2 microL of total volume with a slower rate (0.2 microL/min in 10 min) of infusion. Rats infused with a higher flow rate of infusion underwent striatal NA loss in spite of the administration of DMI. On the contrary, rats infused with a slow infusion flow rate had spared NA axons following DMI. These results suggest that the flow rate and the volume of 6-OHDA infusion are critical to prevent the occurrence of nonspecific mechanical effects.

Cellular biomarkers for monitoring estuarine environments: transplanted versus native mussels

In developed countries, estuarine environments are often subjected to chemical pollution, whose biological impact is profitably evaluated by the use of multi-biomarker approaches on sentinel species. In this paper, we investigate genotoxicity and lysosomal alterations in the Mediterranean mussel (Mytilus galloprovincialis), from the estuary of the River Cecina (Tuscany, Italy), selected as "pilot basin" within the Water Frame Directive (2000/60 European Community). Both native and 1 month transplanted mussels were used in order to compare these two approaches in terms of sensitiveness of specific biomarker responses. Genotoxic effects were evaluated as strand breaks, by single cell gel electrophoresis (or Comet assay), and as chromosomal alterations, by the micronucleus test in gill cells. Lysosomal alterations were assessed by the neutral red retention time (in haemocytes), lipofuscin accumulation and ultrastructure (in digestive cells). Heavy metal bioaccumulation was also analysed. Mussels from the River Cecina showed a general alteration of all the biomarkers investigated, accompanied by an elevation of tissue metal levels. However, some differences in specific responses occurred between transplanted and native mussels. Early biomarkers, such as those based on DNA and lysosomal membrane integrity, were induced at similar degree in native and transplanted mussels; while alterations resulting from cumulative events, as the increase of micronuclei frequency were much more elevated in native specimens (23.1+/-7.6) than in transplanted (9.3+/-4.7) and reference ones (5.8+/-5.2). Similarly, the comparison between lipofuscin accumulation and mean lysosomal diameter in impacted and control sites, gave significant differences exclusively with transplanted mussels. These results suggest that the parallel use of caged and native mussels in environmental biomonitoring can improve the characterization of the study area.

Dynamics of interaction and effects of microplastics on planarian tissue regeneration and cellular homeostasis

Increasing microplastics pollution of marine and terrestrial water is a concerning issue for ecosystems and human health. Nevertheless, the interaction of microplastics with freshwater biota is still a poorly explored field. In order to achieve information concerning the uptake, distribution and effect of microplastics in planarians, Dugesia japonica specimens have been fed with mixtures of food and differently shaped and sized plastic particles. Feeding activity and food intake were non-altered by the presence of high concentrations of different types of plastic particles. However, the persistence of microplastic within the planarian body was a function of size/shape, being small spheres (<10 μm in diameter) and short fibers (14 μm large and 5/6 μm length) more persisting than larger spheres and longer fibers which were eliminated almost entirely by ejection in a few hours. Transmission electron microscopy analysis demonstrated that at least part of microplastics was phagocytized by the enterocytes. Chronic exposure to small plastic did not alter the regenerative ability but caused a significant reduction of the gut epithelium thickness and lipid content of enterocytes, together with the induction of apoptotic cell death, modulation of Djgata 4/5/6 expression and reduced growth rate. The ability of microplastic to perturb planarian homeostasis is concerning being them extremely resilient against mechanical and chemical insults and suggests possible harmful effects upon other more susceptible species in freshwater ecosystems.

