INHIBITORY EFFECT OF GABA ON FIRING ACTIVITY OF ROSTRAL VENTROLATERAL MEDULLARY NEURONS OF RAT IN VITRO

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Author:
CHU XIANG-PING()
LI PENG()
XU NING-SHAN()
Journal Title:
ACTA PHYSIOLOGICA SINICA
Issue:
Volume 50, Issue 05, 1998
DOI:
Key Word:
γ-aminobutyric acid;γ-aminobutyric acid receptors;urnit discharges;rostral ventrolateral medulla;brain slices of medulla

Abstract: Extracellular single-unit discharges were obtained from 106 spontaneously active neurons in the region of the rostral ventrolateral medulla (RVLM) by glass microelectrode from 73 brain slices of Sprague-Dawley rats. Exogenous γ-aminobutyric acid (GABA, 0.1 ~ 3.0 mmol/L) inhibited the electrical activity of 84 out of 106 RVLM neurons dose-dependently. The inhibitory effect of GABA could be blocked by GABAA with BMI or PTX alone, the firing rates of most of the RVLM neurons were significantly increased. In 41 neurons responding to GABA, baclofen (0.1 ~ 3.0 μmol/L), a GABAB receptor selective agonist, inhibited the discharges of 33 of the neurons dose-dependently. GABAB receptor antagonist CGP35348 ( n = 13) blocked the inhibition due to baclofen ( n = 21). After perfused with CGP35348 alone, the firing rates of most of the RVLM neurons were significantly increased. Taken together, the inhibition of GABA on RVLM neurons is mediated through either GABAA or GABAB receptors and some intrinsic GABA neurons exert tonic inhibition activity.

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