Biology of Reproduction, Vol 50, 1287-1296, Copyright © 1994 by Society for the Study of Reproduction

ARTICLES

Response of alpha 2-macroglobulin messenger ribonucleic acid expression to acute inflammation in the testis is different from the response in the liver and brain

AH Li, IH Zwain, C Pineau, N Cazzolla, L Saso, B Silvestrini, CW Bardin and CY Cheng
Population Council, New York, New York 10021.

Recent studies from this laboratory have shown that Sertoli cells derived from 20-day-old rats and cultured in vitro synthesize and secrete a nonspecific protease inhibitor that is structurally and immunologically similar to serum alpha 2-macroglobulin (alpha 2-MG). In contrast to its serum homologue, the testicular alpha 2-MG is not an acute-phase protein in the rat since its protein concentration in the rete-testis fluid does not increase in response to inflammation. In the present study we examined the expression of alpha 2-MG mRNA in the rat testis in comparison to that in the brain and liver following induced inflammation. alpha 2-MG mRNA in the testis did not respond to induced inflammation, whereas its protein concentration in serum and its mRNA level in the brain and liver increased significantly in 20-day-old inflamed rats. In 8-day-old rat testis, where the blood-testis barrier is not yet formed, alpha 2-MG mRNA expression also did not respond to induced inflammation. The mRNA expression of clusterin, another authentic Sertoli cell protein whose secretion appears to be closely related to cell-cell interactions in the seminiferous epithelium, was shown to be unaffected by induced inflammation in the testis, brain, and liver. In view of the unexpected differential expression of alpha 2- MG mRNA to induced inflammation in the testis and liver, we sought to examine whether Sertoli cell alpha 2-MG would respond to FSH and testosterone (T), the major regulators of testicular function. Interestingly, expression of alpha 2-MG and clusterin mRNA in the Sertoli cell was not regulated by FSH, T, or a combination of FSH and T. Since there is an intimate morphological relationship between Sertoli cells and germ cells, we next examined the effect of germ cell- conditioned medium (GCCM) on Sertoli cell alpha 2-MG and clusterin mRNA expression. It was noted that GCCM caused a dose-dependent stimulation of alpha 2-MG and inhibition of clusterin mRNA expression in Sertoli cells, respectively. Therefore, our studies have shown that the regulatory mechanism that modulates the expression of alpha 2-MG mRNA in the rat testis is different from its counterpart in the brain and liver.

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