ON and OFF Pathways in the Mouse Retina and the Role of Stimulation

Emerging evidence underscores an association between age-related macular degeneration (AMD) and periodontal disease (PD), yet the biological basis of this linkage and the specific role of oral dysbiosis caused by PD in AMD pathophysiology remains unclear. Furthermore, a simple reproducible model that emulates characteristics of both AMD and PD has been lacking. Hence, we established a novel AMD+PD murine model to decipher the potential role of oral infection (ligature-enhanced) with the keystone periodontal pathogen Porphyromonas gingivalis, in the progression of neovasculogenesis in a laser-induced choroidal-neovascularization (Li-CNV) mouse retina. By a combination of fundus photography, optical coherence tomography, and fluorescein angiography, we documented inflammatory drusen-like lesions, reduced retinal thickness, and increased vascular leakage in AMD+PD mice retinae. H&E further confirmed a significant reduction of retinal thickness and subretinal drusen-like deposits. Immunofluorescence microscopy revealed significant induction of choroidal/retinal vasculogenesis in AMD+PD mice. qPCR identified increased expression of oxidative-stress, angiogenesis, pro-inflammatory mediators, whereas antioxidants and anti-inflammatory genes in AMD+PD mice retinae were notably decreased. Through qPCR, we detected Pg and its fimbrial 16s-RrNA gene expression in the AMD+PD mice retinae. To sum-up, this is the first in vivo study signifying a role of periodontal infection in augmentation of AMD phenotype, with the aid of a pioneering AMD+PD murine model established in our laboratory.

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The absence of Complexin 3 and Complexin 4 differentially impacts the ON and OFF pathways in mouse retina

European Journal of Neuroscience ◽

10.1111/j.1460-9568.2012.08149.x ◽

2012 ◽

Vol 36 (4) ◽

pp. 2470-2481 ◽

Cited By ~ 10

Author(s):

Immanuel Landgraf ◽

Johanna Mühlhans ◽

Karin Dedek ◽

Kerstin Reim ◽

Johann H. Brandstätter ◽

...

Keyword(s):

Mouse Retina ◽

On And Off Pathways

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Genetic disruption of the On visual pathway affects cortical orientation selectivity and contrast sensitivity in mice

Journal of Neurophysiology ◽

10.1152/jn.00558.2013 ◽

2014 ◽

Vol 111 (11) ◽

pp. 2276-2286 ◽

Cited By ~ 6

Author(s):

Rashmi Sarnaik ◽

Hui Chen ◽

Xiaorong Liu ◽

Jianhua Cang

Keyword(s):

Contrast Sensitivity ◽

Visual Pathway ◽

Response Variability ◽

Stimulus Contrast ◽

Wild Type ◽

Low Contrast ◽

Pharmacological Blockade ◽

Single Unit Recordings ◽

On And Off Pathways

The retina signals stimulus contrast via parallel On and Off pathways and sends the information to higher visual centers. Here we study the role of the On pathway using mice that have null mutations in the On-specific GRM6 receptor in the retina (Pinto LH, Vitaterna MH, Shimomura K, Siepka SM, Balannik V, McDearmon EL, Omura C, Lumayag S, Invergo BM, Brandon M, Glawe B, Cantrell DR, Donald R, Inayat S, Olvera MA, Vessey KA, Kirstan A, McCall MA, Maddox D, Morgans CW, Young B, Pletcher MT, Mullins RF, Troy JB, Takahashi JS. Vis Neurosci 24: 111–123, 2007; Maddox DM, Vessey KA, Yarbrough GL, Invergo BM, Cantrell DR, Inayat S, Balannik V, Hicks WL, Hawes NL, Byers S, Smith RS, Hurd R, Howell D, Gregg RG, Chang B, Naggert JK, Troy JB, Pinto LH, Nishina PM, McCall MA. J Physiol 586: 4409–4424, 2008). In these “nob” mice, single unit recordings in the primary visual cortex (V1) reveal degraded selectivity for orientations due to an increased response at nonpreferred orientations. Contrast sensitivity in the nob mice is reduced with severe deficits at low contrast, consistent with the phenotype of night blindness in human patients with mutations in Grm6. These cortical deficits can be largely explained by reduced input drive and increased response variability seen in nob V1. Interestingly, increased variability is also observed in the superior colliculus of these mice but does not affect its tuning properties. Further, the increased response variability in the nob mice is traced to the retina, a result phenocopied by acute pharmacological blockade of the On pathway in wild-type retina. Together, our results suggest that the On and Off pathways normally interact to increase response reliability in the retina, which in turn propagates to various central visual targets and affects their functional properties.

