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Hellmer CB, Hall LM, Bohl JM, Sharpe ZJ, Smith RG, Ichinose T. Cholinergic feedback to bipolar cells contributes to motion detection in the mouse retina. Cell Rep 2021; 37:110106. [PMID: 34910920 PMCID: PMC8793255 DOI: 10.1016/j.celrep.2021.110106] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 08/11/2021] [Accepted: 11/16/2021] [Indexed: 11/25/2022] Open
Abstract
Retinal bipolar cells are second-order neurons that transmit basic features of the visual scene to postsynaptic partners. However, their contribution to motion detection has not been fully appreciated. Here, we demonstrate that cholinergic feedback from starburst amacrine cells (SACs) to certain presynaptic bipolar cells via alpha-7 nicotinic acetylcholine receptors (α7-nAChRs) promotes direction-selective signaling. Patch clamp recordings reveal that distinct bipolar cell types making synapses at proximal SAC dendrites also express α7-nAChRs, producing directionally skewed excitatory inputs. Asymmetric SAC excitation contributes to motion detection in On-Off direction-selective ganglion cells (On-Off DSGCs), predicted by computational modeling of SAC dendrites and supported by patch clamp recordings from On-Off DSGCs when bipolar cell α7-nAChRs is eliminated pharmacologically or by conditional knockout. Altogether, these results show that cholinergic feedback to bipolar cells enhances direction-selective signaling in postsynaptic SACs and DSGCs, illustrating how bipolar cells provide a scaffold for postsynaptic microcircuits to cooperatively enhance retinal motion detection.
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Affiliation(s)
- Chase B Hellmer
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA; Present address: Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40202, USA
| | - Leo M Hall
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA; Present address: Department of Internal Medicine, St. Mary Mercy Livonia Hospital, Livonia, MI 48154, USA
| | - Jeremy M Bohl
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Zachary J Sharpe
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Robert G Smith
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Tomomi Ichinose
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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Koizumi A, Poznanski RR. Does heterogeneity of intracellular Ca[Formula: see text] dynamics underlie speed tuning of direction-selective responses in starburst amacrine cells? J Integr Neurosci 2016; 14:1-17. [PMID: 26762484 DOI: 10.1142/s0219635215500259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The starburst amacrine cell (SAC) plays a fundamental role in retinal motion perception. In the vertebrate retina, SAC dendrites have been shown to be directionally selective in terms of their Ca[Formula: see text] responses for stimuli that move centrifugally from the soma. The mechanism by which SACs show Ca[Formula: see text] bias for centrifugal motion is yet to be determined with precision. Recent morphological studies support a presynaptic delay in glutamate receptor activation induced Ca[Formula: see text] release from bipolar cells preferentially contacting SACs. However, bipolar cells are known to be electrotonically coupled so time delays between the bipolar cells that provide input to SACs seem unlikely. Using fluorescent microscopy and imunnostaining, we found that the endoplasmic reticulum (ER) is omnipresent in the soma extending to the distal processes of SACs. Consequently, a working hypothesis on heterogeneity of intracellular Ca[Formula: see text] dynamics from ER is proposed as a possible explanation for the cause of speed tuning of direction-selective Ca[Formula: see text] responses in dendrites of SACs.
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Affiliation(s)
- Amane Koizumi
- * National Institutes of Natural Sciences 105-0001, Tokyo, Japan
- † National Institute for Physiological Sciences Okazaki, Aichi 444-8585, Japan
| | - Roman R Poznanski
- ‡ Department of Clinical Sciences Faculty of Biosciences and Medical Engineering Universiti Teknologi Malaysia 81310 Johor Bahru, Malaysia
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Kwon OJ, Lee JS, Kim HG, Jeon CJ. Identification of Synaptic Patterns of NMDA Receptor Subtypes Upon Direction-Selective Rabbit Retinal Ganglion Cells. Curr Eye Res 2015; 41:832-43. [PMID: 26287656 DOI: 10.3109/02713683.2015.1056378] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE The objective of this study was to identify anisotropies that contribute to the directional preference of direction-selective retinal ganglion cells (DS RGCs) in the rabbit retina. We investigated the distributions of N-methyl-d-aspartate receptor 1 (NMDAR1), NMDAR2A and NMDAR2B receptor subunits in the dendritic arbors of rabbit DS RGCs. METHODS The distributions of the NMDAR subunits on the DS RGCs were determined using immunocytochemistry. DS RGCs were injected with Lucifer yellow, and the cells were identified by their characteristic morphology. The triple-labeled images of dendrites, kinesin II and NMDARs were visualized using confocal microscopy and were reconstructed from high-resolution confocal images. RESULTS We found no evidence of asymmetry in any of the NMDAR subunits examined on the dendritic arbors of both the ON and OFF layers of DS RGCs. CONCLUSIONS Our results indicate that direction selectivity appears to lie in the neuronal circuitry afferent to the DS RGCs.
