title: Glycinergic feedback enhances synaptic gain in the distal retina.
abstract: Glycine input originates with interplexiform cells, a group of neurons situated within the inner retina that transmit signals centrifugally to the distal retina. The effect on visual function of this novel mechanism is largely unknown. Using gramicidin-perforated patch whole cell recordings, intracellular recordings and specific antibody labelling techniques, we examined the effects of the synaptic connections between glycinergic interplexiform cells, photoreceptors and bipolar cells. To confirm that interplexiform cells make centrifugal feedback on bipolar cell dendrites, we recorded the postsynaptic glycine currents from axon-detached bipolar cells while stimulating presynaptic interplexiform cells. The results show that glycinergic interplexiform cells activate bipolar cell dendrites that express the α3 subunit of the glycine receptor, as well as a subclass of unidentified receptors on photoreceptors. By virtue of their synaptic contacts, glycine centrifugal feedback increases glutamate release from photoreceptors and suppresses the uptake of glutamate by the type 2A excitatory amino acid transporter on photoreceptors. The net effect is a significant increase in synaptic gain between photoreceptors and their second-order neurons.
authors.affiliation: Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, USA. wshen@fau.edu.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Jiang
authors.forename: Jinnan
authors.initials: J
authors.lastname: Yang
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Purpura
authors.forename: Yufei
authors.initials: Y
authors.lastname: Liu
authors.forename: Harris
authors.initials: H
authors.lastname: Ripps
authors.forename: Wen
authors.initials: W
authors.lastname: Shen
mesh_terms: D000557:Ambystoma; D000818:Animals; D027202:Cationic Amino Acid Transporter 2 / Q000378:metabolism; D002450:Cell Communication; D019706:Excitatory Postsynaptic Potentials; D025461:Feedback, Physiological; D018698:Glutamic Acid / Q000378:metabolism; D005998:Glycine / Q000378:metabolism*; D008027:Light; D010775:Photic Stimulation; D018009:Receptors, Glycine / Q000378:metabolism; D051245:Retinal Bipolar Cells / Q000378:metabolism*; D055211:Retinal Photoreceptor Cell Inner Segment / Q000378:metabolism*; D009435:Synaptic Transmission; D013997:Time Factors
chemical_list: D027202:Cationic Amino Acid Transporter 2; D018009:Receptors, Glycine; C113965:glycine receptor alpha3 subunit; D018698:Glutamic Acid; D005998:Glycine