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Epac1 and Glycyrrhizin Both Inhibit HMGB1 Levels to Reduce Diabetes-Induced Neuronal and Vascular Damage in the Mouse Retina

Journal of Clinical Medicine ◽

10.3390/jcm8060772 ◽

2019 ◽

Vol 8 (6) ◽

pp. 772 ◽

Cited By ~ 7

Author(s):

Li Liu ◽

Youde Jiang ◽

Jena J. Steinle

Keyword(s):

Inflammatory Mediators ◽

Knockout Mice ◽

Interleukin 1 ◽

High Mobility ◽

Sirtuin 1 ◽

Mouse Retina ◽

Necrosis Factor Alpha ◽

Diabetic Retina ◽

Factor Alpha

The role of high mobility group box 1 (HMGB1) in acute diabetic retinal damage has been demonstrated. We recently reported that glycyrrhizin, a HMGB1 inhibitor, protected the diabetic retina against neuronal, vascular, and permeability changes. In this study, we wanted to investigate the role of exchange protein for cAMP 1 (Epac1) on HMGB1 and the actions of glycyrrhizin. Using endothelial cell specific knockout mice for Epac1, we made some mice diabetic using streptozotocin, and treated some with glycyrrhizin for up to 6 months. We measured permeability, neuronal, and vascular changes in the Epac1 floxed and knockout mice. We also investigated whether Epac1 and glycyrrhizin work synergistically to reduce the retinal inflammatory mediators, tumor necrosis factor alpha (TNFα) and interleukin-1-beta (IL1β), as well as sirtuin 1 (SIRT1) levels. Epac1 and glycyrrhizin reduced inflammatory mediators with synergistic actions. Glycyrrhizin also increased SIRT1 levels in the Epac1 mice. Overall, these studies demonstrate that glycyrrhizin and Epac1 can work together to protect the retina. Finally, glycyrrhizin may regulate HMGB1 through increased SIRT1 actions.

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Voltage-clamp recordings of light responses from wild-type and mutant mouse cone photoreceptors

The Journal of General Physiology ◽

10.1085/jgp.201912419 ◽

2019 ◽

Vol 151 (11) ◽

pp. 1287-1299 ◽

Cited By ~ 9

Author(s):

Norianne T. Ingram ◽

Alapakkam P. Sampath ◽

Gordon L. Fain

Keyword(s):

Voltage Clamp ◽

Mouse Retina ◽

Cone Photoreceptors ◽

Wild Type ◽

Light Responses ◽

Α Subunit ◽

Background Light ◽

Connexin 36 ◽

Mouse Lines

We describe the first extensive study of voltage-clamp current responses of cone photoreceptors in unlabeled, dark-adapted mouse retina using only the position and appearance of cone somata as a guide. Identification was confirmed from morphology after dye filling. Photocurrents recorded from wild-type mouse cones were biphasic with a fast cone component and a slower rod component. The rod component could be eliminated with dim background light and was not present in mouse lines lacking the rod transducin-α subunit (Gnat1−/−) or connexin 36 (Cx36−/−). Cones from Gnat1−/− or Cx36−/− mice had resting membrane potentials between −45 and −55 mV, peak photocurrents of 20–25 picoamps (pA) at a membrane potential Vm = −50 mV, sensitivities 60–70 times smaller than rods, and a total membrane capacitance two to four times greater than rods. The rate of activation (amplification constant) was largely independent of the brightness of the flash and was 1–2 s−2, less than half that of rods. The role of Ca2+-dependent transduction modulation was investigated by recording from cones in mice lacking rod transducin (Gnat1), recoverin, and/or the guanylyl-cyclase–activating proteins (GCAPs). In confirmation of previous results, responses of Gnat1−/−;Gcaps−/− cones and triple-mutant Gnat1−/−;Gcaps−/−;Rv−/− cones recovered more slowly both to light flashes and steps and were more sensitive than cones expressing the GCAPs. Cones from all four mouse lines showed significant recovery and escaped saturation even in bright background light. This recovery occurred too rapidly to be caused by pigment bleaching or metaII decay and appears to reflect some modulation of response inactivation in addition to those produced by recoverin and the GCAPs. Our experiments now make possible a more detailed understanding of the cellular physiology of mammalian cone photoreceptors and the role of conductances in the inner and outer segment in producing cone light responses.

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A Possible Role of Neuroglobin in the Retina After Optic Nerve Injury: A Comparative Study of Zebrafish and Mouse Retina

Retinal Degenerative Diseases - Advances in Experimental Medicine and Biology ◽

10.1007/978-3-319-17121-0_89 ◽

2015 ◽

pp. 671-675 ◽

Cited By ~ 9

Author(s):

Kayo Sugitani ◽

Yoshiki Koriyama ◽

Kazuhiro Ogai ◽

Keisuke Wakasugi ◽

Satoru Kato

Keyword(s):

Optic Nerve ◽

Comparative Study ◽

Nerve Injury ◽

Mouse Retina ◽

Optic Nerve Injury

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Neuroretinal Dysfunctions in Regular Cannabis Users: An Impact of Cannabis on Retinal Neurotransmission?

European Psychiatry ◽

10.1016/j.eurpsy.2017.01.1050 ◽

2017 ◽

Vol 41 (S1) ◽

pp. S638-S638

Author(s):

T. Schwitzer ◽

R. Schwan ◽

A. Giersch ◽

E. Albuisson ◽

K. Angioi-Duprez ◽

...

Keyword(s):

Ganglion Cells ◽

Endocannabinoid System ◽

Implicit Time ◽

Significant Difference ◽

Transmission Of Information ◽

Competing Interest ◽

On And Off Pathways ◽

The Waves ◽

The Brain

IntroductionAlthough cannabis is very widespread worldwide, its brain toxicity is poorly understood. The neuroretina is an accessible extension of the brain and could be a relevant site for investigating neurotransmission abnormalities in neuropsychiatric disorders. The retina has a functional endocannabinoid system involved in the regulation of retinal neurotransmission. In animals, the modulation of this system led to retinal dysfunctions measured with the electroretinogram (ERG).ObjectivesTo assess whether the regular cannabis use could affect the neuroretinal function.AimsAssessments of the neuroretinal function in cannabis users compared with controls.MethodsRecordings of pattern, flash and on-off ERG were performed in 55 cannabis users and 29 controls. The amplitude and implicit time of the following waves were evaluated: N95 (pattern); a – and b – (flash); a –, b- and d1 – (on-off).ResultsCannabis users showed a significant increase in implicit time of the waves N95 (P = 0.0001), a- (P = 0.029) and b – (P = 0.002) for the flash ERG and b – (P = 0.016) and d1 – (P = 0.027) for the on-off ERG, compared with controls. No significant difference was found between groups in terms of wave's amplitudes.ConclusionsThese results show a delay in the response of cones, bipolar and ganglion cells of the on and off pathways to constitute a delay of ≈ 6 ms in the transmission of information from the retina to the brain in cannabis users. Cannabis could disrupt the regulatory role of the cannabinoid system and impair retinal glutamatergic neurotransmission. The consequences on visual perception should be explored in future studies.Disclosure of interestThe authors have not supplied their declaration of competing interest.

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Microenvironment-Induced Endothelial Heterogeneity Stimulates Retinal Neovascularization in Sickle Mice.

Blood ◽

10.1182/blood.v108.11.1198.1198 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1198-1198

Author(s):

Kalpna Gupta ◽

Chunsheng Chen ◽

Gerard A. Lutty ◽

Robert P. Hebbel

Keyword(s):

Opioid Receptor ◽

Receptor Binding ◽

Retinal Neovascularization ◽

Mouse Retina ◽

Morphine Treatment ◽

Binding Studies ◽

Inflammatory Microenvironment ◽

Opioid Receptor Antagonists ◽

Opioid Receptor Binding

Abstract Retinopathy is a serious complication of sickle cell disease (SCD) which is accompanied by endothelial activation and a pro-inflammatory microenvironment. We hypothesized that endogenous and exogenous factors modulate the endothelial microenvironment and endothelial specific alterations leading to retinal neovascularization. While VEGF receptor 2/Flk1 is a key player in the process of angiogenesis, opioids used to treat pain in SCD also promote angiogenesis. Therefore, we examined the role of opioids in the regulation of endothelial microenvironment, Flk1 expression and endothelial activity, using wild type (WT) and NY1DD sickle mice with transgenes for human α and βS globin. We injected 9–11 month old mice with morphine subcutaneously (50 mg/day/70 Kg with 10 mg increments every 2 weeks and/or equimolar amount of naloxone) for 10 to 16 months. NY1DD mouse retina exhibited appreciably higher expression of phospho-Flk1 vs WT which was further upregulated by morphine treatment for 10 and 16 months. Naloxone treatment antagonized morphine induced upregulation of phospho-Flk1, suggesting an opioid receptor mediated effect. Upregulation of phospho-Flk1 was accompanied by an increase in cell cycle regulatory protein cyclin D1 and stimulation of phospho-MAPK/ERK and phospho-Akt in morphine vs PBS treated mouse retina. Furthermore, morphine treatment led to a 5 and 20 fold increase in plasma IL6 and TNFα, respectively as compared to PBS treatment and promoted retinal neovascularization. Thus morphine treatment exaggerates the pro-inflammatory micro-environment and orchestrates a pro-angiogenic tone by upregulating Flk1 and activating the growth and survival promoting signaling in NY1DD mouse retina. To specifically delineate the role of opioids in endothelial activity leading to retinopathy, we isolated retinal endothelial cells (REC) from WT and NY1DD mice. Both VEGF and morphine stimulated REC proliferation in a dose-dependent fashion. Maximum proliferation was achieved with 1 μm morphine or 10 ng/ml VEGF in WT REC, but it was unsaturable upto 10 μm morphine or 1 μg/ml VEGF in NY1DD REC. Optimum morphine and VEGF-induced REC proliferation was 1.5 and 3 fold, respectively in NY1DD Vs WT REC, suggestive of a heterogeneity between WT and NY1DD REC. Saturation kinetics and opioid receptor binding studies showed that the Bmax for 3H-diprenorphine and the number of opioid receptor binding sites were 3-fold higher in NY1DD vs WT REC. RT-PCR analysis showed a higher expression of both Flk1 and μ opioid receptor (MOR) in NY1DD vs WT REC. Incubation of WT REC with IL6 as well as morphine for 48h upregulated Flk1 protein expression. Morphine-induced upregulation of Flk1 was abrogated by naloxone, anti-IL6 antibodies and STAT3 inhibitor Ac-PpYLKTK-OH. On the other hand, incubation of WT-REC with VEGF or IL6 for 48h upregulated MOR expression. Together, these data suggest that morphine stimulates Flk1 expression directly via opioid receptor(s) and also by upregulating IL6 via a STAT3 signaling pathway, while VEGF and IL6 also stimulate MOR expression. Therefore, a pro-inflammatory microenvironment in SCD upregulates endothelial Flk1 and opioid receptors, which is further exaggerated by addition of morphine leading to increased retinal neovascularization. It is likely that opioid use in SCD promotes retinopathy and that opioid receptor antagonists may play a preventive role.

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