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Affiliation(s)
- Oh-Ju Kwon
- a Department of Optometry , Busan Institute of Science and Technology , Busan , South Korea and.,b Department of Biology , School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, College of Natural Sciences, and Brain Science and Engineering Institute, Kyungpook National University , Daegu , South Korea
| | - Jun-Seok Lee
- b Department of Biology , School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, College of Natural Sciences, and Brain Science and Engineering Institute, Kyungpook National University , Daegu , South Korea
| | - Hang-Gu Kim
- b Department of Biology , School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, College of Natural Sciences, and Brain Science and Engineering Institute, Kyungpook National University , Daegu , South Korea
| | - Chang-Jin Jeon
- b Department of Biology , School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, College of Natural Sciences, and Brain Science and Engineering Institute, Kyungpook National University , Daegu , South Korea
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Lipin MY, Taylor WR, Smith RG. Inhibitory input to the direction-selective ganglion cell is saturated at low contrast. J Neurophysiol 2015; 114:927-41. [PMID: 26063782 DOI: 10.1152/jn.00413.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 06/09/2015] [Indexed: 01/10/2023] Open
Abstract
Direction-selective ganglion cells (DSGCs) respond selectively to motion toward a "preferred" direction, but much less to motion toward the opposite "null" direction. Directional signals in the DSGC depend on GABAergic inhibition and are observed over a wide range of speeds, which precludes motion detection based on a fixed temporal correlation. A voltage-clamp analysis, using narrow bar stimuli similar in width to the receptive field center, demonstrated that inhibition to DSGCs saturates rapidly above a threshold contrast. However, for wide bar stimuli that activate both the center and surround, inhibition depends more linearly on contrast. Excitation for both wide and narrow bars was also more linear. We propose that positive feedback, likely within the starburst amacrine cell or its network, produces steep saturation of inhibition at relatively low contrast. This mechanism renders GABA release essentially contrast and speed invariant, which enhances directional signals for small objects and thereby increases the signal-to-noise ratio for direction-selective signals in the spike train over a wide range of stimulus conditions. The steep saturation of inhibition confers to a neuron immunity to noise in its spike train, because when inhibition is strong no spikes are initiated.
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Affiliation(s)
- Mikhail Y Lipin
- Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - W Rowland Taylor
- Casey Eye Institute, Oregon Health and Science University, Portland, Oregon
| | - Robert G Smith
- Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania; and
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Sha F, Ye X, Zhao W, Xu CL, Wang L, Ding MH, Bi AL, Wu JF, Jiang WJ, Guo DD, Guo JG, Bi HS. Effects of electroacupuncture on the levels of retinal gamma-aminobutyric acid and its receptors in a guinea pig model of lens-induced myopia. Neuroscience 2014; 287:164-74. [PMID: 25542423 DOI: 10.1016/j.neuroscience.2014.12.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 12/05/2014] [Indexed: 12/01/2022]
Abstract
Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter of the retina and affects myopic development. Electroacupuncture (EA) is widely utilized to treat myopia in clinical settings. However, there are few reports on whether EA affects the level of retinal GABA during myopic development. To study this issue, in the present study, we explored the changes of retinal GABA content and the expression of its receptor subtypes, and the effects of EA stimulation on them in a guinea pig model with lens-induced myopia (LIM). Our results showed that the content of GABA and the expression of GABAA and GABAC receptors of retina were up-regulated during the development of myopia, and this up-regulation was inhibited by applying EA to Hegu (LI4) and Taiyang (EX-HN5) acupoints. Moreover, these effects of EA show a positional specificity. While applying EA at a sham acupoint, no apparent change of myopic retinal GABA and its receptor subtypes was observed. Taken together, our findings suggest that LIM is effective to up-regulate the level of retinal GABA, GABAA and GABAC receptors in guinea pigs and the effect may be inhibited by EA stimulation at LI4 and EX-HN5 acupoints.
