Neurotransmission in the central nervous system is mediated in large part by a group of amino acids that act via specific receptors. Ethanol, at concentrations less than 100 mm, has been shown to affect the functional properties of two amino acid receptor systems (see Project No. AA00479-07): the GABAA receptor-activated chloride current in mouse hippocampal neurons is potentiated by ethanol and the NMDA-type glutamate receptor-activated ion current in adult DRG neurons is inhibited by ethanol. It has been suggested that the neural and cognitive impairments associated with intoxication may be related, in part, to the effects of ethanol on specific receptor systems within the CNS. In order to better understand the molecular basis for ethanol modulation of ligand-gated ion channel function and to identify the sites within these receptor systems at which ethanol may act, we have established a system for the expression of cloned receptor-channel complexes in Xenopus oocytes injected with receptor-specific mRNA. Isolated of rat brain poly (A+) mRNA and injection into Xenopus oocytes resulted in the appearance of GABA-dependent inward currents. We are utilizing this system to study the functional properties of (1) receptors transcribed from mRNAs encoding a number of GABA receptor subtypes and (2) GABAA receptors translated from brain mRNA of long sleep and short sleep mice; and evaluating the effects of ethanol on these ion channel receptor systems.
