[Expression of glucocorticoid receptor gene during development of mouse embryos]

Glucocorticoid, one of the steroid hormones, has been known to play important roles on homeostasis and development. To obtain information about the effects of glucocorticoid on the mouse embryonic development, temporal and spatial expression patterns of the glucocorticoid receptor (GR) gene were examined by the Northern hybridization and in situ hybridization techniques. Transcripts of the GR gene were found on embryonic day (ED) 10 by the Northern analysis. The amount of GR mRNA increased drastically on ED12 and was thereafter maintained at similar levels. On the other hand, obvious signals of GR gene expression were never detected until ED12 by in situ hybridization. On ED14 and afterwards, many organs, i.e. the pituitary gland, tongue, thymus, lung, liver and pre-cartilage, showed a high GR expression. These tissues were previously reported to be the target organs of glucocorticoid. The abrupt increase of GR gene transcripts in the embryonic tissues corresponded with the beginning of their maturation or function. These result suggest that the timing of the GR gene transcription becoming high in the embryonic tissues coincides with the onset of their terminal differentiation and function.