Local renin-angiotensin system: especially in coagulating glands of mice

It is well known that the renin-angiotensin system (RAS) is involved in the control of blood pressure. Recently, all or part of the components concerning the RAS have been reported to be synthesized and secreted outside of classical organs or tissues, at sites including the brain, pituitary and pineal glands, eye, heart, adrenal gland, testes, ovary, placenta, and coagulating glands. The functions and roles of these local RAS are not well known. In the present review, the author explains the history of the RAS, the circulating RAS and the existence of local RAS in multiple organs and tissues, discussing especially the function of coagulating gland renin. Renin protein, the triggering enzyme of the RAS, is distributed generally in certain fixed cells of several organs and tissues, exemplified by the gonadotrops in the pituitary glands and Leydig cells in the testis. Renin mRNA and its expressing cells can also be detected from the above cells as a whole. In some tissues, angiotensinogen-containing cells do not, however, correspond to its mRNA-expressing cells and potent activator angiotensin II-containing cells, as, for example, in the brain. These cases are explained by constitutive pathways of angiotensinogen processing. Coagulating gland renin, which the author is investigating vigorously, is the most recently discovered local renin, and represents significant subject for investigations. It is suggested that coagulating gland renin may play an unique function for sexual organs by exocrine mechanism.