Regulation of androgen receptor mRNA expression in primary culture of Harderian gland cells: cross-talk between steroid hormones.

The androgen receptor (AR) must be considered a transcription factor belonging to the steroid-thyroid hormones receptor superfamily. Previous results gained from the Harderian gland, a tubulo-alveolar gland located in the orbital cavity of the golden hamster, indicate that Harderian gland cells express mRNAs encoding for androgen, glucocorticoid, thyroid hormone (T(3)), and estrogen receptors, respectively. Since in other systems, these receptors have been related to the expression of the androgen receptor, we have studied the regulation of AR expression in primary cultures of the male hamster Harderian gland. Our in vitro experiments show that androgen, and thyroid hormones increase the expression of AR. Retinoic acids also show a positive effect on AR expression, while exposure to glucocorticoid or estrogen blocks AR expression. Since these steroids differently modulate AR expression, our results must be considered in the context of multi-hormonal control of gene expression that could act through cross-talk between members of the steroid-thyroid hormones.