31 research outputs found

    Licht- und elektronenmikroskopische Analyse von Bipolarzelltypen in der Mausretina

    Get PDF
    In the mammalian retina, the light response of the photoreceptors (rods and cones) is processed by an elaborate neuronal network. For many years it has been thought that in the mammalian retina rod and cone signals are relayed by different types of bipolar cells. Since a few years, however, there is strong evidence that in the mammalian retina certain cone bipolar cells receive input from both rods and cones and thus provide for the so called “alternative pathway” of rod photoreceptors. In the present study, cell types were identified that provide for this alternative rod pathway. For these purposes vertical sections and wholemount preparations of the mouse retina were immunohistochemically processed and the labelled cell types were analyzed by confocal laser scanning microscopy. Synaptic connections were confirmed by electron microscopy. Two OFF-bipolar cell types were identified, that form flat contacts to rod and cone endfeet and whose axon terminals stratify within sublamina 2 of the inner plexiform layer. These cells were identified as type 3a- and type 3b-cone bipolar cells. In this study type 3b-cone bipolar cells are described for the first time. Additionally a ganglion cell type was identified whose dendrites co-stratify with the axon terminals of type 3-cone bipolar cells. This ganglion cell type might be postsynaptic to type 3 cells and thus could serve as an output neuron of the alternative rod pathway. For the immunohistochemical labeling of bipolar and ganglion cell types antibodies against hyperpolarization-activated and cyclic nucleotide-gated channels (HCN-channels) were used. For these purposes polyclonal and monoclonal antibodies were generated and characterized immunohistochemically and immunocytochemically as well as by Western blot analysis. The expression patterns of the four different HCN-channel isoforms HCN1 - 4 were analyzed in the adult mouse retina as well as in defined postnatal states by immunohistochemical methods. All four HCN-isoforms are differentially expressed in the adult retina. HCN-channels can already be detected at a developmental state when no light responses can be generated. In the developing photoreceptor cells HCN1 is expressed at the day of birth (P0). In bipolar cells and ganglion cells HCN-channels can be found in the second postnatal week

    Benzo[a]pyrene-induced changes in carboxylesterase, acetylcholinesterase and heat shock protein 70 of Lymantria dispar (Lepidoptera: Lymantriidae) from unpolluted and polluted forests

    Get PDF
    Plant vegetation accumulates polycyclic aromatic hydrocarbons (PAHs) among which benzo[a]pyrene (B[a]P) is recognized as being very toxic, including cancerogenic. Lymantria dispar L. larvae are sensitive to changes in the environment, providing potential signs of pollutant presence. We examined the chronic effects of two concentrations of B[a] P on the activity of carboxylesterase (CaE), acetylcholinesterase (AChE) and heat shock protein 70 (Hsp70) levels in the brain tissue of two populations of L. dispar larvae, originating from unpolluted and polluted habitats. We found that the relative growth rate was significantly lower in both populations and that only larvae from polluted forests were sensitive to low B[a]P concentrations, exhibiting a significant increase in brain tissue CaE activity and Hsp70 concentration. AChE activity showed no changes in response to B[a]P exposure in either population. Examined biochemical parameters indicate that their sensitivity to chronic treatment with B[a]P was highly dependent on the pre-exposure history of L. dispar larvae, suggesting that they could be promising biomarkers of B[a]P and PAH pollution in forest ecosystem

    Overview

    No full text

    Pharmacological Analysis of Intrinsic Neuronal Oscillations in rd10 Retina

    Get PDF
    In the widely used mouse model of retinal degeneration, rd1, the loss of photoreceptors leads to rhythmic electrical activity of around 10-16 Hz in the remaining retinal network. Recent studies suggest that this oscillation is formed within the electrically coupled network of AII amacrine cells and ON-bipolar cells. A second mouse model, rd10, displays a delayed onset and slower progression of degeneration, making this mouse strain a better model for human retinitis pigmentosa. In rd10, oscillations occur at a frequency of 3-7 Hz, raising the question whether oscillations have the same origin in the two mouse models. As rd10 is increasingly being used as a model to develop experimental therapies, it is important to understand the mechanisms underlying the spontaneous rhythmic activity. To study the properties of oscillations in rd10 retina we combined multi electrode recordings with pharmacological manipulation of the retinal network. Oscillations were abolished by blockers for ionotropic glutamate receptors and gap junctions. Frequency and amplitude of oscillations were modulated strongly by blockers of inhibitory receptors and to a lesser extent by blockers of HCN channels. In summary, although we found certain differences in the pharmacological modulation of rhythmic activity in rd10 compared to rd1, the overall pattern looked similar. This suggests that the generation of rhythmic activity may underlie similar mechanisms in rd1 and rd10 retina

