GABA (gamma amino butyric acid) is the most abundant and important inhibitory transmitter in mammalian CNS. It counterbalances the glutamate mediated neuronal excitation. Abnormalities of the interaction of these two transmitters might change the mechanisms of neuronal group selection that according to Edelman [Neural Darwinism. Basic Books, New York] play a role in mediating several brain functions including cognition processes. Indeed imbalances in GABAergic functions were shown to elicit psychoses. They can be obtained by administration of drugs that affect synthesis, metabolism and uptake of GABA and thereby cause a persistent stimulation of GABA(A) receptors or perhaps by genetic abnormalities in DNA transcription, pre-mRNA splicing, mRNA translation and posttranslation modifications of GABA(A) receptor subunits. The complexities in the regulation of GABA(A) receptor subunit structure, synthesis, assembly and the brain location of specific mRNA encoding for these subunits are investigated with in situ mRMA hybridization specific for subunits of GABA(A) receptors. The role of the variability resulting from the complexities in the regulation of GABA(A) receptor allosteric modulation by drugs and putative endogenous allosteric modulators of GABA action at GABA(A) receptors is discussed. This discussion gives relevance to the possibility that genetic abnormalities in the expression of proteins participating in GABAergic function are to be considered as a possible target of the genetic defects operative in psychoses. In line with this thinking, it is suggested that partial allosteric modulators (partial agonists) of GABA(A) receptors and the phosphothioate or methylphosphonate analogs antisense to specific mRNA oligonucleotides that mediate the expression of genetic information concerning GABA(A) and glutamate receptor subunits may become valuable tools in psychiatric research. Perhaps in the future these studies might generate new ideas useful in the therapy of genetically determined psychiatric illness.