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Affiliation(s)
- F Sha
- Shandong University of Traditional Chinese Medicine, Jinan 250002, China
| | - X Ye
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, No. 48#, Yingxiongshan Road, Jinan 250002, China; Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, No. 48#, Yingxiongshan Road, Jinan 250002, China; Eye Institute of Shandong University of Traditional Chinese Medicine, No. 48#, Yingxiongshan Road, Jinan 250002, China
| | - W Zhao
- Shandong University of Traditional Chinese Medicine, Jinan 250002, China
| | - C-L Xu
- Shandong University of Traditional Chinese Medicine, Jinan 250002, China
| | - L Wang
- Shandong University of Traditional Chinese Medicine, Jinan 250002, China; Jining Medical University, Jining, Shandong Province 272000, China
| | - M-H Ding
- Shandong University of Traditional Chinese Medicine, Jinan 250002, China
| | - A-L Bi
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, No. 48#, Yingxiongshan Road, Jinan 250002, China; Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, No. 48#, Yingxiongshan Road, Jinan 250002, China; Eye Institute of Shandong University of Traditional Chinese Medicine, No. 48#, Yingxiongshan Road, Jinan 250002, China
| | - J-F Wu
- Shandong University of Traditional Chinese Medicine, Jinan 250002, China
| | - W-J Jiang
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, No. 48#, Yingxiongshan Road, Jinan 250002, China; Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, No. 48#, Yingxiongshan Road, Jinan 250002, China; Eye Institute of Shandong University of Traditional Chinese Medicine, No. 48#, Yingxiongshan Road, Jinan 250002, China
| | - D-D Guo
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, No. 48#, Yingxiongshan Road, Jinan 250002, China; Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, No. 48#, Yingxiongshan Road, Jinan 250002, China; Eye Institute of Shandong University of Traditional Chinese Medicine, No. 48#, Yingxiongshan Road, Jinan 250002, China
| | - J-G Guo
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, No. 48#, Yingxiongshan Road, Jinan 250002, China; Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, No. 48#, Yingxiongshan Road, Jinan 250002, China; Eye Institute of Shandong University of Traditional Chinese Medicine, No. 48#, Yingxiongshan Road, Jinan 250002, China
| | - H-S Bi
- Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases, No. 48#, Yingxiongshan Road, Jinan 250002, China; Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular Diseases in Universities of Shandong, No. 48#, Yingxiongshan Road, Jinan 250002, China; Eye Institute of Shandong University of Traditional Chinese Medicine, No. 48#, Yingxiongshan Road, Jinan 250002, China; Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine, No. 48#, Yingxiongshan Road, Jinan 250002, China.
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6
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Cheng ZY, Chebib M, Schmid KL. Identification of GABA receptors in chick cornea. Mol Vis 2012; 18:1107-14. [PMID: 22605922 PMCID: PMC3351410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 04/27/2012] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The cornea has an important role in vision, is highly innervated and many neurotransmitter receptors are present, e.g., muscarine, melatonin, and dopamine receptors. γ-aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the retina and central nervous system, but it is unknown whether GABA receptors are present in cornea. The aim of this study was to determine if GABA receptors are located in chick cornea. METHODS Corneal tissues were collected from 25, 12-day-old chicks. Real time PCR, western blot, and immunohistochemistry were used to determine whether alpha(1) GABA(A), GABA(B), and rho(1) GABA(C) receptors were expressed and located in chick cornea. RESULTS Corneal tissue was positive for alpha(1) GABA(A) and rho(1) GABA(C) receptor mRNA (PCR) and protein (western blot) expression but was negative for GABA(B) receptor mRNA and protein. Alpha(1) GABA(A) and rho(1) GABA(C) receptor protein labeling was observed in the corneal epithelium using immunohistochemistry. CONCLUSIONS These investigations clearly show that chick cornea possesses alpha(1) GABA(A), and rho(1) GABA(C) receptors, but not GABA(B) receptors. The purpose of the alpha(1) GABA(A) and rho(1) GABA(C) receptors in cornea is a fascinating unexplored question.
