Excitatory GABA responses in embryonic and neonatal cortical slices demonstrated by gramicidin perforated-patch recordings and calcium imaging. Owens, D F, Boyce, L H, Davis, M B, & Kriegstein, A R J Neurosci, 16(20):6414–6423, October, 1996.
abstract   bibtex   
Gramicidin perforated-patch-clamp recordings in brain slices were used to obtain an accurate assessment of the developmental change in the GABAA receptor reversal potential (EGABAA) in embryonic and early postnatal rat neocortical cells including neuroepithelial precursor cells, cortical plate neurons, and postnatal neocortical neurons. Our results demonstrate that there is a progressive negative shift in EGABAA with the most positive values found in the youngest cortical precursor cells. At the early stages of neocortical development, EGABAA is determined by the chloride (Cl-) gradient, and the internal chloride concentration ([Cl-]i) decreases with development. EGABAA is positive to the resting potential, indicating that GABA serves to depolarize developing neocortical cells. Consistent with this conclusion, GABAA receptor activation with muscimol was found-to increase the internal calcium concentration ([Ca2+]i) in both embryonic and early postnatal neocortical cells through the activation of voltage-gated calcium channels (VGCCs). Postnatal cells exhibit spontaneous postsynaptic synaptic currents, which are eliminated by bicuculline methiodide (BMI) but not glutamate receptor antagonists and reverse at the Cl- equilibrium potential. Likewise, brief spontaneous increases in [Ca2+]i, sensitive to BMI and TTX, are observed at the same ages, suggesting that endogenous synaptic GABAA receptor activation can depolarize cells and activate VGCCs. These results suggest that GABAA receptor-mediated depolarization may influence early neocortical developmental events, including neurogenesis and synaptogenesis, through the activation of Ca(2+)-dependent signal transduction pathways.
@ARTICLE{Owens1996-gh,
  title    = "Excitatory {GABA} responses in embryonic and neonatal cortical
              slices demonstrated by gramicidin perforated-patch recordings and
              calcium imaging",
  author   = "Owens, D F and Boyce, L H and Davis, M B and Kriegstein, A R",
  abstract = "Gramicidin perforated-patch-clamp recordings in brain slices were
              used to obtain an accurate assessment of the developmental change
              in the GABAA receptor reversal potential (EGABAA) in embryonic
              and early postnatal rat neocortical cells including
              neuroepithelial precursor cells, cortical plate neurons, and
              postnatal neocortical neurons. Our results demonstrate that there
              is a progressive negative shift in EGABAA with the most positive
              values found in the youngest cortical precursor cells. At the
              early stages of neocortical development, EGABAA is determined by
              the chloride (Cl-) gradient, and the internal chloride
              concentration ([Cl-]i) decreases with development. EGABAA is
              positive to the resting potential, indicating that GABA serves to
              depolarize developing neocortical cells. Consistent with this
              conclusion, GABAA receptor activation with muscimol was found-to
              increase the internal calcium concentration ([Ca2+]i) in both
              embryonic and early postnatal neocortical cells through the
              activation of voltage-gated calcium channels (VGCCs). Postnatal
              cells exhibit spontaneous postsynaptic synaptic currents, which
              are eliminated by bicuculline methiodide (BMI) but not glutamate
              receptor antagonists and reverse at the Cl- equilibrium
              potential. Likewise, brief spontaneous increases in [Ca2+]i,
              sensitive to BMI and TTX, are observed at the same ages,
              suggesting that endogenous synaptic GABAA receptor activation can
              depolarize cells and activate VGCCs. These results suggest that
              GABAA receptor-mediated depolarization may influence early
              neocortical developmental events, including neurogenesis and
              synaptogenesis, through the activation of Ca(2+)-dependent signal
              transduction pathways.",
  journal  = "J Neurosci",
  volume   =  16,
  number   =  20,
  pages    = "6414--6423",
  month    =  oct,
  year     =  1996,
  language = "en"
}

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