Testicular TGF-BETA1 System Expression and its Participation in Hypertrophy and Hyperplasia of Leydig Cells

GONZALEZ C; GONZALEZ B; RULLI S; FRANÇA LR; DOS SANTOS ML; MATTOS JARDIM COSTA G; HUHTANIEMI I; CALANDRA RS; GONZALEZ-CALVAR, SI

Praga, Republica Checa

Congreso; 12th European Congress of Endocrinology; 2010

Transforming growth factor b1 has a critical role in the regulation of testicular function. Transgenic male mice over expressing aƒn and b subunits of hCG (hCG+) are infertile and testicular steroidogenesis is enhanced showing high levels of circulating testosterone (T) and progesterone (P4). The chronic hCG hyperstimulation leads to Leydig cell (LC) hypertrophy/hyperplasia in prepubertal mice. Aims: To analize: 1) the expression of the TGF-b1 system in LC from WT and hCG+ mice of 21-days old by immunohistochemistry and by RT-PCR; 2) the ¡§in vitro¡¨ effect of hCG, P4 and T on the TGF-b1 system in purified LC from WT mice by RT-PCR; 3) the ¡§in vitro¡¨ effect of TGF-b1 on proliferation markers in purified LC from WT animals and 4) the ¡§in vivo¡¨ effect of TGF-b1 on testicular morphometry in WT mice. TGF-b1, ALK-5 and ALK-1 were immunolocalized in WT and hCG+ LC. The expression of TGF-b1 and endoglin (EDG) was significantly higher in hCG+ LC respect to control (p<0.05). hCG (10 IU/ml) stimulated the expression of TGF-b1 while P4 (10-6 M) increased the gene expression of EDG, and this effect was blocked by RU486 (antiprogestin) (p<0.05). T (10-6 M) failed to modify TGF-b1 system expression. The action of TGF-b1 (1ng/ml) in the presence of P4 caused: a) the phosporylation of Smad1/5 detected by Western blot, b) an increase in PCNA expression levels detected by immunocytochemestry and c) a decrease in the Bax/Bcl2 ratio analyzed by RT-PCR (p <0.05). Morphometric studies revealed that the intratesticular injection of TGF-b1 and P4 (sc) augmented the LC volume (V) due to an increase in the cytoplasmic V (control 341.49¡Ó43.86 vs TGF-b1+P4 511.16¡Ó30.83, p<0.05) and a decrease of the nuclear V (control 144.28¡Ó17.74 vs TGF-b1+P4 125.02¡Ó4.89, p <0.05). These results prompt us to speculate that the TGF-b1-EDG-ALK-1-Smad1/5 signalling pathway could be involved in the LC hypertrophy/hyperplasia.