These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Barbiturate activation and modulation of GABA(A) receptors in neocortex.
    Author: Mathers DA, Wan X, Puil E.
    Journal: Neuropharmacology; 2007 Mar; 52(4):1160-8. PubMed ID: 17289092.
    Abstract:
    We determined if anesthetic and anti-epileptic barbiturates inhibit neurons by different mechanisms. Current- and voltage-clamp recordings were made from somatosensory neurons of neocortex and some thalamocortical neurons in coronal brain slices of rats. We compared effects of pentobarbital, amobarbital, and phenobarbital on inhibitory postsynaptic currents (IPSCs) mediated by gamma-aminobutyric acid (GABA), input conductance, and evoked action potential firing. In neocortex, pentobarbital (EC(50)=41 microM) and amobarbital (EC(50)=103 microM) increased the decay time constant of GABA(A)ergic IPSCs. At higher concentrations, pentobarbital and amobarbital shunted firing by increasing input conductance through agonism at GABA(A) receptors. At anti-epileptic concentrations, phenobarbital increased the IPSC decay time constant (EC(50)=144 microM), and shunted firing by agonism at GABA(A) receptors (EC(50)=133 microM). In thalamocortical neurons, similar concentrations of phenobarbital had negligible effects on GABA(A)ergic IPSCs, conductance, and firing. In contrast to their thalamic actions, barbiturates inhibit neocortical neurons mostly through GABA receptors. Neocortical enhancement of inhibition by pentobarbital and amobarbital, combined with actions on thalamocortical neurons, may contribute to redundant mechanisms of anesthesia. The ability of phenobarbital at anti-epileptic concentrations to inhibit neocortical firing by direct activation and modulation of GABA(A) receptors relates to its specialized therapeutic effects.
    [Abstract] [Full Text] [Related] [New Search]