Glutamine synthetase and glutamate metabolism in the guinea pig cochlea

M. Eybalin, M. D. Norenberg, N. Renard

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Glutamate is thought to act as a neurotransmitter of the sensory hair cells of the organ of Corti. Glutamine synthetase could be involved in a type of glutamate-glutamine cycle in the cochlea which could clear glutamate off the synaptic cleft and replenish the hair cell glutamate neurotransmitter store. Using both light and electron microscopic immunocytochemistry to localize this enzyme in the guinea pig cochlea, we have observed immunoreactive satellite glial cells surrounding parvalbumin-immunoreactive primary auditory neurons in the spiral ganglion. Glutamine synthetase was also detected in Schwann cells of the osseous spiral lamina which form the myelin sheath of nerve fibers. On the contrary, no immunoreactivity could be observed in the cochlear nerve and in the organ of Corti, although this organ contains structures able to take up glutamate. Although they confirm earlier works involving glutamine synthetase in the conversion of L-[3H]glutamate taken up by glial cells, our results suggest that the cochlear glutamate-glutamine cycle is not primarily involved in the recycling and replenishment of hair cell neurotransmitter glutamate. Alternatively, it is proposed that glutamine synthetase functions to limit the perilymphatic glutamate concentrations.

Original languageEnglish (US)
Pages (from-to)93-101
Number of pages9
JournalHearing Research
Volume101
Issue number1-2
DOIs
StatePublished - Nov 1 1996

Keywords

  • Excitotoxicity
  • Glutamate-glutamine cycle
  • Immunocytochemistry
  • Ischemia
  • Neurotransmission
  • Noise trauma
  • Organ of Corti

ASJC Scopus subject areas

  • Sensory Systems

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