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.
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.
Chun
M H
MH
Department of Anatomy, College of Medicine, The Catholic University of Korea, Socho-gu, Seoul. mhchun@cmc.cuk.ac.kr
Kim
I B
IB
Oh
S J
SJ
Chung
J W
JW
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
D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase