Profiling gamma-aminobutyric acid (GABA(A)) receptor subunit mRNA expression in postnatal gonadotropin-releasing hormone (GnRH) neurons of the male mouse with single cell RT-PCR

The present investigation has examined which subunits of the GABAA receptor are expressed by gonadotropin-releasing hormone (GnRH) neurons in the juve nile and adult male mouse. Cells of defined morphology, located in the medi a] septum (MS) and rostral preoptic area (POA), were patch-clamped in the a cute brain slice preparation and their cell contents extracted. A reverse t ranscriptase polymerase chain reaction (RT-PCR) procedure using nested prim ers was used to establish individual GnRH mRNA-expressing cells which were then evaluated for eleven GABAA receptor (alpha1-5, beta1-3, gamma1-3) subu nit transcripts. Single and multiple GABAA receptor subunit mRNAs were dete cted in approximately 70% of all GnRH neurons. A range of different subunit mRNAs (alpha1, alpha2, alpha5, beta1, beta2, beta3, gamma2) were found in juvenile GnRH neurons, with the alpha1 gamma2 and alpha5 gamma2 combination s encountered most frequently within individual cells. The expression profi le in adult GnRH neurons was more extensive than that detected in juveniles with alpha1, alpha2, alpha3, alpha5, beta1, beta2, beta3, gamma1 and gamma 2 subunits all being detected. The major difference in subunit profile betw een GnRH neurons located in the MS and POA involved the beta subunits. The principal postnatal developmental change was one of increasing overall subu nit heterogeneity in maturing POA GnRH neurons. The profile of GABAA recept or subunit mRNAs detected in male GnRH neurons was quite different to that reported by us for female GnRH neurons in the mouse using the same RT-PCR a pproach. Together, these findings indicate that postnatal GnRH neurons are likely to express a range of GABAA receptor subunit mRNAs in a sexually dim orphic and developmentally-regulated manner. Copyright (C) 2001 S. Karger A G, Basel.