mRNA expression of GABA-gated Cl--channels in rat antepituitary was evaluated by using an reverse-transcribed (RT)-polymerase chain reaction (RT-PCR) method with degenerate and specific oligonucleotides. The main result of our findings is that the antepituitary expresses mRNAs encoding alpha 4 and rho 1 GABA receptor subunits. These two subunits are believed to be, respectively, constituents of benzodiazepine-insensitive GABA(A) and GABA(C) receptors in the CNS. This molecular analysis is consistent with the pharmacological diversity of GABA receptors in pituitary cells.