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Affiliation(s)
- Zhen-Ying Cheng
- Myopia Center, Department of Ophthalmology, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Mary Chebib
- Faculty of Pharmacy, University of Sydney, Sydney, New South Wales, Australia
| | - Katrina L. Schmid
- School of Optometry and Vision Science, Faculty of Health, and Vision Improvement Domain, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
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Abstract
Muscarinic agonists act mainly via muscarinic M₃ cholinoceptors to cause contraction of the iris sphincter, ciliary muscle and trabecular meshwork as well as increase outflow facility of aqueous humour. In the iris dilator, the effect of muscarinic agonists is species dependent but is predominantly relaxation via muscarinic M₃ receptors. In the conjunctiva, muscarinic agonists stimulate goblet cell secretion which contributes to the protective tear film. Muscarinic M₂ and M₃ receptors appear mainly involved. In the lens muscarinic agonists act via muscarinic M₁ receptors to produce depolarization and increase [Ca(2+)](i). All five subtypes of muscarinic receptor are present in the retina. In the developing retina, acetylcholine appears to limit purinergic stimulation of retinal development and decrease cell proliferation. In the adult retina acetylcholine and other muscarinic agonists may have complex effects, for example, enhancing light-evoked neuronal firing in transient ON retinal ganglion cells and inhibiting firing in OFF retinal ganglion cells. In the lacrimal gland, muscarinic agonists activate M₃ receptors on secretory globular acinar cells to stimulate tear secretion and also cause contraction of myoepithelial cells. In Sjögren's syndrome, antibodies to the muscarinic M₃ receptor disrupt normal gland function leading to xerophthalmia although the mechanism of action of the antibody is still not clear. Atropine and pirenzepine are useful in limiting the development of myopia in children probably by an action on muscarinic receptors in the sclera, although many other muscarinic receptor antagonists are not effective.
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Affiliation(s)
- Frederick Mitchelson
- Department of Pharmacology, University of Melbourne, Melbourne, VIC 3010, Australia.
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The influences of metabotropic receptor activation on cellular signaling and synaptic function in amacrine cells. Vis Neurosci 2011; 29:31-9. [PMID: 21864448 DOI: 10.1017/s0952523811000204] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractAmacrine cells receive glutamatergic input from bipolar cells and GABAergic, glycinergic, cholinergic, and dopaminergic input from other amacrine cells. Glutamate, GABA, glycine, and acetylcholine (ACh) interact with ionotropic receptors and it is these interactions that form much of the functional circuitry in the inner retina. However, glutamate, GABA, ACh, and dopamine also activate metabotropic receptors linked to second messenger pathways that have the potential to modify the function of individual cells as well as retinal circuitry. Here, the physiological effects of activating dopamine receptors, metabotropic glutamate receptors, GABAB receptors, and muscarinic ACh receptors on amacrine cells will be discussed. The retina also expresses metabotropic receptors and the biochemical machinery associated with the synthesis and degradation of endocannabinoids and sphingosine-1-phosphate (S1P). The effects of activating cannabinoid receptors and S1P receptors on amacrine cell function will also be addressed.
