0013-7227/91/1286-2805$03.00/0 Endocrinology Copyright © 1991 by The Endocrine Society
Vol. 128, No. 6 Printed in U.S.A.
a2-Macroglobulin Is Not an Acute-Phase Protein in the Rat Testis* MICHAEL S. STAHLER, PETER SCHLEGEL, C. WAYNE BARDIN, BRUNO SILVESTRINI, AND C. YAN CHENGf The Population Council (M.S.S., P.S., C. W.B., C. Y.C.), New York, New York 10021; Institute of Pharmacology and Pharmacognosy (B.S.), University of Rome, 00101 Rome, Italy; and The Rockefeller University (C. Y.C.), New York, New York 10021
ABSTRACT. Earlier studies from this laboratory have shown that Sertoli cells actively synthesize and secrete a nonspecific protease inhibitor in vitro; N-terminal sequence analysis, subunit structural analysis, and other biological studies revealed that this protein is the homolog of serum a2-macroglobulin. We have now quantified the relative distribution of a2-macroglobulin in the reproductive compartments and their comparison with nonreproductive organs. In serum and all nonreproductive tissues examined, the concentration of a2-macroglobulin progressively decreased with advancing age. However, in both the testis and epididymis, the levels of this protein increased with the age of the animals. Serum a2-macroglobulin levels were consistently higher than those in any other tissues until 60 days when the concentrations of this protein were the highest in the epididymis. The distribution of a2-macroglobulin in various nonreproductive tissues from female rats was similar to that observed for male
S
ERTOLI cells create a unique physiological microenvironment for germ cell development behind the systemic circulation with the formation of a blood-testis barrier (1). The presence of this barrier prevents free passage of macromolecules from the serum into the tubular lumen and vice versa. Thus proteins found in the seminiferous tubular fluid are either actively transported there from the interstitium or synthesized and secreted into this compartment by testicular cells. It has been shown that the major secretory components of the seminiferous epithelium are Sertoli cells that secrete both testis-specific proteins, including androgen-binding protein (2-4), and testins (5); and serum proteins such as ceruloplasmin, transferrin, clusterin, «i-acid glycoprotein, insulin-like growth factor-I, inhibin (6, 7), and others [for review see (8)].
rats in that its levels tended to decrease with age. However, uterine levels of a2-macroglobulin increased progressively with advancing age, whereas ovarian levels of
Vol. 128, No. 6 Printed in U.S.A.
a2-Macroglobulin Is Not an Acute-Phase Protein in the Rat Testis* MICHAEL S. STAHLER, PETER SCHLEGEL, C. WAYNE BARDIN, BRUNO SILVESTRINI, AND C. YAN CHENGf The Population Council (M.S.S., P.S., C. W.B., C. Y.C.), New York, New York 10021; Institute of Pharmacology and Pharmacognosy (B.S.), University of Rome, 00101 Rome, Italy; and The Rockefeller University (C. Y.C.), New York, New York 10021
ABSTRACT. Earlier studies from this laboratory have shown that Sertoli cells actively synthesize and secrete a nonspecific protease inhibitor in vitro; N-terminal sequence analysis, subunit structural analysis, and other biological studies revealed that this protein is the homolog of serum a2-macroglobulin. We have now quantified the relative distribution of a2-macroglobulin in the reproductive compartments and their comparison with nonreproductive organs. In serum and all nonreproductive tissues examined, the concentration of a2-macroglobulin progressively decreased with advancing age. However, in both the testis and epididymis, the levels of this protein increased with the age of the animals. Serum a2-macroglobulin levels were consistently higher than those in any other tissues until 60 days when the concentrations of this protein were the highest in the epididymis. The distribution of a2-macroglobulin in various nonreproductive tissues from female rats was similar to that observed for male
S
ERTOLI cells create a unique physiological microenvironment for germ cell development behind the systemic circulation with the formation of a blood-testis barrier (1). The presence of this barrier prevents free passage of macromolecules from the serum into the tubular lumen and vice versa. Thus proteins found in the seminiferous tubular fluid are either actively transported there from the interstitium or synthesized and secreted into this compartment by testicular cells. It has been shown that the major secretory components of the seminiferous epithelium are Sertoli cells that secrete both testis-specific proteins, including androgen-binding protein (2-4), and testins (5); and serum proteins such as ceruloplasmin, transferrin, clusterin, «i-acid glycoprotein, insulin-like growth factor-I, inhibin (6, 7), and others [for review see (8)].
rats in that its levels tended to decrease with age. However, uterine levels of a2-macroglobulin increased progressively with advancing age, whereas ovarian levels of