A subcellular analysis of genetic modulation of PINK1 on mitochondrial alterations, autophagy and cell death

Mutations in the PTEN-induced putative kinase1 (PINK1) represent the second most frequent cause of autosomal recessive Parkinson's disease. The PINK1 protein mainly localizes to mitochondria and interacts with a variety of proteins, including the pro-autophagy protein beclin1 and the ubiquitin-ligase parkin. Upon stress conditions, PINK1 is known to recruit parkin at the surface of dysfunctional mitochondria and to activate the mitophagy cascade. Aim of this study was to use a simple and highly reproducible catecholamine cell model and transmission electron microscopy to characterize whether PINK1 could affect mitochondrial homeostasis, the recruitment of specific proteins at mitochondria, mitophagy and apoptosis. Samples were analyzed both in baseline conditions and following treatment with methamphetamine (METH), a neurotoxic compound which strongly activates autophagy and produces mitochondrial damage. Our data provide robust sub-cellular evidence that the modulation of PINK1 levels dramatically affects the morphology and number of mitochondria and the amount of cell death. In particular, especially upon METH exposure, PINK1 is able to increase the total number of mitochondria, concurrently recruit beclin1, parkin and ubiquitin and enhance the clearance of damaged mitochondria. In the absence of functional PINK1 and upon autophagy stress, we observe a failure of the autophagy system at large, with marked accumulation of dysfunctional mitochondria and dramatic increase of apoptotic cell death. These findings highlight the strong neuroprotective role of PINK1 as a key protein in the surveillance and regulation of mitochondrial homeostasis.

Rapamycin promotes differentiation increasing βIII-tubulin, NeuN, and NeuroD while suppressing nestin expression in glioblastoma cells

Glioblastoma cells feature mammalian target of rapamycin (mTOR) up-regulation which relates to a variety of effects such as: lower survival, higher infiltration, high stemness and radio- and chemo-resistance. Recently, it was demonstrated that mTOR may produce a gene shift leading to altered protein expression. Therefore, in the present study we administered different doses of the mTOR inhibitor rapamycin to explore whether the transcription of specific genes are modified. By using a variety of methods we demonstrate that rapamycin stimulates gene transcription related to neuronal differentiation while inhibiting stemness related genes such as nestin. In these experimental conditions, cell phenotype shifts towards a pyramidal neuron-like shape owing long branches. Rapamycin suppressed cell migration when exposed to fetal bovine serum (FBS) while increasing the cell adhesion protein phospho-FAK (pFAK). The present study improves our awareness of basic mechanisms which relate mTOR activity to the biology of glioblastoma cells. These findings apply to a variety of effects which can be induced by mTOR regulation in the brain. In fact, the ability to promote neuronal differentiation might be viewed as a novel therapeutic pathway to approach neuronal regeneration.

The role of peripheral benzodiazepine receptors on the function and survival of isolated human pancreatic islets

OBJECTIVE

Peripheral benzodiazepine receptors (PBRs) are part of the mitochondrial permeability transition pore, and their activation may induce cell death. PBRs are expressed in human pancreatic islets, and cytokine-induced damage is accompanied by changes in their properties. We hypothesized that PBRs can have a role in human islet physiopathology, and evaluated the effects of prolonged exposure to two specific PBR ligands, PK11195 and Ro5-4864 on the function and survival of isolated human islets.

DESIGN

Isolated human islets were prepared from the pancreas of 25 multiorgan cadaveric donors and incubated for 12 h in the presence of PK11195 or Ro5-4864. Insulin secretion studies and apoptosis experiments were then performed, together with assessment of intracellular pathways involved in islet cell function and survival.

METHODS

Islets were prepared by enzymatic digestion and density gradient purification. Insulin secretion was assessed by the batch incubation method, and glucose oxidation was evaluated by the use of D-[U-(14)C]glucose. Apoptosis was studied using the TUNEL technique, ELISA methods, and electron microscopy evaluation. PCR experiments were performed by the use of specific primers.

RESULTS

Glucose-stimulated insulin release was significantly lower after exposure to PK11195 than after exposure to Ro5-4864. This was accompanied by reduced glucose oxidation and no major change of insulin or GLUT-1 mRNA expression. Apoptosis was higher in PK11195-exposed islets, and electron microscopy demonstrated the involvement of beta-cells. The apoptotic effects were prevented by bongkrekic acid and low-dose cyclosporin A, which stabilize the mitochondrial membrane, and were associated with no evident change of inducible nitric oxide synthase (iNOS), B-cell leukemia/lymphoma-2 (Bcl-2) or Bcl-2-associated X protein (Bax) expression. Caspase inhibition markedly reduced the amount of apoptosis, and the role of these proteases was confirmed by the increased activity of caspase-3 and caspase-9.

