In vitro regulation of extracellular superoxide dismutase in sertoli cells

Rat Sertoli and germ cells express extracellular superoxide dismutase (SOD(EX)), however, the relative level of SOD(EX) expressed by these cells was not known. We report herein germ cells consisting largely of spermatogonia, spermatocytes, and round spermatids expressed only one-third SOD(EX) as that of Sertoli cells when examined by semi-quantitative RT-PCR. While cocultures of germ cells with Sertoli cells failed to induce any changes in SOD(EX) expression possibly due to the limited number of cells that can be supported by the in vitro culture system dissimilar to the in vivo condition, incubation of total germ cell-conditioned medium with Sertoli cells was able to significantly inhibit Sertoli cell SOD(EX) expression dose-dependently suggesting a germ cell-derived soluble factor(s) may regulate SOD(EX) in the testis. On the other hand, cytokines such as TGF-beta1, beta-NGF, or FGF and steroid hormones such as estradiol-17beta, progesterone, testosterone, and DHT were unable to effect the expression of Sertoli cell SOD(EX). However, FSH at 100 ng/dish was able to induce a significant increase in Sertoli cell SOD(EX) expression. While cytokines, the known mediators of the inflammatory response, were unable to affect Sertoli cell SOD(EX) expression, the induction of generalized inflammation in vivo was able to cause a 2- to 2.5-fold increase in testicular SOD(EX) expression concomitant with a transient increase in the liver but not in the brain. Taken collectively, these results demonstrate that while SOD(EX) is an important antioxidant enzyme protecting the testis from reactive oxygen species, the mechanism(s) regulating its expression may involve an array of molecules and is a complicated cellular event.