    Excitatory Amino Acid Transporter EAAT5 Improves Temporal Resolution in the Retina

    No full text
    Excitatory amino acid transporters (EAATs) remove glutamate from the synaptic cleft. In the retina, EAAT1 and EAAT2 are considered the major glutamate transporters. However, it has not yet been possible to determine how EAAT5 shapes the retinal light responses because of the lack of a selective EAAT5 blocker or EAAT5 knock-out (KO) animal model. In this study, EAAT5 was found to be expressed in a punctate manner close to release sites of glutamatergic synapses in the mouse retina. Light responses from retinae of wild-type (WT) and of a newly generated model with a targeted deletion of EAAT5 (EAAT5−/−) were recorded in vitro using multielectrode arrays (MEAs). Flicker resolution was considerably lower in EAAT5−/− retinae than in WT retinae. The close proximity to the glutamate release site makes EAAT5 an ideal tool to improve temporal information processing in the retina by controlling information transfer at glutamatergic synapses

    Effects of benzo[a]pyrene dietary intake to antioxidative enzymes of Lymantria dispar (Lepidoptera: Lymantriidae ) larvae from unpolluted and polluted forests

    No full text
    Anthropogenic activity in industrial development has imposed great threats to the environment and wildlife in the form of persistent organic pollutants. Polycyclic aromatic hydrocarbons (PAH) tend to accumulate in vegetation foliage which is the main food source of polyphagous insect species Lymantria dispar L. Origin and multigenerational adaptation of L. dispar population to environmental challenges strongly condition the enzymes’ sensitivity to pollutants. In this study, our aim was to investigate response of the superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) to the chronic dietary exposure of benzo[a]pyrene in the midgut tissues and hemolymph of two L. dispar populations originating from unpolluted and polluted forest habitat. Midgut tissue of the larvae from the polluted forest showed significant increase in SOD, CAT and GST activity, while in unpolluted forest's larvae SOD and CAT showed elevated activities in hemolymph. L. dispar populations adapted to different level of pollution in their environment and expressed distinct tissue-dependent antioxidative enzyme sensitivity to benzo[a]pyrene diet, implying high potential for further elucidation of these enzymes as molecular biomarkers.Chemosphere (2017), 179: 10-1

    Long-term exposure of cockroach Blaptica dubia (Insecta: Blaberidae) nymphs to magnetic fields of different characteristics: effects on antioxidant biomarkers and nymphal gut mass.

    No full text
    PURPOSE The main goal of this study was to analyze the long-term effects of static (SMF) and extremely low-frequency magnetic field (ELF MF) on nymphal gut mass and antioxidant biomarkers in this tissue of cockroach Blaptica dubia. MATERIALS AND METHODS One-month-old nymphs were exposed to magnetic field (MF) for 5 months in three experimental groups: control, exposure to SMF (110 mT) and exposure to ELF MF (50 Hz, 10 mT). RESULTS The gut masses of the MF groups were significantly lower when compared to control. Superoxide dismutase (SOD) and catalase (CAT) activities were markedly higher than for the control and the differences between the MF groups were statistically significant only for SOD. The applied MF had no effect on total glutathione (GSH) content. Glutathione reductase (GR) and glutathione S-transferase (GST) activities were significantly lower in both MF groups in comparison to the control. There was a significant difference between MF groups for GR activity. Principal Component Analysis (PCA) showed that CAT and GST were the main factors contributing to the differentiation of the control group from the treated experimental groups along PCA 1, and SOD and GR along PCA 2. PCA revealed clear separation between experimental groups depends on antioxidant biomarker response. CONCLUSION The applied magnetic fields could be considered a potential stressor influencing gut mass, as well as examined antioxidative biomarkers.This is an Accepted Manuscript of an article published by Taylor & Francis in International Journal of Radiation Biology on 19 Mar 2019, available online: [http://www.tandfonline.com/10.1080/09553002.2019.1589017

    Effects of dietary fluoranthene on nymphs of Blaptica dubia S. (Blattodea: Blaberidae).