CONCLUSIONS

Prolonged binding to PBRs may cause human beta-cells functional damage and apoptosis, a phenomenon which is prevented by stabilizing the mitochondrial membrane; occurs without changes of iNOS, Bax and Bcl-2 mRNA expression; and involves caspase activation. These results suggest an involvement of PBRs in human pancreatic beta-cell function and survival.

Ultrastructural study of oogenesis in the acoel turbellarian Convoluta

An ultrastructural investigation of oogenesis has been carried out on the acoel turbellarian Convoluta psammophyla. Developing female germ cells are not contained in well delimited ovaries but are freely distributed in the parenchyma and are surrounded by narrow cytoplasmic projections of accessory-follicle cells. Oogenesis can be divided into two periods, the previtellogenic and the vitellogenic phase. In the first period the oocyte undergoes a number of cell differentiations necessary for the intense biosynthetic activity of the second period. The ample development of nucleolus, ribosomes, endoplasmic reticulum and Golgi complexes along with the appearance of large lipid droplets and clusters of electron dense granules characterize the previtellogenic phase. The formation of yolk globules is the main feature of the second period of oogenesis. It occurs by an autosynthetic mechanism involving endoplasmic reticulum and Golgi complexes, since no endocytotic activity has been detected in the developing oocyte. The electron dense granules apparently move towards the cortical ooplasm during the late vitellogenic phase and take part in egg covering formation. Hypotheses on the role of follicle cells and on the phylogenetic significance of a comparative analysis of egg inclusions with homologous structures of other Turbellaria are suggested.

Loud Noise Exposure Produces DNA, Neurotransmitter and Morphological Damage within Specific Brain Areas

Exposure to loud noise is a major environmental threat to public health. Loud noise exposure, apart from affecting the inner ear, is deleterious for cardiovascular, endocrine and nervous systems and it is associated with neuropsychiatric disorders. In this study we investigated DNA, neurotransmitters and immune-histochemical alterations induced by exposure to loud noise in three major brain areas (cerebellum, hippocampus, striatum) of Wistar rats. Rats were exposed to loud noise (100 dBA) for 12 h. The effects of noise on DNA integrity in all three brain areas were evaluated by using Comet assay. In parallel studies, brain monoamine levels and morphology of nigrostriatal pathways, hippocampus and cerebellum were analyzed at different time intervals (24 h and 7 days) after noise exposure. Loud noise produced a sudden increase in DNA damage in all the brain areas under investigation. Monoamine levels detected at 7 days following exposure were differently affected depending on the specific brain area. Namely, striatal but not hippocampal dopamine (DA) significantly decreased, whereas hippocampal and cerebellar noradrenaline (NA) was significantly reduced. This is in line with pathological findings within striatum and hippocampus consisting of a decrease in striatal tyrosine hydroxylase (TH) combined with increased Bax and glial fibrillary acidic protein (GFAP). Loud noise exposure lasting 12 h causes immediate DNA, and long-lasting neurotransmitter and immune-histochemical alterations within specific brain areas of the rat. These alterations may suggest an anatomical and functional link to explain the neurobiology of diseases which prevail in human subjects exposed to environmental noise.

