Differences in the expression of GABAA receptors between functionally innervated and non-innervated granule neurons in neonatal rat cerebellar cultures

Shinya Ueno, John Martin Zempel, Joe Henry Steinbach

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

We had earlier found that granule neurons in cultures of small explants of neonatal rat cerebellar cortex could be placed in two groups: cells in one group showed spontaneous synaptic activity and also had a large response to applications of 1 μM γ-aminobutyric acid (GABA) while cells in the other lacked spontaneous activity and also showed much lower sensitivity to GABA [25]. For convenience, the more responsive cells will be termed A-type neurons, while the less responsive cells will be termed B-type. We have undertaken a comparison of the responses mediated by activation of GABAA receptors for the two types of neurons. A-type neurons have a larger maximal response to GABA (about 10 times that for B-type neurons), suggesting that they express more functional GABAA receptors. The concentration of GABA producing half-maximal activation of A-type neurons is somewhat less (12 μM) than that for B-type neurons (41 μM), while the Hill coefficients are similar. Responses of both types of cell desensitize to prolonged applications of GABA. At a given concentration of GABA the responses of A-type neurons desensitize more rapidly than the responses of B-type neurons, indicating that the physiological properties of the receptors differ. Responses of A-type neurons are also potentiated to a significantly lesser extent by either chlordiazepoxide or alphaxalone than are the responses of B-type neurons, indicating that the pharmacological properties of the receptors differ. These data indicate that A-type and B-type granule neurons in our cultures express GABAA receptors which differ in number, physiological properties and pharmacological responsiveness. We have also confirmed the observation that almost all A-type neurons also show spontaneous synaptic currents, while almost no B-type neurons do.

Original languageEnglish
Pages (from-to)49-56
Number of pages8
JournalBrain Research
Volume714
Issue number1-2
DOIs
StatePublished - Apr 1 1996

Keywords

  • Cerebellar granule neuron
  • Development
  • GABA
  • Innervation
  • Neurotransmitter receptor subtype

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