Selective release of N-acetylaspartylglutamate from rat optic nerve terminals in vivo

G. Tsai, B. L. Stauch, J. J. Vornov, J. K. Deshpande, J. T. Coyle

Research output: Contribution to journalArticlepeer-review

77 Scopus citations


Glutamate (Glu) and aspartate (Asp) are considered to be the neurotransmitters of the optic pathway in submammalian species, but their roles in mammals is uncertain. Recently, N-acetylaspartylglutamate (NAAG) has been proposed as a neurotransmitter in mammalian optic pathway; however, the release of endogenous NAAG on stimulation of the optic pathway has not been demonstrated. Using an in vivo microdialysis technique, we now report that electrical stimulation of rat optic nerve markedly increased the extracellular concentration of NAAG but not Glu/Asp in superficial superior colliculus where retinal afferents terminate, whereas non-specific stimulation of neurotransmitter release by high potassium or veratridine increased both extracellular Glu/Asp and NAAG concentration in the perfusate. The release of NAAG was dependent on Ca2+ and the presence of optic terminals. We conclude that NAAG is a better candidate as a neurotransmitter of rat optic nerve terminals than Glu/Asp.

Original languageEnglish (US)
Pages (from-to)313-316
Number of pages4
JournalBrain research
Issue number1-2
StatePublished - Jun 4 1990


  • Aspartate
  • Glutamate
  • In vivo dialysis
  • N-Acetylaspartylglutamate
  • Neurotransmitter
  • Optic pathway
  • Release

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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