Antioxidant, genotoxic and lysosomal biomarkers in the freshwater bivalve (Unio pictorum) transplanted in a metal polluted river basin

The freshwater painter's mussel (Unio pictorum) was used as sentinel species to assess the chemical disturbance in an Italian river (the river Cecina) characterized by elevated levels of trace metals of both natural and anthropogenic origin. Organisms were transplanted for 4 weeks in different locations of the river basin and the bioaccumulation of metals was integrated with a wide battery of biomarkers consisting of oxidative, genotoxic and lysosomal responses. Such parameters included the levels of individual antioxidants (catalase, glutathione-S-transferases, glutathione reductase, Se-dependent and Se-independent glutathione peroxidases, total glutathione), the total oxyradical scavenging capacity (TOSC), metallothionein-like proteins, the assessment of DNA integrity, chromosomal damages and lysosomal membrane stability. Elevated levels of several metals were measured in sediments, but the relatively low tissue concentrations suggested a moderate bioaccumulation, possibly due to a high excretion efficiency, of U. pictorum and/or to a limited bioavailability of these elements, partly deriving from erosion of bedrocks. Among antioxidant responses, those based on glutathione metabolism and the activity of catalase were mostly affected in bivalves showing a significant accumulation of arsenic, mercury and/or nickel. In these specimens, the content of glutathione and the activities of glutathione reductase and glutathione peroxidases (H2O2) were respectively 9-, 6- and 4-fold lower than in controls, while a 3-fold increase was observed for catalase. Despite some differences in the response of individual antioxidants, a significant reduction of the capability to neutralize peroxyl radicals was observed in bivalves caged in all the impacted sites of the river basin; these organisms also exhibited a significant impairment at the DNA, chromosomal and lysosomal levels. Considering the mild contamination gradient in the investigated area, the overall results suggested that some oxidative biomarkers, as well as those evaluating chromosomal and cell damages, are highly sensitive and could be profitably applied to caged painter's mussels for environmental quality assessment in freshwater.

A(2A) adenosine receptor ligands and proinflammatory cytokines induce PC 12 cell death through apoptosis

A(2A) adenosine receptor-mediated signaling affects a variety of important processes in the central nervous system both in physiological and pathological conditions, and has been indicated as possible novel therapeutic target in several nervous system diseases. In the present work, cell death induction was investigated after neuronal PC 12 cell treatment with proinflammatory cytokines and adenosine receptor ligands. Interleukin-1-beta (IL-1-beta, 500 U/mL), tumor necrosis factor-alpha (TNF-alpha, 1000 U/mL) and the non selective adenosine receptor agonist, 5'-N-ethylcarboxamidoadenosine (NECA), caused a significant reduction of cell viability with a maximal effect within 3-48 hr. Moreover, an addictive effect was detected when the cells were simultaneously treated with Interleukin-1-beta and NECA for 3 hr. To investigate the adenosine receptor subtypes involved in PC 12 cell death, the effects of several adenosine receptor agonists/antagonists were evaluated. The endogenous nucleoside, adenosine, and the selective A(2A) adenosine receptor agonist, 2-(carboxyethylphenylethylamino)adenosine-5'-carboxamide (CGS21680) reduced PC 12 cell viability. This effect was counteracted by the selective A(2A) adenosine receptor antagonist, 7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3e]-1,2,4-triazolo[1,5c]pyrimidine (SCH58261), but not by selective A(2B) adenosine receptor antagonist N-(4-acethylphenyl)-2-[4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-yl)phenoxy]acetamide (MRS1706), suggesting the specific involvement of A(2A) adenosine receptor subtype in adenosine-mediated cytotoxicity. Moreover, the selective A(1) adenosine receptor agonist, N(6)-cyclohexyladenosine (CHA), did not induce any significant effect on cell viability. By ELISA immunoassay cell death detection and transmission electron microscopy (TEM) we demonstrated that A(2A) adenosine receptor ligands and cytokines induced cell death through an apoptotic pathway. In conclusion, our results showed that A(2A) adenosine receptors are involved in the control of PC 12 cell survival/death and may contribute to modulate cellular activity in response to tissue damage associated with inflammatory mediator production.

