title: Synaptic connectivity of two types of recoverin-labeled cone bipolar cells and glutamic acid decarboxylase immunoreactive amacrine cells in the inner plexiform layer of the rat retina.
abstract: We investigated the synaptic connectivity of two populations of recoverin-labeled bipolar cells and GABAergic neurons in the inner plexiform layer (IPL) of the rat retina. Two types of cone bipolar cells, type 2 and type 8, were stained with anti-recoverin antibodies, and GABAergic neurons were stained with anti-glutamic acid decarboxylase (GAD) antibodies. Type 2 cone bipolar axons received synaptic input from amacrine cell processes in 177 cases; among these amacrine cell processes, 92 processes (52.0%) were GAD-like immunoreactive. A total of 159 amacrine cell processes, which are presynaptic to type 8 cone bipolar cells, were observed. Among these processes, 117 processes (73.6%) were GAD-like immunoreactive. The postsynaptic elements at the ribbon synapses of recoverin-labeled cone bipolar cells were observed in 482 processes. In both type 2 and type 8 cone bipolar cells, the major output was to amacrine cell processes. At the ribbon synapses of the type 2 cone bipolar cells, 224 of the postsynaptic profiles were amacrine cell processes, 97 processes (43.3%) were GAD-like immunoreactive. In type 8 cone bipolar cells, 45 processes (30.2%) of 149 amacrine cell processes were GAD-like immunoreactive. Our results provide morphological evidence that GABA is a major transmitter involved in the visual processing of type 2 and 8 cone bipolar cells and GABA may have a stronger influence on type 8 cone bipolar cells than type 2 cone bipolar cells in the IPL of the rat retina.
authors.affiliation: Department of Anatomy, College of Medicine, The Catholic University of Korea, Socho-gu, Seoul. mhchun@cmc.cuk.ac.kr
authors.forename: M H
authors.initials: MH
authors.lastname: Chun
authors.forename: I B
authors.initials: IB
authors.lastname: Kim
authors.forename: S J
authors.initials: SJ
authors.lastname: Oh
authors.forename: J W
authors.initials: JW
authors.lastname: Chung
mesh_terms: D000818:Animals; D005260:Female; D005968:Glutamate Decarboxylase / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000502:physiology; D051381:Rats; D012160:Retina / Q000166:cytology* / Q000502:physiology* / Q000648:ultrastructure; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology* / Q000502:physiology* / Q000648:ultrastructure; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase