Effects of estrogen on estrogen receptor expression in the bursal cells of chick embryos and steroidogenic enzymes gene expression in the bursa: Relevance of estrogen receptor and estrogen synthesis in the bursa of chick embryos

Abstract

Estrogen has been reported to act on B cell genesis in the bursa of Fabricius of chick embryos. In this study, we attempted to demonstrate the hypothesis that B cell genesis is controlled by estrogen receptor (ER) in the bursal cells and steroidogenic enzymes synthesized in the bursa. We previously reported the presence of estrogen receptor α (ERα) in the bursa during the late stage of embryogenesis and an increase in the expression of ERα messenger RNA (mRNA) between the 13th day and 16th day. The number of ER-positive cells was maximal on the 16th day. In the present study, ER-positive cells in the bursa during the late stage of embryogenesis increased 4 h after β-estradiol treatment on the 14th to 18th day. The concentration of β-estradiol in the embryonic bursa increased. These results suggest that this stage of embryogenesis is critical in B cell development in the bursa in connection with the effect of estrogen treatment. Our findings also showed that the mRNA expression of five steroidogenic enzymes occurred in the bursa of chick embryos. These results suggest that estrogen is synthesized in the embryonic bursa and estrogen acts on the bursal cells in a paracrine fashion.

Changes in estrogen receptor expression in the chick thymus during late embryonic development

“…Steroid hormone synthesis may be occurring in the BF during the late stage of embryogenesis, because mRNA expressions of steroidogenic enzymes have been demonstrated during this stage (Shin et al . ). Estrogen synthesis may occur in the thymus of chick embryos.…”

“…However, the development of the avian embryo progresses within the egg shell, which is completely independent from the maternal tissue. Steroid hormone synthesis may be occurring in the BF during the late stage of embryogenesis, because mRNA expressions of steroidogenic enzymes have been demonstrated during this stage (Shin et al 2012). In the chick embryo, estradiol is secreted from the testis and ovary (Woods & Erton 1978).…”

“…Our results indicate that the ER expression level in the thymus is independently controlled from the plasma level of estrogen. Steroid hormone synthesis may be occurring in the BF during the late stage of embryogenesis, because mRNA expressions of steroidogenic enzymes have been demonstrated during this stage (Shin et al 2012). Estrogen synthesis may occur in the thymus of chick embryos.…”

Factors Modulating the Avian Immune System

“…Receptors for estrogen are expressed in lymphocytes from the thymus, bursa, and spleen of chickens [49]. The bursa expresses the enzymes necessary to synthesize estrogen, and it is likely that estrogen acts on developing B lymphocytes in a paracrine fashion [50]. The bursa expresses the enzymes necessary to synthesize estrogen, and it is likely that estrogen acts on developing B lymphocytes in a paracrine fashion [50].…”