Ultrastructural and cytochemical aspects of oogenesis in Castrada viridis (Platyhelminthes, Rhabdocoela)

The heterocellular female gonad of the typhloplanoid Castrada viridis consists of a single germarium and two rows of vitellaria. The germarium, composed of a germinative zone and a growth zone, is surrounded externally by a layer of accessory cells the function of which is hypothesized in this study. The main feature of oocyte differentiation is the synthesis of small electron-dense inclusions produced by the rough endoplasmic reticulum (R.E.R.) and Golgi complex. The electron-dense content of the egg inclusions reacts positively to the cytochemical test used to detect polyphenols and is only partially extracted following incubation in protease. The genesis, composition, and peripheral location of egg inclusions in mature oocytes suggest that they could represent residual eggshell granules. The presumed function of eggshell granules is discussed and their fine morphology is compared with that observed in other neoophoran Platyhelminthes.

Ultrastructural and cytochemical aspects of the female gonad ofGeoplana burmeisteri (Platyhelminthes, Tricladida, Terricola)

The ultrastructure of the female gonad of the land planarian Geoplana burmeisteri was investigated by means of electron microscopy and cytochemical techniques. It consists of two small germaria located ventral to the intestine and of two irregular, lateral rows of vitelline follicles, both enveloped by a tunica composed of an extracellular lamina and an inner sheath of accessory cells. Accessory cell projections completely surround developing oocytes and vitellocytes. The main feature of oocyte maturation is the appearance of chromatoid bodies and the development of the rough endoplasmic reticulum (RER) and Golgi complexes. These organelles appear to be correlated with the production of egg inclusions of medium electron density, about 1.5-1.8 microm in diameter, which remain scattered in the ooplasm of mature oocytes. On the basis of cytochemical tests demonstrating their glycoprotein composition, these inclusions were interpreted as residual yolk globules. Vitellocytes are typical secretory cells with well-developed RER and Golgi complexes that are mainly involved in the production of yolk globules and eggshell globules, respectively. Eggshell globules appear to arise from repeated coalescence of small Golgi-derived vesicles and, at an intermediate stage of maturation, show a multigranular pattern. Later, after vesicle fusion, they reach a diameter of 1.3-1.6 microm when completely mature and show a meandering/concentric pattern, as is typical of the situation seen in most Proseriata and Tricladida. The content of yolk globules is completely digested by pronase, while the content of eggshell globules is unaffected. Mature vitellocytes contain, in addition, a large quantity of glycogen and lipid droplets as further reserve material. On the basis of the ultrastructural characteristics of the female gonad described above and in relation to the current literature, we conclude that G. burmeisteri appears to be more closely related to the freshwater triclads, in particular to members of the Dugesiidae, than to the marine triclads.

Effect of itraconazole on Staphylococcus aureus biofilm and extracellular vesicles formation

Staphylococcus aureus is a leading cause of a wide range of clinical chronic infections mainly due to the establishment of a biofilm. Biofilm, a population of bacteria within a self-produced matrix of extracellular polymeric substance, decreases the susceptibility to antibiotics, immune defenses and contributes to antimicrobial resistance. To date antibiotic combination has been considered a strategy to combat S. aureus infection, but this approach does not solves the main pharmacokinetic problem caused by biofilms, consisting in insufficient drug penetration within the structure. Therefore, new antimicrobial agents that could overcome this resistance need to be discovered. Fighting staphylococcal resistance and biofilm formation is an important goal of the pharmaceutical research. Some fungicide has been observed to have antibacterial effect. anyway their use as antibiotics on S.aureus has been poorly studied. The aim of this work was to investigate the effect of the fungicide itraconazole (IT) on S. aureus biofilm formation and explore by SEM the morphological alteration after treatment. A strong biofilm disaggregation and morphologically different extracellular vesicles (EV) production were observed starting from sublethal IT doses. This suggests that IT resistance phenomena on the part of S. aureus are more difficult to establish respect other antibiotics. The adjuvant properties of IT could be used to combat bacterial biofilm and/or to improve antibiotic treatment. Moreover, because the production of EV represents a secretory pathway involved in intercellular communication shared to mammalian cells, fungi, and bacteria, our study is important to increase information that can be generalized to higher organisms.