Distribution and expression of angiotensin II receptor type 1and type 2 in fetal tissues

Objective: To observe the expressions of AT 1 and AT 2 receptors in different tissues of human fetuses. Methods: The expressional levels of AT 1 and AT 2 receptors were determined in human fetuses by immunohistochemical staining and real-time PCR. Results: By immunohistochemistry, the AT 1 receptor protein was mainly expressed in muscle fibers of heart, fetal zone of adrenal gland, proximal convoluted tubule of kidney, cylindrical epithelia of tracheal glands, stratum spinosm, epithelia of sweat glands and hair follicular of skin, smooth muscle fibers of umbilical artery, smooth muscle of pneumonic arteriole, trophoblastic cells of placenta, hepatocytes, etc. While the AT 2 receptor protein was mainly expressed in muscle fibers of heart, fetal zone of adrenal gland, proximal convoluted tubule of kidney, cylindrical epithelium and tracheal glands of trachea, stratum spinosm, smooth muscle fiber of umbilical artery, hepatocytes, etc. By Real-time PCR assay, AT 1 receptor expressed from higher to lower levels in stomach, umbilical cord, lung, trachea, liver, placenta, kidney, heart and adrenal gland, respectively. While from higher to lower levels, AT 2 receptor expressed in umbilical cord, stomach, lung, placenta, heart, kidney, trachea, liver and adrenal gland, respectively. Conclusion: AT 1 and AT 2 receptors were selectively expressed in variety of fetal tissues. AT 1 receptor was mainly expressed in the stomach, umbilical cord, lung, trachea, liver and placenta, while AT 2 receptor was mainly expressed in the umbilical cord, stomach, lung, placenta, heart and kidney. The expression level of AT 2 receptor was higher than that of AT 1 in umbilical cord, heart, placenta, lung, kidney and stomach, which suggested that AT 2 receptor plays a role in fetal development and organ maturation.