Regulated expression of estrogen receptor alpha and beta mRNA in granule cells during development of the rat...

A semi-quantitative RT-PCR approach was used to characterize expression of the mRNA encoding estrogen receptors in developing cerebellar granule cells of the rat. Evidence is presented for expression of both ERalpha and ERbeta transcripts in granule cells throughout the first 15 postnatal days. While transcripts encoding both ERalpha and ERbeta were expressed in granule cells, the relative levels of expression varied significantly during the first two postnatal weeks of cerebellar development. The ERalpha mRNA was expressed at the lowest level on the first day following birth; whereas expression of ERbeta was highest on that day. On the fourth postnatal day the expression of ERalpha increased, while there was a significant decrease in ERbeta expression. Between postnatal day 4 and 15, the expression of the mRNA of each receptor varied in a similar fashion; expression decreased slightly between days 4 and 10 and then increased significantly on day 15. Alternative splicing of the ERbeta transcripts was also investigated and was likewise found to vary during granule cell development. Initially, the mRNA encoding the beta1 isoform was predominant, but by day 4, the beta2 isoform was the major isoform expressed. On postnatal days 7 and 10, there was not a significant difference between the level of beta1 and beta2 expressed. By day 15, beta1 was again the predominant ERbeta isoform accounting for nearly 90% of all ERbeta transcripts expressed.