Detection of estrogen receptor α and β messenger ribonucleic acids in adult gonadotropin-releasing hormone neurons

The behavior of the gonadotropin-releasing hormones (GnRH) neurons controlling fertility is dependent upon cyclic fluctuations in circulating concentrations of estrogen. However, the nature of estrogen action upon these cells has remained controversial due to their dispersed distribution within the brain, and evidence indicating that they do not express nuclear estrogen receptors (ERs) in vivo. We report here an acute brain slice preparation that enables individual living GnRH neurons to be identified within the mouse brain and show, using single cell multiplex RT-PCR, that the greater than 50% of GnRH neurons in adult and prepubertal females contain ER alpha messenger RNA. Approximately 10% of GnRH neurons contained ER beta transcripts that were, always coexistent with ER alpha. Single cell RT-PCR analysis of nonGnRH cells located in the medial preoptic area revealed a similar coexpression pattern of ER alpha and ER beta transcripts. In contrast, single striatal cells were not found to contain ER beta despite ER alpha being present in approximately 25% of cells. The analysis of single GnRH neurons in cycling female mice revealed that the detection of ER alpha and ER beta transcripts was lowest on proestrus (ER alpha, 18% of all GnRH neurons; ER beta, 0%) compared with diestrus (44% and 6%) and estrus (75% and 19%, respectively). Using a novel approach that enables single cell RT-PCR analysis of GnRH neurons, we present here evidence for the cyclic expression of ER alpha and ER beta messenger RNAs within prepubertal and adult female GnRH neurons.