Vesicular glutamate transporter 1 is required for photoreceptor synaptic signaling but not for intrinsic visual functions

Juliette Johnson, Robert T. Fremeau, Jacque L. Duncan, René C. Rentería, Haidong Yang, Zhaolin Hua, Xiaorong Liu, Matthew M. LaVail, Robert H. Edwards, David R. Copenhagen

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


Glutamatergic neurotransmission requires vesicular glutamate transporters (VGLUTs) to sequester glutamate into synaptic vesicles. Generally, VGLUT1 and VGLUT2 isoforms show complementary expression in the CNS and retina. However, little is known about whether isoform-specific expression serves distinct pathways and physiological functions. Here, by examining visual functions in VGLUT1-null mice, we demonstrate that visual signaling from photoreceptors to retinal output neurons requires VGLUT1. However, photoentrainment and pupillary light responses are preserved. We provide evidence that melanopsin-containing, intrinsically photosensitive retinal ganglion cells (RGCs), signaling via VGLUT2 pathways, support these non-image-forming functions. We conclude that VGLUT1 is essential for transmitting visual signals from photoreceptors to second- and third-order neurons, but VGLUT1 is not necessary for intrinsic visual functions. Furthermore, melanopsin and VGLUT2 expression in a subset of RGC simmediately after birth strongly supports the idea that intrinsic vision can function well before rod- and cone-mediated signaling has matured.

Original languageEnglish (US)
Pages (from-to)7245-7255
Number of pages11
JournalJournal of Neuroscience
Issue number27
StatePublished - Jul 4 2007
Externally publishedYes


  • ERG
  • Immunohistochemistry
  • Multielectrode array
  • Photoentrainment
  • Pupillary light response
  • VEP

ASJC Scopus subject areas

  • Neuroscience(all)


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