Cell-specific distributions of estrogen receptor alpha in anterior pituitary glands from adult cockerels as revealed by immunohistochemistry

Estrogens and androgens play important roles in regulating the hormone-secreting functions of the pituitary gland by binding to their corresponding receptors. However, the expression of estrogen receptors (ERs) and the androgen receptor (AR) and the cell types containing ERs and AR in the anterior pituitary gland of adult chickens have not been well-studied. In this study, the distribution of ERα, AR and their corresponding cell types in the anterior pituitary gland of adult cockerels was detected by immunohistochemistry. The results showed that ERα was expressed in 68.63% of luteinizing hormone (LH) producing cells but was not found in thyrotropes, lactotropes, somatotropes, corticotropes and folliculostellate (FS) cells. Pituitary hormone and AR double labeling results showed that about 37% of LH cells and 50% of thyroid-stimulating hormone (TSH) producing cells expressed AR, respectively. In contrast, less than 1% of the somatotropes had an AR positive signal and AR signals were not detected in lactotropes, corticotropes or FS cells. In addition, there were only a few AR and ERα dual-labeled cells observed. These novel results provide evidence for a cell-specific distribution of ERα and AR in the anterior pituitary from adult cockerels by immunohistochemistry. The different distributions of ERα and AR in the LH cells suggest that the feedback-regulating mechanisms of estrogen and androgen on the pituitary hormones secretion are different. The functions and related mechanisms still need to be elucidated further. Keywords ERα * AR * Pituitary hormones * Double-labeling immunohistochemistry * Cockerel