PARENT SESSION
PLATFORM SESSION 14: REPRODUCTIVE TOXICOLOGY AND ENDOCRINE DISRUPTION
Chair: Hoyer, Patricia¹, ¹
Co-chair: Benedict, Jamie¹, ¹
Dover A-C
2:00 PM-4:00 PM

(255) SHORT-TERM METHOXYACETIC ACID EFFECTS ON ANDROGEN RECEPTOR AND ANDROGEN-BINDING PROTEIN EXPRESSION IN TESTIS.

Suarez-Quian, Carlos¹, Tirado, Oscar², Martinez, Elisabeth³, Rodriguez, Olga³, Danielsen, Mark³, Selva, David², Reventos, Jaume², Munell, Francina², ¹ Dept Cell Biology, Washington, DC² Unit Recer Biomed, Barcelona, ES³ Dept Biochemical & Molecular Biology, Washington, DC

ABSTRACT- Evidence suggests that spermatogenesis entails the balance of pro-survival and pro-apoptotic factors likely produced both by germ cells and Sertoli cells. MAA is known to cause significant pachytene spermatocyte (PS) apoptosis at specific stages of the cycle of the seminiferous epithelium, although its mechanism of action is not known. Herein, we test the hypothesis that even though MAA produces significant PS apoptosis, that MAA also exerts a profound effect on vital Sertoli cell parameters (AR and ABP) responsible for maintaining normal spermatogenesis. AR immunohistochemistry in post MAA treated rats revealed that the staining was significantly altered from its control levels; robust Sertoli cell staining became coincident with stages in which MAA exerted its maximal apoptotic effects on PS, but waned in non affected stages. Next, AR and ABP mRNA expression levels were examined as a function of the cycle using seminiferous tubules harvested by Laser Capture Microdissection (LCM), and again MAA exhibited dramatic effects on Sertoli cell activity: both AR and ABP mRNA were significantly altered in a stage-specific fashion. Using mouse Sertoli cell lines, TM4 and MSC-1, positive for either AR or ABP, respectively, we demonstrate a direct effect of MAA on ABP protein and mRNA expression in the MSC-1 cell, but did not detect any effect on AR protein or mRNA expression. Finally, using mouse fibroblasts that express endogenous AR and were stably transfected with two AR promoter/ reporter systems, MMTV-CAT and probasin-luciferase, respectively, we examined the ability of MAA to potentiate DHT activation of AR. Results demonstrate that although MAA did not activate AR directly, it did exhibit the ability to potentiate DHT activation of AR two to four fold. These results are consistent with the interpretation that signals eliciting germ cell apoptosis are likely to be complex and probably entail both specific effects on germ cells themselves, as well as on Sertoli cells. Whether MAA elicits a pro-apoptotic signal from Sertoli cells, or diminishes a pro-survival signal required by germ cells, downstream to altering AR and ABP expression, in a stage-specific fashion, however, remains to be determined.

KEY WORDS: spermatogenesis, apoptosis, testis