A novel signaling pathway from rod photoreceptors to ganglion cells in mammalian retina.
Current understanding suggests that mammalian rod photoreceptors connect only to an ON-type bipolar cell. This rod-specific bipolar cell excites the All amacrine cell, which makes connections to cone-specific bipolar cells of both ON and OFF type; these, in turn, synapse with ganglion cells. Recent work on rabbit retina has shown that rod signals can also reach ganglion cells without passing through the rod bipolar cell. This route was thought to be provided by electrical gap junctions, through which rods signal directly to cones and thence to cone bipolar cells. Here, we show that the mouse retina also provides a rod pathway bypassing the rod bipolar cell, suggesting that this is a common feature in mammals. However, this alternative pathway does not require cone photoreceptors; it is perfectly intact in a transgenic mouse whose retina lacks cones. Instead, the results can be explained if rods connect directly to OFF bipolar cells.
Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
E
E
Soucy
Y
Y
Wang
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S
Nirenberg
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J
Nathans
M
M
Meister
D000613:Aminobutyrates / Q000494:pharmacology; D000818:Animals; D003624:Darkness; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005136:Eye Proteins / Q000235:genetics / Q000502:physiology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008027:Light; D008322:Mammals; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008954:Models, Biological; D010775:Photic Stimulation; D011817:Rabbits; D017949:Retinal Cone Photoreceptor Cells / Q000187:drug effects / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D012168:Retinal Pigments / Q000235:genetics / Q000502:physiology; D017948:Retinal Rod Photoreceptor Cells / Q000187:drug effects / Q000502:physiology*; D017299:Rod Opsins; D015398:Signal Transduction / Q000187:drug effects; D013331:Strychnine / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology
D000613:Aminobutyrates; D018690:Excitatory Amino Acid Agonists; D005136:Eye Proteins; D012168:Retinal Pigments; D017299:Rod Opsins; C095855:long-wavelength opsin; C012729:2-amino-4-phosphonobutyric acid; D013331:Strychnine