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Song Y, Slaughter MM. GABA(B) receptor feedback regulation of bipolar cell transmitter release. J Physiol 2010; 588:4937-49. [PMID: 20974680 DOI: 10.1113/jphysiol.2010.194233] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
GABAergic amacrine cell feedback to bipolar cells in retina has been described, activating both GABA(A) and GABA(C) receptors. We explored whether metabotropic GABA(B) receptors also participate in this feedback pathway. CGP55845, a potent GABA(B) receptor antagonist, was employed to determine the endogenous role of these receptors. Ganglion cell EPSCs and IPSCs were monitored to measure the output of bipolar and amacrine cells. Using the tiger salamander slice preparation, we found that GABA(B) receptor pathways regulate bipolar cell release directly and indirectly. In the direct pathway, the GABA(B) receptor antagonist reduces EPSC amplitude, indicating that GABA(B) receptors cause enhanced glutamate release from bipolar cells to one set of ganglion cells. In the indirect pathway, the GABA(B) receptor antagonist reduces EPSC amplitude in another set of ganglion cells. The indirect pathway is only evident when GABA(A) receptors are inhibited, and is blocked by a glycine receptor antagonist. Thus, this second feedback pathway involves direct glycine feedback to the bipolar cell and this glycinergic amacrine cell is suppressed by GABAergic amacrine cells, through both GABA(A) and GABA(B) but not GABA(C) receptors. Overall, GABA(B) receptors do contribute to feedback regulation of bipolar cell transmitter release. However, unlike the ionotropic GABA receptor pathways, the metabotropic GABA receptor pathways act to enhance bipolar cell transmitter release. Furthermore, there are three discrete subsets of bipolar cell output regulated by GABA(B) receptor feedback (direct, indirect and null), implying three distinct, non-overlapping bipolar cell to ganglion cell circuits.
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Affiliation(s)
- Yunbo Song
- Department of Physiology & Biophysics, Center for Neuroscience, 124 Sherman Hall, 3435 Main Street, Buffalo, NY 14214, USA.
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10
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POZNANSKI RR. CELLULAR INHIBITORY BEHAVIOR UNDERLYING THE FORMATION OF RETINAL DIRECTION SELECTIVITY IN THE STARBURST NETWORK. J Integr Neurosci 2010; 9:299-335. [DOI: 10.1142/s0219635210002457] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Accepted: 08/26/2010] [Indexed: 11/18/2022] Open
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Strang CE, Renna JM, Amthor FR, Keyser KT. Muscarinic acetylcholine receptor localization and activation effects on ganglion response properties. Invest Ophthalmol Vis Sci 2009; 51:2778-89. [PMID: 20042645 DOI: 10.1167/iovs.09-4771] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
PURPOSE The activation and blockade of muscarinic acetylcholine receptors (mAChRs) affects retinal ganglion cell light responses and firing rates. This study was undertaken to identify the full complement of mAChRs expressed in the rabbit retina and to assess mAChR distribution and the functional effects of mAChR activation and blockade on retinal response properties. METHODS RT-PCR, Western blot analysis, and immunohistochemistry were used to identify the complement and distribution of mAChRs in the rabbit retina. Extracellular electrophysiology was used to determine the effects of the activation or blockade of mAChRs on ganglion cell response properties. RESULTS RT-PCR of whole neural retina resulted in the amplification of mRNA transcripts for the m1 to m5 mAChR subtypes. Western blot and immunohistochemical analyses confirmed that all five mAChR subtypes were expressed by subpopulations of bipolar, amacrine, and ganglion cells in the rabbit retina, including subsets of cells in cholinergic and glycinergic circuits. Nonspecific muscarinic activation and blockade resulted in the class-specific modulation of maintained ganglion cell firing rates and light responses. CONCLUSIONS The expression of mAChR subtypes on subsets of bipolar, amacrine, and ganglion cells provides a substrate for both enhancement and suppression of retinal responses via activation by cholinergic agents. Thus, the muscarinic cholinergic system in the retina may contribute to the modulation of complex stimuli. Understanding the distribution and function of mAChRs in the retina has the potential to provide important insights into the visual changes that are caused by decreased ACh in the retinas of Alzheimer's patients and the potential visual effects of anticholinergic treatments for ocular diseases.
