RESPONSE OF ALPHA(2)-MACROGLOBULIN MESSENGER-RIBONUCLEIC-ACID EXPRESSION TO ACUTE-INFLAMMATION IN THE TESTIS IS DIFFERENT FROM THE RESPONSEIN THE LIVER AND BRAIN

Recent studies from this laboratory have shown that Sertoli cells deri ved from 20-day-old rats and cultured in vitro synthesize and secrete a nonspecific protease inhibitor that is structurally and immunologica lly similar to serum alpha(2)-macroglobulin (alpha(2)-MG). In contrast to its serum homologue, the testicular alpha(2)-MG is not an acute-ph ase protein in the rat since its protein concentration in the rete-tes tis fluid does not increase in response to inflammation. In the presen t study we examined the expression of alpha(2)-MG mRNA in the rat test is in comparison to that in the brain and liver following induced infl ammation. alpha(2)-MG mRNA in the testis did not respond to induced in flammation, whereas its protein concentration in serum and its mRNA le vel in the brain and liver increased significantly in 20-day-old infla med rats. In 8-day-old rat testis, where the blood-testis barrier is n ot yet formed, alpha(2)-MG mRNA expression also did not respond to ind uced 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 b e 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, expr ession of alpha(2)-MG and clusterin mRNA in the Sertoli cell was not r egulated by FSH, T, or a combination of FSH and T. Since there is an i ntimate morphological relationship between Sertoli cells and germ cell s, we next examined the effect of germ cell-conditioned medium (GCCM) on Sertoli cell alpha(2)-MG and clusterin mRNA expression. It was note d that GCCM caused a dose-dependent stimulation of alpha(2)-MG and inh ibition of clusterin mRNA expression in sertoli cells, respectively. T herefore, our studies have shown that the regulatory mechanism that mo dulates the expression of alpha(2)-MG mRNA in the rat testis is differ ent from its counterpart in the brain and liver.