    No full text
    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants which exert detrimental effects on living beings. Considering the health risk associated with exposure to these pollutants, their presence in food increases efforts to establish early-warning indicators of pollution. We aimed to examine the effects of environmentally relevant concentrations of fluoranthene (0.2 ng and 18 ng/g dry weight of diet) on the activities of midgut antioxidant and detoxification enzymes in Blaptica dubia. Significant changes of superoxide dismutase and catalase activities, recorded at the higher fluoranthene concentration regardless of the exposure time, suggest that they may be used as biomarkers of PAH pollution. Increased GST activity and decreased total GSH content, detected upon acute exposure to the lower concentration, indicate processes of detoxification. Reorganization of B. dubia mechanisms of defense in response to oxidative stress caused by exposure to dietary PAH point to the necessity for further examination of fluoranthene actions

    Ghrelin effects on midgut tissue antioxidative defense and glutathione S-transferase activity in Lymantria dispar (Lepidoptera)

    No full text
    The aim of the study was to examine changes in Cu. Zn superoxide dismutase (SOD), catalase (CAT), their gel electrophoresis profiles, glutathione reductase (GR) activity, amount of glutathione (GSH), and the activity of glutathione S-transferase (GST) -phase II biotransformation enzyme in the midgut tissue of gypsy moth (Lymantria dispar L. (Lepidoptera: Lymantriidae)) larvae after ghrelin treatment. Four subpicomolar injections of ghrelin (0.3 pmol) or physiological saline (control) were applied every 24 h. The SOD, CAT, GR, GST activity, and amount of GSH were higher in the ghrelin-treated group than in the control. Electrophoresis gel bands of SOD and CAT had higher area and density in the treated group. The effects of ghrelin on the antioxidative defense and GST activity in insects were detected for the first time. The results provided evidence for possible application of insects as simple model systems in future studies of the role of ghrelin in the antioxidative protection of complex organisms.Serbian Ministry of Education, Science and Technological Development {[}173027

    Effect of fluoranthene on antioxidative defense in different tissues of Lymantria dispar and Euproctis chrysorrhoea larvae.

    No full text
    This study examined the effect of long-term exposure to environmentally relevant concentrations of dietary fluoranthene (6.7 and 67 ng / g dry food weight) on defense mechanisms of the polyphagous forest insects Lymantria dispar L. and Euproctis chrysorrhoea L. The activities and expression of isoforms of superoxide dismutase (SOD) and catalase (CAT), the activities of glutathione S-transferase (GST) and glutathione reductase (GR), and total glutathione content (GSH) were determined in the whole midgut and midgut tissue, while SOD and CAT activities were assessed in hemolymph of the larvae. The results showed significant changes of enzyme activities, with more pronounced responses in larval midgut tissues, and between-species differences in patterns of response. Significantly increased activity of SOD was recorded in the whole midgut and midgut tissue of L. dispar larvae, as well as in midgut tissue of E. chrysorrhoea larvae. Fluoranthene increased CAT activity in midgut tissue of L. dispar larvae, and in the whole midgut and midgut tissue of E. chrysorrhoea larvae. Different expression patterns were detected for enzyme isoforms in tissues of larvae exposed to dietary fluoranthene. Total GSH content and GST activity increased in E. chrysorrhoea larval midgut tissue. Significantly decreased SOD activity in hemolymph of L. dispar larvae, and opposite changes in CAT activity were recorded in the hemolymph of larvae of two insect species. The tissue-specific responses of enzymes to dietary fluoranthene, recorded in each species, enabled the larvae to overcome the pollutant induced oxidative stress, and suggest further assessment of their possible use as early-warning signals of environmental pollution
    corecore