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Affiliation(s)
- Christianne E Strang
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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Delgado LM, Vielma AH, Kähne T, Palacios AG, Schmachtenberg O. The GABAergic system in the retina of neonate and adult Octodon degus, studied by immunohistochemistry and electroretinography. J Comp Neurol 2009; 514:459-72. [PMID: 19350652 DOI: 10.1002/cne.22023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
UNLABELLED In the vertebrate retina, gamma-aminobutyric acid (GABA) mediates inhibitory processes that shape the visual response and is also thought to have neurotrophic functions during retinal development. To investigate the role of GABAergic signaling at the beginning of visual experience, we used immunohistochemistry to compare the distribution of GABA, the two isoforms of glutamic acid decarboxylase GAD65/67, and the GABA receptor types A, B, and C, in neonate versus adult Octodon degus, a native South American rodent with diurnal-crepuscular activity and a high cone-to-rod ratio. In parallel, we used electroretinography to evaluate retinal functionality and to test the contribution of fast GABAergic transmission to light responses at both developmental stages. Neonate O. degus opened their eyes on postnatal day (P)0 and displayed an adult-like retinal morphology at this time. GABA, its biosynthetic sources, and receptors had a similar cellular distribution in neonates and adults, but labeling of the outer plexiform layer and of certain amacrine and ganglion cells was more conspicuous at P0. In neonates, retinal sensitivity was 10 times lower than in adults, responses to ultraviolet light could not be detected, and oscillatory potentials were reduced or absent. Blockade of GABA(A/C) receptors by bicuculline and TPMPA had no noticeable effect in neonates, while it significantly altered the electroretinogram response in adults. CONCLUSION In spite of modest differences regarding retinal morphology and GABAergic expression, overall light response properties and GABAergic signaling are undeveloped in neonate O. degus compared to adults, suggesting that full retinal functionality requires a period of neural refinement under visual experience.
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Affiliation(s)
- Luz M Delgado
- Centro de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Chile
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Cimini BA, Strang CE, Wotring VE, Keyser KT, Eldred WD. Role of acetylcholine in nitric oxide production in the salamander retina. J Comp Neurol 2008; 507:1952-63. [PMID: 18273886 DOI: 10.1002/cne.21655] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Although acetylcholine is one of the most widely studied neurotransmitters in the retina, many questions remain about its downstream signaling mechanisms. In this study we initially characterized the cholinergic neurotransmitter system in the salamander retina by localizing a variety of cholinergic markers. We then examined the link between both muscarinic and nicotinic receptor activation and nitric oxide production by using immunocytochemistry for cyclic guanosine monophosphate (cGMP) as an indicator. We found a large increase in cGMP-like immunoreactivity (cGMP-LI) in the inner retina in response to muscarinic (but not nicotinic) receptor activation. Based on the amplification of mRNA transcripts, receptor immunocytochemistry, and the use of selective antagonists, we identified these receptors as M2 muscarinic receptors. Using double-labeling techniques, we established that these increases in cGMP-LI were seen in GABAergic but not cholinergic amacrine cells, and that the increases were blocked by inhibitors of nitric oxide production. The creation of nitric oxide in response to cholinergic receptor activation may provide a mechanism for modulating the well-known mutual interactions of acetylcholine-glycine-GABA in the inner retina. As GABA and glycine are the primary inhibitory neurotransmitters in the retina, signaling pathways that modulate their levels or release will have major implications for the processing of complex stimuli by the retina.
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Affiliation(s)
- Beth A Cimini
- Department of Biology, Boston University, Boston, Massachusetts 02215, USA
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14
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Abstract
Direction selectivity represents a fundamental computation found across multiple sensory systems. In the mammalian visual system, direction selectivity appears first in the retina, where excitatory and inhibitory interneurons release neurotransmitter most rapidly during movement in a preferred direction. Two parallel sets of interneuron signals are integrated by a direction-selective ganglion cell, which creates a direction preference for both bright and dark moving objects. Direction selectivity of synaptic input becomes amplified by action potentials in the ganglion cell dendrites. Recent work has elucidated direction-selective mechanisms in inhibitory circuitry, but mechanisms in excitatory circuitry remain unexplained.
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Affiliation(s)
- Jonathan B Demb
- Department of Ophthalmology & Visual Sciences, University of Michigan, Kellogg Eye Center, Ann Arbor, MI 48105, USA.
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15
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Grzywacz NM, Zucker CL. Modeling Starburst cells' GABA(B) receptors and their putative role in motion sensitivity. Biophys J 2006; 91:473-86. [PMID: 16648160 PMCID: PMC1483088 DOI: 10.1529/biophysj.105.072256] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Accepted: 04/10/2006] [Indexed: 11/18/2022] Open
Abstract
Neal and Cunningham (Neal, M. J., and J. R. Cunningham. 1995. J. Physiol. (Lond.). 482:363-372) showed that GABA(B) agonists and glycinergic antagonists enhance the light-evoked release of retinal acetylcholine. They proposed that glycinergic cells inhibit the cholinergic Starburst amacrine cells and are in turn inhibited by GABA through GABA(B) receptors. However, as recently shown, glycinergic cells do not appear to have GABA(B) receptors. In contrast, the Starburst amacrine cell has GABA(B) receptors in a subpopulation of its varicosities. We thus propose an alternate model in which GABA(B)-receptor activation reduces the release of ACh from some dendritic compartments onto a glycinergic cell, which then feeds back and inhibits the Starburst cell. In this model, the GABA necessary to make these receptors active comes from the Starburst cell itself, making them autoreceptors. Computer simulations of this model show that it accounts quantitatively for the Neal and Cunningham data. We also argue that GABA(B) receptors could work to increase the sensitivity to motion over other stimuli.
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Affiliation(s)
- Norberto M Grzywacz
- Department of Biomedical Engineering, Neuroscience Graduate Program, and Center For Visual Science and Technology, University of Southern California, Los Angeles, California, USA.
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Amthor FR, Tootle JS, Grzywacz NM. Stimulus-dependent correlated firing in directionally selective retinal ganglion cells. Vis Neurosci 2006; 22:769-87. [PMID: 16469187 DOI: 10.1017/s0952523805226081] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Accepted: 07/15/2005] [Indexed: 11/06/2022]
Abstract
Synchronous spiking has been postulated to be a meta-signal in visual cortex and other CNS loci that tags neuronal spike responses to a single entity. In retina, however, synchronized spikes have been postulated to arise via mechanisms that would largely preclude their carrying such a code. One such mechanism is gap junction coupling, in which synchronous spikes would be a by-product of lateral signal sharing. Synchronous spikes have also been postulated to arise from common-source inputs to retinal ganglion cells having overlapping receptive fields, and thus code for stimulus location in the overlap area. On-Off directionally selective ganglion cells of the rabbit retina exhibit a highly precise tiling pattern in which gap junction coupling occurs between some neighboring, same-preferred-direction cells. Depending on how correlated spikes arise, and for what purpose, one could postulate that synchronized spikes in this system (1) always arise in some subset of same-direction cells because of gap junctions, but never in non-same-preferred-directional cells; (2) never arise in same-directional cells because their receptive fields do not overlap, but arise only in different-directional cells whose receptive fields overlap, as a code for location in the overlap region; or (3) arise in a stimulus-dependent manner for both same- and different-preferred-direction cells for a function similar to that postulated for neurons in visual cortex. Simultaneous, extracellular recordings were obtained from neighboring On-Off directionally selective (DS) ganglion cells having the same and different preferred directions in an isolated rabbit retinal preparation. Stimulation by large flashing spots elicited responses from DS ganglion-cell pairs that typically showed little synchronous firing. Movement of extended bars, however, often produced synchronous spikes in cells having similar or orthogonal preferred directions. Surprisingly, correlated firing could occur for the opposite contrast polarity edges of moving stimuli when the leading edge of a sweeping bar excited the receptive field of one cell as its trailing edge stimulated another. Pharmacological manipulations showed that the spike synchronization is enhanced by excitatory cholinergic amacrine-cell inputs, and reduced by inhibitory GABAergic inputs, in a motion-specific manner. One possible interpretation is that this synchronous firing could be a signal to higher centers that the outputs of the two DS ganglion cells should be "bound" together as responding to a contour of a common object.
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Affiliation(s)
- Franklin R Amthor
- Department of Psychology, University of Alabama at Birmingham, 35294-1170, USA.
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